Brakes: Volvo V60 brake query

[Ian dy]

Hi!
I own a Volvo V60 (2011). I have had new discs, pads, actuators,callipers and brake hoses fitted to rear of my vehicle by a Volvo main dealership. I am getting hotter rear brakes than the front, on average 20-30% hotter than the front. The dealership are saying that this is acceptable. Volvo helpline have assured me that the rear brakes should be cooler than the front. Can anyone shed any light on this matter please?

[Dippydog]

Given that the majority of braking effort is done by the fronts Theoretically they should be the hotter although the front discs are bigger and usually vented[which would aid cooling]are the rears vented?By what method are you arriving at the heat difference?How soon after stopping are you checking the heat?

[green van man]

Newer cars actually use the rear brakes a lot more than older models did.
In the past blue black rear discs were common due corrosion because unless towing heavy loads the rear brakes did very little work. On modern cars it is unusual to see corroded rear discs most are as bright as the fronts.

As for the temp difference as asked, how are you measuring and what type and size of disc

If gently brakeing the rears will do most of the work and would be expected to be hotter, if brakeing more harshly then the fronts come into play far more, and you will feel the front of the car dip.

Also is it manual or automatic? Manual the gears can be used to slow the car, autos tend to rely more on the brakes, then we are back to the gentle harsh brakeing thing.

Have to say I am surprised the amount of parts that have been renewed, was it all in one go or over a period of time as it's a compleatly new rear brake system you have there. In my book that's we don't know what the problem is so keep changing bits untill it's fixed, or, it's totally fubared and we had best change it all before it fails. Not very comforting in either case.
I expect to renew the discs every second change of pads as minimum thickness would be reached before the 3rd set of pads were worn out, but why the calipers unless they were siezes or damaged during disc renewal. Have had a dealer snap both rear caliper bleed nipple then expect me to pay for new calipers, reason I change brake fluid myself.

Post some more information and I'm sure a variety of informed views will be expressed from which you can draw a consencious.

Paul.

[Ian dy]

Temps taken with an infra red thermometer (Snap on). Rear discs aren’t vented. Disc and pads replaced in May due to normal wear. Actuators replaced after hydraulic handbrake seized in June. After this work, discs were heating with no brake applied. Checked on rolling road. Car returned to Volvo dealership 3 times. After further inspection, they agreed there was ‘slight binding’ to rear brakes and found callipers were slightly eroded. I asked for both callipers to be replaced at large cost. On removal of callipers, rear pipes were snapped due to erosion. After fitting these components I have monitored temperatures with infra red thermometer and found that on various journeys (short and long distances) when taking temperatures when arriving at destination the temperatures are always hotter on rear brakes (20-30% degrees).

Am I correct in thinking that rear discs should be cooler than the front discs, whether vented or not due to the front brakes doing 65/35% of the work?

[green van man]

Originally Posted by Ian dy

Temps taken with an infra red thermometer (Snap on). Rear discs aren’t vented. Disc and pads replaced in May due to normal wear. Actuators replaced after hydraulic handbrake seized in June. After this work, discs were heating with no brake applied. Checked on rolling road. Car returned to Volvo dealership 3 times. After further inspection, they agreed there was ‘slight binding’ to rear brakes and found callipers were slightly eroded. I asked for both callipers to be replaced at large cost. On removal of callipers, rear pipes were snapped due to erosion. After fitting these components I have monitored temperatures with infra red thermometer and found that on various journeys (short and long distances) when taking temperatures when arriving at destination the temperatures are always hotter on rear brakes (20-30% degrees).

Am I correct in thinking that rear discs should be cooler than the front discs, whether vented or not due to the front brakes doing 65/35% of the work?

I think the way you use the brakes comes into play here. Brake gently and the rears do a lot more than 35% of the work, probably approaching 50% and being smaller and solid will heat more and also hold the heat longer than the bigger vented fronts.

Are the brakes effective with no signs of binding? If so I would monitor the temp as you have the kit for a while and see what results you get.
If you do this , please post your results here, I for one would be very interested in seeing them.

I know that the works 5 ton van due a rear brake pads change. On the way to the garage I decended a 25% hill. An hour later the discs were still too hot to handle.

Paul.

[GrahamBrown1]

I would say this is also normal, a well driven car will go through more rear pads than front ones.

[Dastardly Diesel]

Jack it up - if the wheels are turning freely then the heat is a function of the brakes working, not of the brakes binding.

[Clan]

Originally Posted by Dastardly Diesel

Jack it up - if the wheels are turning freely then the heat is a function of the brakes working, not of the brakes binding.

exactly , the brakes job is to turn the kinetic energy into heat ..