Manually downshifting a 4L60E

[9T8W66]

Ok since I've had 3 different people ask me this tonight I thought it would be easier to make it into a post.

Like I said in the original post everything is dependant on gearing and MPH.
I'll use my old `94 Formula A4 w/2.73's as an example That car could be downshifted manually to 1st gear under WOT anywhere below 45mph.
So a 3.23 or 3.73 geared car will need to be done at a lower speed.
The trick is to hammer the throttle and pull the shifter back at the same time. then upshift the lever to 2nd quickly so the ECM will still upshift the trans.
At WOT the trans will stay in 1st while you move the shift lever because it hasn't reached it's shift point yet. Then after it hits 2nd gear you can move it to 3rd.....
Best way to do it is start at low speeds and practice it until your confident enough to try it from higher speeds.
Keep in mind that the trans will only go to 1st if the car is under it's first gear top out speed which is determined by the rear gear ratio.
I originally started do this on my Old `79 Trans Am
It was a 325HP 400 Pontiac backed by a TH350 and a 2.41 axle ratio. That car could be downshifted to 1st from a 50 roll and was devestatingly fast doing it. The `94 Formula with the 2.73's reacted similarly from about a 45 roll I think, IDK it's been along time.
I've owned my 6spd car for 10 yrs now so my memmory is a little sketchy But I also did it in a Buddies `02 SS and it worked from about a 35 roll.

Like I said pay close attention to mph and rpm while doing this or things could get hairy. Start slow and work your way up.

Anyway hope this explaination was easy enough to understand and have fun.

[Yoeasy69]

good info...

but if i have said it once, i have said it a thousand times..

if you want a manual, get a manual.. if you don't but still want to shift, get a RVB auto... but if you are running a regular trans.. let it do its job.. undue stress and short life is not worth it..

[93formulalt1]

good info...

but if i have said it once, i have said it a thousand times..

if you want a manual, get a manual.. if you don't but still want to shift, get a RVB auto... but if you are running a regular trans.. let it do its job.. undue stress and short life is not worth it..

All the people I've talked to about this (including the transmission tech that rebuilt the TH350 in the Monte Carlo and guaranteed it for up to 900hp) have said that upshifting the transmission manually will not put any noticeably increased stress on the internals, nor will it cause premature failure of the transmission. They have, however, stated that downshifting the transmission while the vehicle is in motion is a bad idea, as the sudden gear change while the vehicle is moving will transfer the energy from the wheels through the driveline into the transmission, which can lead to increased wear and premature failure of the transmission, which can, in turn, lead to engine problems.

Just sharing the information I was given from reliable sources.

I still find it best to sit back and let my 700R4 automatic do what it does best. . . Shift right at redline while the throttle is wide open Trying to shift it manually will usually result in bouncing off the rev limiter (unless you've got lots of practice, which IMO, isn't worth it), costing you precious time getting down the track.

[DETROITMUSCLE]

get a converter and let it do its job.

[93formulalt1]

get a converter and let it do its job.

AMEN!! I'm hoping to put a 2800 or 3200 stall converter in the Formula after some other goodies, and I don't plan on manually shifting. I trust my trans to get me from point A to B quickly, I see no need to meddle.

[9T8W66]

Keep in mind guys this thread is about manually downshifting Not upshifting. I do agree that the ECM will always do a better job on the upshift but when it comes to downshifting Slamming your foot to the floor and waiting that second for the trans to kick down doesn't do the job.
Especially if it doesn't kick down to the optimal gear.
And as long as you pay close attention to Mph and Rpm you shouldn't have any problems

[93formulalt1]

I understand what you're trying to say, and while you do have a point about gaining better acceleration by eliminating the delay between going to WOT and the trans automatically downshifting, you can also accomplish the same task by properly adjusting the throttle kickdown cable. Too many hard downshifts (like throwing it into 1st at 40mph) will most likely cause the transmission to require service or rebuilding. The 4L60E is electronically controlled, so it does prevent the trans from downshifting to 1st when the vehicle is traveling above a certain speed, but older transmissions do not. The 4L60/700R4 did not have these fail-safes, neither did the TH400 or TH350. Putting too much energy through your transmission is going to cause problems in the long run, I guarantee it. When you downshift an automatic transmission the way you are describing, the energy from the engine is being put through the trans from the front, and the energy from the resistance at the ground is being transmitted forward through the trans simultaneously. When those conflicting forces meet, there is a much higher risk of breakage.

Not to mention you are dramatically shortening the life of the POS 10-Bolt at the same time. Manually upshifting is fine, as long as you don't sit there bouncing the thing off the rev limiter all the time, but manually downshifting is just asking for it, IMO.

Same thing can be said for T56's, if you downshift the trans into the wrong gear at the wrong time, it could be devastating for the engine, trans, rear end, driveshaft, basically the entire driveline. I was riding in a friend's Cadillac, and while we were going down the road, some idiot in an LS1 Camaro pulls up next to us and decides he wants to race. He tries to downshift into 3rd at about 55mph, but missed the gear and hit 1st instead. . . He blew his engine. I'm pretty sure he sent a rod through the oil pan, because his car pretty much stopped instantly, and the ground was covered in oil. If you can't afford to replace it, you shouldn't be driving it in a way that is conducive to breaking things.