New Coil-Over Conversion Suspension

[DionR]

When we ran through the suspension analysis we used stock ride heights..

Ah. You've illuminated a blind spot for me. I've always been so focused on comparing improved to improved, never even crossed my mind to compare stock to improved.

Not a knock at all. I just didn't think of the possibility that was what you meant. Makes more sense now.

Not going to argue that your statement is wrong. And now I wonder if that was what the other companies meant as well. I'm going to have to chew on that some.

 

[RustyRatRod]

Ah. You've illuminated a blind spot for me. I've always been so focused on comparing improved to improved, never even crossed my mind to compare stock to improved.

Not a knock at all. I just didn't think of the possibility that was what you meant. Makes more sense now.

Not going to argue that your statement is wrong. And now I wonder if that was what the other companies meant as well. I'm going to have to chew on that some.

Since the stock suspension can be lowered or raised, can it not be tested at whatever rid height of an aftermarket suspension is set for? Like I said, I'm not knocking anything. I know there are some advantages to be had. Room for headers, room for much larger tires and wheels (if you like that kinda thing), but torsion bars are adjustable like coil overs. And leaf springs have been on some of the fastest and quickest cars out there. I always tell folks wondering about aftermarket suspensions that the stock type suspension has been very successful in just about every form of motor sports there is. In fact, I think that's true of the big three.

 

[swisswill]

Since the argument is often made that OEM geometry is just as good, potentially better, than many of these COC’s, but not perfect/ideal, what is the limiting factor? Spindle? And what needs to be changed? If spindle, sounds like DionR and I share a similar idea of a fabricated upright with a Mustang rear wheel hub assembly. I’ve talked to Michigan Metalworks about building something and they’re all for it, they build them all the time for low riding trucks. Build into it a bigger brake option like a Mustang four piston caliper so everything is available off the shelf at your parts store of choice. So if it’s spindle, maybe it’s time to figure that out and get something done? My Suspension Analyzer is long gone for the similar reason someone else mentioned or i’d plot it myself and play with different ride heights and moving the ball joints around. And couldn’t this same idea be used for a front steer rack conversion with a custom steering arm? Other things would have to change in the LCA/ball joint but that’s probably solveable too?

Suspension Analyzer is only $300. So what if 10-20 of us chipped in $30-$50 a piece (cover software and a bit for time), someone downloads and plots it out, gives feedback to the group, and we all know. Then we all finally have all the information needed to make the best decision given intended use, and we know exactly what parts are needed to accomplish the task. And we also have the opportunity to unpack COC’s and know what they bring to the table for geometry. Seems reasonable to me, I’ll throw money in. Heck, if someone near me has a rack, we can use my car to plot it, then jump on a zoom with some of the great suspension minds here and go through it together.

 

[racerjoe]

Since the argument is often made that OEM geometry is just as good, potentially better, than many of these COC’s, but not perfect/ideal, what is the limiting factor? Spindle? And what needs to be changed? If spindle, sounds like DionR and I share a similar idea of a fabricated upright with a Mustang rear wheel hub assembly. I’ve talked to Michigan Metalworks about building something and they’re all for it, they build them all the time for low riding trucks. Build into it a bigger brake option like a Mustang four piston caliper so everything is available off the shelf at your parts store of choice. So if it’s spindle, maybe it’s time to figure that out and get something done? My Suspension Analyzer is long gone for the similar reason someone else mentioned or i’d plot it myself and play with different ride heights and moving the ball joints around. And couldn’t this same idea be used for a front steer rack conversion with a custom steering arm? Other things would have to change in the LCA/ball joint but that’s probably solveable too?

Suspension Analyzer is only $300. So what if 10-20 of us chipped in $30-$50 a piece (cover software and a bit for time), someone downloads and plots it out, gives feedback to the group, and we all know. Then we all finally have all the information needed to make the best decision given intended use, and we know exactly what parts are needed to accomplish the task. And we also have the opportunity to unpack COC’s and know what they bring to the table for geometry. Seems reasonable to me, I’ll throw money in. Heck, if someone near me has a rack, we can use my car to plot it, then jump on a zoom with some of the great suspension minds here and go through it together.

I'm sure I'll get railed for this, but in my opinion, the spindle is the limiting factor on both torsion and CoC. This is the reason we go for the FMJ spindle and some even use taller ball joints with those. Not to mention the limitation on brake options and you are still stuck with traditional tapered wheel bearings. While the brake and bearing situation is good enough, why not have an upgrade there when everything else on the suspension is aftermarket or "improved". On the CoC, I doubt there's a one size fits all there. I chose to go with the CPP M2 spindle that accepts the corvette hub and corvette brake. This opens up tons of options for brakes and I get the benefit of the robust hub and an option to have a wheel speed sensor. The problem is, CPP didn't offer a tall version of the spindle. To me, this shows what their target audience is, hot rodders. The Wilwood M2 spindle is slightly taller than the spindle I have, but the only option is tapered bearings. I'm not familiar enough with that spindle to comment on brake options.
Unfortunately, I don't think there's a big enough business case for anyone to invest the time and money into making a custom spindle for either setup. We need to come to grip with reality that classic mopars are either at the car show or drag strip. Those guys aren't worried about camber gain and roll center. If someone is dedicated enough to the brand to drop big money on building a "racecar" they will likely replace the entire front clip or chassis with something like that Speedtech piece. At some point, there's no reason to re-invent the wheel.
The benefit of the CoC kits, is we aren't limited with the lower ball joint like the stock stuff. As I mentioned previously, I'm sure a GM spindle would work, especially on my HDK since I can adjust everything, I just don't want to spend the money to try it.

 

[Super-Cuda]

Uhh....

View attachment 1716387081

How can anyone build a suspension and steering setup then do something as short sighted as this? That is as bad as the RMS design. Single shear, cantilevered with a Heim joint will not outlast a dropped arm like the stock lower ball joint design had. THIS to reduce bump steer?
It probably rides and steers great going on and off a trailer and up to 15 mph on smooth roads.

Not what I'm experiencing with the RMS suspension I purchased.

I've got just under 8000 miles on mine and it is perfect. I never built it to be a trailer queen and it gets driven hard.

I've had the car up to 130mph and its as solid as a rock .

Anyone who has been my part of the country knows our roads are not great and I've hit a few bad potholes with no damage whatsoever.

After reading comments in the past, I've learned that the factory components can be made to work very well...if you have the knowledge and experience plus the parts availability to do so.

For the rest of us, a complete aftermarket suspension system like those offered by RMS and HDK offer a great solution.

 

[Super-Cuda]

Ohhhh....we understand perfectly.

View attachment 1716387527

We certainly do!!!

 

[gzig5]

Ahh this turned into a can of worms. As others have said these conversions aren’t for everyone so I’m not going to get on here to debate anyone because I’m not a cupcake and will never make everyone happy.. People will always find something to complain about. What I will say, is there are SEVERAL comments about this isn’t “improved” geometry it’s “corrected” but isn’t a correction an improvement? As Denny stated alot of the things guys are complaining about are dependent upon car setup. When we ran through the suspension analysis we used stock ride heights.. Can you make TB suspension work absolutely. I wanted to offer something quality, drivable and adjustable to what each individual driver wants, there isn’t a cookie cutter setup. A modernization of these classic cars that make them handle and drive like something new with the option to update to a modern engine package as well… No swapping k-frame just different engine mounts..

I did look at some GM spindles but didn’t want to get into the cost of what the corvette spindles were going to be..

Does the upright that the top of the shock/spring mount to, tie into the chassis?

 

[Chris Bolander]

Does the upright that the top of the shock/spring mount to, tie into the chassis?

There is an additional bracket not shown in these photos that tie the top of the shock tower to the stock tower location.

 

[swisswill]

I'm sure I'll get railed for this, but in my opinion, the spindle is the limiting factor on both torsion and CoC. This is the reason we go for the FMJ spindle and some even use taller ball joints with those. Not to mention the limitation on brake options and you are still stuck with traditional tapered wheel bearings. While the brake and bearing situation is good enough, why not have an upgrade there when everything else on the suspension is aftermarket or "improved". On the CoC, I doubt there's a one size fits all there. I chose to go with the CPP M2 spindle that accepts the corvette hub and corvette brake. This opens up tons of options for brakes and I get the benefit of the robust hub and an option to have a wheel speed sensor. The problem is, CPP didn't offer a tall version of the spindle. To me, this shows what their target audience is, hot rodders. The Wilwood M2 spindle is slightly taller than the spindle I have, but the only option is tapered bearings. I'm not familiar enough with that spindle to comment on brake options.
Unfortunately, I don't think there's a big enough business case for anyone to invest the time and money into making a custom spindle for either setup. We need to come to grip with reality that classic mopars are either at the car show or drag strip. Those guys aren't worried about camber gain and roll center. If someone is dedicated enough to the brand to drop big money on building a "racecar" they will likely replace the entire front clip or chassis with something like that Speedtech piece. At some point, there's no reason to re-invent the wheel.
The benefit of the CoC kits, is we aren't limited with the lower ball joint like the stock stuff. As I mentioned previously, I'm sure a GM spindle would work, especially on my HDK since I can adjust everything, I just don't want to spend the money to try it.

For the most part I agree. But if we knew for fact that an X inch taller spindle with X degrees extra caster changes the game for stock suspended vehicles, and a fabricated spindle is available that solves the problem while offering a Corvette/Mustang hub with better brake options, ABS possibilities, etc, there are some Mopar guys that will buy said piece for $1,000-$1,500. I would. I may get roasted for this because I don’t have the relationship capital in this community, but I doubt we’ll ever know because no one will do it. Enough people won’t chip in to have the research done and see if an ideal solution can be made; and it won’t be worth one individuals time and effort just for themselves. I’m willing to throw money in the pot with others to have the geometry plotted and see what solution can be had. Are others? I bet the answer is no. And that’s fine, but we need to not get wadded about brand X having all the good stuff.

I’ve already reached out to Michigan Metalworks about a custom spindle using a Mustang hub and four piston caliper. They’ll do it, so I can bring them an FMJ to match the pickups but fitting a replaceable hub and better caliper options. They’ll build it and I got a one-off. They’ve done one-off spindles for $1,500. My goal in it is part service/availability for my daily driver ‘76, as well as performance. Shoot, Chris Bolander could probably use a similar piece to improve his setup.

 

[gzig5]

For the most part I agree. But if we knew for fact that an X inch taller spindle with X degrees extra caster changes the game for stock suspended vehicles, and a fabricated spindle is available that solves the problem while offering a Corvette/Mustang hub with better brake options, ABS possibilities, etc, there are some Mopar guys that will buy said piece for $1,000-$1,500. I would. I may get roasted for this because I don’t have the relationship capital in this community, but I doubt we’ll ever know because no one will do it. Enough people won’t chip in to have the research done and see if an ideal solution can be made; and it won’t be worth one individuals time and effort just for themselves. I’m willing to throw money in the pot with others to have the geometry plotted and see what solution can be had. Are others? I bet the answer is no. And that’s fine, but we need to not get wadded about brand X having all the good stuff.

I’ve already reached out to Michigan Metalworks about a custom spindle using a Mustang hub and four piston caliper. They’ll do it, so I can bring them an FMJ to match the pickups but fitting a replaceable hub and better caliper options. They’ll build it and I got a one-off. They’ve done one-off spindles for $1,500. My goal in it is part service/availability for my daily driver ‘76, as well as performance. Shoot, Chris Bolander could probably use a similar piece to improve his setup.

The Hotchkiss Mopar upper A-arms are nearly $1000 a pair. Double adjustable shocks are $1200 a set. If a custom spindle cost that much and gives the benefits being discussed, I think it should be a slam dunk to add to a custom front suspension. None of this stuff is going to get any cheaper and I'd rather not half-*** it. At the same time, I don't have $12k to throw at it either. I'm looking into C-body spindles on my E-body because they are close to an inch taller.

 

[Super-Cuda]

The Hotchkiss Mopar upper A-arms are nearly $1000 a pair. Double adjustable shocks are $1200 a set. If a custom spindle cost that much and gives the benefits being discussed, I think it should be a slam dunk to add to a custom front suspension. None of this stuff is going to get any cheaper and I'd rather not half-*** it. At the same time, I don't have $12k to throw at it either. I'm looking into C-body spindles on my E-body because they are close to an inch taller.

Just reading this Gzig and please forgive my lack of knowledge here but if the C body spindles were sufficient to work on an E body, why would Chrysler make a duplicate part?

It would seem to me that there would be a fitment issue or, its not entirely safe to swap these critically important suspension parts without introducing safety issues.

Not critizing, just trying to learn something.

 

[gzig5]

Just reading this Gzig and please forgive my lack of knowledge here but if the C body spindles were sufficient to work on an E body, why would Chrysler make a duplicate part?

It would seem to me that there would be a fitment issue or, its not entirely safe to swap these critically important suspension parts without introducing safety issues.

Not critizing, just trying to learn something.

It's not a duplicate part. The C-body version is taller than the E-body, putting the ball joint higher like they are talking about here. A guy on E-bodies.org forum who has quite a bit of circle track experience used them on his Challenger, along with A-body lower control arms which are supposedly longer and a bunch of other custom touches. I won't pretend to understand all the geometry interactions yet but his goal was to reduce bump steer and optimize geometry for handling among other things. I don't think you can just throw a taller spindle in without changing some other components. It has to align and be balanced. Since we were discussing Mustang and Corvette spindles, I thought it would be OK to mention E and C body stuff. Not trying to derail the discussion. But, if there was a better tall spindle available, I might be convinced to spend $1k on them. I have big ambitions of running my car at Road America and other tracks in the upper midwest and want it to handle as well as I can afford to make it. This discussion helps me get a better grasp on the topic.

 

[Super-Cuda]

It's not a duplicate part. The C-body version is taller than the E-body, putting the ball joint higher like they are talking about here. A guy on E-bodies.org forum who has quite a bit of circle track experience used them on his Challenger, along with A-body lower control arms which are supposedly longer and a bunch of other custom touches. I won't pretend to understand all the geometry interactions yet but his goal was to reduce bump steer and optimize geometry for handling among other things. I don't think you can just throw a taller spindle in without changing some other components. It has to align and be balanced. Since we were discussing Mustang and Corvette spindles, I thought it would be OK to mention E and C body stuff. Not trying to derail the discussion. But, if there was a better tall spindle available, I might be convinced to spend $1k on them. I have big ambitions of running my car at Road America and other tracks in the upper midwest and want it to handle as well as I can afford to make it. This discussion helps me get a better grasp on the topic

Cool!

Thanks for the reply.

 

[Mtrhead]

I'm really impressed with your product Chris and I really wish I had the knowledge to go that deep down the Wormhole of suspension redesign I would love to be hired on as a journeyman just to learn the trade and I wouldn't even expect a paycheck for the first 6 months..good luck with sales and hope to be able to afford one of yours or Denny's setups in near future....

 

[DionR]

Since the argument is often made that OEM geometry is just as good, potentially better, than many of these COC’s, but not perfect/ideal, what is the limiting factor? Spindle? And what needs to be changed? If spindle, sounds like DionR and I share a similar idea of a fabricated upright with a Mustang rear wheel hub assembly. I’ve talked to Michigan Metalworks about building something and they’re all for it, they build them all the time for low riding trucks. Build into it a bigger brake option like a Mustang four piston caliper so everything is available off the shelf at your parts store of choice. So if it’s spindle, maybe it’s time to figure that out and get something done? My Suspension Analyzer is long gone for the similar reason someone else mentioned or i’d plot it myself and play with different ride heights and moving the ball joints around.

I am looking at my 4th revision on my custom spindle. I just duplicated the F-Body geometry though and haven't looked at making it taller because at the time it didn't seem like anyone was worried about the stock spindle height. I started with a bolt on setup for a stock disk brake spindle to use the 4 piston Brembo's and 14.2" rotors from a Challenger so I based the custom updright around that setup. I originally tried to use the Challenger front hubs but bought (and then returned) 2 or 3 replacement hubs to check the wheel bolt pattern and found they all used the 115mm bolt circle and wasn't going to go down that road. So I stole the S550 hub idea off the spindles RideTech introduced.

It's all just flat plates welded together and bolts, but I have been trying to come up with a better system to set the hub location. The distance from the hub to the caliper ears is pretty important and the plates have some tolerance on the thickness that can stack and upset things a little. But with flat plates and laser cutting from SendCutSend, I think it was only $500 for a pair but it's been awhile since I did up a quote. The biggest issue is the UBJ mount. I was planning a solid 1" thick bar and a washer to duplicate the stock spindle thickness there and it would require the taper to be reamed into it. More work to do there as well.

The real reason I started look at this was that I wanted to run ABS wheel speed sensors. So this setup has provisions to mount LX/LC sensors.

This most recent go round, I spent some time thinking about brake packages. I like the OEM stuff just because it seems like you can get parts for much cheaper than the aftermarket Baer or Wilwood stuff. Maybe it isn't as good, but hopefully good enough. I was going to jump up to the S550 6 piston 15" rotor package as my 18" wheel should still fit, but I decided I didn't want to put 34# rotors on the car. So I plan to stick to ~14" setups. The S197 4 piston setup seems like a nice package, but the S550 4 piston setup is junk. The only one I didn't look at was the Camaro 1LE stuff, but a Corvette hub, those brakes and a swap to a GM bolt pattern might not be a bad option.

One of the things I looked at was scrub radius. The stock spindle appears to have about a 7 degree SAI and with my setup, I am getting about 2.45" of scrub radius. I think that could be better. Note that my custom upright results in the surface the wheel bolts to being in some compared to the stock spindle by maybe 3/8" or so. Changing the UBJ location and SAI to reduce the scrub radius would require shorter UCA's or the aftermarket adjustable ones. So that's up in the air, too.

Another discovery is that the LBJ isn't centered on the spindle and there is about 0.5 degrees of negative caster built into the stock setup.

I've thought about moving the UBJ hole back about 1" as that would create about 6 degrees of built in positive caster and would keep the wheel more centered in the wheel opening. But I haven't figured out if I will try it, partly because I think I would have to move the caliper to the front of the upright and I'm not sure that won't create issues with the sway bar. I think it would be a better location in the end, just not sure it wouldn't snowball into a custom swaybar like Joe just built.

 

[swisswill]

I am looking at my 4th revision on my custom spindle. I just duplicated the F-Body geometry though and haven't looked at making it taller because at the time it didn't seem like anyone was worried about the stock spindle height. I started with a bolt on setup for a stock disk brake spindle to use the 4 piston Brembo's and 14.2" rotors from a Challenger so I based the custom updright around that setup. I originally tried to use the Challenger front hubs but bought (and then returned) 2 or 3 replacement hubs to check the wheel bolt pattern and found they all used the 115mm bolt circle and wasn't going to go down that road. So I stole the S550 hub idea off the spindles RideTech introduced.

View attachment 1716390203

It's all just flat plates welded together and bolts, but I have been trying to come up with a better system to set the hub location. The distance from the hub to the caliper ears is pretty important and the plates have some tolerance on the thickness that can stack and upset things a little. But with flat plates and laser cutting from SendCutSend, I think it was only $500 for a pair but it's been awhile since I did up a quote. The biggest issue is the UBJ mount. I was planning a solid 1" thick bar and a washer to duplicate the stock spindle thickness there and it would require the taper to be reamed into it. More work to do there as well.

The real reason I started look at this was that I wanted to run ABS wheel speed sensors. So this setup has provisions to mount LX/LC sensors.

View attachment 1716390204

This most recent go round, I spent some time thinking about brake packages. I like the OEM stuff just because it seems like you can get parts for much cheaper than the aftermarket Baer or Wilwood stuff. Maybe it isn't as good, but hopefully good enough. I was going to jump up to the S550 6 piston 15" rotor package as my 18" wheel should still fit, but I decided I didn't want to put 34# rotors on the car. So I plan to stick to ~14" setups. The S197 4 piston setup seems like a nice package, but the S550 4 piston setup is junk. The only one I didn't look at was the Camaro 1LE stuff, but a Corvette hub, those brakes and a swap to a GM bolt pattern might not be a bad option.

One of the things I looked at was scrub radius. The stock spindle appears to have about a 7 degree SAI and with my setup, I am getting about 2.45" of scrub radius. I think that could be better. Note that my custom upright results in the surface the wheel bolts to being in some compared to the stock spindle by maybe 3/8" or so. Changing the UBJ location and SAI to reduce the scrub radius would require shorter UCA's or the aftermarket adjustable ones. So that's up in the air, too.

View attachment 1716390211

Another discovery is that the LBJ isn't centered on the spindle and there is about 0.5 degrees of negative caster built into the stock setup.

View attachment 1716390213

I've thought about moving the UBJ hole back about 1" as that would create about 6 degrees of built in positive caster and would keep the wheel more centered in the wheel opening. But I haven't figured out if I will try it, partly because I think I would have to move the caliper to the front of the upright and I'm not sure that won't create issues with the sway bar. I think it would be a better location in the end, just not sure it wouldn't snowball into a custom swaybar like Joe just built.

So glad you shared your design. I remembered seeing it but couldn’t find it anywhere. That’s what prompted me to go down the “what if” path on a spindle. I want to add ABS, a hub spindle, and better brake options. I recently found Michigan Metalworks who builds beefy spindles for full size trucks and that got me going further.

I was tooling today and found a dual bolt pattern C7 hub, and that paired with a set of readily available GM calipers can be a great option, just need to firm up a rotor.
my thought is to grab a C5 spindle and hub off eBay, get the measurements for the caliper ears and hub mounting, combine that with FMJ pick up points and go. But if going to all that work, it makes sense to go all in and determine what the optimal points are at X ride height for the UBJ and LBJ. If, collectively as a group, we could do that, we could possibly come up with a great solution, or at least know what it would take to get these really dialed in.
A link to Michigan Metalworks website and their fabricated spindle.
Custom Fabricated Spindles

 

[DionR]

I was tooling today and found a dual bolt pattern C7 hub, and that paired with a set of readily available GM calipers can be a great option, just need to firm up a rotor.

Are those the CPP hubs? If so, just be aware they don't have the ABS tone ring in them even if they look to have the rubber cover. I talked to them at SEMA last year and I guess the extra steps and machining to get the dual pattern make it impossible to put the tone rings on. Or something like that.

A link to Michigan Metalworks website and their fabricated spindle.
Custom Fabricated Spindles

Cool! Looks like they could certainly come up with something that would work.

 

[HPP]

Want a taller spindle with more SAI, use a nascar unit. These can be found on ebay for $100 each. Easily a couple inches taller than stock and with SAIs of 7-9*. They are stout. Use big bearings. Go look at the picture I posted back on page three. If you find late model units, they may even already have radial brake caliper mounts for the new 12.73" rotors the Cup boys use these days. If they are older, it wouldn't be too difficult to weld on new mounting blocks.

Concerned with mounting in the car? Use a late B,F,J,M lower control arm with a divorced steering arm and ball joint. Then you can fabricate the steering arms to dial in ackerman, or not, and improve bump curve, or not.

Of course them you need a new upper arm. I'd suggest a custom length tubular with fabricated mounting point's to eliminate the factory anti-dive, or not. Speedway makes tubular upper arms in length from 6-12 inches in half in increments, so I'm sure you could find the exact length you want. You just have to figure out how to mount it to the frame, and then you can dial in how much camber gain you want it to have as well.

BTW, Autoware is having a sale on suspension Analyzer CDs.

 

[Mopar_Taxi_Guy]

I am looking at my 4th revision on my custom spindle. I just duplicated the F-Body geometry though and haven't looked at making it taller because at the time it didn't seem like anyone was worried about the stock spindle height. I started with a bolt on setup for a stock disk brake spindle to use the 4 piston Brembo's and 14.2" rotors from a Challenger so I based the custom updright around that setup. I originally tried to use the Challenger front hubs but bought (and then returned) 2 or 3 replacement hubs to check the wheel bolt pattern and found they all used the 115mm bolt circle and wasn't going to go down that road. So I stole the S550 hub idea off the spindles RideTech introduced.

View attachment 1716390203

It's all just flat plates welded together and bolts, but I have been trying to come up with a better system to set the hub location. The distance from the hub to the caliper ears is pretty important and the plates have some tolerance on the thickness that can stack and upset things a little. But with flat plates and laser cutting from SendCutSend, I think it was only $500 for a pair but it's been awhile since I did up a quote. The biggest issue is the UBJ mount. I was planning a solid 1" thick bar and a washer to duplicate the stock spindle thickness there and it would require the taper to be reamed into it. More work to do there as well.

The real reason I started look at this was that I wanted to run ABS wheel speed sensors. So this setup has provisions to mount LX/LC sensors.

View attachment 1716390204

This most recent go round, I spent some time thinking about brake packages. I like the OEM stuff just because it seems like you can get parts for much cheaper than the aftermarket Baer or Wilwood stuff. Maybe it isn't as good, but hopefully good enough. I was going to jump up to the S550 6 piston 15" rotor package as my 18" wheel should still fit, but I decided I didn't want to put 34# rotors on the car. So I plan to stick to ~14" setups. The S197 4 piston setup seems like a nice package, but the S550 4 piston setup is junk. The only one I didn't look at was the Camaro 1LE stuff, but a Corvette hub, those brakes and a swap to a GM bolt pattern might not be a bad option.

One of the things I looked at was scrub radius. The stock spindle appears to have about a 7 degree SAI and with my setup, I am getting about 2.45" of scrub radius. I think that could be better. Note that my custom upright results in the surface the wheel bolts to being in some compared to the stock spindle by maybe 3/8" or so. Changing the UBJ location and SAI to reduce the scrub radius would require shorter UCA's or the aftermarket adjustable ones. So that's up in the air, too.

View attachment 1716390211

Another discovery is that the LBJ isn't centered on the spindle and there is about 0.5 degrees of negative caster built into the stock setup.

View attachment 1716390213

I've thought about moving the UBJ hole back about 1" as that would create about 6 degrees of built in positive caster and would keep the wheel more centered in the wheel opening. But I haven't figured out if I will try it, partly because I think I would have to move the caliper to the front of the upright and I'm not sure that won't create issues with the sway bar. I think it would be a better location in the end, just not sure it wouldn't snowball into a custom swaybar like Joe just built.

DionR. Why not just get your knuckle 3D printed as a test piece?

Have you thought about designing your knuckle to be 2" taller than stock from the centerline of the hub/spindle and drop the lower ball joint mounting location 1.5" to 2" from the centerline of the hub/spindle? Droping the ball joint mounting location would be the same as what Chris Birdson is doing with the lower ball joint drop brackets he is running on his B-bodies with a longer upper ball joint. I'm not entirely sure where he's ended up for upper ball joint length.

The S550 6 pistons Brembos can fit with a 14" S197 GT500 rotor in an 18" wheel with the right brackets. ;)

The S550 4 piston calipers will work if you machine/grind the outside of the calipers for wheel barrel clearnance.

I need to get back on finishing the bracket design. It currently works with drum brake spindles but I would like to come up with a solution for the disc brake spindles.

 

[DionR]

DionR. Why not just get your knuckle 3D printed as a test piece?

I actually printed my first design. Not ready to print another one yet.

Have you thought about designing your knuckle to be 2" taller than stock from the centerline of the hub/spindle and drop the lower ball joint mounting location 1.5" to 2" from the centerline of the hub/spindle? Droping the ball joint mounting location would be the same as what Chris Birdson is doing with the lower ball joint drop brackets he is running on his B-bodies with a longer upper ball joint. I'm not entirely sure where he's ended up for upper ball joint length.

I looked at raising the hub an inch (1" drop) but the outer tie rod end looked to become a limiting factor on wheel depth. Part of the reason to go to an 18" wheel is so you can run a 9" or 10" rim and a decent offset to get the tire under the fender. 17" wheels run into that problem and are limited in offset to like +30mm on an 8" wheel, and dropping the ride height 1" would put the OTR in about the same spot and create the same limitation.

And I don't think a 19" wheel work on an A-Body as the front tire is about maxed out at 26" OD. That would make the sidewall shorter than I am interested in running.

I haven't put much thought into making the spindle taller, but not out of the question.

Also, my understanding is that an A-Body has pretty good geometry with the LCA horizontal and any slope down to the wheel make it worse. And with the LCA horizontal, the car is pretty low. So a 1" drop spindle would end up with the LCA sloping down at the same ride height and wouldn't be the best idea, in my opinion.

The S550 6 pistons Brembos can fit with a 14" S197 GT500 rotor in an 18" wheel with the right brackets. ;)

The S550 4 piston calipers will work if you machine/grind the outside of the calipers for wheel barrel clearnance.

I could get behind a 14" rotor and 6 piston caliper. Have to keep that in mind.

I haven't heard good things about the 4 piston S550 setup. Vorshlag has nothing good to say about them, partly because of the way the venting is on the rotors but I didn't get the impression he liked the calipers either.

I need to get back on finishing the bracket design. It currently works with drum brake spindles but I would like to come up with a solution for the disc brake spindles.

View attachment 1716390314

View attachment 1716390315

I like it!

 

[DionR]

Have you thought about designing your knuckle to be 2" taller than stock from the centerline of the hub/spindle...

With an 18" wheel with any decent offset and width, I don't believe a 2" taller knuckle would fit. @BergmanAutoCraft has said he is running 1" taller balljoints so that would work, but I would bet that is the limit.

Note that the "inside" of the wheel above is just a line at 9" from the centerline. The wheel is going to take a chunk out of that distance.

 

[Mopar_Taxi_Guy]

With an 18" wheel with any decent offset and width, I don't believe a 2" taller knuckle would fit. @BergmanAutoCraft has said he is running 1" taller balljoints so that would work, but I would bet that is the limit.

View attachment 1716390470

Note that the "inside" of the wheel above is just a line at 9" from the centerline. The wheel is going to take a chunk out of that distance.

When I suggested making your knuckle taller, I had forgotten how much room there isn't between the UBJ and the barrel of the wheel.

 

[swisswill]

With an 18" wheel with any decent offset and width, I don't believe a 2" taller knuckle would fit. @BergmanAutoCraft has said he is running 1" taller balljoints so that would work, but I would bet that is the limit.

View attachment 1716390470

Note that the "inside" of the wheel above is just a line at 9" from the centerline. The wheel is going to take a chunk out of that distance.

We should probably move this conversation to a thread of its own to discuss this more and hopefully get others involved. That said, I have a friend with a waterjet that I can use for cheap so I can cut test mules, but we should get details dialed in, which is where mapping out the geometry, and other smart suspension folk, come into play. Then we can determine additional height available and if the pickups can be moved to improve overall geometry, while deciding on a brake combo. I wonder if we can use the smaller rotor with the six piston caliper?

 

[DionR]

We should probably move this conversation to a thread of its own to discuss this more and hopefully get others involved.

No argument there. I’ve never asked but I wonder if a mod could do that without a bunch of work? @toolmanmike?

If not we could just stop talking about it and I could start a new thread with my post about my knuckle idea.

I wonder if we can use the smaller rotor with the six piston caliper?

@Mopar_Taxi_Guy said it would. Only question in my mind is whether the S197 knuckle is used or the S550 knuckle.

If I remember correctly, the guy at Vorshlag found 18” wheels that fit on a Dark Horse and said that they fit the 15”/6 piston setup as well. So it’s not like someone couldn’t have the whole package. I just decided I didn’t want to do the work to figure out new caliper mounting locations right now.

In the future, the smart play would probably be to set this up for the S197 14”/4 piston setup since that can accept an S550 6 piston caliper with an S197 15” rotor. So plenty of upgrades even without going outside the OEM stuff.

My current design could do the Hellcat 6 piston kit, but I don’t think those will fit in an 18” wheel.

 

[toolmanmike]

No argument there. I’ve never asked but I wonder if a mod could do that without a bunch of work? @toolmanmike?

If not we could just stop talking about it and I could start a new thread with my post about my knuckle idea.



@Mopar_Taxi_Guy said it would. Only question in my mind is whether the S197 knuckle is used or the S550 knuckle.

If I remember correctly, the guy at Vorshlag found 18” wheels that fit on a Dark Horse and said that they fit the 15”/6 piston setup as well. So it’s not like someone couldn’t have the whole package. I just decided I didn’t want to do the work to figure out new caliper mounting locations right now.

In the future, the smart play would probably be to set this up for the S197 14”/4 piston setup since that can accept an S550 6 piston caliper with an S197 15” rotor. So plenty of upgrades even without going outside the OEM stuff.

My current design could do the Hellcat 6 piston kit, but I don’t think those will fit in an 18” wheel.

I can move complete threads to other forums but I can't peel conversations out of a thread and send them somewhere else. The best thing to do would be start a new discussion thread.