shone190

Hi guys,

I have C4 1994 LT1 with auto 4l60-e transmission and just bought used ZF 6-Speed Manual Transmission Conversion Kit from 1989 L98 Corvette C4.

Is this 100% compatible with my car, I mean, do I need something else because it is from C4 with L98 engine and I have LT1 engine?

Also, what about speedo, do I need to change something regarding actual speed and speed on dash? My diff ratio is 3.07.

WVZR-1

The ZF in your image is a '94 by spec and part number. That would not be an unusual find or should it be a problem. There are no obvious situations but the clutch and brake assembly I believe might present an issue. No first hand experience but something to confirm before the start.

Measure the OD of the guide-tube to confirm which release bearing will be required. It's a '94 spec transmission but the guide-tube could have been changed to use the earlier spec release bearing. ZF guide tubes are 1.375 +/- early and 1.305 +/- late I believe, a '94 spec would be considered late. Metric would be just short of 35mm early and 33mm+ for the late.

You're going to need to do a swap of the slip-yoke if you're still a D36 but u-joints should be done anyway so no particularly big issue. A balance would be wise for sure.

The VSS in the transmission is correct for the '94 so that's not an issue with your '94 since the correction can be done in the PCM.

You don't have a C-beam in the snapshots - did you get it should you decide to change to the D44 rear later? Is the D44 still available from the same donor the transmission came from?

shone190

So, I won't know for sure until the conversion kit arrived to me (I'm from Serbia - Europe)

My plan at the moment is to stay with D36 3.07, don't know does it make sense to change it to D44 3.45/3.54? The car will be used as daily driver, so I don't know what will I got/loose with 3.45/3.54.

So, I have to change slip yoke because this propshaft won't fit D36? Which slip yoke do I need, from D44?

No, C-beam is not available in this kit and I'll try to modify my stock, if it is possible?

shone190

One more question, is there a difference between bellhousing and flywheel from L98 and LT1?

shone190

I just found that bellhousings are the same:

GM Chevy C4 Corvette Magnesium 10126448 Bell Housing to ZF 6 speed transmission. Used for L98, LT1 , and LT4 engine.


@WVZR-1

Did you mean on that part of propshaft, that won't fit on D36?

MrWillys

This will require a PCM reflash, because the manual programming is different from auto. Also keep in mind the VSS from a 94 6spd is 17 pulse, and not 40 like the 4L60E. The reflash will solve this issue.

blue94

If you are staying with the D36 you will need to swap the yoke from the manual driveshaft to yours. The rear diff is what determines the driveshaft and c-bean length.

You may need to get a later year's pedals, so before pulling everything apart check the pedals to make sure they will work in your car.

Also be prepared to cut and patch the transmission tunnel. They are not the same.

shone190

Great, so after PCM reprogramming VSS will work OK

I know for the pedals, but will see when the package arrived do I need later models.

I am prepared for cutting and patching, I had done similar thing when I put LT1 and T56 in my 1988 Trans Am GTA


What is your opinion regardin 3.07 gears, do I need to change it and what's the benefits of 3.45 or higher?

blue94

With the 3.07 rear 6th gear will never be used, 5th gear is the same as 4th in the auto (.7). I would change the rear to a D44 and a 3.45