Rear IRS adjustment...

[time907356]

Then this is a swing car...only one knuckle on each half-shaft. That's the reason for the excessive camber in the rear with the lifted rear end. My speedster didn't do that, since it was irs. O.k., now the rethink on adjustable plates...maybe still a solution, but's it's more critical to get the right rear ride height, since the camber is directly affected...

 

[letterman7]

There's a couple of things you can do before attacking the torsion bar settings. Try a camber compensator first. It's about $150, and will do two things: help spring the axles back to a more normal ride height and will help stability in the corners. Additional weight at the rear will also make a difference; I'm guessing you don't have gas in the tank? Mine always looked a little funky when I was doing work on the rear end; once it was on the ground and moved back and forth down the driveway and a couple of 'bounces' on the rear quarters it tended to settle back down. My guess is there really isn't anything wrong - it just needs some road time.

 

[time907356]

Good comments. The spring plates are not on the top of the list of things to do. I spent a couple of hours replacing the master cylinder last night, and will get in to complete the electrical tie ups this weekend. The suspension is one of the highest candidates for post-partem work. I did notice what you said regarding settling. When we rolled the car off the trailer, the camber and travel were huge; I though something was broken! Over time, it has settled down quite a bit. Strapping the suspension for a while helped a bit too.
Based on the amount of "play" in the rear wheels, I'm pretty sure the bushings will be needing replacement as well, so my level of certainty that the change will be made is high. With all of the input you and the vendors have provided, I've concluded that the 21-3/4" Torsion bars and swing axles with solid caps are the spec's I have. I'll order accordingly! Muchas Gracias!!

 

[time907356]

O.K., the adjustable spring plates are here. Since the rear wheels sit so far back in the wells (they scrub the back side of the well if the suspension is loaded up...) what do you (anyone) think about cutting the spring plates, shortening them by 3/4" - 1", and re-welding them back together? I'd have someone other than my(rookie)self do this, of course. I'm trying to move the rear wheels forward on the swing axle set up, and the slots are too short for this amount of move.

 

[letterman7]

Judging by the side photo in your other thread, it isn't so much the wheel/tire/axle is back too far, it's that the body is sitting too high and you've got way too much tire for the opening. You can't cut and weld spring plates - it's spring steel and it'll destroy the give of the steel. You could open up the slots a little more with some creative die grinding, but I think you need to concentrate on dropping the body down a little (and in the process the tire will fit higher into the larger opening of the well) and/or try a smaller diameter tire. Remember, these bodies were designed for a VW chassis, so the dimensions are pretty accurate for a standard wheel/tire combo off a Bug. There shouldn't be any need for a fore and aft adjustment unless the chassis itself had been in a wreck.

 

[time907356]

Rick,
Thanks for the reminder about the spring plate temper; I hadn't considered the annealing affect of welding on them. machining may be the only solution. I originally thought about just lowering the suspension and letting the body/chasis drop into place. So, I used some wratchet straps, and pulled it down (earlier post). When I did, the rear of the two tires hit the back of the wells, as shown below. The tires being too big may be the problem, but the clearance at the front of the well suggests that this setup may work, if I can just bring the axles forward. I'll pay a visit to a machine shop once I have a closer look at the slots. Someone must have raised this car, since it was an Amore factory car; I'm sure it didn't leave this way...If they did, the axles are probably all the way forward already.

 

[time907356]

The Ugliest View ! !

*kiss my butt*
I rode behind my son last night to Church in the family wagon, giving him his first opportunity to drive the Cimbria alone. Wow - what an ugly view!! The wheels are too wide, tall and square, and the car looks like the edge of a sheet of plywood, it's so squatty!! I could have tagged it as a kit-car from 1/4 mile away!!! Very un-appealing. I think the first crack D) I'll have at fixing this will be to get that suspension down. ON with the adjustable spring plates this weekend!! I really just need to knock the torsion bars ahead one click to give it an inch or so, but as discussed, the plates are in the garage, and bushing can always be changed.
I thought I'd share the math that gives the adjustability of the rear end. I got on Samba to remind me how many spline teeth are at either end. Since its a different number at each end of the bars, we have a "differential adjustment" setup. There are 40 teeth on the spline at the center of the tube, and 44 on the outer ends.

40 teeth = 9° adjustment
44 teeth = 8.18° adjustment

going forward one tooth on the inner, and backward one on the outer:

9 - 8.182 = 0.82° : This is the finest increment of adjustment...

I measured the spring plates I have, and they are roughly 16-1/4" between centers of rotation; torsion bars to axles. Assuming they are horizontal on the car, each fine incremental adjustment=

sine(.82) = X/16.25:
X = .233"

So, you can adjust your rear end in ~1/4" increments. For a 1/2" adjustment, go forward two on the inner, and backward two on the outer, and so on for each 1/4" desired. That seems like a lot, so correct me if I'm wrong!

Also, for bigger adjustments, going one full notch on either end without using differential:

1 inner notch = sine(9) = X/16.25: X = 2.54"
1 outer notch = sine(8.18) = X/16.25: X = 2.31"

The angle that the spring plates start at will diminish this some, but not much.

 

[farfegnubbin]

I realize this is an older posting, and I don't know where you are at with the rear suspension at this point, but I just now re-found this thread and had a few thoughts to add.

First of all, I can't help you with the math. There is a reason I wear a calculator watch. *laugh*

(Sad but true. This is my arm on Sterling Sports Cars factory website.)

​

Secondly, I'm a big fan of the idea of adjustable spring plates. They provide for a level of easy fine tuning that you can't get any other way. We should all have them.

Third, your rear really does look suspiciously high/unsprung. I seriously wonder if someone adjusted it before...in an unhelpful direction. I think part of your solution needs to be an adjustment, and you might have to change a spline or two in addition to the adjustability of the new plates.

But here is the important observation: Holy Oh My God are your rear tires large!!! They're friggin' HUGE, which I see as a significant part of the problem.

I've mocked up a bunch of different wheels on the Sterling and Cimbria over time, and I've never been able to get anything bigger than about 28.5 inches to look good or function well on the rear. What is your overall diameter on those rear tires? My thoughts are that, if they're over about 28", then it's simply too much tire for the rear.

I found a photo of the rear tires of my Cimbria SS for comparison. Unfortunately, I'm not around the car in person right now and I don't know what size they are. But they are BIG, yet smaller than yours. And on the rear, they seem to work. (The current front tires are the ones that came with the car and are WAY to big, rendering the car unturnable, but that's a discussion for later.)

But anyway, here's a shot of my rear tires/clearances: (Disclaimer: I have no idea why the previous owner cut hose ugly holes in the side for scoops. They are not my bad idea. I'm proud to make and acknowledge my own bad ideas.)

Unless you plan to do body work and rear fender flares (which I'm not knocking; that would be one solution), I think you're going to need smaller rear tires. That, plus the work you had planned with the torsion bars and spring plates should give you the clearances you want which still having a big powerful rear look without being to squat and kit-car-y like you said you were noticing on your car.

One more comment on the thread: Please be aware that the slots on the adjustable swing axle bolt holes are not to adjust the wheel fore or aft but rather to keep the wheel at a prescribed amount of toe-in (or no toe-in) as the hub is adjusted upwards or downwards. If you enongated those holes and pushed the wheel too far forward, it would also toe in quite a bit. It MIGHT not be enough to ever be noticed. I don't know for sure. But please just be aware of that complication.

Honestly, with slightly smaller tires and that upward adjustment (leading to a lowered rear), I think you're gonna be golden.

Please let us know how the plates (and all of the above) turned out. Also, I'll try to remember to look at the size of my tires next week so we all have a comparison. I like how my rear tires look. The front... well that's a much different story. *sigh*

 

[ydeardorff]

Does a multi-ball setup offer any freedom, or restrictions to tire width and size? I know it negates the need for the torsion tube as a suspension component.


mbt-Engineering

 

[time907356]

Knowing that pictures are worth 1000 words, I'm writing this without pics! I thought I'd update as I've plateu'd (sp?) at the momoent. (Look at the || thread Original Rims/Tires for the background...)
I put the 275/50/15's on the rear, and they look 'reasonable'. I still like the way the LR50-14's looked better, except for the fit. Too fargin' huge is cool to me! The Nitto's 275 is noticably smaller, and they sit inside of the wells, not pushing out as far as the 296's. Maybe 1/2" rim spacers would help? Thoughts??
Now, having the adjustable spring plates is great, but the new tires put the left side out of the range of the screw. It's some strange pitch/dia. combination, which CIP could not help with. I took it to the big box stores, and they couldn't match it. My intent was to get a longer one, but I guess the plates will have to come off, and we'll be asdjusting the torsion bars again!
Anyway, the kid has been driving it daily, and things are o.k. Got another electrical short in the turnsignal, but nothing serious. It stays in the garage on rainy days b/c of the leaky sunroof; another in a long list of projects stretching to the horizon! Pics to come...