rlf105

I am in the process of putting the c5 brakes on the front of my 1990. I ordered a brake bias spring from ZIP which arrived today but came with no instructions. My question is how do I install this in my master?

rodj

http://forums.corvetteforum.com/1544166192-post4.html

http://forums.corvetteforum.com/1559981702-post7.html

rlf105

thank you soo much. thats exactly what i needed to see. Now I feel stupid for not searching first though. thanks again this forum is so great for all the help it gives

rithsleeper

Mid america has the tech manual in a pdf next to the product.

Nathan Plemons

Very worthwhile mod. Be sure though to top off your brake fluid well above the minimum mark after you install the spring. If you don't the first time you slam on the brakes the level may fall low enough to trip the low fluid sensor and therefore disable your ABS.

jmgtp

Don't mean to thread highjack, but I've been curious about the DRM spring. Is the point of the DRM spring only to retain the proper brake bias when upgrading the front brakes to more 'powerful' units?

I don't race my C4 and I don't plan on upgrading to C5 brakes. But, thats not to say I wouldn't want to improve on what I have. I replaced the brake booster a year ago and that made a very noticeable increase in stopping power - primarily because I didn't have to mash the pedal as hard for the same result, my old booster had failed likely from its plastic assembly succumbing to the heat off the headers.

So, the question is: Would there be any benefit to using the DRM spring on stock C4 brakes (mine is a 94)? If it matters, I do run a larger stickier rear tire than stock (295/30/18).

Nathan Plemons

The bias spring works very well on cars with stock brakes. If you upgrade your fronts and leave your rears stock it only becomes that much more important.

jmgtp

Awesome...ordered.

Nathan Plemons

It really is a good theory. Maximum braking force available is determined by your traction which is determined by a lot of factors, but one of which being weight on the wheels. The less weight on the wheels, the less traction they have, thus the less braking force it takes to lock up the tires.

By shifting more bias to the rear you help keep the car from taking so much of a nose drive when you slam the brakes. This helps keep the weight over the rear wheels where it belongs. This means that you can apply more braking force to the rear short of a lockup. More braking force without lockup means shorter stopping distance. Some might argue that since the fronts do most of the braking work anyway you are losing braking power. It's a good theory, but since you can still apply plenty of braking force to the front and lock them up, you're good.

I suppose you could argue that by keeping the weight from transferring to the front you are thereby decreasing it's traction and thus making it more prone to lock up. The only way to know for sure is to do back to back tests and see which one stops shorter.

All that being said, I know this. The car stays MUCH more level with the spring. This helps keep the rear end planted and thus less "twitchy" if you do something stupid like get on the brakes too hard because you headed into a turn too fast.

Aardwolf

From DRM I hope! It's $12 less expensive there and comes with directions. Can't believe that place didn't send them!

http://dougrippie.com/?p=404

jmgtp

Yup, just placed my order directly through DRM. Came to right around $20 total with shipping.

Kubs

This part is actually just the opposite. Increasing weight on the tire improves braking as it becomes less likely to lock up. 99% of cars on the road are over biased in the front from the factory on purpose. Doing this means an average driver in a panic situation can still control the car if the brakes lock. If the rear brakes lock up the rear becomes loose and harder to manage. Cars are designed to accommodate the least experienced person. However, this also means the front brakes are being slightly overworked. You are correct that transferring some work to the rear will help reduce nose dive and overall braking performance is improved because the rears are now helping out more.

Like mentioned the spring will help on a stock car, or with modified brakes.

Nathan Plemons

yeah I t-totally fat fingered that. I meant to say more weight = more traction, less weight = less traction. Let me go correct that.

jmgtp

Follow-up Question on DRM Bias Spring Install.

I have the spring and directions in hand, I looked at the master cylinder and if I remove the ASR unit I should be able to remove the nut off the MC and extract the piston without a problem - thus allowing me to leave the MC bolted in and simplifying the entire process. I read the links posted above and I believe I understand the spring installation.

What I'm a bit hung up on is that the MC is going to be relatively drained. I'd imagine that would require a bench bleed, or am I mistaken? Will conventional bleeding at each caliper void the system of air?

I use a hand operated vacuum pump at each bleed screw as that has been the most successful method for me in the past.

Kubs

The master won't completely drain. Bleeding at all 4 corners will work, but I personally font trust vacuum bleeders. See if you can have someone pump the pedal for you.

jmgtp

Sounds good, why don't you like vacuum bleeders?
I've had great luck using the vacuum pump for removing air from stubborn systems that just could seem to get that last bit out via the 2 man method.

Kubs

I just don't trust them. If the bleed screw is too loose or if there is a slight leak somewhere the vacuum pump will just keep sucking air. I have always used the pedal push method, it seems to be the most straight forward to me. Again, thats just my opinion.

Cliff Harris

I put one of those springs in about 25 years ago. The one thing I do remember was that the new spring is really strong and it took a lot of hard pushing to get it compressed.

jmgtp

I installed mine last night - it took roughly 1 hour from start to finish, but I haven't bled the brakes yet (realized I had no fresh brake fluid). I unbolted the ASR and swung it aside to give myself a bit more room. I used a garage duty turkey baster to suction the resovoir dry. I removed the nut off the Master Cylinder and had someone slowly push the brake pedal until the piston began to move out, then I used a pick to extract it. Expect some fluid to come out with the piston and stuff rags beneath the MC to absorb it. Brake fluid is nasty stuff, be certain not to allow it to touch any paint. I'm not sure if it damages plastics but given the amount of wire loom running around in that area I was not taking chances. I can't wait to bleed brakes and see how my $12 mod works!

Things I noticed:
-The OEM spring is much longer than the DRM spring, but easier to compress than the DRM
-When you release the C clip be ready, the spring turns into a projectile
-a 1/4" nut driver is the perfect size to compress the new spring (with clip resting on top) into the bore. When the clip bottoms out against the bore I used a screw driver to work it in. Another nudge and it snaps into the groove.
-At almost 20 years old the o-rings still looked new
-The piston had some small trace amounts of orange sludge that wiped off easily. I assumed it was some kind of rust sludge, which also means water in my brake fluid. I had done a full flush about 3 years ago when I got the car but I'll be doing it again. The fluid itself had turned a dark amber color.

oldalaskaman

excellent tech. many thanks, bob