TCKline...I need your expertise for an Xi coilover issue

[bombguy]

There has been "grumblings" on this subject for a bit now and I'm hoping you can straighten me and the rest of the Xi owners out on this.

Okay, the word is that if you have an Xi on coilovers, and you lower it as low and it can go without any rubbing issues that it will result in CV joint damage. My thoughts are that it should not affect the joints one bit and heres why:

My argument to this would be that a CV joint is designed to flex and operate at a variety of angles during the course of normal road driving. At times, the suspension may go to full droop or may get pushed into the fender well. Also, look at the steep angle the CV has when the car is not lowered! The stock angle is probably siting at around 15-20 degrees with the car on a flat surface...possibly less. So when you lower the car, it actually straightens the line of the joint (or perhaps changes the angle slightly in the opposite direction), and really doesn't flex beyond that angle much with the stiffer spring rate either. All of these angles, though, are within the normal operating angles the car would experience during normal driving in my mind. So this is the only reason I ask why going lower is an issue on the axles? If you've ever raised a 4wd truck you kinda get the opposite end of the spectrum and you run into the binding issue....the angle being too steep and the CV not being able to rotate properly....but you won't run into that issue on a lowered car.

Also, I have personally been on H&R sport springs for about 3 years now and have not experienced any issues that directly caused any tearing of the CV boots either. Some say that lowering xi's cause the boots to tear. I absolutely do not believe this and I think my car is proof.

So maybe you guys, or someone else can refute or back up what I'm trying to ask. I just want to benefit any Xi owners out there with suspension quandries!! Thanks!!

Out of 58 people viewing this thread....if you have input, I would like to know what you think as well!

[robjohnson]

If you want honest input...I worked in the 'industry' for about 4 years and did hundreds of suspensions. I hated it when people with Xi's would call because of this very reason, I think I sold 2 xi suspensions (not real performance stuff either) ever so probably nobody has any real experience with them. They aren't a performance car, at all, so it's pretty uncommon in the aftermarket to really work with them. In general I also consider the E46 to be a poor quality car for various reasons and the Xi can only be worse because of the increased complexity.

You should remove the spring and run the car through it's full range of shock travel and check the angularity. You can also unhook the shaft and rotate it through it's maximum range to see just what it is. You should probably just do that and not rely on others to get information you need to keep the car reliable. It's very possible you are right, BMW may have designed them for a full sweep with no mechanical interference.

But...I have a friend with an Xi who has had issues (boots tearing and bearing cages breaking) with the CV's with no modifications whatsoever. You may well be ok, but honestly unless they've had an Xi in the shop and done this, I doubt they'll have the answer you want. I'd bet money on you having problems if you slam the car because you not only have vertical angularity but also some introduced from steering. They are pretty freaking expensive Genuine BMW only parts IIRC too.

[bombguy]

If you want honest input...I worked in the 'industry' for about 4 years and did hundreds of suspensions. I hated it when people with Xi's would call because of this very reason, I think I sold 2 xi suspensions (not real performance stuff either) ever so probably nobody has any real experience with them. They aren't a performance car, at all, so it's pretty uncommon in the aftermarket to really work with them. In general I also consider the E46 to be a poor quality car for various reasons and the Xi can only be worse because of the increased complexity.

You should remove the spring and run the car through it's full range of shock travel and check the angularity. You can also unhook the shaft and rotate it through it's maximum range to see just what it is. You should probably just do that and not rely on others to get information you need to keep the car reliable. It's very possible you are right, BMW may have designed them for a full sweep with no mechanical interference.

But...I have a friend with an Xi who has had issues (boots tearing and bearing cages breaking) with the CV's with no modifications whatsoever. You may well be ok, but honestly unless they've had an Xi in the shop and done this, I doubt they'll have the answer you want. I'd bet money on you having problems if you slam the car because you not only have vertical angularity but also some introduced from steering. They are pretty freaking expensive Genuine BMW only parts IIRC too.

Rob, thanks for the suggestion on running the suspension and checking the full range without the springs. I appreciate your input.


I also wanted to thank you for an entirely different reason. Your response was absolutely thought out and well presented...which is very rare on a site that seems overrun with kids and people who just take their cars to the shop to get work done. There are good people on the site and you have just restored my belief in what forums like this should be about!!

[Red Z3]

I have an E36 M3 sedan, TCKline SA with 450/500 springs, UUC bars set to medium, Star Specs on 245/40-17 with Kosei 17 X 8.5.

It picks the front tires up almost 2 inches out of turns. What needs to be done to bring the tires back down?

[TC Kline Racing]

I agree with you on the binding issue. Without getting too technical, if people want to lower the car an inch or so, it should not make a difference.