4L80e WOT 3-4 shift

[slarsen47]

I think it is fairly common knowledge that the 4L60e 3-4 shift should not be made at WOT.

What about the 4L80e? Is the same true?

Can the 4L80e be shifted into 4th at WOT at 750 RWHP and live?

[slarsen47]

Nobody knows?

[TheMechanic]

At 750? If it is built I say yes. If not I say no. Are you that low/numerically high in diff gearing that you can? Or are you doing some kind of Texas mile stuff?

[RDF1]

It can be shifted into 4th but how long it will live is the real issue. Is it stock?
And 750hp in a 2000# car or 7000# truck?

[kingtal0n]

A 4l80e should tolerate the 3-4 shift well. It has a dedicated 4th gear clutch pack and the roller clutch over-runs going into 4th so I don't really see any issue. I do it with 600rwhp frequently on stock parts and borg warner clutches.

Just make sure it shifts nice and firm and no slip with plenty of trans pressure for WOT like 205psi or such at 500+rwhp.

[slarsen47]

This would be quarter mile in a 1998 turbo Camaro at 3600 lbs with a goal of 10.0 at 135.

The 4L80e is level 2 new build, so it is better than stock but not bullet proof, Circle D single disk lockup converter approx. 3600 stall.

The Moser 9 inch happens to have a 4.1 gear set that I would rather not change. I know easiest solution swap gears to 3.5

At 6500 rpm, with a 26.4 inch tall drag radial and with 5 percent assumed slip the mph would be only 118 mph. Clearly more gear multiplication is needed.

Even going to a 28 inch drag radial (did not want to modify fenders) the mph is only 125. Still 10 mph to go to get to 135. Although 7000 gets me there.

But if I want to stick with the smaller drag radial at 26.4 would need way more than 7000 to get to 135.

So after looking at the numbers, one solution would be a 3-4 WOT shift..........if it can do that without too much stress and damage.

A 3.50 gear set would work nicely at 6,500 rpm, 26.4 tire and 139 mph.

Another consideration is that the 3.5 gear might work better off the line than the 4.10 gears with only a 26.4 tire.

I do have one day of experience with the 26.4 drag radial in my D1SC Procharged car (3.06 first gear 4L60e, 3600 Yank) and 3.70 gears. Basically dead hooked launching off 900 rpm idle to a modest 1.62 sixty foot.

Highway cruise is compromised a bit with 4.1 gears as well. 2,800 rpm's at 70 mph.

I think I answered my own question..............lol

Best option is to change to a 3.50 gear.

Definitely lots of factors to consider in the original 3-4 WOT shift question. Still hoping to get some more feedback on the WOT 3-4 shift.

Probably the best answer would come from someone that does it all the time and knows from personal experience whether their own or their friends/customers. But I am suspecting that this is NOT a very common way to get down the track.

Thanks for the responses.

[RDF1]

If your converter slip isnt bad then you can try to lock the TCC around 120ish?

[kingtal0n]

DO not try to lock a single disc converter at wot

Even a triple disc its a bad idea according to Yank converters. Notice their triple disc is not marketed as a WOT lockup unit. Not a good idea for longevity but people do it anyways.

[slarsen47]

Thanks for responses.

[Fast4.7]

Thanks for responses.

Just FYI GM locks the stock single disc at WOT behind the 8.1L or Duramax even in the heavy vans and GMT400 3500HD. They hold up just fine.

[slarsen47]

Just FYI GM locks the stock single disc at WOT behind the 8.1L or Duramax even in the heavy vans and GMT400 3500HD. They hold up just fine.

Thanks!