1987 S4 Brakes Dragging
Thread Starter
AutoX
Joined: Aug 2022
Posts: 10
Likes: 3
From: Valencia, CA
1987 S4 Brakes Dragging
Hey everyone. Long time Rennlist lurker, first time poster. I've been having an issue with my '87 S4 where the brakes seem to be dragging. It seems to be an almost intermittent problem. Some days, I can drive it through the canyons and not have any issues. Other occasions, I can drive it 5 miles and notice it. I first notice it when coasting or when I'm at a stoplight and I remove my foot from the brake pedal, and the car doesn't crawl forward (it is an auto S4). I am starting to think it is temperature related, as I do usually start noticing it in traffic, or after sitting in a long drive thru line - perhaps it can be engine heat related? The last time it happened, I took at temperature reading and both front rotors were at 225°F, while both rears were at 130°F. Anyways, what I have replaced so far is all the soft brake lines to the calipers and a complete system flush. Could it be a master cylinder? Maybe calipers? How can I actually pinpoint this problem without just throwing parts at the car? Thanks in advance.
Rennlist Member
Joined: Jan 2003
Posts: 3,426
Likes: 223
From: Honolulu and sometimes L.A.
I think this is usually the master, though I had a problem with a caliper that did this. The early S4 type caliper don't have dust boots, so they can get pitting on the piston and stick. I would try to figure out which wheels are hanging up. You may be able to do this with an IR thermometer, or even your hand on the wheel (be careful). I suspect that, if it is the master, it effects multiple wheels, and I know that a sticking caliper just the one gets hot.
Thread Starter
AutoX
Joined: Aug 2022
Posts: 10
Likes: 3
From: Valencia, CA
Thanks for the reply, Karl. I have read that the 1987 models do not have a dust cover on the caliper piston before. I am wondering if that can be the issue. I did measured the temperatures with an IR gun, but it read that both fronts were 225°F, and both rears were 130°F. You are correct, I would think if it was a caliper, then it would likely affect only one - unless my luck/timing really is that bad!
Another thing to add, when the car sits for about an hour (cools off) the brakes are not dragging any more and have released. If it was the calipers seizing up, I'm starting to wonder if that would happen, because it seems to be temperature dependent.
Another thing to add, when the car sits for about an hour (cools off) the brakes are not dragging any more and have released. If it was the calipers seizing up, I'm starting to wonder if that would happen, because it seems to be temperature dependent.
Thread Starter
AutoX
Joined: Aug 2022
Posts: 10
Likes: 3
From: Valencia, CA
Yeah, I suppose it could make sense if the pistons do not fully reseat themselves into the bore, as the brakes heat up and expand, now they can be rubbing the pads. Maybe the next steps before committing to a nearly $900 master cylinder (which is pretty ridiculous IMO), would be to inspect my caliper pistons. Would I be able to visually tell if they are pitting/corroded after removing the brake pads?
Team Owner
Joined: May 2004
Posts: 31,302
Likes: 4,271
From: Philly PA
first lets find out what is the service history.
When was the fluid last changed?
what kind of fluid did you use?
I suggest to use ATE Gold fluid.
NOTE mixing different fluids can cause the seals to swell.
When were the brake lines replaced? did you use the stainless steel flexible lines?
Have the calipers ever been rebuilt?
for now please post a picture of your engine bay
When was the fluid last changed?
what kind of fluid did you use?
I suggest to use ATE Gold fluid.
NOTE mixing different fluids can cause the seals to swell.
When were the brake lines replaced? did you use the stainless steel flexible lines?
Have the calipers ever been rebuilt?
for now please post a picture of your engine bay
Thread Starter
AutoX
Joined: Aug 2022
Posts: 10
Likes: 3
From: Valencia, CA
I changed the brake fluid about two months ago. Completely flushed the system. I did use the ATE gold fluid as well. At the same time, I changed the rubber brake lines to the rotors with new OEM ones - not stainless though.
So my thinking is we can knock those factors out of the equation.
I'll upload a photo of my engine shortly!
So my thinking is we can knock those factors out of the equation.
I'll upload a photo of my engine shortly!
Trending Topics
Rennlist Member
Joined: May 2016
Posts: 951
Likes: 206
From: Trumansburg,NY
I had the same problem and found when I pulled the calipoer pistons out, they were covered with some crud. I cleaned black stuff off from the pistons (And inner section with the rubber ring removed) and found that they slid much easier. I did this 2 years ago and have not had a problem since. Later on that year I ended up changing the master cylinder.
Rennlist Stories
The Best Porsche Posts for Porsche Enthusiasts
Genius Porsche-Themed Gifts That'll Make Any Dad or Grad Smile
Joe Kucinski
10 Used Porsches Are Selling for Way Too Cheap
Joe Kucinski
Tuner Is Converting Porsche 911s Into Shooting Brakes
Verdad Gallardo
This Coachbuilt Creation Is A Modern Take on the Legendary Porsche 917
Verdad Gallardo
Is This Convertible Cayenne A Steal, Or A Returnless Investment?
Verdad Gallardo
10 Best Non-Flat Six Porsches You Can Buy For Under $100K
Joe Kucinski
Porsche's Top 5 Most Questionable Naming Decisions
Verdad Gallardo
Pogea Racing's 964 Porsche 911 Reimagination Stands Out in a Crowded Field
Verdad Gallardo
6 Convertible Top MYTHS Most People Don't Understand!
Michael S. Palmer
Rennlist Member
Joined: May 2016
Posts: 951
Likes: 206
From: Trumansburg,NY
Was waiting on new rebuild kits but waited a year due to covid. Never got the kits so just claened them up (really made a difference because there was a build-up of some kind of crud keeping them from returning). Yeah, replaced the master the following year (after about 8 mos.). Just ended up being the end of it's life.
Last edited by Geo55; Sep 25, 2024 at 10:16 AM.
Team Owner
Joined: May 2004
Posts: 31,302
Likes: 4,271
From: Philly PA
engine bay reveals your at the time for an intake refresh.
The air cleaner is upside down, hump to the sky is how it should fit.
A closer picture of the master cylinder would also be beneficial.
NOTE usually brake issues arise after a fluid change and then a few months after the fact.
At this point I think you should take the calipers apart and clean them out,
then if you can get new seals get them,
otherwise clean the ones you have and put it back together and see if things change.
NOTE go drive the car take an IR gun with you,
and then after a few miles with moderate brake use,
Stop and see what rotors are the hottest, then dive some more with minimal brake use and retest ,
the dragging calipers will be evident if you have one or more.
Also you should consider this ,
see if you can still buy a new MC from Porsche and put it in.
use DC111 on the tank inlet grommets to prevent moisture from corroding the tank inlets bores,
every time the car gets wet water will run down the tank and go into these bores.
The air cleaner is upside down, hump to the sky is how it should fit.
A closer picture of the master cylinder would also be beneficial.
NOTE usually brake issues arise after a fluid change and then a few months after the fact.
At this point I think you should take the calipers apart and clean them out,
then if you can get new seals get them,
otherwise clean the ones you have and put it back together and see if things change.
NOTE go drive the car take an IR gun with you,
and then after a few miles with moderate brake use,
Stop and see what rotors are the hottest, then dive some more with minimal brake use and retest ,
the dragging calipers will be evident if you have one or more.
Also you should consider this ,
see if you can still buy a new MC from Porsche and put it in.
use DC111 on the tank inlet grommets to prevent moisture from corroding the tank inlets bores,
every time the car gets wet water will run down the tank and go into these bores.
Thread Starter
AutoX
Joined: Aug 2022
Posts: 10
Likes: 3
From: Valencia, CA
Yes, I am definitely planning on an intake refresh in the near future. Also, wow, I must have put the air filter on the wrong way. The hump goes up? I will have to check - I believe I followed the arrows, but after doing some research, I now know those arrows are useless. Crazy cars we have, eh?
Anyway, yes, my plan will be to inspect and clean the caliper pistons first. I hope I do not need a master cylinder, but if the calipers do not solve the issue, I think I will go with a rebuild from Roger at 928sRus.
Anyway, yes, my plan will be to inspect and clean the caliper pistons first. I hope I do not need a master cylinder, but if the calipers do not solve the issue, I think I will go with a rebuild from Roger at 928sRus.
Rennlist Member
Joined: May 2016
Posts: 951
Likes: 206
From: Trumansburg,NY
If you do go with a new Porsche master,(Which I recommend) here is the one I purchased for my 87 https://www.delawareporscheparts.com...Y4LWdhcw%3D%3D
