I have a T85 behind the Y block in the Model A and I need to replace the synchronizer in it. This means I will need to drop the countershaft down to disassemble it. I know the way to do this is to use a pipe or round stock to hold the needle bearings in the countershaft. Does anyone know what size to make this pipe/shaft, I would like to get set up before I remove the transmission from the car. Also can we talk about the mainshaft end play? what should it be? How to adjust the mainshaft end play, I guess shims behind one of the end bearings or maybe gasket thickness under the front snout/bearing retainer.
Back in the day it seems like I used a piece of 5/8 heater hose, but I don't remember if that was on the T85 or the Chevy transmissions I was working on.
I’m probably the last person to take advice from, nothing too precise about the way I put together a trans since I only use old worn out shit to start with. I make my gaskets from heavy paper down to nothing but a thin coat of Indian head shellac to adjust the front bering retainer
I see no logic in servicing syncros without total disassembly, cleaning all parts, & making sure nothing fails down the road 100 miles when placed back in service. I dislike doing things over ...
End play? There's the complete lack of end play specifications in the Shop Manual. The Shop Manual is usually specific on clearances and this is just the shits: "When installing a new bearing, there are six thicknesses of snap rings. Use the thickest one which will seat fully in the groove. Install the retainer without a gasket and use a feeler gauge to determine the gasket thickness required. Install a gasket or combination of gaskets of the proper thickness." jack vines End play
This is what will happen but I needed the shaft/tube size to hold all the rollers in place to reassemble.
so it sounds like this would give me little to no end play on the main shaft, does that sound right? I Looked at VanPelt's site to see if he has a book but this is newer than his books cover.
I’ve no measurements for you but I try to achieve minimal runout, understand I learned my craft from hacks and old farmers at the school of good n nuff
The shop that taught me to rebuild transmissions used a medium weight all purpose grease to hold the rollers, and it helps hold the thrust washers in place while working the countershaft into place. I've done hundreds of them; never had a problem. "Your results may vary".
I would advise to cut the shaft a tad long and the custom grind it to your exact needs. Back when I was doing transmissions, I remember the shaft needed to be long enough to hold the shims, but short enough to drop into the case and then a tiny taper to help guide the shaft into the case! Might help! Bones
For a dummy shaft I used a smaller dowel and carefully added a couple wraps of heavy "gun" tape around each end to get close enough to the right size.
We only use a dummy shaft now for pushing the factory countershaft pin out of the case during disassembly…..this helps keep the needle bearings in place so one or more don’t fall out of place in this process. There’s really nothing holding the needles in position because the gear oils don’t hold them and if even one needle falls out of position while tapping the pin out, you’ll be fussing with the thing getting it disassembled. I’ve got a box of old countershafts that I’ve cut short for this purpose….each one from a different type transmission. If you don’t have any extras to do this, make one from a wood dowel that is really close to the diameter needed. A piece of plastic tube won’t be sturdy enough to do the job. When it’s time to reassemble the cluster gear, do yourself a favor and buy a little tub of “Transmission Assembly Goo”. It’s real tacky stuff and will dissolve in the gear oil (unlike wheel bearing grease). Smear a bunch inside the bore of the gear. Place the spacer tube inside, then place your factory countershaft pin in next. Place all the needles inside, adding some grease to make sure that they’re well stuck. You only load the needles, the little washers, and the spacer tube. When all that is done, keep a finger on the end washer and slowly pull the pin out. Everything will remain perfectly in place. Use the goo to stick the thrust washers to the inside of the gearbox. It will help to keep the rear most thrust washer back for now. Then just drop the “loaded “ cluster gear into the case, adding the third thrust washer at the back. When it comes time to raise the gear up to align it for the countershaft pin, you can easily align the washers with a drift punch (start with the rear first) and start sliding the pin in carefully. Don’t force anything…..make sure those washers are aligned. When the countershaft is mostly in, work with the front thrust washers to align it before pushing the shaft the rest of the way in. You’ll also need to make sure that the shaft is rotated correctly for its lock pin.
.... Thanks Mac. I'll be on your website to order the parts after the Holliday. No advice on mainshaft end play?
That’s controlled by two things…..first would be the unique snap ring located just in front of the intermediate ball bearing. The advice given above is correct…try to fit the thickest one you can fit in the groove for it. The standard snap ring is probably about 0.080” thick and the thickest one is about 0.090” thick. The major problem with this plan is to try to find any of those new anywhere for the R-11 type that’s joined up with the T-85 transmission. We’ve had two sizes made for the R-10 overdrive but it’s smaller in diameter and thus not suitable here. If you can’t find that specific snap ring, you may be able to use a conventional snap ring and modify the ends to match the correct design. Once again, you’d be searching for the 85 to 95 thou thickness and the diameter needed. I’ve not had to resort to this alternative plan yet. The second method of controlling the end play of the mainshaft would be to use a thinner paper gasket (fitted between the gearbox case and the overdrive adapter casting). I still try to use a gasket here but substituting with an RTV sealer made be your best option. The old cast iron gearbox components don’t have the same precision fit as a modern diecast aluminum housing and can still leak if that bead of RTV isn’t enough. The goal is to keep the main shaft (which is carrying second gear) from drifting towards the rear….and carrying second gear further away from the synchro slider. Along with other factors, excess end play will contribute to popping out of second gear.
I was glad to see this reply as I was beginning to think my understanding of the term, 'mainshaft' was wrong. Mine is the same as yours but some seem to interchange that with Main Drive Gear.
In the transmission business the term “Main Drive Gear” refers to the input shaft/gear at the front of the transmission. The term “Mainshaft” or “Main Shaft” refers to the output shaft coming out of the gearbox. Folks get these confused all the time. Ford uses these terms the same way in all of their parts and service manuals.
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