http://youtu.be/3fN0aUKiJus


I threw some clips of my hop issue. Watch the shifter. I'm applying brakes smoothly and the axle still starters to shimmy. If I brake any harder, it sets it off.

XP20 front pads w/c5 brakes
Autozone rear pads on stock lt1 brakes
Stock torque arm
Relocation brackets (welded) and adjusted to lower control arms are level
Abs removed

Is it possible that when I removed ABS it somehow gave me too much rear brake bias? I'm thinking it has to be.

When you removed abs, did you add a proportioning valve?

When the ABS was removed from my old CMC car, a proportioning valve was put in it's place. Even with the proportioning valve, I had to go to less aggressive rear pads to reduce hop.

LT1:
(IMG:https://lh3.googleusercontent.com/-Z7xwI8XNfA4/U7gwxuGCYgI/AAAAAAAABaY/60x-b5J0FIMfoqW0MC0EmcboSotz0Fp-gCL0B/w964-h723-no/89ec5bf5040a54fa6f5079788078bc6b8f9fc54a172e748c813a97f29fbb385d.jpg)

Thanks for the help guys. I just have a distribution block in place of the abs plump. I'll take a picture later.

Here it is.



(IMG:http://img.photobucket.com/albums/v199/Steve91T/Camaro/image-20.jpg)

(IMG:http://www.frrax.com/rrforum/style_emoticons/default/offtopic.gif) yes, but; You ran in CMC with your factory A.I.R. system enabled and functioning? (IMG:http://www.frrax.com/rrforum/style_emoticons/default/gr_confused.gif)

Yes. For the first 2 years the car was legitimately street legal.

You definitely need a proportioning valve in the rear line. $40 part should fix your issue.

I remember reading a lot about this and it seemed that most people didn't need one, they were able to get the balance right with different pads. Guess that's not the case for me.

I'll order one tonight. Thanks guys for the help!

I can't believe anyone would recommend removing ABS without installing a prop valve. It might be different for the LT1 cars, but I know the LS1 cars bias through the ABS module so you would absolutely need a prop valve or else it would be sending a ton of fluid to the rear.

Yeah it must be the lt1 guys who can get away with it, or at least some of them. Not working for me. If I'm going to have a prop valve, is it worth taking the time to run it into the cabin so I can adjust it on the fly? I'm thinking it would be. I can probably run the lines into the ash tray area where my helmet blower switch is. I just worry about having a high point in the brake line. Not sure if it'll cause problems with bleeding the brakes.

This post has been edited by Steve91T: Apr 17 2016, 01:37 AM

A few more comments:

Yes, having the proportioning valve within reach while driving will help you dial in the balance. Just be careful that you don't fall into that trap where you are always fiddling it because it is there. I've seen a lot of guys adjust shocks between runs/sessions because they had adjustable shocks and I think they started to chase their own changes to the car after a while. Also, I have seen many installed low, on the driver's side of the tranny tunnel where if you drop your right hand from the driver's seat it is right there. The advantage in this arrangement is you can minimize the length of brake line inside the car. With the pressures involved, if a line fails inside the car it would be very bad.

LT1 versus LS1 - My LT1 car had an LS1 front brake setup and I believe it still should have a proportioning valve. Pads with lower coefficient of friction on the rear can do fine adjustments to the rear brake strength but the primary adjustment has to be the pressure.

Even with my setup and weaker rear pads, I still got brake hop occasionally. I found that I would get it when conditions were optimal and when I was close to getting all of the car.

I think you will be glad you did this mod.

Thanks so much. I ordered a valve last night. I'll probably try to mount it inside. I tend to not make many adjustments to the car at the track. I'll tweak tire pressures after my first session, but that's about it.

To run the brake line inside, do you just drill holes through the tunnel or is there a better way?

I think I read somewhere else that the lever version is preferred to the dial version, especially if you mount it in the cabin. I used the dial version under hood because it's in a daily driver. If there was a way to make it look reasonable inside the cabin maybe I'd re-think that.

Drill holes in the firewall/ floor pan. Use bulkhead fittings. Don't just cut a hole and run the line through.

Yes, drill holes thru the tunnel. Do not use bulkhead fittings, they provide zero value, introduce several points of failure. I prefer the dial version valve

This post has been edited by Blainefab: Apr 19 2016, 02:32 AM

Your shifter is pretty lively - thats a symptom of something with too much compliance in the drivetrain mounts. get the rubber out and it will settle down and reduce the tramp.

Moroso makes solid motor mounts for the LT1
ES poly trans mount - they are cheap, replace every season or so.
tighten the upper shock nuts till the rubber is really squished - or replace with rodend shocks
tq the lower shock nuts to 90#ft
tq the TA, BH and T56 mount bolts to spec

Ok. I'll see if I can find a rubber grommet that'll keep the brake line safe.

I remember you saying that years ago....can't remember why I didn't listen. I do have the original 100,000 mile rubber mounts. I'm going to be changing to an LS1 later this year, I'll get solid mounts at that time.

whats the flashing far right gauge?