4L60E to T56 Conversion

[Formulaboy95]

Well, after 103K of abuse... the 1-2 shift was slowly dying in the 4L60E. It was on it's way out, so I had a local shop pull the trans out. I was going to send it to Frank @ CPT for a Pro-Race Rebuild, but he has atleast 4 weeks of work before he can get to it. I can get amost all of the parts to do the T56 swap for about $1000. Only thing is that it is out of a 1993. Anybody know if this will still work? It is a pretty good deal if it will work. 93's were ECM not PCM right? Any issues?

[Jeff_in_Atl]

That doesn't make any difference for the T56. It will bolt in. However the 93 has a bit different gear ratios in it. 1st gear is much lower in the 93 compared to the 94-97. If you like 1st gear acceleration you are going to love the 93 T56.

You will get a SES light after the conversion. You will have to reflash your computer.

[Formulaboy95]

Nice!!! What about the computer though? Is the Electrical any different? The 93 Auto's used 4L60's, not the 4L60E's.... So is there any difference in the PCM, or is it the same?

[Jeff_in_Atl]

You are not using a 93 automatic so it's not an issue. Your 95 has an eeprom so all you will have to do is flash it with a 94-95 6 speed software. I have the stock 6 speed "tune" and you can download the software to flash it. You will need a cable from http://www.akmcables.com/ic.htm

[Injuneer]

Be careful with the 93 T56... not only are the gear ratios different - wider spacing - there are actually two different T56's in the 93's, and the torque rating is lower than the 94+ T56's. The 93 will also not have the skip shift solenoid, but that's no problem. When you reflash your PCM for the M6, have the code for the skip shift deleted, or simply allow it to set. It does not turn on the SES light in the 94/95's.

More info on the T56's from the 4th Gen FAQ:

Q: What are the stock transmission gear ratios and torque capacities?

A: The following were available by year:

Year Model/Optn - 1st -- 2nd -- 3rd -- 4th -- 5th -- 6th -- Final
---- ------------- ---- ---- ---- ---- ---- ---- -----
1993 Manual/M28 - 3.36 - 2.07 - 1.35 - 1.00 - 0.80 - 0.62 - 2.73 (GU2)
1993 Manual/M29 - 2.97 - 2.07 - 1.43 - 1.00 - 0.80 - 0.62 - 3.23 (GU4)

1994 Manual/MN6 - 2.66 - 1.78 - 1.30 - 1.00 - 0.74 - 0.50 - 3.42 (GU6)

The '95s and later have the same ratios as the '94s. Aside from the CAGS provision and different gearing/input shaft (on the post 93's), all of the 6-speed transmissions are basically the same.

Because of differences in the ratios, the torque capacities are different for each model. The shorter the transmission gear (higher numerically), the less torque it can handle. Note that these ratings from GM can be are considered conservative as they are most likely measured at normal load over 100,000 miles:

Year - Model/Optn - Torque Capacity
---- ---------- ---------------
1993 - Manual/M28 - 360 lbs-ft
1993 - Manual/M29 - 400 lbs-ft

1994 - Manual/MN6 - 450 lbs-ft

Note that the '95s and later have ratings that are the same as the '94s as nothing changed.

[Formulaboy95]

Hmmm... Decisions, Decisions...

I have Tuning software as well as pcmforless so I am good on the tune. Now the car is/was running good, and I believe I finally fixed the severe knock retard problem. Before with lots of problems, and before headers, etc... The car put down 275.7/294.6 N/A, and 316.8/376.6 testing the nitrous w/75hp jets. Now that I have completely redone the valvetrain, and the knock is gone I was hoping to put the nitrous back in and step up to 125 possibly 150 shot. Grrr....

Anyway to beef up that transmission? Or should I let this deal go, and just buy a full conversion kit with a 94 or 95 T56.

*Edit* Can I just change the gear ratio? Is it possible/cost effective?

[Formulaboy95]

Looks like the gears are $159ea, and the cluster is $700.... Oh well.... Gonna pass on this one... Might have to settle with a Pro-Built 4L60E, and a 3200 stall.... Unless I can find a good conversion kit soon. Thanks Fred/Jeff.

[Matt Swindle]

Looks like the gears are $159ea, and the cluster is $700.... Oh well.... Gonna pass on this one... Might have to settle with a Pro-Built 4L60E, and a 3200 stall.... Unless I can find a good conversion kit soon. Thanks Fred/Jeff.

Ever think about a 4L80E conversion..?
I've got one for sale complete..:
This is in my '97 T/A (LT1):

TCI "built" 4L80E trans..w/deep TCI pan..
TCI 3800 converter..
TCI controller and software..(with the street and race programs with it..)
TCI Harness..
BMR crossmember..
Mild steel driveshaft w/3350 u-joints (this is my spare driveshaft w/ 10 passes on it)
a write-up on the install is also included and works with your speedo..

this thing will snap your head off when it shifts and drives like a Caddy on the street..
has less than 300 miles and 26 passes on it since TCI
freshened it this last winter..
talk about bullet proof..this is 'the' fix for all those agonizing 4L60 woes!
$2800 get's the whole kit..will not part out!
this is for pick-up..shipping is extra..


going full race next year..gutting the car..cutting weight and putting in a
glide..

Matt

[Injuneer]

What's that thing weigh Matt?

[Matt Swindle]

What's that thing weigh Matt?

what..?
my car?
with my 250 lbs in it, it weighs in at 3860 lbs..

so, how you been Fred?!
Matt

[Formulaboy95]

Well, I ended up going with a Pro-Built Automatic 4L60E.... Pro Street build. Should be fine for what I need. Will handle up to 650HP, so the nitrous can go back in. I still have to order the Vigi 2800 converter. The trans should be built by the end of the month, so I just might make it to the track this year after all. Might even try the spray With the knock gone, new valvetrain & 1.6RR's, and higher stall... hoping for 12's N/A.

[Injuneer]

what..?
my car?
with my 250 lbs in it, it weighs in at 3860 lbs..

so, how you been Fred?!
Matt

You must have put on a few ### since last time I saw you.

I'm doin' OK... but my car just sits in the garage collecting dust.

I was asking how much the 4L80E weighs.

[Matt Swindle]

You must have put on a few ### since last time I saw you.

I'm doin' OK... but my car just sits in the garage collecting dust.

I was asking how much the 4L80E weighs.

I've probably gained 15 lbs since last I was there in Englishtown..
250 @ 6'4"..and the wife still loves me!..LOL

Man..you gotta get that bad bird out and run it!

the specs I have say 250 wet(with fluid) versus 195 wet for the 4L60E..
but the weight made no diff on the et and it sure made it nice driving long distance
and having the confidence to spray the crap out of it without
worrying about hurting the tranny..

Later Broh,
Matt

[Injuneer]

Those were the "good ol' days".......

[Matt Swindle]

Those were the "good ol' days".......

yeah buddy!
they sure were!