951 Brake Upgrade

[Thom]

I don't want to hijack the thread but how we get rid of brake lag when installing larger calipers?
I like my Big Blacks but having to pump up the pedal once to load them is getting a old.

Just thought I'd mention that the issue was inadvertently solved by the guy at the periodic technical check this morning, as he apparently pumped hard during the brake efficiency measurement and when I drove out the issue was gone. The biting point remains now at the same height on the pedal and with regular consistency. I suppose some pistons didn't slide freely enough, as perhaps I put the calipers back together after having them powder-coated with too little grease on the scraper seals. Very nice however to solve a problem without even trying.

[Thom]

Thom, did you install the 5/33 brake bias valve, 928 355 305 02 when you switched to the big reds?

Sorry, I just noticed I had not replied to this. Initially I was still running with the stock valve but upgraded to the 5/33 valve shortly after and as many others have reported it improved nicely the balance in braking power between front and rear.

[Latitude48]

Thom, did you install the 5/33 brake bias valve, 928 355 305 02 when you switched to the big reds?

Sorry, I just noticed I had not replied to this. Initially I was still running with the stock valve but upgraded to the 5/33 valve shortly after and as many others have reported it improved nicely the balance in braking power between front and rear.

I'm also running the 5/33 valve and like the balance. When I installed one in my S2 in 1999 the cost was $54.92. When I purchased one for the 951 in 2021 the cost had jumped to $240.83. Ouch!

[cda951]

Thom, did you install the 5/33 brake bias valve, 928 355 305 02 when you switched to the big reds?

Sorry, I just noticed I had not replied to this. Initially I was still running with the stock valve but upgraded to the 5/33 valve shortly after and as many others have reported it improved nicely the balance in braking power between front and rear.

I'm also running the 5/33 valve and like the balance. When I installed one in my S2 in 1999 the cost was $54.92. When I purchased one for the 951 in 2021 the cost had jumped to $240.83. Ouch!

https://tiltonracing.com/wp-content/upl ... -Valve.pdf

I use this adjustable proportioning valve on one of my non-ABS cars (Alfa GVT6), works very well. It is a good option for non-ABS 944s, so should be considered for those who have a non-ABS 944 with larger than stock brake calipers.

[Tom]

Sorry, I just noticed I had not replied to this. Initially I was still running with the stock valve but upgraded to the 5/33 valve shortly after and as many others have reported it improved nicely the balance in braking power between front and rear.

I'm also running the 5/33 valve and like the balance. When I installed one in my S2 in 1999 the cost was $54.92. When I purchased one for the 951 in 2021 the cost had jumped to $240.83. Ouch!

https://tiltonracing.com/wp-content/upl ... -Valve.pdf

I use this adjustable proportioning valve on one of my non-ABS cars (Alfa GVT6), works very well. It is a good option for non-ABS 944s, so should be considered for those who have a non-ABS 944 with larger than stock brake calipers.

Very nice. How do yo go about adjusting the bias -- just trial and error based on driving style/conditions?

[cda951]

Very nice. How do yo go about adjusting the bias -- just trial and error based on driving style/conditions?

In the case of my Alfa, it happened to be raining the day I installed the adjustable proportioning valve, so a few panic stops in a wet parking lot and it was dialed in

My '86 951 doesn't have ABS, and next on the list is larger front brakes, so one of these valves will be part of the equation.

But, I also just spent that money on a 944 S2 cab (it needed a clutch and the customer didn't want to fix it, got it for cheap), so that will have to wait. But in the meantime I have a nice cruiser/daily driver.

[Pefa]

Factory 944 Turbo Cup cars had that Tilton adjustable bias valve.

[michaelmount123]

[/quote]
Very nice. How do yo go about adjusting the bias -- just trial and error based on driving style/conditions?
[/quote]

Many brake 'upgrades' result in less than stellar results due to F/R brake bias. Bias adjustment is a must-do after brake hardware changes are made. Otherwise, brake improvement is compromised at best. Here's a simple method that I used for my race cars for many years and found it surprisingly effective. It's much more accurate than trying different non-adjustable bias valves, and applies to both street and track cars. Note that it requires two people.

Have someone sit in the car to use the brakes. Have them push down on the brake pedal gradually and slowly as you turn/rotate the front tire. As soon as you can’t turn the wheel any more, have the driver hold that pressure on the pedal. Go to the rear and turn the wheel – you should be able to just barely turn it. This will mean the fronts have a little more bias than the rears. This technique might take a few times to get it right, and it’s something that you get a feel for, but it’s surprisingly effective.

If this method shows too much front bias, put an adjustable bias valve in the front brake circuit. If it shows too much rear bias, then put the bias valve in the rear circuit.

You'll be quite pleased with the results and your braking will be dramatically improved. Simple and effective.