DCP

I assume the brake bias spring upgrade, such as the one offered by DRM, changes the ratio of pressure applied to the front vs. rear brakes. What is it doing, exactly? More of a braking bias toward the front? More toward the rear? And how does this improve stopping distances?

I have searched on this to no avail. Any info appreciated.


David

teufelhund

Basically the stock spring loads a majority of your fluid (stopping power) to the front rotors which is what you want in everyday driving and drag racing. The bias spring evens out the stopping power and distrabutes it more evenly to all four tires. This will make it easier to brake later entering a corner on a road coarse. Because if you brake late into a corner you don't want all your braking done up front which will make your steering sluggish. The bias spring is a great upgrade for auto-x and road coarses as well as the weekend twisty runner. Very cheap but is med. level on the install. Going to be doing one myself soon to get my car ready for auto-x's this summer.

Semper

Aardwolf

It puts more to the rear. You didn't find any info? There have been a bunch of threads, there was a HUGE one a while back with very detailed info.

Braking into a corner would be trail braking, an advanced skill, with incorrect modulation you can have snap overseer and spin into a wall. The bias spring will help with nose dive, but so will a stronger front spring. A lot of people brake before the corner, let the car settle, then turn in.

The install wasn't to bad at all. I just finished it up two weeks ago. It took many tries to get that clip back in. Tearing it all down was very quick. The C5 calipers are huge compared to the small stockers.

coupeguy2001

the purpose of the bias spring is to change the pressures to the rear brakes. The initial brake application has the same pressures front and rear. the spring changes the rear pressure by moving a internal second smaller piston at a predetermined cracking pressure. at the cracking pressure the two pistons work together to control the pressure bias.

vinnies87

Just a note on searches, include archives, and do a search in each c4 section for best results...Just did a search and found 4 pages of bias spring posts.

CentralCoaster

Pretty much it. It leaves the rear brakes at full pressure for longer before finally reaching the crack point where rear pressure increases at a lesser rate than the fronts.

GM underbiases the rear brakes for safety/liability reasons. There is quite a bit of room for improvement, especially on a car with such a low center of gravity and good weight distribution. I believe GM continually increased the rear bias through the C4 run as if they gained more confidence in their engineers. I haven't verified this yet though.

pcolt94

With all the bias springs being installed and some of the stories of parts flying around, I have decided to document this information of my procedure.

Hear is how I did it;
- Follow DRM instructions. This is additional info to get the spring in the valve
- Remove master from car and end nut that holds valve in and small tapered spring.
- Strike master on end to remove valve from master, (use wood). Remove O-ring and metal spacer.
- Record all configurations of parts removed.
- Take a 19mm deep socket and place in vice vertically.
- Wrap the valve in a paper towel to protect it and slip into socket so C clip is up.
- Take snap ring pliers and remove C-clip and spring.
- Drop new spring in valve.
- Get a straight blade screwdriver wide enough to depress spring into valve.
- Place C-clip thru screwdriver and grab clip with snap ring pliers and place screwdriver onto spring.
- Press spring with screwdriver down into cylinder, lower C-clip with pliers and snap in.

If you mess up, you wont loose the C clip. Getting it in the first time is easy.

- lube piston valve and re-assemble master in proper order.
- Bench bleed master and install back in car.
- Bleed master at fittings and or system.

Best of luck




Spring in valve and valve in socket.




Ready to push spring into valve




Spring pressed in valve and ready to drop C-clip in.

DCP

Okay, so now I understand what it does and why this helps in the twisties. Thanks!

So which would stop in the overall shortest distance, stock spring or upgraded spring?

Also, is the spring more/less/same desirable with the C5 front brakes upgrade as with stock C4 front brakes? (I guess what I'm wondering here is if it wouldn't be better to have more bias to the front when you have upgraded to to a beefer front setup.)

I'm considering the C5 upgrade in front and am trying to decide whether the bias spring should be part of my mod.

Thanks for all the info guys. (and the search tips)
David

Aardwolf

The upgraded spring stops better and is more important to put in when going to the C5 calipers. I just picked up a set new, PM me if you need a set, he might have more.

CentralCoaster

On the contrary, when you upgrade the front brakes, you need to counter it by giving the rears more bias. This is because the new fronts with larger/more pistons and bigger rotors is doing more work with the same amount of brake pressure, so they'll lock up or engage ABS prematurely.

I don't see all the trouble with installing the spring. I had no issue with mine. It's stiffer, but shorter, so the preload is the same as the stock spring.

DCP

PM'ed you!

steve40th

Archives arent in my options? Is there something new going on?