Overhauling a gearbox - any BTDT tips

[tdskip]

With my A-type O/D shipped off to Brad (thanks Brad!) for an overhaul I still need to recondition/overhaul the main part of the gearbox.

I'm getting a bit more confident that I can swing it, but wanted to see what tips or lessons learned in addition to the Buckeye site you all would have for me.

Thanks.

 

[Tinkerman]

Biggest problem when I did mine was keeping the gears, bushings and spacers in alignment. I had a fellow helping me and we did not keep them in alignment BIG problem! I finally boxed them up and sent them to a pro and he got them in order for me.
Take loads of pictures, take your time and do follow the Nelson Reidel article.It is a persnickity job but doable.

Good luck, Tinkerman

 

[DougF]

Perform the job in an area where little balls and springs can be easily found. 3rd and 4th gear synchros are probably good, don't replace unless necessary. Originals quality tend to be better than new ones.
Keep everything organized and you'll do well. It's another job that carries a big stigma, but isn't difficult. If things aren't working properly, it's generally easy to sort them out.

 

[tdskip]

Thanks guys - are there any differences in the approach from an early gearbox to the TR250/TR6 write up?

 

[HerronScott]

It's been a long time but I managed to rebuild my TR4A transmission around 1985 with no mechanical training (and some would argue little ability!). Converted it to overdrive during the rebuild and it was still working well after 75,000 miles.

As Dale and Doug indicated, I do recall being very careful about keeping things in order as I removed them. Sorry that I can't recall any particular details after all this time.

Scott

 

[TR4nut]

And Tom, when you figure out an easy trick to get that circlip off the mainshaft, let me know! To save you some time, two screwdrivers and a lot of swearing doesn't work.

 

[sail]

I just got mine back together with the od conversion. I have not been able to test it yet but hopefully this week. I used both Greasy Hands found at VTR and Buckeye Triumphs as there are some variations. The shims are what were the most questionable for me to get right. Number them. If all goes well this week I have a couple of spares you can have. I also spent $70 at a speed shop to have them pull the countershaft bearings and press in new ones, press the input shaft bearing as well as drill and tap the top cover. Search Glemon's post he had some good ones.

 

[70herald]

And Tom, when you figure out an easy trick to get that circlip off the mainshaft, let me know! To save you some time, two screwdrivers and a lot of swearing doesn't work.

There is no easy trick. two screw drivers and once you get it to lift up a bit jamb something like a toothpick under it until you get it out. Big pain.

 

[mallard]

tdskip as for the synchros check with Brad I think he gets his from Racetorations, or Revington in the UK. Thay are more expensive and he said they do require some machining. The ones you see on ebay for $17.00 I would be a little bit suspect on the quality. NOS do come up on ebay sometimes but be prepared for an active auction, or high buy it now price.

 

[TR3driver]

Thanks guys - are there any differences in the approach from an early gearbox to the TR250/TR6 write up?

There are some detail differences (depending on just how early yours is), but overall it's pretty similar. As I recall, the articles on the VTR web site show an earlier, 3-synchro box.
https://www.vtr.org/maintain-index.shtml

As suggested, lots of photos as you take things apart; and be sure to save ALL of the old parts until you're sure you have the right new ones. Some of the new bushings I got were too short and I wound up reusing the old ones.

When undoing the taper pins that hold the shift forks to the shaft, I recommend buying a proper 8-point socket to fit (the more common 12-point is more apt to round the corners), and using a T-handle to turn it (so no side load applied). Those pins tend to be really tight, and twist off easily. Maybe new ones are available now, but I didn't find any last time I went through this.

The seals commonly sold for the shift shafts don't fit the cavity snugly and tend to leak. I found some "double seal" O-rings at MMC, plus Teflon "backing rings" to take up the slack; the combination worked very well. (When Herman does these, he machines a washer from brass to fill up the cavity.) According to Herman, the ring should protrude from the cavity by .005 - .010" before you install the retaining plate.

To check the synchro ring condition, slide the ring firmly onto the cone of the gear, then measure the space between the ring & dog teeth. Minimum clearance is about .025"; new is around .045". (This is in addition to the usual visual inspection for damage, etc.)

I use a total of 4 screwdrivers for the big circlips; 3 larger ones (but not so large the blade won't fit between the splines) and a much smaller one. The 3 big ones pry the rig clear of the splines (two near the opening, one opposite the opening), while the 4th one is used to work the ring past the end of the splines.

I tried duplicating the Churchill tool from water pipe, but the iron pipe wasn't strong enough. Might try it again someday with carbon steel so I can harden & temper the teeth after machining ... but probably I'll just keep using the screwdriver method.

Never try to reuse that circlip; have some spares on hand in case you goof the first time it's installed. I tried to reuse a 'new' one once (after discovering I had a shift hub on backwards), and it broke about 15,000 miles later.

All I can think of, offhand.

 

[HerronScott]

And Tom, when you figure out an easy trick to get that circlip off the mainshaft, let me know! To save you some time, two screwdrivers and a lot of swearing doesn't work.

Oh wait, I think this was one of those horrible memories you find yourself repressing until someone reminds you. I do recall this involving much swearing and I believe I also used Randall's method with 4 screwdrivers.

Scott