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TR2/3/3A Transmission Rebuilding

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SteveBones

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The like both driving and working on my Triumphs. I am considering whether to rebuild my TR3A transmission (non synchro first) vs having it done by a professional.

Condition of the Transmission
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The biggest issue is the size of the oil leak from the front seal. The car had been sitting for 10 years. Also, the clutch is engaging very late so it needs to be replaced soon. The transmission also requires slow and deliberate shifting to prevent grinding between gears. Otherwise the transmission works fine. No major problems other that what seems to be seal and maybe synchro wear.

No Previous Experience But..
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If I try to rebuild the transmission myself, it will be the first time. I am becoming interested in the idea after going through the documented rebuilt phase 1 and 2 publications on the VTR website. Though from the Triumph manuals, there are a list of various Churchhill tools listed for the job, from the Triumph Transmission Phase 1 and 2 documents it looks like I will only need a piece of angle iron for removing the rear flange, and a bearing puller in addition to my regular tools.

What do I really Need?
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I wanted to ask for your thoughts on rebuilding the transmission myself based on likely needing to replace seals, bearings, countershaft, and synchro's. I am expecting this to be a 6 to 8 hour job (not including the removal and installation of the transmission itself). Is this a reasonable expectation? Are there other difficult to find or expensive tools required?

Any feedback based on your own experience is greatly appreciated. I am interested in the idea of rebuilding a transmission at least once if it is not a major time sync or headache.

Thanks,

Steve
 
I replaced all my bearings and counter shaft when I had a tooth come off the counter shaft gear. I did the work my self. I used normal bearing and gear pullers. The only tool I made 6 1/2" long and as close to the same diameter the shaft that goes through the counter shaft. With the help of some I was able to pray up the main shaft circlip with a screw driver. The other person holding the clip up and working another screw driver working around the shaft get the clip at off the grove and the sliding the clip off the shaft. Putting the clip back find a couple screw driver that fit slots of the main shaft. Have your helper hold these drivers an use two more spread the clip and slide it on the shaft. Use a heat the case around the main shaft with a heat gun when it get hot enough the main shaft will slide right. Also remember to heat the case when going back together.
 
I have rebuilt most every component on Triumphs and other british cars over the years, not that I haven't made mistakes, but most all of the rebuilds have been successful, except transmissions. I tried my first rebuild a few years back on my TR250, a later version of the TR3 tranny. It worked fine at first, but then 2nd gear went from being a little hesitant sometimes, to not wanting to engage at all (like hitting a wall). Since I did not at first succeed, I tried tried again. Second gear was worse than ever, I took it to a shop, I kind had figured out the problem before I did, which was I had one of the synchro hubs on backwards, which sort of stemmed from having an "expert" help me with it, and in fact he was an expert, but he sort of stepped in then stepped out and didn't keep everything in line and order like I would have, and there was no parts book or online reference that I could figure out which way that hub was supposed to go on, and hard to tell it there was something wrong until you drive the bearing in. Anyway I know plenty of DIY guys have successfully done trannys, and maybe you can and maybe you can't, but my experience they are harder than engines, suspensions, carbs, etc, by a pretty good margin in the expertise and knowledge required. And worst part, very hard to test and figure out if something is wrong unless you go through all the trouble of putting it back in the car.
 
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I think that you can do it. The manual and Moss' depictions are pretty good, and you've got Moss Technical Support and the likes of some real pros around here. My guess is that ten or more folks will respond to your questions, though Randall might just answer them all the same day like he did when I rebuilt by overdrive. I was a nag, but I sure learned.

You will NOT be able to do it in six hours. You'll spend that time looking at the pictures and drawings, and planning the disassembly. You'll then spend another bunch of hours assembling and even making a few tools, finding the right pullers, etc. You might spend two or three full days looking for tools, or making one or two, especially for what it takes to pull that front hub off--the front cover.

You'll have time ordering gaskets and you'll get distracted and find yourself checking the top shifter housing as well.

My guess is that from the time you remove the top cover to the time you're ready to reinstall the transmission, you will have spent weeks. Maybe you're better than me, and maybe you won't bother changing syncros or anything else, but I highly doubt a day will do it.

Part of the job is knowing when to leave a part alone, and when to replace. If it were me, I'd spend a few days checking the condition of parts and confirming they can be re-used.

I think you'll have fun, and if you don't, the lessons learned will be quite valuable.
 
I have never tackled this but our local club did have a tech session where we got to watch 2 members rebuild an MGA gearbox. First Saturday morning they took it all apart at a leisurely pace and identified what parts needed replacing -- took about 3 hours. A few weeks later (after all the parts were in hand) we gathered again to watch them put it back together. Another 3 hours with them doing a lot of showing and explaining as they went.

Main thing I took away from this (in addition to being quite impressed with their skills) is that I hope I never have to try it myself. They did things on the first try that I am sure would take me 10 tries and they knew tricks and techniques mastered through many repetitions that I would never know.

By all means tackle it and learn. Worst case you call John Esposito and have him send you a rebuilt gearbox with an OD attached (that's what I did). Not a bad alternative when you get right down to it.
 
I rebuilt mine; it is not that difficult. Besides you can buy them in all kinds of conditions for a few hundred dollars, little to lose much to gain for a hobbyist, The Haynes manual has a great section on rebuilding the trans.
 
A tranny is not hard...except that main shaft circlip! But if it is your first, you will need some guidance. When you get it apart, there are always gear teeth that are worn and chipped, and it takes some experience to know how worn is OK. You could spend thousands if you take the usual "want it perfect" approach to parts replacement. If you don't have a local gear head to ask questions, the expertise is on the forum here...just post a lot of pics
 
Thanks for the heads up. This will help me be aware of the potential areas were it is important to be carefull. I really appreciate you sharing your experience.
 
donbmw said:
I replaced all my bearings and counter shaft when I had a tooth come off the counter shaft gear. I did the work my self. I used normal bearing and gear pullers. The only tool I made 6 1/2" long and as close to the same diameter the shaft that goes through the counter shaft. With the help of some I was able to pray up the main shaft circlip with a screw driver. The other person holding the clip up and working another screw driver working around the shaft get the clip at off the grove and the sliding the clip off the shaft. Putting the clip back find a couple screw driver that fit slots of the main shaft. Have your helper hold these drivers an use two more spread the clip and slide it on the shaft. Use a heat the case around the main shaft with a heat gun when it get hot enough the main shaft will slide right. Also remember to heat the case when going back together.
Click to expand...

Thanks for highlighting (and reminding me) of a couple of other items involved that I did not point out. Including needing help with extra hands and screw drivers to undo the main shaft chip. All important and helpful reminders. Thank for sharing.
 
sp53 said:
I rebuilt mine; it is not that difficult. Besides you can buy them in all kinds of conditions for a few hundred dollars, little to lose much to gain for a hobbyist, The Haynes manual has a great section on rebuilding the trans.
Click to expand...

I was thinking the same thing. Making sure I have a backup plan via a replacement. Thanks
 
CJD said:
A tranny is not hard...except that main shaft circlip! But if it is your first, you will need some guidance. When you get it apart, there are always gear teeth that are worn and chipped, and it takes some experience to know how worn is OK. You could spend thousands if you take the usual "want it perfect" approach to parts replacement. If you don't have a local gear head to ask questions, the expertise is on the forum here...just post a lot of pics
Click to expand...

Thanks. I am figuring that the main shaft circlip is the biggest headache. I appreciate the heads up regarding the gear teeth. I will definitely be asking for help (and send pictures) to figure out what gears really need to be replaced. There is a local Triumph club that I have not yet taped into. This project might help motivate me to join.
 
Geo Hahn said:
I have never tackled this but our local club did have a tech session where we got to watch 2 members rebuild an MGA gearbox. First Saturday morning they took it all apart at a leisurely pace and identified what parts needed replacing -- took about 3 hours. A few weeks later (after all the parts were in hand) we gathered again to watch them put it back together. Another 3 hours with them doing a lot of showing and explaining as they went.

Main thing I took away from this (in addition to being quite impressed with their skills) is that I hope I never have to try it myself. They did things on the first try that I am sure would take me 10 tries and they knew tricks and techniques mastered through many repetitions that I would never know.

By all means tackle it and learn. Worst case you call John Esposito and have him send you a rebuilt gearbox with an OD attached (that's what I did). Not a bad alternative when you get right down to it.
Click to expand...

Good points. My 3 hour estimate I figured might be a optimistic. I will need to decide if I want to involve the local club experts to assist. It would be the smart thing to do, but........there is a part of me that likes to trouble shoot and try to figure out things myself......I refer to this as part of my Triumph sickness......for some strange reason I enjoy it. Also, thanks for the heads up regarding work time vs wait time (ordering parts). All very helpful info.
 
KVH said:
I think that you can do it. The manual and Moss' depictions are pretty good, and you've got Moss Technical Support and the likes of some real pros around here. My guess is that ten or more folks will respond to your questions, though Randall might just answer them all the same day like he did when I rebuilt by overdrive. I was a nag, but I sure learned.

You will NOT be able to do it in six hours. You'll spend that time looking at the pictures and drawings, and planning the disassembly. You'll then spend another bunch of hours assembling and even making a few tools, finding the right pullers, etc. You might spend two or three full days looking for tools, or making one or two, especially for what it takes to pull that front hub off--the front cover.

You'll have time ordering gaskets and you'll get distracted and find yourself checking the top shifter housing as well.

My guess is that from the time you remove the top cover to the time you're ready to reinstall the transmission, you will have spent weeks. Maybe you're better than me, and maybe you won't bother changing syncros or anything else, but I highly doubt a day will do it.

Part of the job is knowing when to leave a part alone, and when to replace. If it were me, I'd spend a few days checking the condition of parts and confirming they can be re-used.

I think you'll have fun, and if you don't, the lessons learned will be quite valuable.
Click to expand...

Great feedback. I really appreciate it. It makes sense that there will be periods of time spent making and finding tools, inspecting and trying to decide what to replace and leave alone. I agree this will be part of what makes the project interesting. What has helped me with your input as well as others, is the need to get help during the inspection process to determine what actually needs to be replaced vs reused. I will for sure be asking for help from those that know on this site. Thanks
 
Steve,

I managed to rebuild my TR4A transmission and concert it to overdrive at the young age of 24 with very little mechanical experience. This was before computers and the Internet so I had my Bentley and Haynes manual and a sheet of notes I had gotten from someone at the time and managed to successfully rebuild it and then drive it for 70,000 miles as my daily driver. :smile:

As others have mentioned that mainshaft circlip was the worst part that I recall (it was a long time ago) but I managed to pry it off without any special tools. Good luck and I hope your experience goes well and even if you have problems, there are people here that can help you work through those issues.

Scott
 
To redo mine with a longer main shaft to accommodate OD took a couple months. Part of that was waiting on the machine shop to pull and press bearings in the countershaft and drill the shaft of the release fork for an extra pin. A lot of that was looking at it wondering if it would ever go back together. Measuring tolerances on the main shaft was tricky as I recall as it needs to be assembled and disassembled, access to a press would be a help. No new tools were purchased but improvised from garage stuff. I had little trouble with the circlip. In the end it went together and works, the OD is sweet and I saved some money.
Daunting though.
 
Here is my gearbox story. I rebuilt an MG TD gearbox one winter night in 1973. Everything went fine in the disassembly until one point when a part - I forget which one - had to be removed - maybe a circlip? Anyway, when the part was removed, 24 steel balls went flying across the cellar floor - the MG Workshop manual (by one W.E. Blower, no less) neglected to say that the part was spring-loaded and to take care. It was now 11 pm. I grabbed a magnetic tool and set about retrieving the balls - no mean feat in a dimly-lit cellar. I finally corralled them all, finished the job about 1 am and tried to shift the gears. They would not go into either 2nd or third, I don't recall which one after 40 years. I had 2 choices. 1. Go to bed, or 2. try to finish the job. You can guess what I did. I re-disassembled the box and discovered that I had threaded a gear on the shaft backwards. I corrected the problem, buttoned the box up and it shifted perfectly. It was now 4 am. You need a good manual and lots of patience, but how different could the Triumph gearbox be? And beware of springs. All springs, no matter how big or small. End of report.
 
I think 6-8 hours is way low. For your first time, you'll need to allow at least double or triple that, just for the time spent actually working on it. Then add weeks waiting for parts to come in that you didn't order ahead of time.

A few other tips:

1) Always replace the big circlip on the mainshaft once it's removed (especially when using the 3 screwdriver method), even if you just installed a new one. The removal process distorts the clip, making it more prone to slip out of place in the future. Last time I had a main gearbox go sour, I had disobeyed my own advice and it slipped out about 10,000 miles later. I had only bought 3 new ones and it wound up taking me 4 tries to get the mainshaft back together just right.

2) Don't forget to check the detent force on both the shift rails and the shift hubs. The detent force on the hubs is important for good synchro action, and I suspect may be part of the reason so many rebuilt boxes tend to clash. IMO it is worth buying a good digital scale just for checking these forces.

3) Double check the clearances for the mainshaft bushings, even if you just bought new ones. All but one of the new ones I got last time wound up being unusable; and I still had to modify the one I did use by lapping the bore larger. Oh yeah, they do need to move easily on the mainshaft, you'll need to modify them if they don't. The books all assume that new parts are made properly.

4) Likewise, check the fit of new synchro rings onto the cones. They aren't always right either.

5) Take lots of pictures as you disassemble your gearbox. The photos in the various articles are good, but sometimes not good enough.

6) It's best IMO to find some way to save the order and orientation of things as you disassemble the mainshaft. Lay them out on a board or something, with the input side always up.

I'm not sure if I should mention this, maybe others will have more recent input : 15-20 years ago, someone had a big run of synchro rings made that had a problem. I don't know that it was ever established conclusively what the actual problem was, all of the vendors kept insisting there was nothing wrong and continued selling them. But many of the gearboxes built by experienced professionals with those rings still had shifting problems. Herman van den Akker, for example, flat refused to use anything other than NOS synchro rings, because he was tired of having to redo boxes that didn't work with the aftermarket rings. (This was obviously before he got completely involved with selling Toyota 5 speeds.)

Hopefully those bad rings are all out of the system by now and it won't be a problem. But if the new rings you get look a lot thinner (less beefy) than the old ones, be suspicious.
 
OK, as long as we are telling stories...

My first transmission rebuild was on my current TR6, between wives. I took it all apart and rebuilt it on the kitchen island, since it was too hot in the garage and the kitchen wasn't being used for anything anyway. It took me a few months and I did it with only the manuals help. The transmission had the typical countershaft and countershaft bearing failure, but that caused massive damage to the inside of the 1st/cluster. Once the parts were collected, it probably took me over a week to get it back together (properly). I didn't measure anything, but it worked fine for some time. Since then, I became more active in the local club and now am good friends with someone I consider to be an expert in these matters.

When I broke a tooth off 1st gear a year or three later, I was given some practical hints and advice. One thing I can still hear him saying is 'remember, heat is your friend'. If you put the main shaft in the ice box over night, the bearing (at room temperature) will slide right on, as if it were made to fit together. Also, buy a new cir-clip and use a dremel to cut most of the way through the old one, then break it away. A short length of PVC pipe will help put things back together a lot easier. Use a hose clamp to hold the gear set together while installing into the housing. -There were so many tips, that I need to find my cheat sheet. With his guidance, I think the 2nd time re-assembly took about an hour (still done completely by myself).

During the second rebuild, I measured everything and had to order a non-typical spacer, but afterwards, it shifted perfectly into/out-of any gear. -Until I broke another tooth off first gear. Some stories seem to repeat, but each time it gets a little better. I have a whole new (used) box to put in this time, but I still have to take it apart and have the insides looked at by someone who knows better.

If you are committed and take your time, you can do it. There may be easier ways to accomplish any given task and an 'expert' may save a lot of time. Having someone look over your parts and talk over your replacement plan is a good idea -'new' does not always mean 'better'.
 
TR3driver said:
I
I'm not sure if I should mention this, maybe others will have more recent input : 15-20 years ago, someone had a big run of synchro rings made that had a problem. I don't know that it was ever established conclusively what the actual problem was, all of the vendors kept insisting there was nothing wrong and continued selling them. But many of the gearboxes built by experienced professionals with those rings still had shifting problems. Herman van den Akker, for example, flat refused to use anything other than NOS synchro rings, because he was tired of having to redo boxes that didn't work with the aftermarket rings. (This was obviously before he got completely involved with selling Toyota 5 speeds.)

Hopefully those bad rings are all out of the system by now and it won't be a problem. But if the new rings you get look a lot thinner (less beefy) than the old ones, be suspicious.
Click to expand...

No personal experience with the bad synchros but I'm told that the Moss "premium" rings at about $40 are good. Why they would offer the standard (bad??) rings also for twelve is beyond me.
Tom
 
I will say despite my bad outcome in rebuilding my tranny, I didn't find the big circlip to be that big a deal, had more trouble fitting the little retention bar in the door handles, I didn't use any special tools, just three screwdrivers, but different people, different days, things can go easier or harder, but certainly don't be put off by that aspect of it.
 
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