Club 80-90 Forums

Hi all, I have a little query about my front brakes on my bus.

How hot should the disc get during normal driving??

I Just went round feeling all the wheels as i do every so often to make sure the brakes arent binding, and the wheels were just a bit warm really, but the discs were hot. Not majorly hot, just hot!

I have had sticking brakes on other vehicles before and normally the wheel and caliper get hot, but the caliper was cool.

Also i can push it by hand quite easily when its in neutral, which i wouldnt imagine i would be able to if the brakes were sticking.

Should i be worried?? I will hopefully get it in the air tomoro at somepoint and spin em round and see what happens.

Cheers people.

Your discs are meant to get hot, that’s what their purpose is.
In basic terms the moving energy of the van is turned into heat energy by the brakes and absorbed (mostly) by the discs.
I don't have specific details for a T25, but In a normal road car the brake pads are designed to withstand a continuous working temperature of about 250-300 C and in reality will probably only reach this with fairly continual or heavy use. Solid discs like those fitted to a T25 do not cool as quickly as vented discs, so will retain heat longer. Unless your discs are turning blue they probably aren't getting as hot as you think.
If they are not in use whilst driving they should not heat up. This can be difficult to check because to come to a stop to check them you need to use them, so they heat up again!
If you can (safely) go for a long run where you don't need to use the brakes then coast to a stop they shouldn't be noticeably hot. If they are more than just warm, then you may have a problem.
Regards,
Mike.

Ah right, i getcha.

I suppose if they were sticking on then the caliper and wheel would get hot too right??

Well thats not the case so hopefully its all good!!

Cheers!!

You'd be amazed how hot tyres can get after a long run too

CovKid wrote:You'd be amazed how hot tyres can get after a long run too

I'd be worried rather than amazed if your tyres get much above 40-50 degrees after any length of normal driving. If they are too hot to touch then you need to be checking for a problem.

Well I didn't say hot enough to fry an egg, but tyres do get hot - think of all the friction going on.

it can get a bit like that of here now and again

think of all the friction going on

If your discs are reaching their wear limit they will not only get hot, but you will suffer severe brake fade.
As the discs are not vented, they rely on heat sink, to cool them down after braking. So VW fitted thick discs, that will soak up the heat and even transfer it to the hub, from the hub to the wheel, from the wheel to the air in the tyres.

thin discs just get very hot and the pad material looses it's friction coifficient, the hotter disc will radiate heat to the wheel.

R0B wrote:it can get a bit like that of here now and again

think of all the friction going on

Thats why I use the talcum powder Rob

In the 3 years of owning my bus i have rebulit both the front calipers (quite easy), as debris had slowly built up inside, resulting in the pads not fully retreating, this is made worse by the fact that the bus is lad up for along time over the winter. Its probably worth jacking up the front end and getting someone to operate the brake and see if what the resistance is like aat the wheel when the brake isnt in use- just to be on the safe side!