Firming up shifts in GM transmission with fluid

[Alex89gp]

Hello,

I came across this forum post that claims you can just add a bit of F-type ATF to a GM transmission to firm up shifts. It is claimed by some that no extra wear and tear will be added to the transmission. What do you guys think of this?

I figure the firmer shifts would lengthen the life of the transmission but I am wary of doing things like this without proper research. For example, will fluid with less friction modifiers cause increased valve body wear? And would additional wear on gears, bearings, and thrust washers be significant enough to make a noticeable change on the lifespan of these components?

 

[Colt45ws]

In the past I switched the 3T40 in my Cavalier to Type F because it seemed to me to slip. But that is pretty much fully hydraulic in operation. Well, except for the Torque converter lockup, but that is about as complicated as a light switch. Ancient Trans design. I wouldnt do it in anything with electronic controls as they expect shifts to happen in a certain way. Go outside of expected and they will go into limp mode.

 

[rshaw125]

The 4 speed GM transmissions (4T65) seem to operate better on a thicker fluid like Maxlife than Dex Vl. Also the mod to do is install a shift kit from trans-go.
I would do a fluid change to Maxlife and while I have the pan of drop the valve body and install the kit. This improves the shifts and operation of the trans.

 

[sciphi]

The 4T60 (or maybe it's still a 440T4) in your 1989 has an vacuum modulator that might need replacing if the shifts are getting sloppy. Replace that (it's fairly easy since it's external to the transmission), tighten the adjuster screw in it a little at a time, and firmer shifts will result.

The 4T65E in the 2001 can only have its shifts adjusted by a shift kit or by reprogramming the PCM. Fluid will make the shifting faster/smoother, but won't firm them up. The shift kit or reprogramming will do that.

I'd recommend a TransGo shift kit and Maxlife ATF for the 2001, and an adjustable vacuum modulator for the 1989. Not Type F.

 

[mechtech2]

Using type F in a Gm 350 or 400 trans is an old trick [for old trannys!].
It DOES firm up shifts, and can net street racers 2 tenths at the strip.
Probably longer clutch disc life, too, on the street.

With modern transmissions, who knows? You may gain in one area and lose in 6 others!

 

[SteveSRT8]

You go first!

I would not do this in any modern slushbox.

 

[FusilliJerry82]

Originally Posted By: rshaw125
The 4 speed GM transmissions (4T65) seem to operate better on a thicker fluid like Maxlife than Dex Vl.


Maxlife is among the thinner/midrange ATF's on the market.

 

[KCJeep]

Lubegard Red will also firm up the shifts and is a far better option than type F to do so IMO.

And what he said...the newer MaxLife is no longer particularly thick since they changed it to a Universal type synthetic and hint it is fine for DexVI and ATF+4 applications now. Super Tech HM is still thick I believe, someone mentioned Castrol HM ATF is as well.

 

[KCJeep]

And I'm in the opposite boat, my 04 Chevy is shifting hard and I want to soften them a bit, but it didn't like DexVI and started slipping on that. Not sure what I'm gonna do, obviously I'm trying to avoid work as long as possible.

 

[SteveSRT8]

We have used LG red in many different slushboxes and it can have amazing results.

I would try some, member Trav here has recorded some amazing temp reductions with no other changes!

 

[ponderosaTX]

Since Valvoline reformulated MaxLife ATF in 2008, MaxLife has essentially the same viscosity as Dex VI (6.1 vs 6.0 cSt@100C). Look at the specs:

http://www.gmcworkshop.com/new_force/Maxlife_ATF.pdf
www.valvoline.co.il/img/uploads/products/13043513571032511566.pdf

Valvoline lowered the viscosity of MaxLife so that they could claim MaxLife meets Dex VI specs even though it is not certified as Dex VI (which requires using a proprietary additive package made by Afton and a maximum viscosity of 6.0).

Valvoline apparently wants to obscure this fact since they no longer post viscosity figures for MaxLife ATF at the Valvoline web site.

 

[Torino]

Type F is a help and won't harm anything. John--Las Vegas

 

[Boss302fan]

LG red is the answer, great stuff...

 

[ponderosaTX]

+1 on Lubegard Red.

Correction: the Afton Lube Specifications Handbook includes specifications for Dexron VI. See

http://www.aftonchemical.com/Lists/Brochure/Attachments/40/Afton_Lube_Spec_Handbook_2012.pdf

The maximum viscosity at 100C is 6.4 cSt not 6.0 cSt.