What happened to this mainshaft?
#1
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What happened to this mainshaft?
This mainshaft came out of a 99 Vette transmission. This is a pic of where the 5/6 cluster gear was. If I'm not mistaken, there's supposed to be splines all the way down this area? The gear just slid off without a press and it even moves a little on the shaft.
#2
FormerVendor
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The 5/6 cluster gear is supposed to press onto the mainshaft. When you spend a lot of time accelerating in 5th and 6th gear you will eventually cause that gear to fret against the mainshaft and it will wear the press-fit area of the shaft out. This allows the gear to more slightly at the splines. Given enough time the 5/6 gear will wear through the splines on the mainshaft and you will lose 5th and 6th gear.
#3
LS1Tech Premium Sponsor
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Looks just like my old CTS-V mainshaft looked. Jeremy from RPM Transmissions has you covered.
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Glenn ***
Sales Tech
www.bmrsuspension.com
813.986.9302
Find a Quality alignment shop near you!
#4
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Jeremy helped me out a ton with ordering replacement parts and answering questions for me. I know who I'll be shopping with for my transmission needs fro now on...
#6
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The 5/6 cluster gear is supposed to press onto the mainshaft. When you spend a lot of time accelerating in 5th and 6th gear you will eventually cause that gear to fret against the mainshaft and it will wear the press-fit area of the shaft out. This allows the gear to more slightly at the splines. Given enough time the 5/6 gear will wear through the splines on the mainshaft and you will lose 5th and 6th gear.
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#10
FormerVendor
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WOT shifting into 5th gear is never a good idea. The stock 5th and 6th gear aren't strong enough to take a high RPM shift behind a high horsepower engine. If the car is less than 400hp it shouldn't hurt it. But if you are going to regularly shift into 5th gear I would recommend upgrading the 5th and 6th gear to a G-force gearset.
#11
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More information on the issue here:
https://ls1tech.com/forums/manual-tr...vibration.html
The real reason for the issue is a shitty design in the way the 5/6 cluster gear fits the main shaft IMO. There is not enough "press fit area" built into the design to ensure good reliabilty. This is the reason it was redesigned for the 03 Cobras that have tighter fitting, individual 5 and 6 gears.