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Hot Drum
Allbones - June 3rd, 2014 at 10:37 PM

So I have a hot drum, but I'm not sure what is causing it.

Car is a 1964, but I believe it has a later model swing axle.
I do have the car dumped two splines on the outer.

The indicator was the car burning through brake fluid. We though it was a leaky brake cylinder so we replaced the front two (As one was suspect) and moved to the rear.

The rear didn't appear to be leaking at all but we thought we should do all four at the same time. It was at this point we noticed that the paint on the rim on the passenger had bubbled from heat, and we believe this may have been evaporating the brake fluid.

We then tried to remove the axle nut and that was a no go. We had so much lever that we started turning the engine over with the handbrake on (probably not the best adjustment I will admit) before we could break the thread.

The car sat for 6 weeks and we come to tonight. We heated the nut (and subsequently the hub) with a heat gun and tried to break the thread using a cold chisel. This didnt work so we gridded the nut until we could open it with the chisel.

At this point ignited brake dust fell out of the inside of the drum (from the grinding and heat gun). We looked at the inside and didnt see any purpley heat marks to imply the brakes were locking on. We also pulled the seals back and couldn't see any of these marks on the ball bearings either, they also appeared to be intact, there was blackening on the inside of the bearing seal that slipped around the ball bearings where it was in contact with the axle. It's worth noting there was still a fair amount of oil on the bearing, even after sitting for 6 weeks.

So my dilemma is what is causing the heat? The brakes don't appear to be locking on and the wheel bearing doesn't look like it has collapsed at all.

My tendency is to think that when I last worked on the drum assembly, I have over tightened the axle nut and the tightness against the backing plate has caused the whole unit to heat up. (Possibly even igniting the brake dust and having that smoulder inside the drum as well. After all, we did ignite the dust just from the heat from the grinder and heat gun).

Has anyone else had a problem with the drum heating up? Does this sound like the culprit?

Thank you for reading,
John/Allbones

psimitar - June 3rd, 2014 at 11:34 PM

To be doubly sure the bearing is OK I'd remove it and turn it by hand to listen or feel for rough running.

I had a bad bearing on the front that made the hub to hot too touch and that was a sod to get off the spindle.

Anyway, if the bearing is OK and getting a good supply of oil then overtightening is probably the issue as it'll cause the ball bearings to be pushed against one side of the races.

vwo60 - June 4th, 2014 at 10:24 AM

There are only two things that will cause the heat, a bearing running without oil and failing or the brake shoes dragging, did you check that the drum was free before you tried to take it off, you need to remove the backing plate and inspect the bearing, if it has discoloured then you will need to replace it, you can get a cheap flogging spanner that will remove the nut without issues, http://www.vollks.com.au/store/VW-Axle-Nut-Removal-Tool-36mm-Type-1-2-3-and-4... works every time, try running a sealed bearing in the axel and remove the out seal and pack it with grease. probably last longer that the normal bearing. when you run that sort of camber. over tightening the axel nut will not cause the backing plate to rub, it would be obvious it it had.

Allbones - June 4th, 2014 at 11:17 AM

Quote:
Originally posted by vwo60
There are only two things that will cause the heat, a bearing running without oil and failing or the brake shoes dragging, did you check that the drum was free before you tried to take it off, you need to remove the backing plate and inspect the bearing, if it has discoloured then you will need to replace it, you can get a cheap flogging spanner that will remove the nut without issues, http://www.vollks.com.au/store/VW-Axle-Nut-Removal-Tool-36mm-Type-1-2-3-and-4... works every time, try running a sealed bearing in the axel and remove the out seal and pack it with grease. probably last longer that the normal bearing. when you run that sort of camber. over tightening the axel nut will not cause the backing plate to rub, it would be obvious it it had.


In our excitement of finally getting the nut off, we didnt check to see if the pads were sticking, with that said, I did try to remove the wheel with the handbrake on, As soon as I took the handbrake off, the wheel came stright off with no hassle. As mentioned also, there doesnt appear to be any heat markings inside the drum to indicate any hotspots. There did seem to be alot of brake dust though.

We then removed the plate in front if the bearing that held all the seals in place, this didnt appear to have rub marks on the front of it, this was also how we inspected the bearing. We stopped at this point because the bearing wouldnt pull off the axle (we assumed it was pressed on and the whole axle would need to be removed to take it out, is this correct?)

From what I can gather, it sounds like I need to pull abit more apart and
get at the back of the bearing. Is the bearing pressed on or should I be able to remove it?

Thanks very much for your help so far guys. It's always appreciated.

John.

Edit: It is worth noting we adjusted all the brakes and handbrake when we did the brake cylinders. I beleieve drive around like this for anohter week or so and still had heat issues.

vwo60 - June 4th, 2014 at 08:59 PM

You need a puller to remove the bearing, you should be able to inspect it once you get the bearing cap off,, if is getting that hot it will be discoloured.

vduboy - June 8th, 2014 at 08:36 PM

Have you ever replaced the master cylinder or put a kit through it? Sometimes the small relief ports get partially blocked up with sludge and can drag the brakes when hot but seem ok when they cool down..

Allbones - June 10th, 2014 at 09:04 AM

Quote:
Originally posted by vduboy
Have you ever replaced the master cylinder or put a kit through it? Sometimes the small relief ports get partially blocked up with sludge and can drag the brakes when hot but seem ok when they cool down..


No, I havent. I may give this a try now.

We double checked the bearing on the weekend and it seems fine. No heat marks and doesnt seem grindy or gritty.

As mentioned earlier, as we were investigating this problem we re-adjusted all the brakes, so this may have inadvertantly fixed the problem back then, even though we though it was the bearing.

If it keeps getting hot I will try the above. As it has to be the brakes now, seeing as the bearing is fine.

Thanks for all your help guys.

*EDIT*

Another theory I have just been informed about may be the brake lines. When I installed my narrowed beam, we replaced the front brake lines. I've just been told that this may be causing the rear brake lines to swell (as the new ones are braided) and clamping the rear brake on until the pressure is gone. This makes a fair bit of sense seeing as we cant isolate why else it would be doing it. Anyone heard of this before?

Allbones - June 11th, 2014 at 08:24 PM

"A worn out brake hose usually does not leak, it collapses internally (this is by design). When this happens, it will prevent brake fluid from getting to or leaving the wheel cylinders which will either cause a pull to one direction when braking or a sticking brake. Normally, when one brake hose is going out, its best to change all four at the same time. Here's why: if one hose has gone out, most likely the other hoses are the same age and have been subjected to the same amount of wear and tear and are bound to fail soon thereafter. Also, as you will need to bleed your brake system after installing even one hose, it's easier, faster, and cheaper to only have to bleed your system once instead of after every new hose."

Guessing this is my problem in a nutshell. Straight from Das Resto site, on the brake line page as I went to order. Very helpful haha :tu: :yes:

psimitar - June 12th, 2014 at 09:25 PM

Quote:
Originally posted by Allbones
Quote:
Originally posted by vduboy
Have you ever replaced the master cylinder or put a kit through it? Sometimes the small relief ports get partially blocked up with sludge and can drag the brakes when hot but seem ok when they cool down..


No, I havent. I may give this a try now.

We double checked the bearing on the weekend and it seems fine. No heat marks and doesnt seem grindy or gritty.


Did the bearing sound noiseless? A brand new bearing should be so smooth that it doesn't make any noise. Any sort of thrumming etc noise means it has a problem.

If you're sure it was OK then old flexi hoses may well be the cause.

Allbones - June 12th, 2014 at 10:09 PM

Yeah, we double checked the bearing, we are pretty confident it is the lines.