GM Remanufactured Transmissions

[padgett]

Found my transmission book but the bad news is that none of the 4T60s (all used into 1991) show as available from GMPartsDirect.

FYI the remanufactured transmission part numbers are (all for 3800 4T60s)

24212203 - 2.84 axle ratio

24212204 - 2.97

24212205 - 3.33

also 2424192 - 2.8L 3.33, 24212201 & 02 3.1L 3.33

[charlie1]

ZZZ

Edited August 2, 2009 by CHAS1 (see edit history)

[D-a-n-i-e-l]

I know it does not help with finding the numbers.

I would look for the HD veriation. Stronger and a bolt in for the 91s. I forget wht the axle ratio is, but I am almost certain it is diffrent from the 91' Reatta. Also rebuild places I have spoken with do not show any diffs in the HD or norm, as far as rebuilds are cocerned.

[Guest spyhunter2k]

Daniel,

The 4T60 HD isn't electronically controlled, and would only bolt up to the 88-90 as far as I know, but not the 91. Are you referring to an HD version of a later transmission?

[D-a-n-i-e-l]

I am using it in my car and had to add a second computer to control it, a 91' passenger side axle, and modify the passenger side tranny mount. It is out of a 1996 Park Ave Ultra.

There was not 4t60-HD, only a 4T60E-HD started in 96, and ended when the 4T65E took its place. Also the 96' 4T60E is a direct bolt on for the 91' Reatta.

Here is a link to ID the trannys. Once again the HD started in 96'

http://dtcc.cz28.com/transmission/index.htm

[Guest spyhunter2k]

The 4T60 HD exists, and was used in one car only--the '89-'90 Turbo Grand Prix, which made HP similar to that of a Series I S/C engine.

Here is what one TGP owner on w-body.net said in regards to TGP-specific mods made by the factory:

<span style="font-style: italic">--Tranny setup is unique, larger tranny cooling lines and an aux tranny cooler in fender well.

--Hardened Gears and Gear Carrier Set.

--Additional Nested Accumulator Springs, other little changes to the tranny, some not listed until it's taken apart for inspection.

--1898 rpm Stall Converter, not a High-Stall as the stock turbo is not large enough to warrant it!

--Vacuum Line Check Valve/Bleeder at Modulator, Vacuum Line has internal restictor in-line to limit boost pressure and to allow check/bleed to fuction.

--Larger (Blackstone) 3 Core Radiator that is plumbed for the larger tranny cooling lines.

--Other than that, the valve bodies are different(they have "Turbo" stamped on them and provide firmer shifts. The shift speeds are also a bit different from NA versions)</span>

Another member reported:

<span style="font-style: italic">The GP had hardened Diff (95 or 96 z34 had the last of the hardened units), sunshell, more cluches in 2nd, high element sprag, two clutch 4th, and a turbo specific valvebody (linepressure i assume). </span>

Many others on that forum can back up the existence of this tranny. It is claimed to be superior even to the F7 variant of the 4T60 since it was set up for boost. It was created for a similar reason as the F7--the 4T60 couldn't handle the power they planned to make with the engine. The F7 was meant to accomodate the NA V8, but the beauty of the 4T60 HD in the TGP was that it was made for a boosted engine.

I'm not knocking the approach you took at all. I may go that route myself, but likely because 1) it's very hard to find a used 4T60 HD as used in the TGP, and 2) no one (that I or the TGP folks know of)presently builds a comprehensive rebuild kit specifically for it vs the "normal" 4T60.

If, on the other hand, you could find a 4T60 HD from a low-mileage TGP that didn't need to be rebuilt, I would be all on that.

[D-a-n-i-e-l]

Good info to have. I will have to look into it a bit more. Although I still could not have beet my $65 tranny find, with absolutley no signs of ware. (recent rebuild from Goodwrench)

[Guest Bill_Boro]

They beefed up the transmission on the Turbo Reatta proto type (the test car that the reporter crashed at the GM test track and killed the program)

It is described with pictures and a build sheet of trans modifications on another Reatta web site.

Also how is the 5 speed Getrag conversion going that we have had treads on? Any news? My Stealth has front wheel drive with a Getrag and it is a pleasure to drive. I thought the cable shift linkage would be less than perfect but works quite well after a little 30w oil was drizzled on its moving parts.

[D-a-n-i-e-l]

I will tell yo in another 150K, but I would imagine not. As the rebuild kits (as far as I have found) are the same. This is assuming that the kits are not updated to match the hevier tranny.

[Rawja]

Wouldn't an F7 transmission from an Allante be a drop-in HD transmission?

[D-a-n-i-e-l]

Yes for 88-90, 91 is electronic controlled. Keep in mind the rebuild kit is still the same so ware out parts are not any better than ours (unless the rebuild kits are udated/upgraded).

[Guest spyhunter2k]

The problem that many Allante owners report with the F7 transmission used in the earlier cars is the non-availibility of the 3rd/4th solenoid. They tend to go bad and often it takes weeks or more to track down a used replacement, if one can be found at all within a reasonable time frame.

The 4T60 HDs in the TGPs don't have any such weak links in the form of an easily broken part that is discontinued/unavailable. The owners of these cars are just faced with the fact that no one offers a rebuild kit specifically for their strengthened tranny. They are forced to use the rebuild kit for a normal 4T60 and try to individually source some of the relatively few upgraded parts available for the 4T60 to incorporate into the rebuild.

[Guest F14CRAZY]

I'll figure out the F40 six speed someday, just give me some time. If I had my way I'd also figure out one of the new six speed autos for you guys

[Guest Bill_Boro]

Hi Phil,

Good to hear from you again. Is the six speed still in the box? or have you fitted it in to your subframe yet?

I know that you referenced another later factory GM(Pontiac?) installation with pictures. Can you refresh our memory on the web site the other installation was from?

I know that I can get drummed out of the forum for even mentioned it but do you think that installing another subframe with a manual transmission is feasable? for example maybe a twin turbo Dodge/Mitsubishi. My old rag of a Stealth has a NA 24 valve V6 double over head cam engine that is rated at 222 HP. Some of the same engines with factory twin turbos put out 500 HP. It may actually be easier to mess with sub frame

to body mounting than mating the new manual trans to a car that has an automatic trans.

Also, some day in retirement I thought that it might be fun to stuff a SBC and rear wheel drive into an old Reatta w/insurmountable electric and/or drivetrain problems.

[padgett]

Some of the greatest conversions known started with a ded car in one bay and a surplus engine in another. Almost anything can be done (look at what they put in the Mustang in "Tokyo Drifting").

That said, if the clutch is hydraulic, it is not that difficult, pedals are really the hard part.