Mostmint Racing 1989 Corvette Build
Le Mans Master
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From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
The C5 brakes are a slightly smaller rotor diameter than the J55 C4 brakes, but the caliper pistons are larger. Not a huge difference but an improvement. The benefit of the C5 stuff is the thicker rotor. It will handle the heat of continuous lapping better than the thin C4 stuff.
Oil Producer
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The C5 brakes are a slightly smaller rotor diameter than the J55 C4 brakes, but the caliper pistons are larger. Not a huge difference but an improvement. The benefit of the C5 stuff is the thicker rotor. It will handle the heat of continuous lapping better than the thin C4 stuff.
kubs c5 is actually better than c4 j55/grandsport? ive never seen any documented failures or direct comparisons.
Le Mans Master
Joined: Oct 2007
Posts: 9,702
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From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
J55 caliper pistons are 40mm (I think, going off memory) and the C5 is something like 42.5mm.
Again, not a huge change in overall braking performance but will be able to withstand heat a little better.
Side note, with the larger piston calipers in the front it changed my bias on my '90 enough that I could no longer threshold brake. Going into a braking zone the ABS would go nuts if I was too hard on the pedal (but not hard enough to lock the brakes). That was with a DRM bias spring also. I ended up pulling the ABS fuse to get me through that day and then eventually ripped out the whole system. I could stop harder and faster without the ABS than I could earlier that same day with the fuse in place. Maybe it was an electronics failure or something else that showed up after the changing the brakes, but I never diagnosed why it did that.
Last edited by Kubs; Oct 29, 2019 at 12:40 PM.
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Kubs, did you have the bias spring changed and it still licked up to early?
Also, when your abs did kick in, did you end up in the grass when that happened? ive heard stories of the abs from c4’s putting people off track. When i was at track this summer i unplugged the abs pump.
Also, when your abs did kick in, did you end up in the grass when that happened? ive heard stories of the abs from c4’s putting people off track. When i was at track this summer i unplugged the abs pump.
Le Mans Master
Joined: Oct 2007
Posts: 9,702
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From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
Kubs, did you have the bias spring changed and it still licked up to early?
Also, when your abs did kick in, did you end up in the grass when that happened? ive heard stories of the abs from c4’s putting people off track. When i was at track this summer i unplugged the abs pump.
Also, when your abs did kick in, did you end up in the grass when that happened? ive heard stories of the abs from c4’s putting people off track. When i was at track this summer i unplugged the abs pump.
It happened so early in braking that fortunately I noticed it during my warm up laps (lower speed), so I was still able to drive through the corners. Then for the rest of that session I experimented knowing that the issue existed. I never went off.
Last edited by Kubs; Oct 29, 2019 at 02:21 PM.
Thread Starter
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From: Wadsworth, Ohio
I have the base JL9 setup right now. Still untested in a performance environment. With stock HP, street tires, 400+ lbs lighter and some cooling they may be adequate
Team Owner
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From: Park City Utah
Would you happen to know if the extra thickness is due to extra thickness of the rotor surfaces or extra room between them?
I have the base JL9 setup right now. Still untested in a performance environment. With stock HP, street tires, 400+ lbs lighter and some cooling they may be adequate
I have the base JL9 setup right now. Still untested in a performance environment. With stock HP, street tires, 400+ lbs lighter and some cooling they may be adequate
Last edited by Tom400CFI; Oct 29, 2019 at 09:49 PM.
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Would you happen to know if the extra thickness is due to extra thickness of the rotor surfaces or extra room between them?
I have the base JL9 setup right now. Still untested in a performance environment. With stock HP, street tires, 400+ lbs lighter and some cooling they may be adequate
I have the base JL9 setup right now. Still untested in a performance environment. With stock HP, street tires, 400+ lbs lighter and some cooling they may be adequate
my ambient is likely less than the southern states!! so not sure how the rotors would hold up in an endurance setting but the quality of brakingin 2hrs straight should have degraded and they didnt.
given the 2x rule, id think a set of baers would even be doable. ill stick with the j55 for now.
also, i didnt have my bias spring installed yet.
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Oil Producer
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https://youtu.be/3Pju-FdhjME
After a lot of work and not quite everything in order, the car ran 150 miles yesterday including some track time at Nelson Ledges.
After a lot of work and not quite everything in order, the car ran 150 miles yesterday including some track time at Nelson Ledges.
woo woo! nice job. The auto trans did fine?
Thread Starter
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Joined: Dec 2018
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From: Wadsworth, Ohio
For the limited track time it had I say yes. I used 2nd and 3rd only on this course. Trans oil temps never went over 190. Of course it was 30 degrees outside which helped, and power steering fluid would overheat (260 degrees) in 10 minutes so had to keep to short stints. Engine oil temps were up to almost 300 which is not sustainable either. This car does not have the factory coolers for power steering or engine oil.
There is still a LOT of work to do to get this car prepped for a race. By spring hoping to be ready for a serious track day effort with a lot more track time.
Also the switch to fiberglass roof is just to meet rules.
There is still a LOT of work to do to get this car prepped for a race. By spring hoping to be ready for a serious track day effort with a lot more track time.
Also the switch to fiberglass roof is just to meet rules.
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[QUOTE=Mostmint;1600433330]For the limited track time it had I say yes. I used 2nd and 3rd only on this course. Trans oil temps never went over 190. Of course it was 30 degrees outside which helped, and power steering fluid would overheat (260 degrees) in 10 minutes so had to keep to short stints. Engine oil temps were up to almost 300 which is not sustainable either. This car does not have the factory coolers for power steering or engine oil.
There is still a LOT of work to do to get this car prepped for a race. By spring hoping to be ready for a serious track day effort with a lot more track time.
Also the switch to fiberglass roof is just to meet rules.[/QUOTE
nevermind! i see u dont have it.
it really does make a big difference.
what temps were the coolant?
There is still a LOT of work to do to get this car prepped for a race. By spring hoping to be ready for a serious track day effort with a lot more track time.
Also the switch to fiberglass roof is just to meet rules.[/QUOTE
nevermind! i see u dont have it.
it really does make a big difference.
what temps were the coolant?
Last edited by VikingTrad3r; Nov 4, 2019 at 10:23 AM.
Team Owner
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From: Park City Utah
I agree with you that those temps are too high.
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From: Wadsworth, Ohio
This has truck heads and cam. It was very flat over 4400 and not seeing 5000 rpms. Does yours have the factory oil cooler?
On track water temps were under 210 I think - with the 1" radiator (will update with exact info tonight after I check my notes)
This is the first ever I have collected data on oil temps (My 1.9 Saturn we just put in an oil cooler and never thought twice about it.) At highway speeds water temps were 180 and oil temps were about 210 with air temp of about 30 degrees.
On track water temps were under 210 I think - with the 1" radiator (will update with exact info tonight after I check my notes)
This is the first ever I have collected data on oil temps (My 1.9 Saturn we just put in an oil cooler and never thought twice about it.) At highway speeds water temps were 180 and oil temps were about 210 with air temp of about 30 degrees.
Le Mans Master
Joined: Oct 2007
Posts: 9,702
Likes: 3,472
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
My '90 had factory coolers and would constantly see 300+ oil temps and 230+ water at a track day within a 20 minute session. No offense, but if you're not getting there in your LT1 you probably are not driving it hard enough. C4 cooling is terrible. Im not at all surprised it got that hot at 30° out. It wasnt until I added an aftermarket oil cooler that water stayed below 230° and oil below 280° during a 20min session. Now that its a race car I have an even bigger oil cooler and I can run all day at 200° water and 230-250° oil.
Last edited by Kubs; Nov 4, 2019 at 12:57 PM.
Race Director
Joined: Jun 2004
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From: WI
A PS cooler was one of the first things I did when I started tracking. When I removed the stock oil "cooler" my oil temps dropped fifty degrees. It's more of an oil warmer! Stock brakes hmm it's possible but unlikely they will be okay. They didn't work out well on the tracks I go to. I switched to C5 brakes partly because the rotors have been half the cost so there's that aspect too. The auto needs a large cooler and any other help you can give it.
Team Owner
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From: Park City Utah
Racer
Joined: Mar 2018
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From: Las Vegas
Tom is your LT1 stock? If you're racing near park city then you're probably around 7k feet. There's 26-30% less oxygen up there, which means 25-30% less fuel being injected and 25-30% less waste heat generated. Of course there is 25-30% less airflow through the radiator as well, so who knows how all that will affect max oil temp, but it's an interesting thought.