Wheel heating up.

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Boosh
Joined: Sun 30 Nov, 2014 22:40
Posts: 304

  Z3 roadster 1.9i

Wheel heating up.

Post by Boosh » Sun 27 Mar, 2016 16:44

Hi all,
I noticed a while ago a wheel (rear right) heating up, and giving out a burning smell. It wouldn't happen all the time, but was worrying enough. I followed some advice on here and removed, inspected, and refitted the pads, but they seemed fine. Caliper was pushed back, all seemed in order. But the wheel carried on heating up. The last mot reported corroded handbrake cables, so I thought that might be the issue. Because of the lack of access, I supplied the parts (shoes, springs, cables, for both sides) to my garage, that replaced the cables and fitted the new bits. However, after a short trip, wheel got hot again, with slightly different 'hot smell.' I tend to think it might be the shoes not releasing their 'grip' on the inside of the top hat disc, and intend to have a look tomorrow. This is becoming a problem as I plan on attending my sister's wedding with RedZed all dressed up, in a fortnight. But only if I can sort that issue out. As always, all help appreciated.
Thanks,

Boosh.
Last edited by Boosh on Mon 28 Mar, 2016 16:57, edited 1 time in total.

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BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
Posts: 2220

  Z3 roadster 1.9

Re: Heating wheel.

Post by BladeRunner919 » Sun 27 Mar, 2016 16:58

If you jack the car up with the handbrake off and turn the wheel by hand, does it bind at all?

Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2115

  Z3 roadster 1.9

Re: Heating wheel.

Post by Del » Sun 27 Mar, 2016 17:16

If the wheel is moving easily with the handbrake off, my guess is that this sounds like a sticking calliper issue. If the handbrake shoes and cable have recently been replaced (and were working and adjusting OK at that time) there isn’t really anything on the handbrake mechanism that can seize.

Some people advocate stripping callipers and buying refurb kits from firms like “Big Red” and others (like me) prefer to replace the calliper. I bought “remanufactured” ones for my front, from GSF – from memory they were about £60 each after exchange. If you have a brake hose clamp it is a relatively easy and quick job – no need to remove the calliper carrier.

Boosh
Joined: Sun 30 Nov, 2014 22:40
Posts: 304

  Z3 roadster 1.9i

Re: Heating wheel.

Post by Boosh » Sun 27 Mar, 2016 19:20

When I took it all apart before the garage changed the cables and refurbed the handbrake mechanisms, I loosened the shoes with the little wheel adjuster and tested the handbrake, albeit with the old cables. Being on my own, it was difficult to appreciate the range of movement of the shoes, but I already suspected they would not come back enough. I think the shoes might be catching on the splash guard, not releasing pressure on the disc. Is that possible, or do you reckon I'm barking up the wrong tree?

Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2115

  Z3 roadster 1.9

Re: Heating wheel.

Post by Del » Sun 27 Mar, 2016 23:17

If the handbrake shoes are seated properly into both the adjuster and cable-pull mechanisms and held in by the spring pins and horizontal springs, they can’t be sufficiently out of position such that they would seize against the inside of the drum. There is a small, natural amount of contact between the brake shoes and backing plate – but not enough to cause a “locking-up” and the horizontal springs should be more than strong enough to pull them back into position when the handbrake cable is released. No harm is examining and checking everything to satisfy yourself, but my guess is that the piston is not moving freely inside the calliper.

Boosh
Joined: Sun 30 Nov, 2014 22:40
Posts: 304

  Z3 roadster 1.9i

Re: Wheel heating up.

Post by Boosh » Mon 28 Mar, 2016 17:23

Well, the plot thickens!
After stripping the rear right wheel (the troublesome one) to check that pulling and releasing the handbrake lever affected the position of the handbrake shoes, I noticed that, even with the handbrake on, I could spin the wheel by hand, whereas the rear left wheel was, as expected, rock solid. So I set out to adjust the position of the rear right shoes with the little cog mechanism. Still couldn't get handbrake to seize the wheel. I eventually stripped out the rear left wheel (the working one) to measure the gap between the shoes at both top and bottom. To my surprise, the shoes on the right wheel were exactly the same distances apart. I inspected the discs, and noticed that the right one didn't seem as evenly worn on the inside as the left one. So I swapped them over and put all the bits back on. Before letting the car down, I put the handbrake on and tried to spin the wheels by hand. This time, it's the right one that was rock solid, and the left loose, implying that the right disc ( now on the left side) was faulty. I then took the car out for a quick test drive. On my return, the right wheel was hot again! I'm now puzzled: the fact that it is the same wheel heating up would point to a faulty caliper, but why would a loose wheel on the handbrake travel with the disc? I know that renewing calipers and discs+pads wouldn't do any harm, but I'd rather not spend all that kind of money in one hit.
As always, any help or experience much appreciated.
Thanks in advance,

Boosh.

John Wilson
Joined: Fri 12 Jun, 2009 13:11
Posts: 240

  Z3 roadster 2.0
Location: Diss

Re: Wheel heating up.

Post by John Wilson » Mon 28 Mar, 2016 17:35

Could it be the wheel bearing, and nothing to do with the brakes?

Boosh
Joined: Sun 30 Nov, 2014 22:40
Posts: 304

  Z3 roadster 1.9i

Re: Wheel heating up.

Post by Boosh » Mon 28 Mar, 2016 18:04

I thought of that, but there's no play at all in the bearing, and wheel spins as freely as other side when stripped of brake disc and caliper...

Boosh.

bertiejaffa
Joined: Fri 26 Jul, 2013 10:28
Posts: 1715

  M roadster S50
Location: Manchester

Re: Wheel heating up.

Post by bertiejaffa » Mon 28 Mar, 2016 18:15

If the brakes are good then I second the Bearing comment.

My M had its brakes fully rebuilt twice last year but still suffered with a heating rear wheel and some squeaking. I eventually realised that the squeak happened when I weaved the car left but disappeared when I weaved right. Took it back to my garage and the stripped it down and examined the bearing, no play in it, and no noises even through a stethoscope - however, bearing changed and the issue went. They admitted they had never seen it before.
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Boosh
Joined: Sun 30 Nov, 2014 22:40
Posts: 304

  Z3 roadster 1.9i

Re: Wheel heating up.

Post by Boosh » Mon 28 Mar, 2016 20:12

Thanks, John, Bertie,
I imagine that the heat caused the disc to move in such a way that the handbrake shoes lose their grip on it, explaining why the 'loose' wheel changed sides when I swapped the discs over. They will therefore (eventually, along with the pads) need changing. But how can I determine whether the heating-up was caused by the caliper or the bearing in the first place? Short of playing the parts roulette, I'm not sure: I wound both calipers back in today, with very similar resistance on both sides. And I checked the wheel for play in the bearing, which I couldn't detect.
Any suggestions?

Boosh.

bertiejaffa
Joined: Fri 26 Jul, 2013 10:28
Posts: 1715

  M roadster S50
Location: Manchester

Re: Wheel heating up.

Post by bertiejaffa » Mon 28 Mar, 2016 20:53

Boosh wrote:Thanks, John, Bertie,
I imagine that the heat caused the disc to move in such a way that the handbrake shoes lose their grip on it, explaining why the 'loose' wheel changed sides when I swapped the discs over. They will therefore (eventually, along with the pads) need changing. But how can I determine whether the heating-up was caused by the caliper or the bearing in the first place? Short of playing the parts roulette, I'm not sure: I wound both calipers back in today, with very similar resistance on both sides. And I checked the wheel for play in the bearing, which I couldn't detect.
Any suggestions?

Boosh.
If the caliper winds back in easily it is fine - the only other problem part there could be the slider pins corroded. If you really want to change out the brake components first then maybe PM spursfan who might be able to sell/loan you some rear calipers.

My money is on the wheel bearing - as I say there was no play at all on mine when I tested it but under load it was the cause of the problem.

EDIT:

When you drive is there an any audible noises from the wheel, squeaks, knocks etc
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Boosh
Joined: Sun 30 Nov, 2014 22:40
Posts: 304

  Z3 roadster 1.9i

Re: Wheel heating up.

Post by Boosh » Mon 28 Mar, 2016 21:09

Thanks, Bertie,
Yes, calipers got back in ok, pins with no corrosion, and greased up. However, no discernable play, squeak, or noise in/from bearing, though it seems the likely culprit...It's gonna be one of those 'cheap part, expensive labour' jobs, isn't it?

Boosh.

bertiejaffa
Joined: Fri 26 Jul, 2013 10:28
Posts: 1715

  M roadster S50
Location: Manchester

Re: Wheel heating up.

Post by bertiejaffa » Mon 28 Mar, 2016 21:29

Boosh wrote:Thanks, Bertie,
Yes, calipers got back in ok, pins with no corrosion, and greased up. However, no discernable play, squeak, or noise in/from bearing, though it seems the likely culprit...It's gonna be one of those 'cheap part, expensive labour' jobs, isn't it?
I can't remember personally but yeah i seem to recall it was around £120 ish.... you never know they might be able to confirm it is gone before they do it to at least take the guessing out of it.
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Boosh
Joined: Sun 30 Nov, 2014 22:40
Posts: 304

  Z3 roadster 1.9i

Re: Wheel heating up.

Post by Boosh » Sat 16 Apr, 2016 12:47

Well, finally got it sorted. A home mechanic came to have a look, pushed the caliper back to feel the resistance, jiggled the hub about, inspected the discs and noticed that though they had plenty of meat left, the pads looked old and the contact surfaces with the discs on the internal and external faces of the discs were uneven. Caliper felt fine, and he found no play in the hub. So I ordered new discs and pads for both sides, obviously. And hey, presto! everything's fine again. The wheels still heat up with use, but both sides symmetrically, and without burning smell like it used to. One can only conclude it was the pads 'licking' the discs a bit too close. Slight issue with the handbrake not gripping quite enough, but this might improve as the new shoes and new discs get some use.
In any case, my heating wheel was simply due to old pads/discs: easy fix!

Hopes that helps anyone with similar issue,


Boosh.

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