Inverting/Swapping front strut mounts E36 M3

[sebdavid]

Looking for inexpensive ways to reduce understeer on my car all over the Internet, I came across this:

http://forums.bimmerforums.com/forum/showthread.php?t=995556

It talks, among other things, about swapping the front strut mounts on 96+ E36 M3s. It's not the first time I see this, too.


Swapped 96+ M3 upper strut mounts
- (free if you have a 96-99 M3, or about $75 used on bf.c)
- relatively easy to install
- gain about -2 deg. camber (about -3 deg total per side)

[...]

Q. How do I find/install the 96+ upper strut mounts?
A. If you have a 95 M3, you can find some used on bf.c. If you have a 96, 97, 98, or 99 M3 you already have these. These upper mounts or "top hats" are a steel plate with 3 studs to bolt to the shock tower, and a ball bearing in the center that holds the top of the strut shaft. You'll have to remove the entire spring/shock assembly on each side, and using a spring compressor to keep tension on the spring. Then you will need an impact tool to remove the top strut nut. Once the nut is off, you simply swap the strut hats from Left to Right, and reinstall. [It is a good idea to clean and repack the bearing before you install/re-install them]. You should have about -2.5 to -3 deg. camber. Don't forget to get an alignment afterwards.

Anybody try this? What do you think?

I know buying camber plates, or even better a complete suspension setup including camber plates would be the real way to go, but right now I'm not willing to spend much money on this, I'd rather have more track time. I won't keep the car forever, but the skills I gain on track will stay with me a long time.

[LagunaM3]

I've heard of a few people doing this. I haven't heard of any problems. You will be stuck with a lot more camber, so I wouldn't do this on a daily driver. And you're going to want to get an alignment afterward, too.

Also, keep an eye on the strut housings for cracks. I don't know if swapping the mounts will make them more prone to crack or not, but I know that area is sometimes weak. Just keep an eye on it.


Looking for inexpensive ways to reduce understeer on my car all over the Internet, I came across this:

http://forums.bimmerforums.com/forum/showthread.php?t=995556

It talks, among other things, about swapping the front strut mounts on 96+ E36 M3s. It's not the first time I see this, too.



Anybody try this? What do you think?

I know buying camber plates, or even better a complete suspension setup including camber plates would be the real way to go, but right now I'm not willing to spend much money on this, I'd rather have more track time. I won't keep the car forever, but the skills I gain on track will stay with me a long time.

[sebdavid]

Guess I'll start out with trying the 235's all around, then if I still get too much understeer I might try this... or go with camber plates.

[Emre]

My feeling is that unless you can buy the strut top mounts for very, very little money, it's probably not worth it. Unless you're doing the work yourself, most of the cost will be labor. And the labor cost will be exactly the same regardless of whether you install OEM top mounts or aftermarket camber/caster plates.

Even if you can do the job yourself, it's a bit annoying (especially if you've got some corrosion, as most Quebec cars do). You'll need some tools that a typical hobbyist might not have easy access to: a spring compressor, a solid bench-top vice, and maybe an impact gun.

Considering you should be able to find new or used camber/caster plates for not much more money than a set of new OEM top-mounts, it's probably not worth the hassle. Used mounts are often in rough shape and generally not what you'd want for reliable track use. Unless you can get like-new OEM mounts for close to free, I wouldn't bother.

[sebdavid]

Emre... I have a '98 M3... I would use my stock strut mounts. So only labour cost.

Apparently there isn't too much tire wear on the inside by doing this with a daily driver. Seeing as my car doesn't see huge mileages, I think that wouldn't be too much of an issue for me, at least certainly not as much as the outside tire wear I see on track.

But again, I'll try one event with just the square tire setup, see how much that improves things, then if it has to come to that I'll try this mod.

Only trouble is it'll cost me another alignment if I do it, so that's yet more labour.

Why is my hobby not Sudoku or something?

[LagunaM3]

Apparently there isn't too much tire wear on the inside by doing this with a daily driver. Seeing as my car doesn't see huge mileages, I think that wouldn't be too much of an issue for me, at least certainly not as much as the outside tire wear I see on track.


You'll minimize your tire wear if you align the front with 0 toe. Toe in or toe out will increase the wear. And 0 toe will be pretty good on the track.

[sebdavid]

Yup, that's what the FAQ I linked to above recommends.


Q. What is a good track/autox alignment?
A. Most track guys already know what to do here, but for general FYI, a good baseline is:

Front
Camber: -3.5 deg per side
Toe: 0 (0.10-0.20 total toe out for autox)

Rear
Camber: -2.0 to -2.5 deg per side
Toe: 0.20 total toe in (IIRC this is 1/8" total toe in)

[Emre]

Emre... I have a '98 M3... I would use my stock strut mounts. So only labour cost.Sorry, I misunderstood. I thought you were taking about putting newer top mounts onto an older car. But it looks like you're talking about switching your existing mounts from left to right.


Apparently there isn't too much tire wear on the inside by doing this with a daily driver. Seeing as my car doesn't see huge mileages, I think that wouldn't be too much of an issue for me, at least certainly not as much as the outside tire wear I see on track.Minus 3 degrees of negative camber is not a crazy amount. As Pritpal mentions, your toe settings will have a bigger impact on uneven tire wear compared to your camber settings. If you set the car with 0 toe all around, your tire wear shouldn't be excessive at all...especially if you do a balance of street driving (more wear on the inside) with track driving (more wear on the outside).

[LagunaM3]

If you set the car with 0 toe all around, your tire wear shouldn't be excessive at all...especially if you do a balance of street driving (more wear on the inside) with track driving (more wear on the outside).

I wouldn't do 0 toe in the rear. That will make the car real twitchy. That's good if you're autocrossing. 1/16" toe-in per side at the rear is what I'd go with, but that's just MO.

[Emre]

Good point. Besides, with a little bit of toe-in at the rear you'll have something close to 0 toe under power. Seems perfect.

I actually used to run my Evo with 1/8" toe out in the front and 1/16" toe out in the rear. Sounds crazy, but it worked very well with the stock suspension and street tires. Made it pretty easy to rotate the car at corner entry and keep it 4-wheel-drifting under power. Otherwise, there was more understeer than I was comfortable with.

[sebdavid]

Well it's good to see that your suggestion is exactly the same as is mentioned in the link I gave (see quote above).

I think I'll give it a try.

[Gregster]

driving in Montreal actually creates negative camber :p