NewOrleansLT1

When you guys are at the drag strip are you running in Drive or OverDrive for best times/results?

Jeremy@RPMTransmissions

iTrader: (12)

Running in D vs OD won't change the performance of your car in the 1/4 but it will help your 4L60e trans live longer by applying the over-run clutch to help support the sprag.

Shownomercy

iTrader: (1)

If you run out of gear and shift into OD, that will kill some ET no?

What transmission OP?

96capricemgr

iTrader: (1)

The 2-3 shift is improved with the selector in OD so that is what you will find most tranny guys suggesting. At least that was the case a few years ago, I think they are always finding tweaks.

bowtienut

iTrader: (1)

Unless your valvebody is setup to provide more fluid volume (less restriction) during the application of the 3-4 clutches, shift quality and 3-4 clutch life is best by running in "OD". Running in "D" robs pressure from 3-4 clutch application during that critical split second of the 2-3 shift.
In a really high powered application, I agree with Jeremy's point; just make sure you have the valvebody mods to do it.
I've not hurt the sprag in mine by running in OD, racing it for 4 seasons with 500+ hp.

NewOrleansLT1

I have a 4L60e and I noticed that my car bounces off the rev limiter once or twice during the 2-3 shift when running wot in D. I had shift points lowered with no luck. I thought the tranny was on its way out. Then I made a test hit on the street in OD and it shifted fine. I just never understood why..

bowtienut

iTrader: (1)

That makes sense. Your 3-4 clutchpack isn't getting the fluid volume required, so full pressure arrives too late. Clutches are slipping as the revs continue to rise. Yours is a case in point for running in OD.
Also, if your shifts occur really close to the limiter, you may find it hits the limiter when cold but not when hot. I'll sometimes hit it on the 1-2 shift 1st pass at the track, but not thereafter. The higher viscosity of the colder fluid slows the shift down by a few mSec.

Mystery Bird

iTrader: (7)

When I had a 4l60e I always ran in OD at the track for reasons already mentioned.

DUDCOUPE

My trans did the same thing, its the begining of the end of your trans. Your really not supposed to run your car wot in OD

bowtienut

iTrader: (1)

Says who?

96capricemgr

iTrader: (1)

Says the ignorant guy who didn't bother to read the whole thread.

As has been discussed selector in OD has benefits.

Now WOT in actual 4th gear has not really been discussed here.

pancho toco loco

iTrader: (8)

Wow this good tread. I had it backwards, I thought your over-run clutch was applied when in D. I've always run D at the track. Never had any issues but tomorrow I will make a run in OD and see how it is. My friend who builds trans and races runs his in D, ( non Electric 700r4) Thanks guys.

madmike9396

iTrader: (29)

I always use (R) for Race lol

96capricemgr

iTrader: (1)

I think the overrun clutches are applied if you select a lower than OD gear manually BUT the 3/4 clutches get more pressure at the 2-3 shift if the selector is in OD.
Look at bowtienut's first post in this thread.

Maybe in a perfect world you would launch in a lower selected gear and then get the selector into OD before the 2-3 shift but that opens up a lot of human error possibility.

transbird95

iTrader: (4)

[QUOTE=madmike9396;18241458]I always use (R) for Race lol[/QUOTE


Lol made my day, thanks!

pancho toco loco

iTrader: (8)

I guess you could launch in with selector in 2nd then after the 1-2 move the shifter up to OD, but like you said that opens up lots of room for error.

NewOrleansLT1

If I'm not mistaken I think if you have the selector in 2nd at the starting line it will take off in 2nd and not 1st.. Your car will launch like a turd..

pancho toco loco

iTrader: (8)

I believe the later 4th gens had that, being a 94 I don't have that issue, plus if I did with my gearing and converter I doubt my car would ever launch like a turd ie 2.2 plus 60ft times

DUDCOUPE

When i mean od, i mean 4th gear with converter locked up.

96capricemgr

iTrader: (1)

In 4th lockedup would only ever come into play in atop speed or salt flats car geared to use all available engine rpm and I don't think anyone would do it that way they would use numerically low gears and just keep it in the more efficient 1:1 third gear.

Maybe a standing mile car would use 4th locked since they need acceleration of deeper gears and still top speed