I put the 1LE brakes on over the weekend. The most interesting part of the job was modifying the spindles on the car. It wasn't too hard to do. I enlarged the bolt holes by starting with a small 5/16" bit (I think) and moved to a 3/8" and then the 13/32" bit. I took my time and used a low drill speed. Worked just fine. Drilling the second side went a lot quicker since I was more confident that I knew how to do it properly. The left side ssbc bracket is shaped slightly differently (better) than the stock bracket, and I could leave more metal on the spindle. I put Earl's stainless lines on while I was at it.

The brakes are better, but not spectacular. The pedal feels solid, but the brakes still don't grab hard. I used a miti-vac on the booster vac line and it will hold 18" of vacuum. This seems reasonable. I've searched the board and found numerous complaints about the combo valve. Some people have talked about modifying the stock valve, others talk about putting an adjustable unit in-line with the rear brakes. I've even seen talk of using 4th gen MC's to get better pedal feel.

Does anyone have any conclusive answers? Should I get the 4th gen MC, an adjustable prop valve, and pay a shop fabricate the lines to connect the prop valve to the rear brakes and have them run a line straight from the MC to the fronts? Or should I just get a new GM 10164112 combo valve?

Thanks.
Joe92 Z28

 

I don't know about your options that you mentioned. Just DO NOT get an adjustable proportioning valve. They are for racing and you will encounter so many changing road conditions that you will end up locking up the rear brakes and spinning! Bad news no doubt. They are even a little tricky in race cars but at least the road conditions are consistent.

 

Did you do the pad bedding procedure after installing your brakes? If you didn't, follow the instructions in the Baer brake link below, and see if that helps.

www.baer.com/bedding_street/

 

I haven't done anything as elaborate as Baer recommends. I drove using them lightly for a while and let them cool over night. Then I warmed them up the next day and tried some heavier braking. Their bedding procedure says to brake heavily "at a point just pending wheel lock". Don't think I could get near wheel lock right now. I'll try the extended seasoning/bedding plan and see if it gets better.

As for an adjustable proportioning valve being for racing only, if the rears lock too easily, then don't you just need to reduce their pressure? Is the front/rear pressure balance and having the balance off with rears getting too much pressure the concern? Does the stock unit compensate pressure differently or just reduce the rear pressure more?

 

an adjustable valve is placed in the cockpit with a ****. you turn it till you get the fronts to lock just before the rears do. the problem is that you have to test it out and on the street, there are puddles, potholes, dirt, etc... you won't find out your rears are locking till it's too late...

 

GM 10164112 ? Where did you get that part # from?

Here is what I did when I did my 1LE upgrade. I had the same conditions you describe. So I took the car out to a long quiet raor and went from 50 to ZERO as hard as I could press on the pedal for 10 consecutive times. On the eight attempt smoke began to rool from the brakes. At the ninth attempt I was pulled from my seat by the brakes so hard that the seat belt shoulder strap mechanism latched. At the tenth attempt I experinced predictable and controlable wheel lock up on all four wheels.

That's what I did. This is all contained in the 1LE questions post.

Thanx,ANDYZ28

 

The left side ssbc bracket is shaped slightly differently (better) than the stock bracket, and I could leave more metal on the spindle.

What do you mean by this?

 

Hey Andy,

10164112 is the number from my local Chevy dealer. The 1LE combo valve that I've seen listed before (10136840) seems to be obsolete, and replaced with the 4 wheel disc brake valve (10164112). A google search on 10164112 turns up a very nice combo valve/MC reference table at http://www.usol.com/~okfoz/modification/brakes.htm. I haven't verified all of the numbers in the table, but the 91-92 disk combo valve is correct and the '90 1LE valve number is what people tend to list.

Speaking of the 1LE Q's post, have you put the Vette caliper info into it yet? They were smaller as the pics showed, and won't fit over the 1.1" thick 1LE rotors.

As for the ssbc bracket, it's not a completely cast part like GM's, there's some machined sides to it. I'll attach a picture, though it doesn't show much. The dark gray is the GM part, and the light gray/silver is ssbc. The side that is next to the spindle is the machined part, and it is cut slightly differently. I didn't have to cut as close to the bolt holes for the ssbc bracket. For the GM bracket, I was cutting right next to the raised metal around the bolt holes, with the other bracket I could leave more metal outside the raised section. I assembled the left side first and didn't realize there was that much difference until I was trying to get the GM bracket to align properly. I would have taken more pictures of the modified spindles to compare them if I knew the spindles would be cut differently. Anyway, the left side was already assembled and I didn't have time or incentive to take it apart for pictures.

Basically, it was easier to make the cuts for the ssbc since it required less metal to be removed from around the bolt holes. I consider this a better design for strength (probably unnecessary though) and for ease of installation - less of the "damn, not enough taken off yet" factor.

Time to go heat the brakes some more...

 

OK, I've done something similar to the Baer seasoning step 3 instructions, and the brakes are working much better. Much much better. No more wooden block feel. You ought to emphasize in bold type the importance of abusing the brakes to get them working better. Not just braking hard a few times - though 10 times would have done it, but something more planned out like Baer's seasoning instructions. Hope they keep getting better as I season them more and then do some bedding.

 

The bracket in your picture is commonly referred to as "the caliper carrier".