Tilton Brake Bias valves - Problems

[Roops]

Anyone have one of these installed and working ok. I have just had a set of AP calipers and a tilton brake bias installed in my e30 M3. Initial brake bite is good but it then fades away, coming back as the car is almost at a standstill. Not very inspiring at all. Have already replaced the tilton valve once and it was better for a while then returned to being poor again. A new master cylinder is going to go in, but anyone have any other ideas. Brakes bled thoroughly, no sign of leaks and different pad compounds tried, all to no avail.

[Tim Falce]

Er, what's an e30 M3? I ask because I read on another forum from someone with a similar problem

[Mackmot]

Find out if you are using the right fluid for the seals in the caliper or maybe change the seals. Posible you could also be boiling the fluid if you are using the brakes heavily and do not have enough cooling or a standard fluid

[Red Dog]

I have heard of hydraulic bias valves causing rear brakes to stay on slightly after the pedal has been released. I have a Wilwood and it does not cause any problems, however the adjustment range is small.

If you have good bite initially you do not have air in the system. The pedal will be very soft.

If you boil the fluid you will have no brakes - the system will be full of air and again the pedal will be very soft or even useless.

By fade do you mean the pedal sinks or do you have a firm pedal but you're not slowing?

If you have a firm pedal it sounds a bit like the pads at one end are fading while the others are coming up to temperature!

[Roops]

Thanks Red Dog. My thoughts exactly, I didn't think there was air in the system as you say.

The sensation is that the the brakes start to stop then the it's as though the pressure in the system drops off. You retain pressure on the brake pedal but the initial sensation of stopping has dissipated. The car is slowing, but not like it was, the as the car is almost stopped the brakes start to bite again.

Pedal feel is not great, not like pushing against an immovable object, it feels like there is quite a lot of travel before the brakes start to bite and even then they pedal travels a fair amount but not to the floor.

Rgds & thanks

Roops

[tzei]

How is it arranged in your BMW - I mean the bedal set up. Could there be somesort of a mechanical problem that effects how parts can move?
- had to tune my systen a bit to get it operate (bought a balabce-bar and did the rest myself)

[Chris Y]

Could it be that the AP calipers are too large a volume for the master cylinder to keep up with? That would increase the pedal travel, although i'm not sure about the uneven braking potential.

I suppose you've already worked through things like making sure the calipers are not sticking, and the pads are bedded in and not wearing unevenly?

Also, make sure the pipework is tidy and not kinked anywhere..

[avsfan733]

could it be the master cylinder?

[graham bahr]

sounds to me like your calipers and the master cylinder are miss matched size wise, for what its worth i've just installed a mk2 escort bias pedal box in my e30 and it was quite easy to do, if you want decent brakes then in my opinion a proper non servo'd pedal box is the only way to go

[Tim Falce]

Post deleted

[listernoble]

Originally Posted by graham bahr

sounds to me like your calipers and the master cylinder are miss matched size wise, for what its worth i've just installed a mk2 escort bias pedal box in my e30 and it was quite easy to do, if you want decent brakes then in my opinion a proper non servo'd pedal box is the only way to go

I have not logged on for a while and just saw this post.
Re hydraulics,I had a lot of problems with a clutch not releasing properly on a Mod Prod car and it was just what Graham says,a mismatch between master and slave cylinder.
I fiited a different size master cylinder and never had any more problem.
Sorry I can't be more precise as it was a while ago.
Lister

[Roops]

Thanks for the tips guys.

I know that the guys who fitted the kit and have done so on similar cars without problems. However with the master cylinder being fairly old, I am going to change it anyway for a slightly larger version which is a direct replacement. I post more news once fitted and tested.