Adjusting rear camber with spring pads

[cyberman]

Since I purchased the car a couple of years ago, there was a small, but noticeable difference in the rear camber with the driver's side splayed out a bit more than the other side. I assumed the weight of the driver had caused the spring to sag a bit and note that first year's production had a varying wire diameter as well as a varying overall diameter. I swapped the left and right and the sag followed the spring.

I tried one manufacturer's replacement springs, and they jacked the rear end up considerably, unnaturally. Nobody makes an exact replacement spring for my 96 now and I'm reluctant to invest in more springs.

I measured the height difference, fender arch to ground and it's about a quarter of an inch lower on the sagging side. So, I'm wondering if I could adjust the height with some spring pads of different heights such as this set from TMS: https://www.turnermotorsport.com/p-5...pring-pad-set/

Given there is geometry involved, there cannot be a one-to-one correspondence between ride height and spring pad thickness changes. But I don't know how to calculate that, and in any event, I don't feel like paying to get it measured. I just want the two rear wheels to be even.

Does anyone have some thoughts on this? I assume those of you who lower the car have to deal with camber changes.

[zellamay]

As I remember, the rear ratio is 2:1, so if you want to raise it by 1/4", you need a 1/8" thicker pad. That's about 3 mm .... not much. I wouldn't bother with it, but I'm not you. ..... $48 to adjust the height seems expensive to me, given how easy it is to do. You could take it apart and measure what you've got, then get a pad 3mm thicker. ..... Raising it by 1/4" won't significantly affect camber.

EDIT: I tried to find the exact ratio, in two places Icame up with 1.6:1 and 1.7:1. Somebody here will know exactly. ...... So, if it is 1.65:1, then if you want to raise it by 1/4", you need a 4 mm thicker pad (not 3 as I said before). These difference are insignificant. You'll really figure it out by trail and error. .... Also, remember your pads are decades old, so they are compressed from original thickness.

[cyberman]

EDIT: I tried to find the exact ratio, in two places Icame up with 1.6:1 and 1.7:1. Somebody here will know exactly. ...... So, if it is 1.65:1, then if you want to raise it by 1/4", you need a 4 mm thicker pad (not 3 as I said before). These difference are insignificant. You'll really figure it out by trail and error. .... Also, remember your pads are decades old, so they are compressed from original thickness.

Thanks for the feedback and research. I do have new spring pads, along with everything else suspension. I think I put on standard 5 mm pads, at least I think that is the standard. So, if I go with a standard 10mm spring pad, well that's going to raise it slightly higher than optimal, but the difference would not be as extreme as it is now. Standard 10mm pads cost $8.28 plus shipping here: https://www.getbmwparts.com/oem-part...mm-33531136387

It might be worth a try as it doesn't take that much effort to change them out. I wish I'd saved the old pads, might have been able to use one as a spacer.

[zellamay]

" I wish I'd saved the old pads, " I often say "never throw anything away". I can't count the times I've tossed out junk, only to need one little part 6 months later. When I take parts off the car, or my bicycles that I also hobby with, I don't throw parts away for months ..... just in case ..........., or if anything goes wrong or is in question I can look at the old part.

[pepz]

" I wish I'd saved the old pads, " I often say "never throw anything away". I can't count the times I've tossed out junk, only to need one little part 6 months later. When I take parts off the car, or my bicycles that I also hobby with, I don't throw parts away for months ..... just in case ..........., or if anything goes wrong or is in question I can look at the old part.

+1

I kept many old parts when doing a cooling refresh, even the old radiator, which is still in good shape. I plan on doing the same when I do the suspension refresh. I'm thinking it might be easier to refurbish these parts if they ever become NLA as some parts are now. I've also seen car restoration shows where the restorer has to pay obscene prices for very hard to find parts. There will be value in our old parts down the road.

[cyberman]

Got my 10mm lower rear spring pad. Finally, a single coolish day. All perfect: until I jacked her up, removed the wheel and discovered the new spring pads I'd purchased within the last two years were 10mm. What, I thought 5mm was standard and didn't think it about it when I ordered them. So, back to square one, I purchased those stackable pads for $50 because when I looked for a 15mm spring pad:

1. The ones that came up with the correct picture and notations were about $40 each (NLA?, supply drying up?).
2. Many came up with the notation that they were upper, even though they looked like a lower (my uppers have a bumper cone on them).

So, rather than chance another wrong purchase, I went with the stackables and added a $2 tire dressing applicator to bump me over the $50 free shipping limit.

I also ordered a magnetic bubble-level caster gauge tool from Amazon for $15 since at this point, I have no idea what the caster readings actually are. My Indy aligned it after I refreshed the front suspension but made no mention of the caster in the back. Now, I have no idea how to correlate caster readings with spacer thickness, but I guess I'll learn via trial and error. Painful trial and error since each change involves removing the spring. I do recall the lower shock nut torque is 74 ft-lbs. I only recall that as I had to repeatedly install and uninstall springs when I went through the fiasco with Lesjofors and their incorrect rate springs (which they never made good on). Thank god I'm semi-retired and have time for all these shenanigans.

[cyberman]

So, I finally got around to putting in the full stack (5mm + 6 mm + 3.5mm) of pads and now the ride height is equal on both sides. And, there is no noticeable difference in camber between the two sides. I'll have the actual camber measured next time I've got it in the shop as there was no way to secure the gauge to the disk in-situ. The magnetic base is too large and catches the edge lip on the rotors.

But at least I've quelled a two-year annoyance as that uneven look bothered me since I got the heap.

Now, I have the three stackable disks left over as I doubt, I'll ever need them. So, if anyone wants them let me know (PM me) - they should be easy to mail (light and small). They're a harder material than the rubber lower spring seats and I have visions of the edge of the spring wire slowly digging into them, but we'll see. I also haven't taken them on a test ride yet, so I don't know if they'll transmit more road noise/chatter.

[tiMASTER]

Looks like you are all sorted out now, but I might as well post this (from my 318ti engine swap book):

Lower Spring pad data:

Pad Thickness	Pad Color	Part Number	Cost
5mm	White	33-53-1-136-385	$9.71
7.5mm	Black (standard)	33-53-1-136-386*	$6.25
10mm	Red	33-53-1-136-387*	$10.60

*Also used on BMW Motorsport, E30 M3 Gr.N, Coupe, S14, MANUAL, EUR, (ST01)

And for springs, the E30 is the same rear spring as the ti and Z3 roadster (and Z3 Coupe), so you can experiment there with used springs or whatever.

E30 M3 Group A / DTM rear springs (should fit ti rear using ti spring pads):
COIL SPRING 100-60-115 31.33.2.222.939
COIL SPRING 100-60-120 33.53.2.222.153
COIL SPRING 100-60-140 33.53.2.222.154
COIL SPRING 100-60-160 33.53.2.222.155
COIL SPRING 100-60-180 33.53.2.222.208

(I think all of these are now NLA, but you might find something kicking around...)


Also, Condor Speed Shop sells (or did sell) adjustable rear spring pads to dial the height/corner weighting in. I imagine others do as well now, if they don't.

Remember to align the car with the tank full and the driver in the seat (or something the same weight).