Mixing springs on a cabrio

[Jon '92 325ic]

I recently had Bav Auto Springs installed on my car (replaced the Boge shocks and struts and put 3mm pad in front, 10mm pad in rear). My only reason for doing this was to get rid of the front end gap that you get with the OEM setup. The Bav Auto Springs are supposed to lower your car on average 30mm or 1.25". The only other suspension mod I have is a Strong Butt Strut, which I love.

After a couple months of driving, I'm thinking I'd like to raise the rear a bit (maybe .25" - .50") from where it sits now with the Bav Auto Springs. The reasons I want to raise the rear a bit is to provide a little extra clearance for the Strong Butt Strut.

Besides doubling up on the spring pads in the rear, what can I do here? Can I replace the rear springs with either e30 M3 springs or M-Technic springs or go back to the OEM springs? Or is it not advisable to mix front and rear spring sets? Would having front springs from a different manufacturer than the rear springs put the driveshaft deflection angle out of whack? Is another option to install aftermarket rear camber adjustment plates (like IE's)? Do these plates raise the rear at all?

I'm just seeing what my options. None of these options above are appealing to me, but hopefully someone knows more about this and can help.

Any advice is appreciated. Thanks

[Digitalwave]

Your best bet is to stack spring pads in the rear in my opinion. I don't know what a strong butt strut is though, and why do you need more clearance for it? Let me cover some of your options:

Mix and match springs is a bad idea. Every spring company matches the front and rear rates for balanced handling, but not all spring companies use the same rates. Putting some other rear springs and keeping your fronts can severly mess up your handling. You MIGHT be able to pull off M3 rear springs, just because Bav Auto springs are so soft. But I wouldn't think these will raise your car up. I had them in my 325i and the rear was level with the fender, maybe a little tuck. With the extra weight of the cabrio, it will still be low in the rear.

The driveshaft deflection has nothing to do with ride height, since the subframe and diff stay static regardless of ride height. It's the handling issue that is the problem.

There is no such thing as rear camber plates. The spring is not mounted on the shock in the rear, and there are no control arms. The way to correct camber in the rear is by modifying the subframe, and it doesn't raise your car up.

To recap, I think you should either stack more spring pads in the rear, OR buy a set of cabrio-specific springs. H&R Sports are available in a cabrio-specific drop and spring rate. They don't lower the rear as much, and the rear springs are a little stiffer. You could even stack some more rear pads with those springs and have a nice factory looking stance.

[Jon '92 325ic]

Thanks for the thorough reply

Here's my thoughts on stacking rear spring pads (2 - 10mm pads). If BMW thought it was ok to stack rear spring pads that high, they would have made an option of a 20mm spring pad, in addition to the 3mm, 6mm and 10mm options made available during manufacturing and gladly charged us a ridiculous amount of money for them too. The fact that a 20mm rear spring pad was never an option leads me to believe that BMW engineers don't recommend using rear spring pads that tall. I know guys have done it and have no problems, but it just sounds not worth the risk to me.

Thanks for your feedback though. Definetly not gonna even consider mixing/matching springs. Will give doubling up on pads some more thought though.

BavAuto springs are cabrio specific and although advertise the least amount of drop, not happy with the results (too low for comfortable daily driving in Los Angeles). Perhaps I'll look into either e30 M3 springs, or M-Technik springs or the shortest of the three different OEM spring heights available for the '92 cabrio.

[Digitalwave]

I think E30 M3 springs will be too low as well, and they are too soft (bottoming out) to be comfortable. They dropped my 325i about an inch all around, and on a heavier cabrio its going to be too low in the rear for your tastes.

I hope you find something that you can be happy with.

[Sean]

I stacked two spring pads in the rear of my car, just to get a bit more rake and eliminate any rubbing from my tires and no issues here.