hawkls7

recently my supercharged warhawk with et ls7 heads was being tuned on dyno , first run made 940 rwhp . due to diff pinion gears breaking we stopped second run. We then stripped down the trans an noticed the updated over run sprag has failed, the little springs have been sqashed in their little case. my understanding is the overrun gear only gets used in d for drive, on our dyno pull we had it in third gear overun should not ingage. also with the sprag failure our converter stall had changed from 4000 to like 5700on the dyno. Any thoughts would be appreciated.

Gilbert@Ace Racing

Hello Hawk,

We talked on the phone recently regarding this issue.

The Overunning Clutch (sprag) in the 4L80E is applied in Manually selected 1,2,3 and off in 4 (or overdrive). It is not applied in any gear when the shift lever is in OD / 4. The Overunning clutch provides engine braking in 1,2 and 3 manually selected gear ranges.

So, that means that if your pull was made in manually selected 3 then indeed the overunning clutch would take the hit when the rear axle let go.

There is no replacement part that will withstand that sort of punishment at that power level that I am aware of. It is simply a matter of the part taking a significant shock when the axle let go. My recommendation would be to replace it in full confidence that it is the best part you can buy for the job.

I say build and and hit it!

Hope that helps,

g

john kilgore

l think you will find that the input one way clutch is applied in all forward gears except 4th when it over runs. the springs being smashed is caused by power being applied on and off very quickly and vilantly. good luck

cablebandit

iTrader: (37)

lol..John I know you know your **** when it comes to trannies but I think you mean "violently"

Websy21

iTrader: (34)

So does this mean that you should make your pulls starting in OD than?

FLT

iTrader: (1)

No 3rd gear.

Gilbert@Ace Racing

That's a very good way of explaining it. Meaning, if the engine is at WOT and the axle let's go the Overruning Clutch has no choice but to engage, same as a decel event only much more violently as mentioned. And when that happens it will be damaged in most cases as it happens at a max power level at high speeds.

g