Caster and Camber.

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KrisKringle

KrisKringle

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Kürten, Germany
Jeepers, I can figure side-loads, piston speeds for ring float, mean-time to failure on Aluminium rods to mention a few things, but I am a complete dolt when it come to alignment. Here in Germany there is a dirth of shops that can deal with two eccentrics to set castor and camber. The last shop set the car up so that when it came off the rack, the front tyres looked like a John Deere row crop. I told him "that was not right." I ended up setting the thing up myself. Well, maybe setting it up at 0 degrees camber was not the best thing...no return to 0 when driving. Hoping to get an appointment at the shop that has an idea about alignment...I have the factory specifications, but can anyone give me the "compromised" specs for a correct alignment?
 
A-Body suspension geometry is really well engineered (thank you Scott Harvey) and since I had an SCCA/A-Sedan 65 Barracuda that I found and converted to a street car in the mid-70's, I've been a student of tuning for handling. My general rule of thumb with a stock front end is to ask an alignment shop to start at one degree neg camber and then crank back to maximum positive caster available in the eccentrics. Toe I like at zero but that's autocross/race territory where it'll nibble on the street so a little bit of positive toe is maybe more comfortable. I do that myself by cranking equal-count turns on the collars, half a turn at a time both sides, until it feels good. You can use Moog offset upper control arm bushings to increase neg camber/positive caster throw, aftermarket upper control arms that move the upper ball joint back or a 1/8" inch aluminum spacer between the spindle to lower ball joint mount for similar effect.
 
Credit to Rick Ehrenberg for sussing out some of these values btw, I've tried to pay attention and have experimented on my own but Rick has documented much of this, see MOPAR Action (Not MOPAR Muscle!) archives for solid engineering references.
 
This is what you want...

E3409855-DB91-4AF4-8B46-A46A18EEED4A.jpeg


Without the offset UCA bushings you’ll probably be stuck between “granny” and “typical street performance” for your range of caster adjustment. With the Moog K7103 offset bushings you should be able to get up around +3* to +3.5* on the caster side. For a basic street car -.25 to -.5* camber is fine.

In general I think the chart is good, but I think it under values positive caster. Part of that is that it’s an older chart, and to get more than +4* of caster you’ll likely need tubular or adjustable tubular UCA’s which weren’t as widely available as they are now.
 
Good point 72bluNblu, re "Granny". Factory specs had to accommodate the little old lady Valiant with 24-1 manual steering that she needed to parallel park. Zero caster eases the steering wheel load but is hell for high speed stability. Add fat tires and find a tree. I've had as much as two degrees neg camber and five degrees pos caster in an aggressive car. Firm Feel power steering is much appreciated at that point but you can dice with Porsches and Corvettes with confidence. (given the rest of your setup of course, ie 500 HP is nice)
 
I run my Duster with -1.0* camber, +6.5* caster, and about 1/16” toe in. That’s with 16:1 manual steering turning 275/35/18’s up front. Steering is heavy below 10-15mph. Above that it’s great. But getting that much caster requires tubular UCA’s. Mine are SPC adjustables with Delrin bushings from BergmanAutocraft. It’s set up pretty aggressively, but it is my real daily driver.

It really depends on the car you’re setting up. If you’re running 14” or 15” rims with BFG T/A’s then running the “typical street performance” numbers from the SKOSH chart is fine. If you can get +3.5* caster with the rest of those specs even better.

I run all that caster on my car to help with the rut tracking and self steering tendencies of the 275mm wide front tires. With a set of 225’s up front (for example) you can get away with a lot less caster.
 
Nice! Lottsa caster, more then I've ever run. Impressed that you're strong arming that with fast-ratio manual steering. I'm too old for that! (But don't call me Granny!)
 
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My Barracuda is set at -.9 degrees of Camber, + 4.9 degrees of Caster and about 1/16" of toe-in. We didn't intentionally set it there. I just told the shop to get the Camber somewhere between -.5 and -1 degrees of negative Camber and as much Caster as they could get, and that's where we ended up. I have the K7103 Moog offset bushings in mine and it drives good. Doesn't wander around our country highways and tracks well.

I'm running a 400 4spd, with Firm Feel 20:1 steering gear and 225/60-14's up front. Turning the wheel at a stop takes a little energy, but once you're moving it's not bad, and at road speeds, it has nice feedback.
 
Thanks for the responses...I have a stage 2 Firm-feel box in the car...whole front suspension is new. I remember way back when I first set up the car (in the '80's) Homer Bieber told me about the offset bushings. Should have put them in. Oh well. I will quick oder a set or two to have in stock here. Appointment is in an hour or so for this round at the alignment shop. I will let you know what happened. Thanks again.
 
I'm getting close to tackle this also, I have been wondering how I want to set everything, to top it all off my rear is four link that adjustable so I have to get that straight first. I'm also running 18's 245/35's in the front and 255/35/18 in the back.
Ive got all QA1 control arms with the big BJ's up front and 1.03 T-bars. Any advice would be greatly appreciated. I should say I want the car to carve the corners but not be to much effort for normal driving. m running Borgensen box with a 850 psi pump.
 
@A408Cuda I think given your aftermarket control arms that specs like Frnknsteen's should be an easy dial-in. Your power steering will take the gorilla out of it. I've never run wheels bigger then 15" so 72bluNblue's bigger caster numbers might be in order for your 18's but I'd personally start around +5. My experience says experiment. Watch tire wear, I suspect the high aspect ratio modern tires with little sidewall on tall wheels are less forgiving of negative camber that will take the inside tread to cord quickly. Don't be afraid to move the settings around to find your personal sweet spot. I've had dozens of A-bodies with modified suspensions for handling and I don't think any two ended up identical in spec.
 
View attachment 1715340771 View attachment 1715340772 Sorry for the delay in replying. It has been quite a week, my B-Day, Wedding Anniversary, and Daughters' Birthday on top of having a flu/cold...well I managed to get the Alignement done at the competent shop. The coloured picture is the Alignement at the idiot shop. The BW picture is the settings now. I have to say, I am still not happy with the handling. The steering wheel returns like it "should" but it is pretty lazy. Powering through corners, the handling is better.

The offset bushings will be here in a week or so. So more dumb-assed questions:
  1. In which direction should I install the offset bushings?
  2. Should I install only one bushing in the front or rear?
Thanks for your help. Put 120 miles on the girl in the last week...kind of a shock. 11 mpg. Well, it is a bit hard to keep the foot off the floor when it feels and sounds so good. Jeepers, never thought writing in English would be so difficult.

PS, have a rear sway bar to install from a 94 Grand Cherokee, pretty much a bolt-in since I have had the B or C-body plates installed on the axle/spring perches since the last 20 years or so. I will make pictures and post them in another thread.

View attachment 1715340771

View attachment 1715340772

I notices the photos were not clear. Here are the Dropbox links:

Dropbox - achsevermessung0001.jpg - Simplify your life

Dropbox - achsevermessung0002.jpg - Simplify your life
 
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72bluNblu said:
I run my Duster with -1.0* camber, +6.5* caster, and about 1/16” toe in. That’s with 16:1 manual steering turning 275/35/18’s up front. Steering is heavy below 10-15mph. Above that it’s great. But getting that much caster requires tubular UCA’s. Mine are SPC adjustables with Delrin bushings from BergmanAutocraft. It’s set up pretty aggressively, but it is my real daily driver.

It really depends on the car you’re setting up. If you’re running 14” or 15” rims with BFG T/A’s then running the “typical street performance” numbers from the SKOSH chart is fine. If you can get +3.5* caster with the rest of those specs even better.

I run all that caster on my car to help with the rut tracking and self steering tendencies of the 275mm wide front tires. With a set of 225’s up front (for example) you can get away with a lot less caster.
Click to expand...

I need to check my tire sizes. IIRC, 215 14 60 front 235 14 60rear...I had the rims widened way back when...added an inch to the stock rallye rims. Yep, BFG radials...
 
Here's what I see if I understand correctly.
Caster: Almost 3 degrees postive. That's good.
Camber: 0 to 0.5 degrees positive. Not negative enough for flat roads and performance radial tires.
Toe: 0.4 + 0.6 = 0.9 mm. Funny. I'm sure that's just tolerance stack up. 1/8" to 5/32 = 3 to 4 mm. So maybe a little more total toe in than needed.

My suggestion is next time to get a little bit of negative camber, 1/2 degree would be fine. It will cost some caster. Drive it, observe tire wear. See which you prefer.

Very important, first thing to check is the "ride height". For 68 Barracuda, factory spec was around 1 7/8" IIRC. It is important because as the chassis moves down relative to the wheel, caster increases and camber gets more negative. This is a good design. But one consequence is changing the initial height (angles of the control arms) changes the caster and camber.

If you drive on smooth roads, you can use a lower ride height. Only caution is that you already have a realtively short tire up front.
 
72bluNblu said:
I run my Duster with -1.0* camber, +6.5* caster, and about 1/16” toe in. That’s with 16:1 manual steering turning 275/35/18’s up front. Steering is heavy below 10-15mph. Above that it’s great. But getting that much caster requires tubular UCA’s. Mine are SPC adjustables with Delrin bushings from BergmanAutocraft. It’s set up pretty aggressively, but it is my real daily driver.

It really depends on the car you’re setting up. If you’re running 14” or 15” rims with BFG T/A’s then running the “typical street performance” numbers from the SKOSH chart is fine. If you can get +3.5* caster with the rest of those specs even better.

I run all that caster on my car to help with the rut tracking and self steering tendencies of the 275mm wide front tires. With a set of 225’s up front (for example) you can get away with a lot less caster.
Click to expand...

Long as you have room to get the sumbitch rollin, it's probably ok........but in a tight, I bet it IS heavy. lol
 
Frnknsteen said:
My Barracuda is set at -.9 degrees of Camber, + 4.9 degrees of Caster and about 1/16" of toe-in. We didn't intentionally set it there. I just told the shop to get the Camber somewhere between -.5 and -1 degrees of negative Camber and as much Caster as they could get, and that's where we ended up. I have the K7103 Moog offset bushings in mine and it drives good. Doesn't wander around our country highways and tracks well.

I'm running a 400 4spd, with Firm Feel 20:1 steering gear and 225/60-14's up front. Turning the wheel at a stop takes a little energy, but once you're moving it's not bad, and at road speeds, it has nice feedback.
Click to expand...

Those are really good numbers for just having offset bushings! Usually you can't get quite that much + caster with just the offset bushings and stock arms.

Valiantjim said:
@A408Cuda I think given your aftermarket control arms that specs like Frnknsteen's should be an easy dial-in. Your power steering will take the gorilla out of it. I've never run wheels bigger then 15" so 72bluNblue's bigger caster numbers might be in order for your 18's but I'd personally start around +5. My experience says experiment. Watch tire wear, I suspect the high aspect ratio modern tires with little sidewall on tall wheels are less forgiving of negative camber that will take the inside tread to cord quickly. Don't be afraid to move the settings around to find your personal sweet spot. I've had dozens of A-bodies with modified suspensions for handling and I don't think any two ended up identical in spec.
Click to expand...

It's not so much the rim diameter that makes the difference, it's the width. The wider the tires get the more they tend to track road features like ruts and things. So, adding caster counteracts the tendency of the wide front tires to steer the car with the road imperfections.

As far as the camber goes I've found that up to about -1° of camber there really isn't much change to the wear pattern as long as you're doing some cornering where you drive. Above that and the camber wear starts to show up on the tires. But even then it depends on how much you drive your car. I would venture that most of us "time out" tires before we wear them out because of the amount of miles getting driven. Even the 6 year old KDW2's on my Duster are starting to check, and they have good tread left still. Seems like tires don't last as long as they used to.

A408Cuda said:
I'm getting close to tackle this also, I have been wondering how I want to set everything, to top it all off my rear is four link that adjustable so I have to get that straight first. I'm also running 18's 245/35's in the front and 255/35/18 in the back.
Ive got all QA1 control arms with the big BJ's up front and 1.03 T-bars. Any advice would be greatly appreciated. I should say I want the car to carve the corners but not be to much effort for normal driving. m running Borgensen box with a 850 psi pump.
Click to expand...

With the power steering you shouldn't have any issues with steering effort. I would think +5° to +6° caster would be just fine. More than that starts to effect things other than just steering, as the "jacking" effect of angling the tires so much on turn in can upset the handling.

RustyRatRod said:
Long as you have room to get the sumbitch rollin, it's probably ok........but in a tight, I bet it IS heavy. lol
Click to expand...

Ha! Yeah it's not as bad as you might think. At one point I had it up as high as +8° of caster, that was really heavy. But that was actually jacking the front corners and noticeable altering the ride height as I was turning. I cranked it back to about +6°, which was great for the steering effort. But a lot of my daily driving follows "truck routes" so a lot of roads have significant rutting from heavy truck traffic and the rut tracking was noticeable at +6° with the 275's up front. So I went back up to +6.5°, which seems to be some kind of tipping point for the suspension. It tracks a lot less but doesn't jack the car as much, so it's a good balance between stability and steering effort. With narrower tires or smoother roads it wouldn't take as much.
 
72bluNblu said:
Those are really good numbers for just having offset bushings! Usually you can't get quite that much + caster with just the offset bushings and stock arms.



It's not so much the rim diameter that makes the difference, it's the width. The wider the tires get the more they tend to track road features like ruts and things. So, adding caster counteracts the tendency of the wide front tires to steer the car with the road imperfections.

As far as the camber goes I've found that up to about -1° of camber there really isn't much change to the wear pattern as long as you're doing some cornering where you drive. Above that and the camber wear starts to show up on the tires. But even then it depends on how much you drive your car. I would venture that most of us "time out" tires before we wear them out because of the amount of miles getting driven. Even the 6 year old KDW2's on my Duster are starting to check, and they have good tread left still. Seems like tires don't last as long as they used to.



With the power steering you shouldn't have any issues with steering effort. I would think +5° to +6° caster would be just fine. More than that starts to effect things other than just steering, as the "jacking" effect of angling the tires so much on turn in can upset the handling.



Ha! Yeah it's not as bad as you might think. At one point I had it up as high as +8° of caster, that was really heavy. But that was actually jacking the front corners and noticeable altering the ride height as I was turning. I cranked it back to about +6°, which was great for the steering effort. But a lot of my daily driving follows "truck routes" so a lot of roads have significant rutting from heavy truck traffic and the rut tracking was noticeable at +6° with the 275's up front. So I went back up to +6.5°, which seems to be some kind of tipping point for the suspension. It tracks a lot less but doesn't jack the car as much, so it's a good balance between stability and steering effort. With narrower tires or smoother roads it wouldn't take as much.
Click to expand...

Yeah and people don't understand why. The reason is, the more you lay the steering axis back at the top (positive caster) the more you are picking the front end of the car up in turns. This is the same reason you get good returnability with a decent amount of caster. The front end of the car is pushing down on the suspension which in turn brings the spindles back to center.
 
RustyRatRod said:
Yeah and people don't understand why. The reason is, the more you lay the steering axis back at the top (positive caster) the more you are picking the front end of the car up in turns. This is the same reason you get good returnability with a decent amount of caster. The front end of the car is pushing down on the suspension which in turn brings the spindles back to center.
Click to expand...

Yup, exactly. What amount works best depends on the chassis, suspension design and set up. All I know is my car is pretty happy at +6.5°. Some of the new performance cars run as much as +7 to +8° in their factory specs, the Dodge SRT8 Challenger specs call for a +7.3 to +9.3° range for caster on the left and +8° to +10° on the left. Base model Mustang's are also in the +7° to +8° range.
 
72bluNblu said:
Yup, exactly. What amount works best depends on the chassis, suspension design and set up. All I know is my car is pretty happy at +6.5°. Some of the new performance cars run as much as +7 to +8° in their factory specs, the Dodge SRT8 Challenger specs call for a +7.3 to +9.3° range for caster on the left and +8° to +10° on the left. Base model Mustang's are also in the +7° to +8° range.
Click to expand...

You should do an alignment on some Mercedes cars. Some of them have as much as 12* caster. So drastic of an angle that you have to basically adjust caster, camber and toe all at the same time with each setting in mind. A small caster adjustment will throw everything else out a lot, so you have to make adjustments with all settings in mind. It's a trick for sure.
 
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