Brakes gone bad after sitting, trackday tomorrow!

[ben_r1]

Ah bad times! Got a track day tomorrow morning so got the 197 out last night for a clean and once over, it's been sitting in the garage for approx. a month and a half unattended.


During the drive to the jetwash I noticed the brakes were very poor, almost zero bite and on a damp road emergency stops from 40-50 mph aren't even strong enough for abs interaction! The pedal seems to travel a long way for very little response in the brakes, once again there is zero bite.


Took it for a 40 test drive to sweep the discs and no improvement, got heat into them and no improvement. Stripped and cleaned front calipers and bled calipers with what I had spare (500ml). Nothing seems to have improved them. Upon inspection of inner disc faces there is heavy corrosion where the pads have been sitting over winter, the fault?


Tomorrow I have a trackday so I need to decide if I should take the 197 and hope the discs sweep clean on the 3 hour drive upto Cadwell Park and the brakes come back OR if I take the unprepared 172 ( road tyres ).


Setup is RC5+ pads, ktec 2 piece discs, braided lines and motul RBF 660 fluid, never harangue problems before.


Anyone got some advice or point me in the direction of the possible fault?

 

[Scrooge]

You'll probably have more fun in the 172 anyway tbh

I would do a full fluid change incase of moisture and really ride the brakes for a bit if there's still corrosion on them.

 

[Rob]

I'd say you need to really wear them back in, those RC5's are a stupidly hard pad iirc? So if they've built up a bit of a thick "skin" due to the severe cold, I'd go out and really give them a pasting, find some clear dry road (reservoir comes to mind) and do some "70"-20's and "70"-0's, I reckon they'll wear back in.

If the pad surface is getting on a bit, and the discs have got a lot of surface corrosion on them, I wouldn't be surprised if getting some proper heat back in them, and cleaning up the surfaces would take some time.

 

[Dan@M.A.D]

I'd say you need to really wear them back in, those RC5's are a stupidly hard pad iirc? So if they've built up a bit of a thick "skin" due to the severe cold, I'd go out and really give them a pasting, find some clear dry road (reservoir comes to mind) and do some "70"-20's and "70"-0's, I reckon they'll wear back in.

If the pad surface is getting on a bit, and the discs have got a lot of surface corrosion on them, I wouldn't be surprised if getting some proper heat back in them, and cleaning up the surfaces would take some time.

This.

The trophy was the same after sitting for 3 months, Just go on a drive.

 

[ben_r1]

Would dirty pads/discs cause the long travel? I may attempt one last thrashing of it tonight before I head up.

 

[bozothenutter]

Bleed the brakes?

 

[Space Cadet]

Sounds like its fluid to me, although you can pop the pads out and lightly take off half a mm with some very fine paper and then re-bed them in. Also 660 is race fluid and needs to be replaced at least once a year, may be worth swapping to 600 and you can just treat it like normal fluid. I use 660 but change it probably every 6 months and sometime the car is sat for a month or two with no problems.

 

[ben_r1]

My money was on the fluid too but I managed to get round all four calipers a couple times each with the 500ml and didn't see any air plus the pedal is solid with the engine off. It is 660 but had a full flush mid December for the last trackday. Certainly didn't overheat the brakes then either.

 

[Fred@BTM]

your car has ITB's from memory? check the vaccum pipes coming off the inlet manifold, TDF like using rubber tubing that has a nasty habit of being sucked flat/is insecure

check the vacc lines aren't crimped or squashed anywhere

 

[Space Cadet]

As above. I'm no mechanic but could it therefore be something to do with the brake vacuum which actives when the engine is running, perhaps a hose has perished while its been sat??

 

[bozothenutter]

If he had no vacuum the pedal would be hard as no vacuum means no assistance

 

[Fred@BTM]

its just an idea, i've seen al sort of installs on ITB'd cars, some of them being dangerous, its worth checking at least!

 

[Space Cadet]

If he had no vacuum the pedal would be hard as no vacuum means no assistance

As the OP has said, he has a hard pedal when engine not running, hence we're all suggesting it may be something to do with the vacuum assistance.

 

[MG cup]

Going on the assumption there is no fluid leaks then crack out the rough emery to de glaze pads it won't touch them with fine.Flatten the pads then put the car in gear on axle stands and give the disks a good rub with emery too. That will get rid of any disks/pad worries unless there totally past it which I can't see from sitting in a garage for a while. Bleed them and pump up brakes with ignition off, holding foot on pedal start the car and if it goes down then your servo/vaccum will be fine.

 

[MG cup]

As the OP has said, he has a hard pedal when engine not running, hence we're all suggesting it may be something to do with the vacuum assistance.

Its meant to be hard with engine off???

 

[ben lee]

have you checked the rear brakes is the piston returning? is the handbrake arms returning?

drive down the road with the hand brake on a few clicks if the travel is reduced will indicate a fault with the rears.

 

[ben_r1]

Pedal is rock solid with engine off and goes softer when started, but not soggy. It seems to me the feel is okay just the amount of travel for braking force is too long, the brakes just don't react.

Fred yes it's running ITBs, has done two trackdays with that setup and been fine but I do know hey used rubber hose so that's defo worth investigating further. If all else fails you may be introduced to my car lol

thanks for everyone's help anyway. I've given up and committed the 172 into active duty, never had a mk2 round track before so an experience for me I'm sure!