[XutvJet]

About a week and a half ago, I installed Dinan springs on the rear axle only of my M235. I also did the Dinan rear spring spacers so the drop wasn't so aggressive and also did the bumpstop kit. I did the rear axle springs only because:

1) I've always felt the rear axle pogoed around way too much. The Dinan springs add 30% more rate and have a 1" drop without the spacers and around a 3/4" drop with the spacer.

2) I thought the rear gap was a bit excessive in stock form.

3) I like the look of cars like the 1M or older M cars where the rear wheel gap is tighter than the front. The Dinan springs achieved this. The front gap (still stock), is about 2 fingers and the rear gap is barely 1 finger after settling. Most of the settling occurred on day 1.

4) I didn't do the front springs because they only add 10% more stiffness and 1/2" drop. I didn't want the drop and I've never had issues with the front axle except for too much understeer and the lack of camber killing the tire shoulders. I've addressed this by running 245/35s up front. It doesn't fix the camber issue, but the tires have much stiffer sidewalls and there's a ton more lateral tread now.

I am astounded in how much more controlled the rear axle is now. I had no idea the rear springs were so bouncy and weak. The car feels more stable, far less pogoing, less roll, more steering directness, and just a better ride. The reduced roll reminds me of adding a rear sway bar, but without the sway bar compromises in tight and bumpy turns. The car in Comfort mode feels very acceptable too and much more sporty and taunt. It's crazy to me the difference. This is really the way the car should have come from the factory. This setup is exceptional for sporty daily driving. The only negative is when you hit a really big bump. Only in those situations is the reduced travel apparent and the car will bottom out quicker. In all other situations, it's superb.

Before. Stock springs.


After. Dinan springs, rear only. Stock front springs.

[jondagger]

if you were to make your wheel width 8.5 instead of your 8".... do you think the additional 0.25" inward thickness of the wheel would make contact/clearance issue to strut?

saw you noted a 8mm clearance to strut.... thats like 0.3"

[XutvJet]

The issue with 8.5 rims is that extra 1/2 inch. You might get the offset correct to barely clear the strut, but the inner edges of the tires may contact the fenders liners. I think my 18x8et43 wheels with 245/35 tires is as far as you can safely go in the front. Keep in mind the front tires are dang near flush with the fender too with this setup. Yes, the tires clear the strut by maybe 8mm, but when tires are expanding and suspension is moving around in its mounts, I would imagine that clearance is further reduced a bit.

If you can get wheels custom made, then do a 18x8et43 in the front. This setup looks VERY meaty in the front. I have no issues with rear traction either on 245s. The LSD and MP4S tires do just fine putting down the power.

[jondagger]

Originally Posted by XutvJet

The issue with 8.5 rims is that extra 1/2 inch. You might get the offset correct to barely clear the strut, but the inner edges of the tires may contact the fenders liners. I think my 18x8et43 wheels with 245/35 tires is as far as you can safely go in the front. Keep in mind the front tires are dang near flush with the fender too with this setup. Yes, the tires clear the strut by maybe 8mm, but when tires are expanding and suspension is moving around in its mounts, I would imagine that clearance is further reduced a bit.

If you can get wheels custom made, then do a 18x8et43 in the front. This setup looks VERY meaty in the front. I have no issues with rear traction either on 245s. The LSD and MP4S tires do just fine putting down the power.

Well said.

If i start rubbing liners, ill just push them in if possible. I dont want to buy customs, although BC Forged would be the way to go if i do (cheapest/highest quality customs forged). Probably doing Apex EC7 with some 2mm/2.5mm spacer in front for the et43/et42.5 8.5" wheels. Probably have to get 35 profile tires..... 5mm spacer rear for et53 essentially.

Drove my buddies m235i on camber plates, 245 front firestone, and KW coil overs. The car was so confident inspiring and the camber plates helped alot with front stiffness. Also, those tires are a massive help too! He wasnt even using PS4S and they were 19" wheels, so there is even room for improvement. I drove it to test his strut bar but there was so much shit going on, i think the strut was negligible