8 replies to this topic

[Eakin]

Does anyone know of any tricks to improve how well their park brakes work, beyond the obvious starwheel and hand lever adjustments or new parts?

I recently co-bought a 98 S70 T5 (FWD, manual) to run as a RallyCross car. The back brakes were overhauled last week with new rotors, park brake shoes (one of the old ones had a lining fall off), park brake springs/hardware and pads. I went through the park brake adjustments twice (adjusting the star wheel until the wheel locks, then backing it off 2 notches, then adjusting the lever to engage fully at 3-4 notches and no drag when released) to make sure that I had it right, but haven't been happy at all with the results. As far as holding the car when parked, it engages at 3-4 notches and holds the car on a hill without any problems. While the car is moving though, it requires a lot of force to lock the rears, and the results were intermitant at best.

We just had our first event with the car earlier today, and decided that we would just run it as is and see how it went. The car had a lot of issues with using the park brake to get the back end to break loose with TRACS turned off (or on for that matter). I realize that the park brake on these cars isn't stellar when it's new, but I'm talking about very loose conditions (loose snow, ice and gravel). When I was running my Matrix in the same conditions a couple of weeks ago, it had zero problem locking up it's rear drums and swinging its butt around, so I'm at a loss as to what to do.

Perhaps someone can offer some suggestion to try next, a specific brand of shoes that might work better, or anything that might help. Any help would be greatly appreciated

[scumcity14]

Using new (or good) pads and hardware follow these steps.

1: Remove both wheels, Calipers, and rotors..
2: inside car remove the hatch in the center console and release all tension (t46 or t50) on the cable adjuster..
3: remove and replace any hardware and shoes you may need..
4: while shoes are off check that both cables are functioning properly (a second person makes this easy, one to pull lever and one to hold pad actuator...if cables are good move on to #5. I lubed the actuators with some grease btw.
5: when putting the shoes back on turn the adjusters for the shoes all the way down (the star wheel one)
6: put rotors back on and tighten with the guide pin and 2 lug nuts opposite each other.
7: Using a small screwdriver through the hole in the rotor turn the star wheel until rotor doesn't move..do this for both.
8: now, with the rotors tightened take a 2.5# sledge (or other hammer...heavy rubber mallet) and smack the rotor hat (not real hard)..you will find the rotor turns again. repeat this adjusting and smacking until rotor stays tight after the smack. do this on both rotors.
9: now back off the star wheel in each rotor @ 2 clicks until rotor moves. it should move freely but you will hear some scraping (this is fine and will go away as soon as you drive).
10: inside car adjust cable tension until the lever moves about 2 clicks and engages the shoes. double check that rotors are free when lever is released.
11: put the calipers and wheels back on and enjoy a perfect parking brake..

Edited by scumcity14, 06 February 2012 - 12:17 AM.

[Eakin]

Thanks for the walkthrough, but I was looking for some insight beyond the remove, replace and readjust. I've already gone through this process twice with new parts. I guess I'll give it one more shot before I start to throw tools.

[bergmjs]

You can get something like this:
http://www.speedwaym...paign=CSEGOOGLE

Fab up some custom brackets and reroute the stock cable out of the transverse arms to it. Just make sure the calipers wide enough for your rotors.

[Eakin]

^^^ Now that's a great idea! I just looked in to the maximum rotor thickness though, and it can only handle a 0.25" rotor. A new rear rotor is .378", so it wouldn't work. I'm going to see if there's a similar option that can handle a thicker rotor.

[Eakin]

I think that I found a winner! It looks like Wilwood offers three different versions of those calipers for various rotor thicknesses. This model can handle a .25" to .50", so a .378" is right in the middle of that range and would work great for my application:
http://www.jegs.com/...roductId=757779

I'm going to give the drum surface and shoes a light scuff and see if I can 'bed' them a bit first. I'll try that setup at the next event in a couple of weeks and see how it performs. If I'm still not getting a decent bite out of the drums, then I'm going to give the Wilwood calipers a serious look and start fabing up a bracket to mount them using the factory caliper mount holes and run two calipers on the back. That should look interesting.

[James A Sousa]

To bed in drum brakes ,in the old days, racers used to cover brake shoes with chalk and then apply brakes lightly - then they would file/sand the clean areas of the shoes until the shoes were evenly clear of chalk after a light application.

How about a handbrake lever extension? You can apply more force until the cables start breaking!

[James A Sousa]

Another thought.

Some older rally cars had two emergency brake levers - Perhaps if you fabricated two levers, you could lock up one wheel easier than two. That might even work better.

[Eakin]

James, I like where you're going with this. Thanks for the shoe bedding tips. I'll give that a shot on the next round. I have a feeling that I'll be swapping out the shoes again before the end of the season. We managed to get the brake working considerably better with the last tear down. I ran some Tri-Flow lube down the cables (an old bicycle mechanic trick), to help them out (even though they seemed fine), and then we got rid of the shitty no-name shoes that we bought from the local parts store and got a set from the Volvo indie shop that I use when I don't have time to do my own work. He had them out of the box already, but I think they were Raybestos. Anyhow, he swore by them, claimed that they worked better than any other brands he had tried....held better, less likely to have the lining tear off, etc. We put those on with a fresh scuff of the drums as well as the lubed cable and things finally started working properly. Looks like we just had some shitty parts in there. I'll get a hold of him later this week and find out what brand they were.