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Pumping pedal problem
karmannghia60 - June 6th, 2005 at 09:12 AM

This is a weird one. You would expect this to happen if the drums need machining. It was fine till I put on my Empi 5s then it started happening whenever I hit the brakes. Turning the back wheel (not sure which side yet) one or two holes up will fix the problem. Any idea why?
Raf


matara - June 6th, 2005 at 09:30 AM

Raf, I want some of what your on mate! Couldn't make much sense of your post!

I think you might be talking about a brake pulsation now you have the EMPI's on? If so I expereiced this problem too! Its caused because the EMPI is pretty flat and when you torque up the nuts it distrorts the drum, mainly because the hole are so near to the edge on a 5x205PCD.

First try torqueing the wheel nuts on the EMPI up to spec. Second, make sure that there is no crap between the mating surface of the wheel and the drum. Third option is to have the back of the EMPI machined, just a light skim to make sure it is flat and true (there are some very rough cast EMPI's knocking about).

If all this fails you can put early Type 3 brakes on the back, and some sort of disk brake (CSP, CB, Sherman) on the front.

Cheers

Steve

[Edited on 5-6-2005 by matara]


karmannghia60 - June 6th, 2005 at 11:26 AM

Sorry Steve, its Monday morning Mate
Thanks for the explanation, will try them out
Cheers


eirecooled - June 7th, 2005 at 05:11 PM

check that your mag wheel nuts are not protruding to far into the brake area and hitting the pads when stopping.


Anthiron - June 8th, 2005 at 02:40 AM

VW brake drums are cast alloy are they not? so over tightening of the wheel nuts such as done but tyre places with rattle guns or really really strong people can warp the drums. try loosening the nuts off a bit. the reccomended torque of the nuts is really pretty low compared to a modern car ( i forget what the actual torque is) but i tighten them by hand with a wheel brace just untill where it sqweaks and back it of a teeny bit. i used to have a lot of pulsating and this fixed 90% of it.


Che Castro - June 8th, 2005 at 04:17 PM

Nope they are cast iron. Porsche and VW dumped the wide 5 pattern because of these problems. I havent had these problems before, I only have the stock rims.


Grey 57 - June 9th, 2005 at 07:25 AM

I would say the stiffer alloy wheels are probably pulling the drum out of shape Raf. Try torqing (with a torgue wrench) to the correct tightness and see if that changes anything. If not you might have to get the drums skimmed with the wheel attached and torqued correctly.

My Oval had red paint markd on each drum and wheel. Didnt know why until I mixed the wheels up one day when I had both the fronts off. Found out soon as I hit the brakes, Huge shdder and pulsing pedal.
Refitted them with the paint spots lined up and all good again. Some had gone to the trouble of getting the drums machined and matched to each wheel.


karmannghia60 - June 9th, 2005 at 12:23 PM

Sound like you guys nailed the problem. I will try swapping, rotating and cleaning on the weekend
Thanks a lot


Doug Sweetman - June 9th, 2005 at 12:30 PM

Definetely check how long your bolts are, esp in the rear - I have empi 8's on my L bug and the bolts were about 6 or 8mm too long, I had a weird tapping noise when I braked - turned out it was the end of the bolts hitting on the handbrake cable inside the drum !!! not good....

If that fails, try getting the rims on car balanced, that helped me once.


karmannghia60 - June 9th, 2005 at 01:37 PM

Things is when I rotate the wheel one bolt up, the problem goes away. So doesn't look it its the bolt length but still, I will make sure they are the right size while I am at it