Got a bearing grinding noise in all gears but 4th. Worse under hard pull uphill. Same thing but quieter under engine braking. Goes away when clutch depressed. Research says 4th is direct, so symptoms mean transmission rebuild/replace in my future. 190k. Stock 12a with RB manifold and exhaust so not massive horse power.

- Am I barking up the correct tree?
- Can a careful amateur mechanic rebuild a transmission? This is the first car I have worked on, and have successfully rebuilt the engine, suspension, rear axle etc. Or does the need for special tools and hard to find replacement parts mean buying a replacement transmission is best?
- Any magic fluid I can add to get me about 1000 miles or so? Car drives fine right now, just noisy.

Thanks!

 

You could try a good synthetic 75w90 gear oils and see if it helps. Some folks also mix in some auto transmission fluid as well and have reported success doing that. It will be hard to say what needs to done until you pull it and take it apart to see what the issues are. Also check the fluid when draining and the drain plug to see if there is metal flakes in there.

 

I don't think its out of your realm to rebuild it. There is a factory rebuild manual out there with detailed parts diagrams. Comes in handy to verify the correct order for everything. There is also at least one special tool you'll probably need to source. It's an extra long bearing remover that needs to reach over the main shaft.

The bearings would be the major parts to change, might need to replace the syncros / shift forks while you're in there too. Swapping in another would be less work as long as the unit is good. If I was keeping the car, I'd buy a spare tranny just to have anyhow, and at least attempt to rebuild the existing unit.

 

rebuilding the trans is possible, although since you're sort of local, you could have Barry do it, https://www.hartzelautomotive.com/

if you decide to try it, you need Mazda's really deep socket, its like 18" , or weld a piece of pipe to a socket, its the same as the steering box, so its a big nut


and then the puller set, its pretty normal except it has extensions, basically it needs to go past the tail shaft


you also need some way to lay out the parts, IN ORDER, for each shaft. there are a LOT of little pieces, and they need to go back exactly right
i think i recently saw someone use a dowel so you take the part off, and slide it on the dowel, seems like a better idea than a tray.

 

Definitely possible to do it yourself. I did a Ford top loader 4 speed back in the day for my Pinto with simple hand tools. You will need that long socket from what I have heard, plus what the others have said. Do it!

 

From the manual I referenced above. I don't believe this one is on the Foxed site. Probably available from eBay. Covers both 4 and 5 speeds.

 

Alrighty... gonna give it a go. Replace or rebuild, either way I have to remove the transmission, and once removed I may as well give it a go. I like the dowel idea for keeping parts in order and orientated. Used to do the same thing for bike cassettes when I ran a bike shop. Will report back November/December. Going travelling so no car time for three or four months. Appreciate all the help.

 

Yeah, I don't see that manual on Foxed.ca, I wonder how different it is since the whole car manual also covers a transmission overhaul.

 

Just found this wonderful idea. A gear abacus. Arrange the gears on dowels as they come off the transmission. But here is the genius part... have a matching set of dowels so if you need to access a part in the middle of a stack, you just slide parts from one dowel to the other until you get to the part you need. That way nothing gets in the wrong order and nothing gets turned the wrong way around. I am now kinda excited about the project... Except for getting the damned transmission back in. I have had the transmission out twice, and each time getting the pointy thing on the transmission to go into the hole thing on the engine (scuse lack of real words) has been a total wrestling match. Last time I did it I vowed to pay someone to do it next time, but that was a while ago and pain has no memory.

 

I would suggest replacing the trans with a known good unit. Unless you have a press with adapters for servicing transmissions, the rebuild will not go in your favor. You will have to pay a trans shop to press the gears off of the shaft and then back on with new synchronizers and cones. I have two 4spd 79 transmissions and I would be happy to give you one if you were closer. Though, a 5spd would be a better option. I don't have an SA 5spd trans, just two S5 5spd transmissions.

 

I chickened out. Last time I was wrestling the transmission back into place I vowed to have some else do it next time. So I listened to my own advice and took it to Hartzel Automotive. He did an excellent job, and was a fascinating guy to talk to. Thanks for the recommendation.