Lone Star Caliper and MC SS sleeving

[Terry M.]

Re: Lone Star Caliper and MC SS sleeving

I had the brake calipers and the MC sleeved by Stainless Steel Brakes Corp on my 67 back in April 1992 and used silicone brake fluid when I re-installed them. Drove the car to the Western Regional from Los Alamos to Albuquerque and back and have no problems and trust me you want your brakes to be working on that trip. Pete

Pete,
Seems to me there is some change in elevation during that trip. What are the numbers?

There has been some accusations that DOT 5 can have air entrainment issues at elevation. What was the elevation where you were during the install in 1992?

[Peter L.]

Re: Lone Star Caliper and MC SS sleeving

Terry - LA is at 7200' then down to the Rio Grande river at ~6000', back up to Santa Fe at ~7000' and then down to Albuquerque ~5000'. The drive down from LA to the Rio Grande is a 2 lane road along the edge of the mountain. Great views but it's best to keep your eyes on the road. Pete

[Joe L.]

Re: Lone Star Caliper and MC SS sleeving

Pete,
Seems to me there is some change in elevation during that trip. What are the numbers?

There has been some accusations that DOT 5 can have air entrainment issues at elevation. What was the elevation where you were during the install in 1992?

Terry-----


I have had the problem with spongy brakes at high altitude. In fact, the brakes in my car acted almost like an "altimeter"-----the higher I go, the more spongy they get. At almost 10,000 feet elevation at Tioga Pass on SR 120, they are extremely spongy. As I continuously reduce elevation going westbound, the brakes become increasingly firm until, at Sacramento and nearly sea level, they are rock hard.

Could it be the silicone fluid? I would say yes EXCEPT that I had the EXACT SAME problem with DOT-3 fluid. In fact, one of the reasons that I long ago switched to silicone DOT-5 was the hope that it might solve this problem. It did not.

When I was still using DOT-3, I tried bleeding the brakes when I was at Susanville, CA (elevation 4,200') and I could not get a firm pedal no matter what I did. So, I took it to a service station there and had them try power bleeding. They couldn't get a firm pedal, either. But, when I returned to the bay area at near sea level, the brakes were rock hard.

After I switch to DOT-5 silicone fluid, I tried bleeding the brakes at Mammoth Lakes California, elevation 7,500'. No matter what I did I could not get a firm pedal. But, once again, after I returned to the Bay Area, I had a rock hard pedal.

The only thing I could figure is that there is some air in the system and the bubble size increases as atmospheric pressure decreases. However, I'll be damned if I know how to get that bubble out. It's another one of the reasons that bleeding the brakes on a Corvette is one of my most feared activities.

Based upon my experience, I believe that there is some problem with a Corvette brake system that can cause the brakes to become spongy at high altitude. However, I don't think it has anything, at all, to do with what type of fluid is used in the system.

[Terry M.]

Re: Lone Star Caliper and MC SS sleeving

Whatever your issue is Pete apparently doesn't have the same. Pete didn't answer my last question, but I am pretty sure he installed the DOT 5 in the suburbs of Chicago -- or about 300 to 400 feet in elevation.

DOT 5 does have slightly more compressibility than glycol/ester fluid, but that should not be an issue for most of us unless we spend a lot of time on the race track and are very skilled drivers.

I have some thoughts about air entrainment, and they revolve more around ambient temperature than altitude. I have no supporting data, so there is not too much to it. Next time the ambient temperature gets into triple digits -- not very often where you live I am sure -- you might try pressure bleeding the system. Also a rubber mallet striking the calipers might free any bubbles hanging on the caliper walls.

[Joe L.]

Re: Lone Star Caliper and MC SS sleeving

Whatever your issue is Pete apparently doesn't have the same. Pete didn't answer my last question, but I am pretty sure he installed the DOT 5 in the suburbs of Chicago -- or about 300 to 400 feet in elevation.

DOT 5 does have slightly more compressibility than glycol/ester fluid, but that should not be an issue for most of us unless we spend a lot of time on the race track and are very skilled drivers.

I have some thoughts about air entrainment, and they revolve more around ambient temperature than altitude. I have no supporting data, so there is not too much to it. Next time the ambient temperature gets into triple digits -- not very often where you live I am sure -- you might try pressure bleeding the system. Also a rubber mallet striking the calipers might free any bubbles hanging on the caliper walls.

Terry------


I've beaten the calipers "senseless" with a rubber mallet during brake bleeding.

[Peter L.]

Re: Lone Star Caliper and MC SS sleeving

Terry - Correct. I used the silicone brake fluid when I re-install the sleeve calipers and MC back in '92 when I and the car were in the Land of Lincoln. Boy do I miss that traffic. Pete

[Terry M.]

Re: Lone Star Caliper and MC SS sleeving

Terry------


I've beaten the calipers "senseless" with a rubber mallet during brake bleeding.

At elevated temperatures? I am guessing that is the key, but give it a shot -- what have you got to lose?

[Terry M.]

Re: Lone Star Caliper and MC SS sleeving

Terry - Correct. I used the silicone brake fluid when I re-install the sleeve calipers and MC back in '92 when I and the car were in the Land of Lincoln. Boy do I miss that traffic. Pete

I kind of figured it was here. The other option was Houston, and that is lower.

You are just complaining about the traffic because you narrowly avoided it in November. Enjoy your low humidity out there. Boy did Fall end with a bang here.

[Jack H.]

Re: Lone Star Caliper and MC SS sleeving

We had an RMC member with similar observations. He lived with his Corvette at/near sea level for about 7 years with DOT-5 fluid installed and NO PROBLEMS.

He moved to the foothills outside Denver and after one year, the brake pedal went to the floor coming down the hill to Denver! Needless to say, the experience took his breathe away...

Sooo, he bled the brakes and topped off with fresh DOT-5. The problem came back twice but not as severely!

He consulted with the chapter's Technical Advisor who builds & crews vintage race Corvettes as a serious sideline. The advice was to TOTALLY empty the brake system of existing DOT-5 fluid, blow it clean/clear with brake cleaner & compressed air, then re-fill it with fresh DOT-5 fluid AT OR ABOVE the altitude he normally operates the car.

He took the advice and no problems since...