Axle Stands, now a question about brakes

[BigFas]

Need to do some work under the car today, as there will be a lot of shaking and testing, I want to be safe and use axle stands, however, I don't know where to place them.

Do I put them under the control arms? If so, surely when I release the weight of the car, the suspension will make the control arm travel up?

Do I put them under the sill, near the jacking part (this is the most obvious I think??)

Anywhere else?

Just off to halfords to buy some copper grease, so will check in a few.

Thx fellas

[Silver]

http://m3.madrussian.net/diy_jacking.shtml

read very carefully

[Chaos]

Aye drop them under the jack pads bro. That site is pretty good Silver, nice find.

[BigFas]

Thanks for the info on the axle stands. Came in useful.

Anyway, now I think I may have a problem with my brakes. When we recently went to the Ring and also to Rockingham yesterday, was driving along when suddenly, on perfectly smooth roads, it felt as if I was driving over cats eyes in the motorway. Every second, a thud came through the steering wheel.

When we went to the Ring, Dan mentioned it could be a sticky caliper and when we went to Rockingham yesterday, I pulled over to the hardshoulder and there were copious amounts of steam (water from the rain) that was coming from the front passenger side wheel.

Jacked the car up today to have a look see. When I took the wheel off, I tried to free-wheel the brake disc. It moved fine EXCEPT that one section of the disc seemed to catch on the pads like it was warped. I'm talking MINIMAL contact, i.e. a few thousands of a mm, it continued to free-wheel through the contact area, i.e. when contact between the pads and disc was made, it still carried the momentum through to continue as opposed to gripping fully and stopping.

My assumption is that when driving, the heat builds up, disc expands and the rubbing becomes more noticeable. Now, this is the REAL question.

Why doesn't the judder happen all the time? The judder has only happened twice. Both of those times I pulled over, waited about 2 minutes having a walk around and scratching my head, then continued my journey with no problem at all. On the way back from Rockingham, and even the Ring, it never happened, so continued driving at high-speed doesn't necessarily bring it on.

I tried to remove the brake pads to pack the back of them with grease, but I couldn't figure out how to get the pads out. I managed to get access to them, just couldn't figure out how they physically slid out.

Anyway, any other ideas about what I can do? What the problem is? Resolutions?

THx

[peppernick]

Either the disc or one of the pads/both pads are not seated properly. This is my guess. It's worse when it gets hot and the effect is felt most at a certain speed. Going faster kind of 'overcome' the feedback. I had similar issues with my old APs but other than touch-grinding, the brakes were 'moaning' as well.

First thing I'll do is to completely rebuild the effected side. Sometimes a piece of gunk or similar might get stuck in between flush fit components, eg: the discs and the wheel hub surface.

Also, swap your discs round as they are most likely not heating up and cooling down efficiently as they should when the flow vanes are rotating in the opposite direction.

Pad removal from BBKs is easy. Remove the 2 screws holding down the pad retainer (the two above and on either side of the StopTech logo) and you should be able to pull the pads out of the caliper. They are loose fit once the retainer is off. If not, your pads have seized inside the caliper, which is probably the source of your probem. Pry them out with a flat head screwdriver and clean the pads and the inside of the caliper rigourously with brake cleaner. Once the pads are out, you can just undo the single cap screw holding the disc to the hub and the whole disc just fall out.

[BigFas]

Nick, I removed those two screws and removed the access panel to the pads, the pads just weren't coming out. If you're free next weekend, maybe I can tempt you with a pizza? :)

Also, would you recommend using WD40 on the brakes? I was hesitant as it's a flammable liquid and there was nothing on the can about working in high-temp environments.

[peppernick]

would you recommend using WD40 on the brakes
Noooooo!!!! Never! Don't! WD-40 can destroy the piston seals and if any of the stuff gets between your disc and pads, you'll have trouble. A good clean and copper grease will do the trick nicely.

Should be able to next weekend. I'll give you a call later in the week. I need to speak to Jason about my front respray, so Sat am should be good.

[adood84]

Fas I saw the guy at the dealer do my brakes a couple of months ago and he used some kind of Brake cleaner spray can and he was spraying it all over the brakes pads ...ect , BMW sells this stuff to customers

[Chaos]

WD40 is a lubricant, and that's bad for brakes. I'm guessing there's some crap on the top or bottom surface of the brake pad that's sticking now and again. Possibly a caliper piston but I'd expect to see that happen more often than we have. A strip-down should hopefully resolve it, I'll pop over next weekend and help out if I can be of use (other than eating, of course, which I'm really useful at :p).

[BigFas]

Thanks for the heads up fellas, Dan, definitely use your spanner monkey help :)

When I mentioned is WD40 a good idea to use, I meant, with regard to unseizing the brake pads. I bought a tub of copper grease for final assembly.

Hopefully between myself, Nick and Dan, we should be able to strip down and rebuild the calipers.

Would anyone be interested in a "How To"???

[adood84]

I think we need a HOW to section on the forum for things like this it would be helpful since most of the people on here are modders :)

[Chaos]

Aye it's probably about time we cooked up a DIY section.

With regard to the WD40, it was a valid idea, but the trouble is that the damn stuff gets everywhere, and you just don't want that within a thousand miles of the braking surface so better to not use it at all bro.

[Stock323iSaloon]

Fas, sounds as if u too have a sticky caliper. I too had the same problem (excessive dust brake fromone side, hot caliper!) and I just rebuild my caliper over the w/e. it is very easy and only took about an hour, including bleeding the system. u need to get a caliper repair gasket set from stealer (12 quid). it consists of an inner piston chamber seal ring and an outer dust boot/sleave. My DIY is as follows:

1. Pull off the dust boot.
2. Put a block of wood between the piston and caliper body (where the brake rotor would go). Push the piston out of the caliper using comressed air. Cover everything with a rag to keep brake fluid out of your eyes. The block of wood will stop the piston from shooting across the room or through your skull.
3. Clean the outside of the piston and inside of the caliper bore with brake cleaner and inspect.
4. If there are any deposits, polish them out with a brake cylinder hone or finest scotch brite pad you can find.
5. Clean everything again with brake cleaner.
6. Put a new seal in the piston chamber
7. Slide the dust sleave thru the piston in place
8. Insert the piston into the caliper using only new fresh brake fluid as a seal lube.
8. Reseat the remaining part of the dust sleave
9. Bleed the system as normal (don't forget to put new pads)

If you're stuck, drop by my house and I can help out.

[BigFas]

Stock, would that procedure be the same for a BBK?

What I think I'll do is take out the pads, see if there are any obvious deposits, remove and rebuild as necessary. If the problem persists, do a full strip down component by component and rebuild

[Stock323iSaloon]

yup, same. the culprit can be...

- rusted piston surface
- rust/gunk in the chamber
- trapper air
- gunk on the carrier bolts

one or more of these can cause the sticky caliper situation. before u go ahead with the full rebuild, u may be able to break the blockage by forcing the piston back to its normal position using a c-clamp, but remember to open the brake fluid reservior, and wrap a towel around that area in case the fluid spills over.
if u find that it's your piston, it can be pushed out using normal pedal pressure, or by compressed air (~15psi). once u cleaned the piston, push it back down very straight (not crooked) using a C-clamp or else u will damage the inner seal. in my case, there was some rust on the piston surface and this led to some rust deposit inside the chamber and it got stuck. if u can change brake pads, u can rebuild the caliper!

[Nickleback]

Fas I saw the guy at the dealer do my brakes a couple of months ago and he used some kind of Brake cleaner spray can and he was spraying it all over the brakes pads ...ect , BMW sells this stuff to customers

This stuff is called BMW Brake Cleaner, comes in an spray can & I quote:
" An advanced formulation for the safe & effective removal of dirt, grease, oil & brak fluid from brakes, clutches, transmission components etc, Specially formulated to evaporate quickly in order not to delay reassembly" so as to avoid cold Pizza ! :D

Have used it often, great stuff [ok