Lancer Register Forum banner
1 - 19 of 19 Posts

·
Registered
Joined
·
74 Posts
Discussion Starter · #1 ·
Car: 99 Evo 6 GSR (380BHP)
Front Brakes: Brand new AP 6 pots on front (DS2500 pads);
Rear Brakes: STD brembo (red stuff pads)
Hoses: Braided hoses all round
Brake fluid: Castrol SRF

Brakes are absolutely fantastic. Firm pedal on the road without any problems.

After 6-8 laps on the track the pedal starts to go soft.... do one more lap and there is pretty much no pedal at all. The problem is not brake fade... it's like the car has no fluid in it. There is no fluid loss at all!

I was talking to another evo owner on Sunday who had AP's on front and std brakes on rear (still with flexi hoses on the rear brembo's). Seems that he doesn't have the same problem.

Any ideas?
 

·
Registered
Joined
·
3,231 Posts
Sounds like you've boiled your fluid.

Get it changed (fully flushed through) and bled properly and see how you go from there.

Castrol SRF is very good but, can't defy physics. You might just be very heavy on the brakes... :smthumbup

Paul
 

·
NR555
Joined
·
7,425 Posts
how old is the fluid?
 

·
Premium Member
Joined
·
807 Posts
I had a similar problem with my Alcon set up and standard brembo rears, I changed to XP8's all round and the pedal is perfect now.
 

·
Registered
Joined
·
74 Posts
Discussion Starter · #7 ·
Thanks for all the posts.

Castrol SRF was put in the car on Thursday. Fully flushed through so no problems there.

I have a sneaky suspicion one of the rear calipers is sticking. Need to check that though.

Do you think that could cause the problem (even with SRF)?
 

·
Premium Member
Joined
·
807 Posts
Yeah, just like you said really. Not brake fade as such just alot of travel and very little stopping power.

The pedal was like this with 2500's on front and back, then changed fronts to XP8 only slightly better but was night and day when I changed to XP8's all round.
 

·
Premium Member
Joined
·
1,857 Posts
Thanks for all the posts.

Castrol SRF was put in the car on Thursday. Fully flushed through so no problems there.

I have a sneaky suspicion one of the rear calipers is sticking. Need to check that though.

Do you think that could cause the problem (even with SRF)?
did you fully flush through the fronts, rears and clutch or just the fronts?
 

·
Premium Member
Joined
·
16,921 Posts
Sounds like fluid issues to me, the ds2500 isnt a great pad but in AP 6pots it should take more abuse than you describe!. The ferodo pads can go a bit mushy when overheated but shouldnt be as bad as you describe, Castrol SRF fluid is good but it isnt magic and it will still boil if your on the brakes far too long, however as above if not fully flushed properly this could be the problem.

As you say make sure all calipers are freeand nothing is binding generating excessive heat, bleed system fully putting through a good litre of the stuff and see how it goes.

Cheers
Ian
 

·
Registered
Joined
·
74 Posts
Discussion Starter · #12 ·
Thanks All.

I ran out of posts hence the silence. I should really stop being a tight arse and get myself registered properly on here.

The fluid was flushed through the front and rears. My mechanic said it won't make any difference flushing through the clutch.

Today he checked the callipers were not sticking… all seems well.

We tried buying a set of cheapo std pads to put on the rear. The theory was that the front set had everything which came with the AP's, whereas the rear was a bit of a mix n match job. Std discs and red stuff pads.

Tonight I took that car to a long straight and did more than 20 start and stops... sometimes trailing the brakes (more heat). It took a while but eventually I started to get some brake fade (never had that on the track). After another 3 fast stops, the pedal went (a little more gradually than it had on the track), however there was absolutely no pedal at all - right to the floor... no brakes!!

The road I did this on was exceptionally dark and when I jumped out all 4 discs were glowing red! I didn't want to let the brakes cool while stationary so started driving again. After a good 3-4 miles the pedal started to come back, but very gradually.

I pulled over again after 10 miles to check the brakes. Looks like I've managed to melt the DS2500's to the disk. There are bits of mushy pad stuck in the drill holes of the disk!

I’m guessing I’ll need to buy new pads (going to try these XP8’s all round), however can anyone confirm if I’ll need to buy new disks. They feel a little rough, however it does look like the pad has rubbed off on them a little (not sure if they will still be rough when that comes off). The car has done < 300 miles since fitting the AP’s though!

For the XP8’s, any problem using these with my standard rear discs?

Any other input on the above would be most welcome.

Jondo
 

·
Premium Member
Joined
·
16,921 Posts
Sounds like youve really fried the ds2500!...it does make a nasty mess once heated to this level, discs should clean up with more aggressive pad but will also be a good idea to take them off and try and remove as much as you can with a coarse emery paper first, or send them back to AP to be skimmed clean.

Also as per PM drilled discs are prone to cracking when used hard, keep an eye on them ;)

Rear XP8 work fine on stock discs as long as they have no nasty lips on inner outee edges etc, if they do discs will need a skim or replace if too thin.

Cheers
Ian
 

·
Premium Member
Joined
·
16,921 Posts
Good to speak to you today Jondo, XP8 front and rear on there way and should be with you tommorow :D

Let us know how you get on :)

Cheers
Ian
 

·
Premium Member
Joined
·
16,921 Posts
Indeed, this is an intriguing story. Look forward to hearing the result on XP8's.
From speaking to Johndo today its sounds like the inital problem was fluid going off due to being on brakes a long time and dragging into corners, generating a lot more heat than normal track use, also possibly the lack of feedback/bite from ds2500 didnt help.
Im sure with the XP8 in front and rear that brake confidence and stopping power will improve dramatically resulting in being able to brake later/harder but for shorter periods of time, hence generating less heat and giving fluid an easier time :)

Cheers
Ian
 

·
Registered
Joined
·
74 Posts
Discussion Starter · #17 ·
Hi Ian,
Likewise. Thanks again for all your help.

Should have them on the car today/tomorrow, and will be at Knockhill on Saturday.

Also just fitted some ex WTCC yokohama slicks to my track wheels so if it's a dry day I should be able to give the brakes some real punishment.

As you say below, I'm almost certain my braking style wasn't helping so I'm hoping the extra bite allows me to be on them harder and for less time.

Will post up some feedback on Sunday/Monday.

Thanks again.
Johndo.
 

·
Registered
Joined
·
74 Posts
Discussion Starter · #18 ·
Was at Knockhill with the car on Saturday.

XP8's are the business. Followed the suggestions of braking harder and for less time, and found that I was stopping miles before the corners. As the day went on I was braking later and later (achieving 58.8 second laps), however I'm still not braking as late as these things are capable of.

I now see what everyone was talking about by the initial bite. The best way I can think to describe the difference between XP8's and DS2500's is that there is a very slight lag with DS2500. The DS2500's seemed to have a short delay between initial application and maximum braking power. On top of this, the DS2500's require a much heavier foot to achive the same stopping power you get with a much lighter press on XP8's. Since you really have to jump on the DS2500's, it can be difficult to avoid locking up the fronts. Losing this "lag" and the increased feel on XP's makes it much easier to control the force on initial application which avoids locking up the wheels (again giving enough confidence to brake a lot later).

No sure if I've explained the above well, but feel free to post any q's.

In short, these are great pads. A mate of mine already has a request in for quote.

Big thanks to Ian (theTyrant) for all his help.

Cheers,
J.
 
1 - 19 of 19 Posts
Top