Fabricated A-Body spindle ideas and discussion

[DionR]

The S197 and S550 stuff seems super easy to source. RockAuto has black S197 four piston calipers for $116 a piece, rotors from $41, pads from $10, and hubs from $63 (sometimes get what you pay for with pads/rotors/hubs), but this can be done for a very reasonable price.

Yep, prices are pretty good. And the S550 6 piston calipers can be had in black for $205/$212.

Not clear on the hubs though. The S197 hubs are for a pin style spindle, we would want a cartridge style hub off a S550, either the rear with a bolt or the front off a magna-ride car.

 

[DionR]

We are. A few different acronyms have been used over the years.

• Invert the LBJ. This will raise the ball center about an inch and more effective than moving the UBJ.
• By putting the stud boss in the LCA, the end of the LCA is shorter. The LBJ can also be further outboard/closer to the rotor without the end of the LCA contacting the rotor at full bump.
• You probably don't want to do this, but floating calipers allow the rotor to be closer to the wheel center, reducing scrub from a given wheel offset. The floater needs no more than the clearance required with a new outer pad. Fixed calipers are thicker outboard of the rotor to fit pistons.
• Design the arms to clear more rim offset and still have an adequate turning radius.

Thanks!

One thing I have resisted doing is adding custom control arms to the project, so I have been sticking to more of the standard parts for those.

Awhile ago there was the idea to use a later B-Body (I think?) LCA and steering arm. This setup has the LBJ in the arm and the steering arm is a bolt on. Unfortunately, this doesn't really invert the LBJ location and I doubt would improve the KPI.

What's your definition of excessive KPI/SAI?

 

[Mopar_Taxi_Guy]

The one drawback to the S550 rear hub is that it requires a bolt to squeeze the bearings. The Mach 1 hub doesn’t require that and doesn’t seem to be more expensive, but the bolt pattern is not symmetrical and might be difficult to fit around the LBJ bolts.

There are two different front hubs for the GT350, GT350R and Mach 1.

HUB395 has the longer wheel studs that would have been on the GT350R
HUB328 has the regualr length wheel studs.

I'm with you guys, my goal is around wheel bearing, ABS, and better/more simplified brake options. Improved geometry is a side benefit for me, but if we can do it, let's do it. I only throw out alternative designs and production options because that's what I found in my research. I think we're best off coming up with a design that we can have a few sets made up to begin with, then others can have the files and build their own if they wish. Michigan Metalworks takes a different approach and I bring it up because it's stout, maybe lighter/maybe not, and they've already said they could do it, and if we brought them the design and files, it'll cost that much less to have it produced. But just another option.

On the rotor, if using a Ford hub, why not simplify the rotor fitment and use a Ford rotor? The '15 Mustang has a rotor that is 13.9" diameter while the SRT rotor is 14.17". All the necessary holes are perfectly sized to the hub already, same thickness, almost same diameter which means the four piston SRT calipers should have no problem playing nice with the rotor, and there is no need to use feeler gauge material.

Mustang
View attachment 1716391448

SRT
View attachment 1716391449

Have you seen MillerBuilt's fabricated spindle? It's a super nice piece.
Fabricated C5/6

Years ago I bought suspension analyzer to layout my '69 front and rear suspension. I'm going to see if I still have the CD for that. I was on a mac at the time and when I went back to PC forever later, I had all but forgotten about it. I might still have it. I'm going to look this weekend. If I do, I'll get it installed and then we can start getting measurements. Or maybe I send it to one of you guys that has better access to a vehicle than mine in storage.

The 14.2" SRT rotor has a lot more offset to is as opposed to the S197 2012 14" GT500 rotor. Using the SRT rotor will move the calper away from the wheel spokes.

The S197 rotor is a better idea, still 14" and a better design. And if the knuckle were based about the S197 4 Piston brakes, the S550 6 piston calipers would bolt on with the 13/14 GT500 15" rotor. Or so I have read.

The SRT rotor has the advantage in my mind though as it is slightly bigger in diameter and has more offset so the caliper doesn't stick out as far.

That said, the S197 setup has the advantage for upgradeability. The SP setup upgrades to the HC 6 piston brakes but that takes a wheel bigger than 18".

I looked for GT350 calipers on RockAuto and didn't see any. This makes me think that while they might be easy to source, they aren't as widely available as the 14" S197 and S550 stuff.

I have all the part numbers for the S550 6 piston Brembos and the GT350 6 piston Brembos. The GT350 calipers are radial mount and not a bad price right from your local dealer. I'll get the part numbers added in here later.

 

[Mopar_Taxi_Guy]

Here is the clearance to the back side of the spokes on my 18x10 Welds with the S197 14" GT500 rotor on a cut down factory rotor turned into a hub.

It's been so long since I have had the calipers installed on my car. I'm pretty sure I needed a wheel spacer installed to clear the calipers. Hence why I feel the SRT caliper is the beter way to go.

 

[MV8]

Thanks!

One thing I have resisted doing is adding custom control arms to the project, so I have been sticking to more of the standard parts for those.

Awhile ago there was the idea to use a later B-Body (I think?) LCA and steering arm. This setup has the LBJ in the arm and the steering arm is a bolt on. Unfortunately, this doesn't really invert the LBJ location and I doubt would improve the KPI.

What's your definition of excessive KPI/SAI?

Imho, too much steering effort to parallel park. More than 10 deg is typically for reasonable scrub with low profile, wide tires and offset by having power steering. I've seen as high as 17 deg from an oem. It's all a compromise.

In that case, I'd look at wheels where the calipers will clear the center out near the rim and maximize back space. I forget the minimum spec for caliper to rim clearance but Brembo published it. I think it was around .080" with a fixed caliper.

Also, at risk of preaching to the choir and I just skimmed the hubs discussion, but if there is supposed to be a cv stub through it, a used stub axle can be machined to remove the cup, leaving a bolt with sealing surface to hold it together. A tool to hold the hub by the bolt circle can be used to loosen and tighten the stub bolt. I made one from 3/8" steel plate and drilled to accept two wheel studs. Didn't need to countersink the plate. The stub cup (extremely hard material) can be rough ground off with an angle grinder, then spun while holding the grinder with light contact to be more precise for balance purposes.

 

[swisswill]

Mustang wheels seem to be a common go to when moving to 18’s so I don’t know if there is a need to push the wheel away from the caliper more. It’s worth keeping in mind. The benefit of the Mustang platform seems to be availability of calipers and the opportunity to go bigger. Could probably be just as simple with SRT goods but my recollection is six piston SRT calipers are quite a bit more money than six piston Mustang calipers. I could be wrong though. We probably need to pick a platform and roll with it, then work on geometry.

 

[72bluNblu]

Awhile ago there was the idea to use a later B-Body (I think?) LCA and steering arm. This setup has the LBJ in the arm and the steering arm is a bolt on. Unfortunately, this doesn't really invert the LBJ location and I doubt would improve the KPI.

The 73/74 B body LCA does a couple of things, but no it doesn’t do anything to improve SAI/KPI. Depending on the version it uses a screw in or press in lower ball joint, which isn’t an A-body specific part. Howe makes ball joints that fit those arms, so you introduce rebuildable lower ball joints that can have the studs exchanged for different heights or tapers. That gives you more flexibility with altering geometry or even changing spindles.

The other thing it does is increase the clearance between the LCA and frame, so, more suspension travel. You can’t necessarily use it for travel unless you also raise the inner fenders, but you could return to using a more progressive bump stop vs a thing poly stop.

And if you did decide to alter the steering arm geometry you could modify one set of steering arms, and you wouldn’t be stuck doing it again when the ball joint wears out because they’re separate parts.

 

[swisswill]

Thinking about the idea of custom upper control arm to improve geometry more. I think the great thing about this is project is ie being plates welded to gather and caster designed in, anybody with a stock suspended a body can fab one of these up, improve geometry, assuming that actually happens, get a better hub assembly, and better brake package for minimal investment. Such a great idea.

 

[swisswill]

@72bluNblu, you have enough time doing research on these things, what are your thoughts on spindle changes to actually improve geometry?

 

[72bluNblu]

@72bluNblu, you have enough time doing research on these things, what are your thoughts on spindle changes to actually improve geometry?

Honestly from my end I haven’t spent a ton of time looking into spindle improvements. I’ve looked into enough suspension geometry to recognize some of the shortcomings of the factory parts and the MII set ups, but awareness of that is still a ways from new designs.

It really depends on what you’re trying to accomplish and how much custom work you really want to do. If you use the factory mounting points, for example, it ultimately limits what you can do from a geometry standpoint even if you start from a blank page with the spindles.

I think with the factory points it’s pretty well shown that a slightly taller spindle is a benefit for the roll center and camber gain. More SAI would help some things but that’s a trade off. Even the camber gain is car set up dependent, the goal is just to counter the body roll so there’s definitely a point where more isn’t better.

Having a lower ball joint that separates the steering arm out is super handy and allows for more adjustment to tune geometry, not to mention better quality ball joints. I know there are benefits to flipping the ball joint, but I don’t honestly know if that’s a good option if you’re retaining the rest of the factory mounting points.

I think you actually get to a point of diminishing returns fairly quickly. Using the factory points and spindles if you lower the car, run adjustable control arms and a slightly taller ball joint you actually get pretty decent geometry. Sure there’s more improvements out there, but unless you’re being super competitive with what you’re doing with the car the drivers skill level becomes more important really quickly.

I think a lot of the improvements from changing the spindles out aren’t strictly geometry based. Like Dion mentioned the ability to have ABS, or certain brake, steering or sensor packages is probably a larger benefit than pure geometry improvements. To me there’s really only a few people that have really tuned the suspension with the factory spindles to a point where they’ve gotten everything they can get out of them.

I honestly think for me what I want is achievable with the FMJ spindles I’m running. I’m not particularly interested in adding ABS to my cars, I like the Viper brakes I’m running, and until I map out and tune what I’ve got I don’t know that getting into custom spindles is really a rabbit hole I need to go down. Which is not at all to say it’s not a worthwhile project, just like a lot of things it’s probably not a direction I’m headed in myself.

 

[Mopar_Taxi_Guy]

GT350 radial front calipers in black:

Driver side: FR3Z-2B121-G
Passenger side: FR3Z-2B120-F

GT350R radial mount front calipers in red:

Driver side: FR3Z-2B120-G
Passenger side: FR3Z-2B120-G

 

[DionR]

Mustang wheels seem to be a common go to when moving to 18’s so I don’t know if there is a need to push the wheel away from the caliper more. It’s worth keeping in mind. The benefit of the Mustang platform seems to be availability of calipers and the opportunity to go bigger. Could probably be just as simple with SRT goods but my recollection is six piston SRT calipers are quite a bit more money than six piston Mustang calipers. I could be wrong though. We probably need to pick a platform and roll with it, then work on geometry.

There are many Mustang wheels that won't work with the S197 4 post calipers. I used an '08 GT500 as my "model" on American Muscle and there were plenty that they said didn't fit. Including the 18x9 +24 they sent me by mistake. That on is in my Scat Pack brake thread and fit fine on those brakes.

Regardless, I'm not saying anyone has to go with the SP setup. I still vacillate but because I already have the needed info for the SP brakes, I haven't bothered to go get the info for the Mustang brakes.

I was hoping to home much sooner and take some chassis side measurements but that didn't happen.

 

[DionR]

Thinking about the idea of custom upper control arm to improve geometry more.

I think with the SPC UCA's on the market, not sure we can improve things much more on that side. Unless we start throwing out the factory mounting points.

 

[DionR]

I think you actually get to a point of diminishing returns fairly quickly. Using the factory points and spindles if you lower the car, run adjustable control arms and a slightly taller ball joint you actually get pretty decent geometry. Sure there’s more improvements out there, but unless you’re being super competitive with what you’re doing with the car the drivers skill level becomes more important really quickly.

I think a lot of the improvements from changing the spindles out aren’t strictly geometry based. Like Dion mentioned the ability to have ABS, or certain brake, steering or sensor packages is probably a larger benefit than pure geometry improvements. To me there’s really only a few people that have really tuned the suspension with the factory spindles to a point where they’ve gotten everything they can get out of them.

I honestly think for me what I want is achievable with the FMJ spindles I’m running. I’m not particularly interested in adding ABS to my cars, I like the Viper brakes I’m running, and until I map out and tune what I’ve got I don’t know that getting into custom spindles is really a rabbit hole I need to go down. Which is not at all to say it’s not a worthwhile project, just like a lot of things it’s probably not a direction I’m headed in myself.

Exactly why I think something like this has to stay fairly cost effective. There is potential that moving the UBJ back might make something better, but based on what we have seen so far with TB suspension I doubt it is going to be earth shaking and the incentive for someone to want to do this will be low. Almost means that the other benefits would have to create the need.

I do see one other benefit with the cartridge style bearing; no more stub sticking out past the wheel and causing fitment issues and custom center caps. But that's a pretty minor addition.

 

[DionR]

GT350 radial front calipers in black:

Driver side: FR3Z-2B121-G
Passenger side: FR3Z-2B120-F

GT350R radial mount front calipers in red:

Driver side: FR3Z-2B120-G
Passenger side: FR3Z-2B120-Gn

I can see a potential method to add threaded holes at 90 degrees to the plates. But without that it feels like radial mount calipers are more work. I like them, but I have been working hard to keep things to a "flat plate" methodology and a radial mount caliper is hard to do in that case. And adding a bracket like that means getting something machined.

Basically add a notch to the hub mount plate that another plate turn 90 degrees could be be nested into to locate it and weld it solid. The plate turned 90 degrees would have to be drilled and tapped to match the radial mount caliper and probably wouldn't be difficult to be fairly precise with. But it would require machining to get the holes located in the plate correctly, not something I would expect to get right with a drill press.

 

[DionR]

Is something like the Lexus adjustable upper ball joint just too weak to be of any help?

Sorry, I meant to comment on this earlier in the morning and ran out of time. I'm not familiar with the Lexus UBJ you speak of, any links to info?

But at the same time, I wouldn't want to do anything that required custom control arms in addition to the idea of a spindle. So I could see not being able to use it even if it is strong enough.

 

[DionR]

Also, at risk of preaching to the choir and I just skimmed the hubs discussion, but if there is supposed to be a cv stub through it, a used stub axle can be machined to remove the cup, leaving a bolt with sealing surface to hold it together. A tool to hold the hub by the bolt circle can be used to loosen and tighten the stub bolt. I made one from 3/8" steel plate and drilled to accept two wheel studs. Didn't need to countersink the plate. The stub cup (extremely hard material) can be rough ground off with an angle grinder, then spun while holding the grinder with light contact to be more precise for balance purposes.

Yes, the hub I have been working with expects a CV stub. RideTech has washers that they supply and a 3/4" bolt when they use the hub in their SLA kit for FoxBodies. So I bought a set (2 pair) so I didn't have to worry about it. But a cut down CV axle would be workable as well. Or a pivot to the magna-ride equipped front hub that doesn't fit as well, but also is designed not to need the bearings squeezed.

Front SLA Suspension System | 1979-1993 Mustang (Stock K-Member) - Ridetech

 

[Mopar_Taxi_Guy]

I can see a potential method to add threaded holes at 90 degrees to the plates. But without that it feels like radial mount calipers are more work. I like them, but I have been working hard to keep things to a "flat plate" methodology and a radial mount caliper is hard to do in that case. And adding a bracket like that means getting something machined.

Basically add a notch to the hub mount plate that another plate turn 90 degrees could be be nested into to locate it and weld it solid. The plate turned 90 degrees would have to be drilled and tapped to match the radial mount caliper and probably wouldn't be difficult to be fairly precise with. But it would require machining to get the holes located in the plate correctly, not something I would expect to get right with a drill press.

https://lmr.com/item/SVE-GT350PP-K/sve-gt350-caliper-pp-rotor-adapter-bracket-kit-15-20

These adapters are to bolt the GT350 calipers onto a regular GT with the regular factory 6 piston Brembos with 15" rotors.

Since my brackets are for the regular 6 piston Brembos with 14" rotors, these adapters should allow the GT350 calipers to bolt right over the 14" rotors.

Just providing the info for another cost effective caliper option.

 

[DionR]

https://lmr.com/item/SVE-GT350PP-K/sve-gt350-caliper-pp-rotor-adapter-bracket-kit-15-20

These adapters are to bolt the GT350 calipers onto a regular GT with the regular factory 6 piston Brembos with 15" rotors.

Since my brackets are for the regular 6 piston Brembos with 14" rotors, these adapters should allow the GT350 calipers to bolt right over the 14" rotors.

Nice. That would solve the issue.

I would suggest if someone went down the road of using Mustang brakes, I would try and find adapter plates that allow the GT350 calipers to be used on the S197 knuckle for the 4 piston calipers, and then setup the A-Body to match those S197 mounting lugs. This would allow (in theory) for the same lugs to mount a 14"/4 piston setup, a 15"(S197)/6 piston (S550) setup and a GT350 caliper with whatever rotor the adapter was built for.

I would not use the S550 mounting lug locations though as the 14"/4 piston setup is junk and would mean the only good options would 15"/6P and the above GT350 caliper kit. And any aftermarket kit that was available, but generally those are $$$.

 

[Mopar_Taxi_Guy]

Nice. That would solve the issue.

I would suggest if someone went down the road of using Mustang brakes, I would try and find adapter plates that allow the GT350 calipers to be used on the S197 knuckle for the 4 piston calipers, and then setup the A-Body to match those S197 mounting lugs. This would allow (in theory) for the same lugs to mount a 14"/4 piston setup, a 15"(S197)/6 piston (S550) setup and a GT350 caliper with whatever rotor the adapter was built for.

I would not use the S550 mounting lug locations though as the 14"/4 piston setup is junk and would mean the only good options would 15"/6P and the above GT350 caliper kit. And any aftermarket kit that was available, but generally those are $$$.

The caliper mount lugs on the S197 and S550 are the same. It's just the height of the calipers that is different. I started out with S197 caliper brackets. All I did was moved the caliper mount holes down to work with the 14" rotors on the brackets I had made.

To directly fit S550 Brembos onto an S197 car, all you need is the calipers and a pair of 2013-2014 15" GT500 rotors.

 

[DionR]

I'm almost 100% certain the mount lugs on the S197 and S550 are the same. It's just the height of the calipers that is different. I started out with S197 caliper brackets. All I did was moved the caliper mount holes down to work with the 14" rotors.

Could be. I just keep seeing that the S550 6P caliper needs the 13/14 GT500 15" rotor rather than the S550 15" rotor on an S197. Makes me think they are different. The other thing I don't know is if the spindle is different between say a GT with standard brakes and a Boss 302.

FYI, looks like Full Tilt Boogie Racing has brackets to bolt GT350 rotors and calipers to S197 spindles.

 

[Mopar_Taxi_Guy]

Could be. I just keep seeing that the S550 6P caliper needs the 13/14 GT500 15" rotor rather than the S550 15" rotor on an S197. Makes me think they are different. The other thing I don't know is if the spindle is different between say a GT with standard brakes and a Boss 302.

FYI, looks like Full Tilt Boogie Racing has brackets to bolt GT350 rotors and calipers to S197 spindles.

Right.

The S197 knuckle is the same for all the cars from V6 all the way through to the GT500. Including the Boss 302. It's the rotors and calipers that are different. The original S197 brackets I bought allow the use any of the S197 brake combinations.

As I edited above. All you need to mount the S550 Brembos onto an S197 car is the calipers and a pair of 2013-2014 GT500 15" rotors. So that would mean the GT350 calipers with the SVE adapters (I linked above) and the 2013-2014 GT500 15" rotor would bolt right into an S197 car as well.

The GT350 rotors are 15.5". SVE also has adapters to make that work on an S197 as well.

 

[DionR]

I wonder how important the downward slope of the UBJ mount is. Be nice to make it flat.

I see a lot of custom knuckles and it seems like most or all of them are flat at the top.

 

[Mopar_Taxi_Guy]

I wonder how important the downward slope of the UBJ mount is. Be nice to make it flat.

I see a lot of custom knuckles and it seems like most or all of them are flat at the top.

As long as you have enough articulation in the UBJ though the suspensions entire range of motion you could have it flat. I'm assuming that the LBJ mount on the control arm is at the same angle when the car is at the factory ride height.

 

[jos51700]

Is there is a material thickness limit?

Sorry, I just saw this. I'm not sure what the upper limit is, but I'll find out. We cut up to 1/2" pretty regular.

That said, please realize that the accuracy goes down on thicker pieces. The edges of the part aren't 'square' to the top surface.