Problem after R32 front brake upgrade- please help diagnose - Page 2

Nash_TDI · May 15th, 2012, 07:16

If its down to mms then it MAY be ok. Something with the wheel bearing/hub assembly might not be fully seated. I just did mine Sunday.

Addamsonflint · May 15th, 2012, 07:53

Quote:

Originally Posted by LNXGUY

Something is definitely a miss if one side lines up and the other doesn't....

Yes, there is definitely something. I mean...we're talking about a very slight variance, but very odd, and very few items to cause the issue.

Any thoughts?

Doc_Oc · May 15th, 2012, 08:14

What rims are you using? Replicas? Cheppos? There might be a difference from rim to rim. Try one of the rear wheels instead and see what the clearance is like.
If the bore size is off a little on one of them it could sit in or out by as much as 5 mm.
I would blame it on the wheels before anything else.
Also, if the spindles, carriers, are off a wrecked car, who knows how they got hit: curb impact, side impact with another car...
I would say 1-2 mm is to little clearance, especially in 18" wheels. They do flex ever so slightly.

millerlite · May 16th, 2012, 11:54

Are your pads used? the difference could be because of the fact that the pads on one side are worn more than the other causing the calliper to stick out more (they are on sliders after all)

LNXGUY · May 16th, 2012, 12:58

Quote:

Originally Posted by millerlite

Are your pads used? the difference could be because of the fact that the pads on one side are worn more than the other causing the calliper to stick out more (they are on sliders after all)

Calipers are bolted to carriers which are bolted to the spindles.. That's static and never changes. Pad thickness won't have anything to do with it.

millerlite · May 16th, 2012, 13:12

I need to draw a pic. It depends on what part of the wheel its rubbing, but the calliper moves in towards the car as the pads wear. Think about it for a second. Your disc is static, the callipers are not. As the outside pad wears, the piston pushing the inside pad against the rotor which pulls the entire calliper inward, providing more clearance between the wheel and calliper. I have seen this first hand, my wheels needed spacers after I replaced my pads.

LNXGUY · May 16th, 2012, 13:18

(Closing eyes and picturing caliper in my head, lol)

I think you might be onto something here. Makes perfect sense seeing that one side fits, and the other doesn't.

1854sailor · May 16th, 2012, 13:45

Easy way to find out if it is simply a tolerance issue would be to switch the wheels side to side.

Addamsonflint · May 16th, 2012, 15:53

Yeah, that is definitely the case. Basically, I can put a washer in between the carrier and the spindle, and without using too thick of one, it shouldn't make too much of an issue, but we will see. If you used a really thick washer, or several washers, the problem you would run into would be, when you go back to put the caliper on top of the rotor, and slide it down, you would run into the carrier, rather than fit past it, at the point where you screw in your slide pins.

However, if your outside pad were thinner, it would allow for more room for the caliper to move inward and clear the carrier. Again, this is all taking into account modifying spacing at least 3-4+ mm. At 3mm or less, I don't think it will be a problem, but we will see. My spacers arrive tomorrow and then I'll take my carriers off too, and see what the washer spacing does. I may not even need it, but I want to at least try it for future reference.

FlyTDI Guy · May 16th, 2012, 16:09

Just a side note (not to add to your grief) but... how thick did you order and are your current lug bolts long enough to accommodate? You don't want to short yourself too many threads or bad things could happen.

The primary question of WHY the sides are not the same remains. Like yourself, despite having a 'band-aid' available, I'd sure want to get to the bottom of it. Pad thickness may vary between mfg's but with piston completely retracted, a new pad should fit with some tolerance for clearance on the rotor. Using used pads, it's possible to put the inboard pad on the outboard side of the rotor and then, visa-versa on the other side creating an uneven clearance to the wheel. Inboard pads (piston side) always wear faster due to the physics of a sliding caliper design. Forgive my ignorance but, are the R32's a nice 2 or 4 pot design?

alhutch · May 16th, 2012, 21:10

Any pictures of the affected area? What wheels do you have?

HUVW · May 16th, 2012, 21:48

Quote:

Originally Posted by HUVW

Are your wheels straight?

Good luck.

Like many have mentioned, switch wheels to address the problem most easily identifiable.

Then you can start taking the brake system apart to insert washers and install the spacers if the wheels aren't the issue.

Again, good luck.

JettaGetUpandGo · May 18th, 2012, 19:41

I had the same issue trying to fit wheels over R32 brakes last summer. One side had 2-3mm less clearance than the other side. I caved and ground a little bit off the calipers to create more clearance in addition to using a small spacer.

Addamsonflint · May 18th, 2012, 20:15

Quote:

Originally Posted by JettaGetUpandGo

I had the same issue trying to fit wheels over R32 brakes last summer. One side had 2-3mm less clearance than the other side. I caved and ground a little bit off the calipers to create more clearance in addition to using a small spacer.

I get why some would cringe at shaving a caliper- but if done carefully and in very small proportion, it doesn't hurt much. My wheel spacers were supposed to be here tomorrow, which would be an easy and solid fix, but they won't get here until Monday- but I will have plenty of garage time this weekend, that I can look at several different things, that others have mentioned. I am going to see what some moderate washers between the carrier and spindle do. I am also going to swap wheels to look at that as a possible culprit.

I'm also going to take some solid measurements, especially because of the curiosity- because at that point in the drivetrain, there are very few components that could contribute to the issue. I fully seated my bearings and circlips. I pressed my wheel hubs in all the way, and while it would be pretty hard to miss 3+mm, torking my axle nuts past spec 200 ft-lbs, would have seated my hubs the rest of the way, had I missed it to such a big distance.

After that, the only parts that will affect spacing are my carriers and wheels. I mean....calipers, spindles, these are hugely solid cast metal parts, and OEM factory parts forged in the same iron molds they cast thousands of other parts- the issue simply isn't there. But the wheels are aftermarket, not cheap, but there is at least the possibility of imperfection, and maybe a carrier is slightly bent or something.

I will measure this weekend, and post the results...