How much shaft play is acceptable?

[Sailor Bob]

Just brought my 5 spd to the shop (didn't want to mess up the car) to drop it off befor I brought the car in. The owner of the shop came out to take a look and tinkered with the shaft inside the bellhousing - he noted play and made a remark "in a modern tranny you wouldn't have this".

I didn't think it was significant - maybe it is. To me it was barely perceptable - question: Is it normal to have some play? If so how much? Would it have been more noticable with no fluid in the tranny?

Presently panicing.

[sblake01]

I always replace the bearings when I get a used tranny. That minimizes the play in the input shaft. You say "barely perceptable" which sounds like it would be acceptable but I always replace the bearings, syncro rings and seals just because I don't want to have to go back in there later. And as far as 'no fluid in the tranny' it was probably just low. Was it noisy? The lower the fluid, the noisier they will be. Often just filling them up willl cure that as long as they haven't been run too long in that condition.

[geezer]

I can understand the "panicing". Many of us, no matter how versed we are with mechanicals in general, enter a grey area when it comes to transmissions or differentials. The reason being, there are a lot of specialty tools needed to do the required work. Precise measurements also are key, just as a machinist or engine builder, a transmission specialist relies on his math skills, knowledge base and special tooling. Sure, some of us can take them apart and put them back together, but not with the degree of expertise as a pro. Over the years many things have changed/improved, such as design, materials, fluids, etc. With these changes modern transmissions have much tighter tolerances and as a result less play which directly results in a longer service life. I think the comment made by your transmission shop owner reflects this. He would notice this play much more than we would. Having fluid in it or not would not change his opinion. Why did you bring it to him? What problems did you have?

[Arne]

I just recently finished rebuilding the Type A 4 speed in my red 240Z, due to a slow second gear synchro and excessive countershaft end play which caused a torque-related clunk in first through third gears. I totally agree with Stephen about going through a used transmission before installing it permanently, although for me personally, I'd install it and run it for a short time just so that I could assess its true condition prior to tearing it down.

Ron is also right in his comments concerning improvements, modern transmissions are better - generally stronger, more durable, and quieter. And yes, most people including fairly skilled mechanics do panic at the thought of disassembling a transmission. On the other hand, if you have a service manual with a decent set of instructions regarding transmission disassembly and servicing (the early factory service manuals do, although just barely), I find that rebuilding a manual transmission to be easier than rebuilding an engine. It is fussy work, and you do need a few tools that you may not already have (such as gear and bearing pullers, and an accurate micrometer), but it's not really difficult, especially not the second or third time.

First time can be mildly un-nerving, though...

[Sailor Bob]

I sent it to an import auto specialist - his background is largely german high end models - did so because I simply do not have the gear to get into it myself (at this time). He gave me an time estimate of 6.1 hrs to change clutch and install 5 spd - from what I have read and assessed (guessed) this seems correct and discussion with him made me feel comfortable about his knowledge of Zs. I selected this shop because he has a passion for older cars which leads me to believe that my expections of due dilligence will be met. I mentioned that the frame should be protected when it was lifted - he was aware - amazing how few shops give a s--t.

As to the bearings - I found small rotational (lash?), but no tranverse/longitudinal play. The tranny is empty - I drained to see what the fluid looked like - nothing unusual. As to noise - gear noise - not really, lash noise - perceptable.