New Transmisson

[Yellow78]

I have a 78z that the grinds when shifting from first to second and then from second to third. It works ok if I shift slow but if shift fast or high RPMs I get grinding. So I want to replace the transmission but not sure which one to go with. Should I go with the Nissan close ratio transmisson from 81 to 83 or the Borg Warner T5?

I would appreciate any input.

[EuroDat]

The T5 is considered the better of the two. I went for a 300ZX © transmission and change the bell housing to fit it to the L28. That is a third option, but its a little more work and you need to dismantle the transmissions to do so or have it done.

Here is a blog explaining about it. http://www.motortopia.com/cars/1973-datsun-240z-11118/car-pictures/240sx-transmission-swap-14041/DSC04293JPG_Thumbnail1.jpg-266482

Chas

[tlorber]

It is definitely less work to go with the 81-83 tranny, since it will drop right in. I put one into my '73. Yours sounds like it is probably just the baulk rings (synchro rings) that need to be replaced. Parts would be around $150.00 (including bearing and seals) but the labor is a bit intimidating to keep everything in order. Keep in mind that whatever tranny you buy should have the same work done to it before installation-unless you buy one that has been rebuilt.

If you plan on really cranking up the horsepower, then you might consider the T5.

[Carl Beck]

How many miles are on that Tranny? Might be a situation where the clutch is not fully disengaging the disc from the flywheel. I'd check the operation of the clutch first especially if you experience the problem in all gears at the same time. Second, I'd try changing the Tranny Fluid - to one of the Redline or Royal Purple synthetics.

Also agree - I wouldn't put a 30 year old used transmission in the car - without having it rebuilt in the first place. Personally I'd go with the 83 5 spd. - it is plenty strong.

FWIW,

Carl B.

Edited December 27, 2012 by Carl Beck

[Yellow78]

I'm running redline it now that help a lot. I have replace slave cylinder and when with a SS line. I got the clutch disengaging I think all the way you possibly get out of it. The car sat for 20 years and only has 27k on it.

[Wade Nelson]

I'd pay a professional mechanic to make sure your clutch is fully 100% disengaging before I'd replace a tranny for the symptoms you describe.

You get any grinding when you go into reverse? That's a clear indication the clutch is NOT fully disengaging since there's no synchro on reverse.

[Carl Beck]

If you have an experienced/knowledgeable early Z mechanic to turn too -it wouldn't hurt to get a second opinion.

Sitting for 20 years - it is possible that the Synchro's have built up corrosion. If that turns out to be the case - you'll have to pull the tranny anyway. If the car is a 4spd. now and want the 5spd. - then have one rebuilt - or buy one that is already been rebuilt..

Then you get into the "while I'm at it" mode - and you might wind up replacing the clutch and turning the flywheel..

Good luck..

Carl B.