Audi A4 B8 2.0T Quattro wheels very hot

[cocog]

Having issues with hot wheels. My car has had all the brakes replaced or overhauled. 

As it stands new discs, pads, HEL high performance brake lines, new rear calipers including EPB, refurbished front calipers and brake fluid changed out and bled through.

The problem I have is discs are all getting very hot even with very little braking. In particular the rears getting hotter than fronts.

Long motorway journeys usually lead to smell coming from brakes particularly the rears. Not driving hard and gentle braking.

Car has been checked over by garage and can't find anything. Understand rears are solid discs so don't cool as quick as vented front discs but I'm not used to having rear brakes getting hotter than fronts.

This is the first permanent Torsen quattro car I have owned but wouldn't have thought that would make braking different.

Does anyone have any experience of this issue and know of any fix? Surely this isn't normal.

Any suggestions?

 

[cliffcoggin]

Colin.

You mentioned long motorway journeys so I assume the pads have bedded in by now.

Is it definitely the discs that are the source of the heat, rather than the wheel bearings? If so, the pads must be rubbing, which points directly at the changes you have made to the braking system. Are the new parts standard Audi components? Thicker than normal pads and discs are a possible explanation, but I fancy it is more likely the pistons are not retracting as they should.

 

[cocog]

Garage took car a drive and checked after. Rear discs were 10 degrees hotter than fronts and wheels were turning. I guess they wouldn't spin as freely with it being quattro compared to a fwd drive.

Discs and pads genuine. Aftermarket brake hoses so smaller diameter hoses it appears compared to standard ones.

Wheel bearings don't show any signs of play or noise and spin freely with calipers removed.

New calipers and fitted using correct EPB procedure with scan tool retraction.

Both wheels the same heat so not one worse than the other.

I would have said pads rubbing but garage didn't think so. 

Would the smaller diameter brake hoses cause any issues? The brakes are exceptionally good but could they cause any pressure problems causing caliper not to retract properly.

The car had been sitting for over a year before all this work was done to put car back on road.

My understanding is the front door most of braking and I've never had a car with rear discs getting as hot as this.

I have even driven very carefully over short journeys hardly touching the brakes and the rears are still very hot.

Looking at rear the only things are brakes and wheel bearings. Could wheel bearings cause this heat and both sides the same as each other?

The wheels do turn but do spin easier after brakes pushed fully into piston.

It is brand new calipers so wouldn't thing there is an issue with the pistons on both so could these aftermarket hoses be the issue? The brakes do seem to be exceptionally good compared to normal

[cliffcoggin]

You say the discs are hot, but how hot is hot? Do you have a temperature measurement?

I can't imagine that smaller bore hoses would cause this. It is possible the bearings are too tight. Have they been changed?

Perhaps the handbrake is not releasing fully. That would cause rubbing of the rear pads, assuming the handbrake is on the rear wheels.

[cocog]

Discs way too hot to even consider touching. You can smell the heat and the alloys are getting hot to touch. They are hotter than any rear brakes I have had on a car. Used to front discs getting hot but not the rears getting so hot and hotter than the fronts.

It is electric parking brake and done through proper retraction method.

The bearings haven't been changed but new backing plates fitted so hub would have been removed to do this I think.

How can you tighten wheel bearings too much? Would you not notice when turning if too tight?

[cliffcoggin]

3 hours ago, cocog said:

How can you tighten wheel bearings too much? Would you not notice when turning if too tight?

I would have thought so. Nevertheless the only causes of friction that occur to me are the bearings and the pads. Perhaps we can get some insight from others.

[cocog]

Totally agree can only be pads or wheel bearings that can cause friction. My gut feeling it is the pads but can't work out why they are catching. Everything on brakes brand new including caliper carrier and sliders. The only difference is the brake hoses which are aftermarket.

This issue is baffling me.

Would you expect the wheels to spin freely on quattro rear axle? The wheels don't spin freely like non quattro axle wheels but don't appear to be catching pads when turning them. There does appear to be some resistance which I thought would be normal.

Going to strip rear brakes down again and check over but don't know what else to do.

[cliffcoggin]

14 hours ago, cocog said:

Would you expect the wheels to spin freely on quattro rear axle? The wheels don't spin freely like non quattro axle wheels but don't appear to be catching pads when turning them. There does appear to be some resistance which I thought would be normal.

There is bound to be more resistance from a wheel that is moving a differential than a wheel that is not, but that's more a matter of greater inertia than greater friction.

From a purely logical point of view, if the problem started after work was done on the brakes, then surely that work was the cause of the problem. If we assume the standard parts are correctly sized and correctly fitted, that only leaves the non-standard parts i.e. the hoses. I know I dismissed them earlier but I now wonder if they are kinking or twisting as the suspension moves up and down. It seems unlikely but I am clutching at straws and don't know what else to suggest.