Rear end & differential on Hardtops

[UtahZR1]

Mike, I was reading an article and this fellow had a 1999 convertible six speed C5, and he was doing speeds on a 500 mile trip in excess of 150 mph for about 32 minutes. He claimed that the tranny and rear end starting grinding and making a lot of noise and wound up having it towed to a dealer. The dealer said that they never saw this problem on a C5 before, and every part from the transmission to rear end couldn't be reused. As I read on, they said that the with the T56's idler shaft being used in all the gears, there are more parts rotating. If this is happening at very high speeeds for extended periods, it can cause a lot of heat buildup. Since the tranny is bolted directly onto the rear-axle assembly, the heat is transferred into the rear through the output shaft. At normal speeds, this isn't an issue. But at high speeds without synthetic oil there is a lot of heat buildup. I know they have transmission & rear axle coolers on racing vehicles and use synthetic oil. My hardtop has a transmission cooler, but has the recommended oil that came with the car from the factory. Do they have a rear end cooler aftermarket that I can install, and should I change to synthetic oil for the tranny? I do enjoy the car and bring it up to high speeds, so I am concerned about the overheating. Have you heard of any incidents like the above one I described, in any '99 hardtops?:chevy:

[MKOTZE]

Originally posted by UtahZR1
Mike, I was reading an article and this fellow had a 1999 convertible six speed C5, and he was doing speeds on a 500 mile trip in excess of 150 mph for about 32 minutes. He claimed that the tranny and rear end starting grinding and making a lot of noise and wound up having it towed to a dealer. The dealer said that they never saw this problem on a C5 before, and every part from the transmission to rear end couldn't be reused. As I read on, they said that the with the T56's idler shaft being used in all the gears, there are more parts rotating. If this is happening at very high speeeds for extended periods, it can cause a lot of heat buildup. Since the tranny is bolted directly onto the rear-axle assembly, the heat is transferred into the rear through the output shaft. At normal speeds, this isn't an issue. But at high speeds without synthetic oil there is a lot of heat buildup. I know they have transmission & rear axle coolers on racing vehicles and use synthetic oil. My hardtop has a transmission cooler, but has the recommended oil that came with the car from the factory. Do they have a rear end cooler aftermarket that I can install, and should I change to synthetic oil for the tranny? I do enjoy the car and bring it up to high speeds, so I am concerned about the overheating. Have you heard of any incidents like the above one I described, in any '99 hardtops?:chevy: Hello UtahZR1, I have made some phone calls and no one has heard of this kind of problem as being a characteristic of this model. Unfortunately, your hardtop does not have a cooler for the manual transmission. What you're probably seeing is the cooler for the power steering. It would be very involved to add a cooler to the trans or the rear end as there is no internal pump to circulate the fluid. I feel that you really do not need to have a cooler for the manual trans. I would however recommend that you switch to Mobile 1 synthetic automatic transmission fluid, it will hold 4.1 quarts. For more information check on the forum under the Mobile 1 tech consultant. Hope this helps. Good luck. :chevy: MKOTZE

[fatherlarry]

Originally posted by UtahZR1
Mike, I was reading an article and this fellow had a 1999 convertible six speed C5, and he was doing speeds on a 500 mile trip in excess of 150 mph for about 32 minutes. He claimed that the tranny and rear end starting grinding and making a lot of noise and wound up having it towed to a dealer. The dealer said that they never saw this problem on a C5 before, and every part from the transmission to rear end couldn't be reused. As I read on, they said that the with the T56's idler shaft being used in all the gears, there are more parts rotating. If this is happening at very high speeeds for extended periods, it can cause a lot of heat buildup. Since the tranny is bolted directly onto the rear-axle assembly, the heat is transferred into the rear through the output shaft. At normal speeds, this isn't an issue. But at high speeds without synthetic oil there is a lot of heat buildup. I know they have transmission & rear axle coolers on racing vehicles and use synthetic oil. My hardtop has a transmission cooler, but has the recommended oil that came with the car from the factory. Do they have a rear end cooler aftermarket that I can install, and should I change to synthetic oil for the tranny? I do enjoy the car and bring it up to high speeds, so I am concerned about the overheating. Have you heard of any incidents like the above one I described, in any '99 hardtops?:chevy:

UtahZR1,

I wanted to clarify something, because I see you are confused about the transmission cooler. Mike is right, when he tells you that the '99 has a power steering cooler, not a transmission cooler. There was a special racing package which debuted and it included the transmission cooler. Like Mike recommended, go with the synthetic if you are concerned, specifically Mobil 1 Synthetic ATF in the C-5 Six speed.

BTW, the tranny cooler you're referring to is in a special racing package. See article below.:smoke:




CHEVROLET CORVETTE DEBUTS ROAD RACING PACKAGE

DETROIT, MI -- Chevrolet's commitment to amateur road racing is evident with just a glance under the hood of the 1999 T1 Corvette that will visit nine American cities as part of the Hot Rod Magazine Power Tour May 13-23.

"The Corvette has been a mainstay of road racing since its introduction in 1953," said Ken Brown, a GM Motorsports engineer, who oversaw development of the T1 package. "The '99 Corvette hardtop presents a perfect opportunity to reassert that dominance."

Brown explained that the 5.7 liter V-8 fixed-roof development car showcases a new GM Performance Parts T1 suspension package that builds upon the foundation of the standard Z51 sports suspension on all hardtop Corvettes. It includes larger anti-roll bars, stiffer springs and a manual transmission oil cooler kit for endurance road racing venues. Front control arms with heavy duty bushings were also added to this particular vehicle.

"The Accu-sump will be tested on the Power Tour as a possible future addition to the kit," Brown added. "Other future GM Performance Parts enhancements for the T1 include high performance camshafts and valve springs."

Chevrolet is the title sponsor of the Hot Rod Magazine Power Tour, a cross country trek of as many as 2,000 high performance vehicles. After a kickoff in San Bernadino, CA the tour will hit the road, making evening stops in the following communities: Flagstaff, AZ; Albuquerque, NM; Amarillo, TX; Tulsa, OK; Kansas City, MO; Madison, IL; and, Louisville, KY. This year's tour concludes in Nashville, TN, May 22-23.