obZidian

iTrader: (2)

Basically, I cannot remember if it was "ok" or not since i've researched this a while back but generally speaking, would it be considered "fine" to wot-shift into 4th/od with a 4l80e?

I ask because I'm calculating my tire/rpm/gear ratio's and wanted to know if to stick with the 26" tire and shift into fourth or go with a 28" tire and have enough mph (170mph est.) in 3rd and not shift into OD.

I know with the 4l60e, its a no-no, i blew the trans. twice doing this... but in the 4l80e, can it be done without hurting the clutches?

A.

Car will be around 800rwhp, 4l80e, 3200 yank stall, 3.23 gears, etc.

cablebandit

iTrader: (37)

mightymouse did it

Firechikn

iTrader: (15)

I've done a few times on the street. When I pulled apart the trans., the OD clutch showed just the slightest sign of slip on the steels. I think you could do a few times and be fine, but you wouldn't want to do on every run. I'm actually changing my rear gear to a 3.00 when I put the car back together for this very reason.

obZidian

iTrader: (2)

So, even though an 80e can hold a WOT-shift into OD, it would probably be wise to avoid it? I'm sure some will say to not do it and others will say its ok.

I think i'm going to just go with the 28" rear and unless i'm going over 167mph WOT, then i'll go into 4th/od.

Thanks!

What's up cable? Hows the kit treating you? We are VERY, VERY close to get her done. She us running but we need to wait for the weather to clear up so we can begin the tuning process and break in. The motor has been sitting for so long that we have to be careful in turning her over and making sure everything is working just correctly.

tptransmission

The O.D. clutch is not on if 4th overdrive. It will not see any heat. The 4th clutch and O.D roller take the brunt of the power. For the most part if you upgrade the 4th friction material they can handle the power. The production roller clutch will eventially fail. Overrun clutch plate only apply when you manually downshift to D3, D2, D1.

Firechikn

iTrader: (15)

I'm talking about the overdrive clutch. Last, largest clutch drum behind the pump. It's not engaged in 4th? I sure don't claim to be a trans guy, but I thought it was 4th gear. My overrun clutches looked perfect still.

Circle-D

iTrader: (21)

Are you calculating in the lock up clutch? It might make sense to bring on the clutch instead of the OD. You might need a multi disk converter to make sure it does not slip at those power levels. Might be safer than the OD clutches and will keep you 1:1 instead of OD.

Chris

obZidian

iTrader: (2)

Interesting. Currently, i'm running a single disk yank and though i can manually lock it, i don't know how it would react to the extra heat. I feel that i'm going to go with the 28" tires on the 17's. Effectively, I should be fine till 167 @ 6500rpm's.

Now, running with the converter unlocked, will the mph i calculated be exact with the nature slip in a converter skew that some? Meaning, in a m6 car, mph is exact, well almost, to gearing/rpm. Should I expect the same through the auto or should i calculate whatever mph differences i might have?

A.

Circle-D

iTrader: (21)

You need to calculate in at least 5% loss, probably more to get a realistic number. It is not suggested to lock a single disk converter under power, especially at your levels. It is just a thought, but if you went with a multi plate converter, then it would be zero loss. But if you were already using zero slip then your finish RPM just went up, not down. Sorry about that.

Chris

tptransmission

Sounds like a simple terminology difference. The large Clutch behind the pump is the 4th clutch, the overrun clutch is inside the housing attached to the turbine shaft.