Hi all
I need some advice with my 4 speed gearbox. Anything higher than 120km/h results in a vibration that starts to become worse the faster I go.
I asked my mechanic to check when I did the last gearbox oil change and he found that there is a play where the prop shaft goes into the gearbox. I also picked up that if I replace the seal here it only lasts a short time and then leaks again. My mechanic said that it is fixed by honing the gearbox and then doing something to get it back into spec. This will then solve the problem. I have never read on this site about you guys experiencing such things with your datsuns. Is this a common thing. He said it is quite common on rear wheel drive gearboxes.

look at your prop shaft unis as well. Its usually the uni that flog out first, which then leads to excessive wear in the friction bearing that the prop shaft yoke slides on in the extention housing. Fix the cause of the problem as well as the worn part.

Thanks Benny
This is actually what I am trying to do. I don't know very much about how this part of the gearbox and prop shaft works. Trying to get an idea what is worn before getting it fixed. My gearbox was overhauled a couple of years ago and less than 30 000km ago. I don't know what is involve in this procedure but I am very unhappy that this part of the gearbox was not inspected for wear and fixed in the process.

From memory the friction beearing in the extention housing is a non replaceable part and nissan recommends replacing the extention housing as the fix. Look up posts from 1200 forum member "Peter Zerket", as he had found a suitable friction bearing and method required to replace the bearing.

or alternatively find another extention housing for your gearbox with a bearing within service spec. being a 4sp, this should be very easy to locate. if you have no luck in ZA i have several housing in OZ you can have for the cost of postage.

cheers

when you slide the slip yoke of your tailshaft into the rear of your gearbox, not only does it match up the splines and slide over
the ouput shaft, it also slides into a bushing thats there to keep it centred and running true.

the bush will look something like this..




benny was spot on. These bushings should last decades, so fixing the cause at the same time is definately the way to go.
To replace the extension housing bush, id expect you might have to split the extension housing from the gearbox and press the old bush out, and a new one in. i could be wrong on that one though

good luck

That the information I was looking for. Thanks Ange. And you also Benny. I needed to get an understanding of what is wrong with the gearbox and also to try and understand what the gearbox place is talking about to fix the problem. It also sounds now to me that the idea they are having to fix this problem is not a long term solution.
The mechanic said that this bushing ANGE was talking about wears out. They then hone it (or something like that) and then get it back to specs again with a sleeve or something.
I am just afraid I pay for this work to be done and it doesn't work. It sounds more to me that the correct way is to disassemble the gearbox to fix it right.

if you cant get a new bush. like benny said another option is to swap your extension housing for one with a bush thats within spec

Thanks for the help guys. You know, I am so negative about the service we south africans are getting. A couple of years I took the gearbox in and asked them to completely go through the box and replace all bearings and check that everything is within specs. I was still living with my parents and didn't see the freeway much with the car. Now I find out that this part is worn that was suppose to be checked and fixed. I am so sick of this $hit. I phoned around to find out about maybe replacing with a relatively new 5 speed box. It seems the crazyness with these 5 speeds that are experienced on your side has rolled over to our side. They are plainly crazy with the prices. If I now roughly convert to Aus $ it comes to $1000 to $1200 for a brand new box. and something like $800 to $900 with boxes that are used.

its hard to get good service in australia these days aswell.

although, over here i bet there would be plenty of members who'd pay $1200 for a "brand new" 5spd if we could get them!

I understand that b110 5sp prices are expenive, but I would pay $1000 - $1200 for a new one from the factory. I think I may make some inquires in ZA for supply of one. Im guessing they are 60 series H pattern?. As for your repair, I think the cheapest option is find a second hand extension housing with the a rear bearing in spec. In OZ a second hand 56 series 4 sp can be had for as little as beer money if not free. Like I said before, I have a couple of spare 56 series 4sp extension housings, you can have for the price of postage. cheers
benny