'95 S4 Brake Problems Solved

[Riddlemr2]

I have seen a few threads about brake problems so I thought I'd provide a detailed explanation of the symptoms the car exhibited and the fix as I imagine others might have the same issue in the future.

Before I bought the car I noticed that it had a flashing ABS light, the brake pedal pushed back against my foot and sort of modulated in and out in a 2 second period, and there was about a one second delay between when I pushed the pedal and when the car actually began to stop (something quite terrifying at times).

I had the PO replace the ABS accumulator and that cured the ABS light. Others on this board said the "push back" feeling was normal, so I bought the car and accepted it as a Lotus quirk. After a week, I couldn't stand it anymore so I took the car to "Foreign Toys" in Ft. Lauderdale. They found that the system was only making 1800psi rather than the (I believe) 2800psi it was supposed to.

After trying a different pressure switch with no success they thought the brake system was bad so I debated buying a used unit for $800 or paying $780 to have Prior Remanufacturing try to rebuild it. Before he removed it, Paul (the owner of the shop) pulled the cap off the fluid reservoir and noticed that the fluid was NOT DOT4, but some sort of Jaguar fluid. In the course of the service he also found that the thermostat had a hole drilled in it so the PO's mechanic wasn't exactly ready for F1 pit duties.

After flushing the system with DOT4 fluid and replacing three damaged seals in the master cylinder, the brakes feel much better. Apparently, the bad fluid had damaged the seals, and the fluid was travelling in a loop from the pump past the seals and back again, cauing the modulating feeling.

The brakes now have no delay between pedal depression and stopping power. The pedal does still "push back" but only once at the beginning of brake application. I will also install the revised pressure switch eventually which will hopefully make for a completely normal brake feeling.

Hopefully this can serve as a "search" resource to others who might have brakes that feel like something ghostly has posessed the system!

[esprits4de]

I am awaiting the replacement of the switch as well. Some time in this month I ought to get the switch.

I talked to my shop and the guy said that the pumping feeling would still be there. He sais that he got rid of his "pumping" after installing 320mm disks to go with his AP's, but I just can not seem to follow that thought just from the logics of the system.

Anyway nex year, or in fall, I will go for the AP's and will be able to tell.

[Jonathan]

You probably had DOT5 in there which can damage seals as it is based on a different fluid.

It has a higher boiling point but not suitable for cars with DOT4 and DOT5.1 recomendations.

Keep a close eye on your calipers as well.

[greeny]

i have a partly related problem on my s4s.

When i turn on my ignition the abs light sometimes stays on and sometimes goes off.The brake pedal constantly has a long travel to begin with and after 10 minutes of driving and braking the pedal rises to where it should be effective and is nice and hard.I replaced the pressure switch a couple of months ago and have fiddled with the brake pedal switch which was loose and tending to keep my brake lights on.So realy my main problem is the long travel of the pedal when i first drive the car in the morning.

Any suggestions?

[Riddlemr2]

Hi All.  Resurrecting this post from over a decade ago.  I had the EXACT same problem happen to me again.  This time Flow Lotus in Winston-Salem put the wrong brake fluid in the car (even though I gave them a large bottle of the correct stuff), and I had to have Foreign Accents in Greensboro flush and install the correct DOT4 brake fluid.  

I had a flashing ABS light so I started with the accumulator - nope.  Then the pressure switch was swapped by me with a Lotus Marques unit - still flashing.  I finally realized I had a leaking brake line which was causing the pressure to nosedive and setting off the ABS light.  Had Flow Lotus replace the brake lines with a stainless set from JAE.  ABS light went out, but the brake delay was back (press the brake, count to two, then the brakes would activate).  Popped off the brake fluid lid, and sure enough it smelled funky.  System flush, new proper DOT4 fluid installed, and brakes are normal (for now anyway).

The last time I had this problem, I was young and had hair.  Now I'm bald with a family, but the car's problems never change

[Giniw]

On 19/10/2020 at 23:39, Riddlemr2 said:

This time Flow Lotus in Winston-Salem put the wrong brake fluid in the car (even though I gave them a large bottle of the correct stuff)

How is that even possible? I mean, the DOT 3-4-5.1 is the rule and the DOT5 the exception, why would they use (or even have) DOT5?!

[Jacques]

On 19/10/2020 at 23:39, Riddlemr2 said:

Hi All.  Resurrecting this post from over a decade ago.  I had the EXACT same problem happen to me again.  This time Flow Lotus in Winston-Salem put the wrong brake fluid in the car (even though I gave them a large bottle of the correct stuff), and I had to have Foreign Accents in Greensboro flush and install the correct DOT4 brake fluid.  

I had a flashing ABS light so I started with the accumulator - nope.  Then the pressure switch was swapped by me with a Lotus Marques unit - still flashing.  I finally realized I had a leaking brake line which was causing the pressure to nosedive and setting off the ABS light.  Had Flow Lotus replace the brake lines with a stainless set from JAE.  ABS light went out, but the brake delay was back (press the brake, count to two, then the brakes would activate).  Popped off the brake fluid lid, and sure enough it smelled funky.  System flush, new proper DOT4 fluid installed, and brakes are normal (for now anyway).

The last time I had this problem, I was young and had hair.  Now I'm bald with a family, but the car's problems never change

Nope, it's called stability

Any other old car would have deteriorated completely in the meantime.

Giniw: maybe because it said "racingfluid" or " high temp resistance" or whatever on the bottle. It's not the first time someone educated does something uneducated.

I can think of a few persons here I'd rather trust my car, than those Lotus workshops...

Or do it myself

Cheers,

and take car(-e)!

Jacques