Heat Issues with only Driver Front - DBA T3 4000 and Ferodo DS2500
 

Hi All,

I grabbed the DBA T3 4000 front and rears kit (lines, pads, rotors, fluid, etc).

I am having issues with the Driver Front rotor.

Initially when I installed the new rotors and pads, i could feel the driver front sticking a bit. The wheel would not spin as freely as the passenger front. I took the whole assembly apart again and removed the shims between the caliper and the pads (did this on all four corners). This accounts for ~2mm of space.

After doing this, I was able to freely rotate the wheel as well as move the caliper along the caliper pins. I inspected the caliper pin bolts while it was apart and they freely move.

After this was done, I took the car out to bed the brakes. Driving around the neighborhood was fine, car did not pull while driving. Out on the highway, I was able to do some braking ~90mph - ~10mph, using around 50% to 70% braking and the car responded normally. No pulling, could take my hands off the wheel and brake without pulling.

After getting off the highway, the driver front pads were smoking a bit. I could also feel some drag here, along with some squeeling when driving without the brakes on. I am guessing that was maybe from expansion while hot. When I pulled off to check it out, the rotor outside paint turned from black to white. The thermal paint had changed green->white, orange->yellow, red was still red. This means the rotor got somewhere between 550C (1022F) and 630C (1166F). The other three corners did not have the green paint change color, so they stayed under 458C (856F).

http://i.imgur.com/5gtqy5R.jpg

After a bit of cooling (~30m), and putting the car on a lift, the tire freely spin still. Taking the driver front caliper off and inspecting, everything looks normal. This was done at a garage I trust, and multiple people checked it out.

Today I tried driving the car, and checking rotor temps with a new heat gun I picked up. Even when driving normally for ~20m on the highway, if I check rotor temps the passenger front will be ~120F but the driver front will be ~180F. After a couple hard braking runs, the passenger front measures ~200-250F, but the driver front measures ~300-350F.

So the questions:
1. What is going on ?
2. Is this rotor still OK to use ?
3. How to troubleshoot more and fix the issue ?

TLDR; Driver front new rotor is getting too hot, passenger and rear are fine, don't know why.

Have you tried troubleshooting the caliper to see if it's dragging or caliper pistons are sticking? I'd start there.

From there, it's going upstream: ABS module > master cylinder > ABS electronics > wheel sensor > etc.

-alex

I plan on taking it apart and measuring pad thickness to see if i notice any differences between different sides of the pad, or the front/rear pads. Ran out of time for this today.

As for the drag/sticking pistons, would I not have got a significantly hotter temp when doing normal driving (~20m on the highway I did)?

It seems as if the driver front is just getting hotter proportionally to the passenger side, however if it were braking harder would I not feel a pull to the driver side ?

Had some more time to look today.

So I took it apart and measured the pad thickness.

driver front
passenger front
Does this mean that I may have a sticking top piston in the caliper on the driver side ? How could I troubleshoot if the caliper is at fault ?

Does not sound like a pad or rotor problem. Definitely sounds like caliper. Did you clean and regrease all the pins when you installed the new parts?

Is it even possible to mount these calipers at an angle, and not perpendicular to the disc? I guess getting stuck on the bottom could do that too and much more likely.

I greased the caliper pins, and checked to make sure they are moving freely.

As for mounting the calipers or support brackets on an angle, I don't think that happened as they are clean machined surfaces.

A replacement caliper is $299.99 from the dealer for an OEM part, ~$220 online. I called a dealer and they said they would not warranty the caliper since it has aftermarket parts on it. :-(

I am thinking I will just grab a used caliper from a wreck on ebay for ~$70.

The AP Sprint kit is only a little bit more... ;) That said, I'd probably be doing the same - even if it's just to see if it helps. $70 isn't too much (to me) for something that could become a safety issue - that's too much heat for normal highway driving!

Haha yeah I had the same thoughts. If this doesn't solve it I will be going AP Sprint Kit, already have the rims to fit the kit but would need a 10mm spacer for street rims. I like things to work as expected.

Well, new caliper arrived today.

After swapping it in, the same thing is happening. After some heavy breaking, driver side was ~600F and passenger side was ~350F.

What I am going to try next:

- Swap pads
- Swap rotors
- Swap caliper bracket (got another one with the replacement caliper)

After that, not sure what to do next.

Don't just throw parts at the problem, try to diagnose it a little better. I can't help you with that, but you're going to spend a fortune if you start replacing everything.

Make sure the pads aren't binding in the caliper/bracket either.

Sorry, when I said swap, I meant from the passenger side.

Check the flex line as well. It's a long shot on such a new car, but I had a flex line go bad and cause the caliper on that side to stick. Tried everything else (caliper, pads, etc), replaced the flex line and the problem went away.