Rebuilding a 5-speed

[Alfadog]

Well, as my synchro has gone in 2nd my father, a mechanic we know and myself are going to take apart my gearbox next week and replace whatever needs replacing (hopefully just the synchro).

My question to you is how long do you think it will take if everything goes to plan, and is there anything we should know before ripping the box out?

[2ManyZs]

Be careful and don't lose the detent balls when you take it apart. They like to fall out when you aren't expecting them, and they like to roll under things and hide. You will find out that the Z trans isn't too complicated unless you find a detent ball after it is all back together.:disappoin

I've helped a couple people take them apart in the past, and they can require an extra pair of hands when you are putting them back together lining everything up correctly. If you don't have one already I suggest getting a good diagram out of a service manual to aide you.

Hopefully you have access to the bearings in the center plate if you find them to be bad, I read a post recently that they are getting hard to find from the obvious suppliers.

[Rob]

Yep, that's true. Datsun 5 speeds are no problem at all, except the housings can be a bit of a bugger to separate. There is a post about separating housings somewhere on this forum. TO get mine apart I had to bolt a piece of angle iron to the gearbox mounting lugs, hook the bellhousing over a lip in my (quite solid) workbench and whack the angle iron 956 times with a mallet!

I've heard of others that just come apart though. Good luck!

[Ed]

Sorry to change the subject but do all transmissions shift slow, I mean when you change gears there is a "delay" around the "neutral" area. Making shifting hard. You can't "slam it" from first to second, it takes about 1-2 seconds before it will engage.

[2ManyZs]

Ed, the problem you describe could be a couple possibilities. It could be the synchronizer is nearing the end of its life span, but more than likely it is an shift fork or rail problem. It may be the roll pin is bent holding the shift fork on the rail and it is binding it up. I would check it out soon. If it breaks completely you will be left with only one or two gears to choose from, usually 3rd or 4th which could make it hard to get it home.

"Banging" a hard 1-2 shift is the easiest way to shear a roll pin off, they will take only so much and then it's time to replace. You can drill them out and fit a slightly larger roll pin or just find a hardened pin of the same diameter. Some racers even go so far as to double pin them.

One or two seconds to complete a shift is not normal, although they are not the fastest shifters in the world, they are still very good considering the age of the cars. They won't be as quick as some of today's cars, but they are much better than most.

If you have already replaced the shifter bushings the problem is almost certainly in the shift rail/fork area.

[Ed]

Well, I just went for a drive and I guess I exagerated with the 1-2 seconds. It takes about 1/2 a second to switch gears, but there is definately a slight hesitation between gears. If I remember correctly my four speed did the same thing. Hopefully it's just normal. Thanks.

[wilby34]

I have a hard time shifting with my five speed to. I am going to try a couple things (like taking out the short ****er and putting in the stock linkage) but I think that it is normal.

as for the time on a tranny rebuild, I think that when we rebuilt a datsun tranny in my auto class we took about 4 hours. but we were taking our time to learn, so maybe less, if you know what you are doing and have all the parts you need before you take it apart. as I recall it was kinda hard to get in and out of the car. but with three people it shouldn't be a problem.

[zorro]

One of the local Zed specialists builds his own competition boxes comprising of 240Z gear ratios but using 280ZX synchro rings. The synchro's in the 280 are alot stronger and can take more punishment then the standard rings. These gearboxes are comfortably handling over 300BHP. It is amazing what time and a good lathe operator can build.