Yelo

GM says max shift point is 5200 rpm's, ALL of us running it shift it higher than that.....but HOW HIGH can you go before you really run into a problem ??

I've kinda finalized my cam decision (GM HOT cam) and want to make sure that the tranny will be able to live to the 6500 rpm's that I want to spin the motor....

TIA

Dutch SS

iTrader: (3)

I am shifting at 6300....no problems yet

jimmyblue

iTrader: (11)

I think it's likely a time-at-temp, time-at-RPM
limit. Like on the 4L65 they rated the RPM lower
because of the 5-planet cluster not having the
oil passages needed to cool it as well as the
'60. A few seconds at a time will probably not
kill you but it might not be happy on sustained
high RPM runs.

Would be interesting to know what GM had in
mind as the RPM limiting components.

James B.

iTrader: (1)

I would think it has to do with how much heat the clutches can take without overheating. The higher the RPM is the wider the RPM difference the shift has to make up. GM is not going to compromise shift smoothness for clutch life ever. Shifting it faster (more firmly) would result in less heat in the clutches but degrade shift "smoothness." Also, performance friction materials would help too. The less time the clutches take to engage the more power you can shift and I would guess the higher RPM it could safely happen at.

A word of caution though, the drums in these are all steel, not aluminum. That is great for strength but it's also a lot of weight to be spinning in there and if they come apart it will tear up the car and the occupants.