rear calipers dragging

[Mark Babb 1]

Ever since i built my E30 race car last year i have had an issue with the rear calipers dragging on, to the extent that i have gone thru 3 sets of rear pads. They just get so hot and brake up after each race. These calipers have been completly overhauled and the handbrake shoes have been backed off so much that it does not actually work anymore, so i can elimate them. The front pads are just fine with no heating of the discs when driving normally on the road, but just after a few km the rear discs get really hot... someone mentioned a while back that the E30's (320 FL) have a bias valve in the line somewhere?? could this be faulty?

any other suggestions would really be appreciated. I also had an issue with the rear bearing grease flying all over ther inside of the wheels...this i guess is due to the rear brake/hubs getting so hot that the grease sort of melts under the heat and easily passes thru the bearings.

Thanks

Mark

Edited September 7, 2007 by No overtaking

[Silver Fox 43]

Quit moaning, you don't need brakes at Pukekohe.

Just load your 75kg into the boot.

[tibbs.james 1]

Rebuild the rear calipers again or borrow some diffierent ones.

Thats a quick answer to if its the calipers or something else. Plenty of E30 rear calipers around to buy/borrow.

[Mark Babb 1]

Quit moaning, you don't need brakes at Pukekohe.

Just load your 75kg into the boot.

God i just can't hide from you can i... actually i dont want brakes..thats my problem the rears are just dragging on constantely, always have since the car was built...just imagine how much quicker i could have gone if they had freed up...reckon a 1.15 could have been achieved.

something is applying pressure to the rear calipers just enough to heat the discs up and destroy the pad material. drove up the road for about 10km today, did not use brakes and yet when i stopped rear discs were hot and yet fronts were stone cold. guess i might have to check out master cylinder or this brake bias valve that someone mentioned is in the line.

actually are the rear calipers the same for 318/320 and 325.? might aswell replace nothing lost i guess.

Thanks for assistance

Mark

[thompsonmc 0]

Its not the calipers, and not likely to be the bias valve (below the mastercylinder) Change the master cylinder first and make sure all the pedal linkages are free and that that the M/C cylinder has free play.

[Mark Babb 1]

Its not the calipers, and not likely to be the bias valve (below the mastercylinder) Change the master cylinder first and make sure all the pedal linkages are free and that that the M/C cylinder has free play.

Thankyou, actually when the car was built over at race FX they told me only recently that you can adjust the rod from the brake pedal to the master cylinder to take up free play. apparently this is what they did do, but what kinda of confused me (not difficult) is that i thought if it had been over adjusted the front would also be dragging too. anyway thanks for the advice will check to make sure there is free play.

Mark

[Mark Babb 1]

Think i've found the problem with rear calipers dragging... the retaining springs that fit over the calipers and stop the pads from vibrating actually was holding the pads against the disc, hence getting hot etc. After doing a little research it appears other E30 drivers around the world have had similar problems with no real soloution...Only taken 12 months to find the reason and 3 sets of pads...may have just gained another 4/5hp as well...or wishfull thinking.

[Silver Fox 43]

Think i've found the problem with rear calipers dragging... the retaining springs that fit over the calipers and stop the pads from vibrating actually was holding the pads against the disc, hence getting hot etc. After doing a little research it appears other E30 drivers around the world have had similar problems with no real soloution...Only taken 12 months to find the reason and 3 sets of pads...may have just gained another 4/5hp as well...or wishfull thinking.

Wishful Thinking

[conrod 1]

I am not sure I believe this theory to be honest. Take it for a test drive with the clips removed to confirm, they don't do that much apart from stopping the pads wearing into a taper and the caliper rattling around a bit.Possibly not legal to run without them, but at least you will prove a point.

As TMS said, check free play on the pushrod to the master cylinder- this is critical! Also, if your calipers have been overhauled with the incorrect size seals this can happen too. They come in very small increments of size sometimes, and fitting one that is too tight will cause this to happen.

[photomagik 0]

Hi Mark,

It sounds like either a master cylinder issue, or the push rod to the master cylinder doesn't have any/enough free play.

[gmccormack 0]

Was the car originally fitted with rear discs or was it a drum to disc conversion??