Stripped down my gearbox (ok ok...transmission ) for a tickle up and check over. The 5th gear synchro ring seems to have plenty of movement in and out before I took it apart. Will check the clearance today between it and the hub.. Mr Haynes tells me it should be between .035" to .060" it still has very clear ridges on the cone side and the teeth look fine. But it seems to be a thinner lighter build than the other synchro rings in the box? It has always shifted fine into 5th. In fact all gears selected well.

Just a light rattle at about 1500-2000rpm under load which I think might be unmatched propshaft yoke angles causing a vibration under load at low revs and rattling the front slider inside the tail shaft housing bush.
I will be altering the angles soon on pshaft.

So other than giving the box innards a good look over are there any other clearances I should be checking- thrust clearances etc? Anything that if loose could cause rattles/vibrations under load.

And I have read that these boxes can jam in third? What causes this and what should I look for?

I think my box is a series 3. I see that there are two possible front layshaft bearing sizes. Mine has the 15mm wide bearing. Which boxes have what. I think there are a few subtle differences between series 2 and 3 boxes. This might be one?

Last thing- has anyone bought a kit like these from ebay?....

http://www.ebay.com/itm/220653970465?ss ... 1423.l2649

Seems like a decent price compared to what I have found here in NZ- even with shipping. But i would like to know what the quality is like.

Cheers
Alex

 

those rebuild kits are ok, i see that one has the roller bearing which basically makes it OEM. the OE bearings were either koyo or NSK

the original center countershaft bearing was a double row ball, and these are the ones that make noise after a while

the 5th gear synchro is different, and the FC and later boxes use different synchros for different gear pairs

for the front bearing, its best to just measure yours, Mazda did a lot of updating to these transmissions, and in the US they were rebuilding em under warranty

 

Cheers for reply. Yeah my box has the 15mm front layshaft bearing so I now presume its the later revised series 3 box.

Any ideas on what can cause these boxes to jam in third gear and what to look for?

Anything else like particular end float measurements I should check. I don't feel that the Haynes manual is particularly detailed.

 

The springs in the gear engagement hub thingys break and allow themselves to rotate. Once they spin enough they let one of the three little detent spacers slip sideways and it jams the barrel against the gear it is in.

Sorry for the technical terms, I'm looking for an exploded view of the trans to point to the part. The spring is like a c clip with a little tail that fits in a hole on the part that fits on the shaft. That tail breaks off and bad things start too happen.

 

Ahhh I know the bits you mean. Cheers!