My regular driver - Autocross - Roadrace Monza

[tinsfci]

A closer look at the braking system after trackday!

First the wheel with heat bubbles and grease transformed to more like "fluid" leaking out:

IMGP1176.jpg

Plenty of brake dust:

IMGP1179.jpg

Plastic sleeves meltdown:

IMGP1180.jpg

Used brake pads (To be honest they were not new, but surely 2/3 left before the race (which was approx. 2 x 10minutes!)

IMGP1186.jpg

[72 SS PNL]

dam that is some hard brake usage

think you need some air ducts to bring air to the brakes , plus larger brakes

[Kenova]

It is definetly time for a brake up-grade!
As for the camber issue, don't put too much focus on the inside tire. Most of the cornering load is taken by the outside tire. Having said that, after looking at your photos you could use a little more negative camber gain on the outside wheel. You don't have very many options for improving it and all options will require a fully adjustable upper control arm.

Ken

[rpoz-29]

You could have a set of the sleeves machined out of metal. I've gotten them mushy before, but nothing like what you have there. I would also upgrade to better pads. Are the rotors still okay? It looks like you got into the rivets a bit. Finally, I think a better set of tires would keep you from having to work the brakes so hard.

[tinsfci]

Hey thanks for your replies and suggestions!
For those of you that havent seen the pics from the track, and my thoughts about strange camber angles, go one page back or click on viewtopic.php?f=12&t=24282&start=15

[tinsfci]

Better brakes are on my wish-list, so are new tires as well

If I should put the list in some order, I beleive it would be like:

1. Fix cooling to brakes, something like this:

brake_cooling1.jpg

brake_cooling2.jpeg

It would be fun to see the difference. I think it means a LOT.

2. Buy better brake pads with friction material designed for rough use. I though it would be impossible to find such pads for our cars, but Carbotech has (at least for the ´76 and up Monza):

http://www.ctbrakes.com/pads/chevy.html

3. I must buy new tires, those BF Goodrich´s are.... OLD But I am in some kind of Catch-22 here... it´s hard to find good tires for 13" wheels, so I better buy new 14" or 15" wheels...but wheels with 4-bolt patterns are rare, therefore I better upgrade to 5-bolt, and if I do that, I better replace the whole brake system (rotors,brake cylinder etc)

[tinsfci]

Btw, I (and some other guys) took some pics of the other cars at Track Day, after my brakes not willing to race anymore

(In Swedish I´m afraid)
http://rejsa.nu/forum/viewtopic.php?t=59449

[rpoz-29]

I would look at those wheel bearings while you're working on it. You can get "R" compound tires in 13", and some decent street tires. 14" and 15" 4 lug wheels are available, but I imagine shipping would be expensive to Sweden.

[73astregt]

have you road race guys ever had problems with snapping the rotor hats off the hubs from cornering? we used to run the pure stock roundy round races here years ago and used to snap the hats and sometimes the center of the wheel broke too! our problem was always with the right front corner. we cured it with larger wheel studs and used the monte carlo, corvette style wheels(rallys) and leaned the top of the tire in as much as we could get away with and still stay legal.

[rpoz-29]

Back in the late 80's when I started running "R" compound tires, I cracked the centers on several GT wheels. The crack usually went from bolt hole to bolt hole. When I went to Cosworth wheels, I didn't have any more issues. Much less flex.

[ck_carnut]

Used brake pads (To be honest they were not new, but surely 2/3 left before the race (which was approx. 2 x 10minutes!)

IMGP1186.jpg

Looks a lot like the brakes on my Cosworth after my runs at Pocono back in May. 3x 20 minute runs. Pads were almost new when I started. The Vega rotors are not veted, and the pad area is smaller!

I'm in the process of putting on the later Monza vented rotors and larger pads, but it looks like it may not be enough!

[NixVegaGT]

I went to a track day about 3 weeks ago, that was fun!
Hmmm...take a look at the front wheel angles:

I have about 2-3 degrees "static" negative camber for auto-x:ing, but that looks a lot more...due to my worn out control arm bushings?

And GM's weak justification for moving the center of rotation outside the front wheels:

The stability factor is even MORE pronounced as the car rounds a curve. The centrifugal force throws more weight on the outer wheel so that this wheel moves up.… because the bottom of the tire shifts inward as it moves up the center of gravity of the car shifts also. It shifts into the curve to help counteract the centrifugal force pushing the car outward.

WHAT??!!! Even crazier to me is that they kept this setup for YEARS!.

[NixVegaGT]

OH I also wanted to post about the brakes.

2. Buy better brake pads with friction material designed for rough use. I though it would be impossible to find such pads for our cars, but Carbotech has (at least for the ´76 and up Monza):

This will make a HUGE difference. I have been fighting this issue with my SRT4. The brake pad compound changes everything. The heat will still be an issue but will be mitigated a bit by a more effective compound that works at higher temps. You will encounter a lot lower temps overall and way less pad breakdown.

One thought on the vent idea. I would want to move the outlet to the vent more toward the center of the spindle so it ducts the air as close to the hub as possible. That way the air can flow better through the vents of the disc. I know we are limited by the bulk of the spindle itself but it's probably worth trying to get the air as close as possible. Cool idea using the lower marker light as a vent.

It may be worthwhile to do the S10 spindle upgrade. There are also a bunch of relatively inexpensive "Big brake" kits.

Just a thought. Keep up the good work.

[tinsfci]

The stability factor is even MORE pronounced as the car rounds a curve. The centrifugal force throws more weight on the outer wheel so that this wheel moves up.… because the bottom of the tire shifts inward as it moves up the center of gravity of the car shifts also. It shifts into the curve to help counteract the centrifugal force pushing the car outward.

WHAT??!!! Even crazier to me is that they kept this setup for YEARS!.

Thanks Nic for that quote. I had missed that topic http://forums.h-body.org/viewtopic.php?f=10&t=28432#p150648
Quite interesting. I can agree to the first reason when going over a bump with one wheel, but the one on cornering doesn´t make sense to me either.

[tinsfci]

One thought on the vent idea. I would want to move the outlet to the vent more toward the center of the spindle so it ducts the air as close to the hub as possible. That way the air can flow better through the vents of the disc. I know we are limited by the bulk of the spindle itself but it's probably worth trying to get the air as close as possible. Cool idea using the lower marker light as a vent.

Absolutely Nic! The outlet should end in the center of the rotor, NOT on the rotor braking surface. I think many has missed this important thing on vented rotors, that the air is being sucked in at the center of the rotor on the back, and goes out thru the fins on the rotor. I´ve made a note about that in some other thread, that when upgrading to ´76 and later brakes on a ´75, dont forget to replace the dustshields too, because they have air-holes for the vented brakes!

The brakes on the pics I borrowed for the air-vent has much bigger rotors, so the outlet is actually quite OK.

It may be worthwhile to do the S10 spindle upgrade. There are also a bunch of relatively inexpensive "Big brake" kits.

Yes. I might do the S-10 swap. Have you seen my fellow swede grandam75:s observation that the S-10 spindle mounted is actually longer, and not shorter than the original spindle? viewtopic.php?t=26198

I dont know if anyone considered the difference in spindle height when using S10 ball joints. Yes the stock spindle is about 1/4" taller than the S10 but if you measure the height with the ball joints attached you find that the S10 spindle with S10 ball joints is about 15mm, 1/2" taller. This should help camber gain.

Interesting!