3rd and 4th gear baulk/rings

[Johnny]

Finished assembling the main gearset in my BJ7 and after installing the selector forks and shafts discoverd I can no longer shift into 3rd or 4th gear? I have the transmission out of the car and sitting on my workbench and am in the process of making sure I can shift manually all gears. I replaced the lay gear, reverse gear, and 1st gear with hub. All those work super smooth now but when trying 3rd or 4th, no luck. removed the (3rd/4th) shaft thinking it could be binding, nope, it's something inside the sliding hub. Oh, I also replaced all 3 baulk rings/synchros. I'm thinking the new synchros are preventing the hub from sliding. Any other ideas I'm overlooking? Has anyone else had this problem? Reluctantly, I now have to remove the gear set and replace the new baulk rings with the originals and try that. I thought I'd ask here first though. Any ideas? :confuse:
Oh, I installed the 3rd/4th rings facing each other (you know the points facing the center of the hub, I think thats correct.

 

[Randy Forbes]

If you can't slide the outer collar of the 3rd/4th synchromesh hub, the balls/springs could be holding it up.

I think it would be impossible to install the synchro rings incorrectly, but if the outer diameter of the "points" is too great, that would prevent the collar from sliding over them.

Compare the new rings to the old ones by putting them against each other.

 

[Randy Forbes]

BTW, did you take the synchro-hub apart; because if it doesn't have the correct orientation between the inner/outer halves, it won't work.

See:

 

[Johnny]

As always Randy, thanks so much for looking at my problem. I didn't remove the sliding hub, but not that the PO may have. How do I know which is correct? I can't tell from the excellent photo's shown? Do you merely align the inner half section with the gaps? I remember replacing the springs and balls but as for as I can tell it looked okay. Are you saying I wouldn't of been able to slide the hub far enough to engage the gear if it were installed wrong?

I did compare the brass synchros with the originals and they looked very much the same except (In diameter, meaning the tops all aligned correctly)only not as worn.

With the gear set in the transmission I cannot slide the outer hub either direction far enough to engage the gears. What's wrong? Is it turned in the wrong direction? Do I need to flip it around?

 

[Randy Forbes]

It should go on the mainshaft as shown in the last picture posted above, but I don't think you could've put it together wrong, I don't think there's "room" to put it togther backwards.

Yes, the gaps inner/outer, should be aligned. After thinking about it, I don't think the rings could go in if they're not aligned.

I think you're going to have to pull it apart and see why the hub doesn't slide.

A note to anyone building up a gearbox (or anything else) is that it's always a good idea to test things as the assembly progresses. It's bad enough to have to undo a few steps, but imagine if Johnny didn't find this problem until completely assembled.

 

[Johnny]

Well, I probably will have to pull it apart to find out the problem. Last night I even loosened both ends of the mainshaft thinking they might be binding, "naw" no difference still won't slide over the gear, either 3rd or 4th won't move (almost) but not enough to engage. I remember sliding the hubs both fore and aft after installing on mainshaft and even after while on the bench. Remember, I didn't remove the driven gear (front) just the rear most gear assembly. Even the manual says it's not necessary. However, had I removed it I could of pre-assembled all and tested before reinstalling in the case. Now I'm thinking as the rings wear they'll recede slightly allowing the gears to mesh, but I can't wait for that to happen so I will have to remove all. At least it's on the work bench and not in the car, as you said. Thanks again for your help. I'll keep in touch.

 

[Randy Forbes]

Yes, I'm curious to know why too.

A short story about a problem that occurred with my side-shift during a trip between Atlanta & my folk's place in Florida (1985?); I had made a fast shift from 3rd into 4th (after passing on a 2-lane road) and a huge blast of smoke came up through the cockpit (top & sidescreens in place).

I couldn't immediately pull over (in front of the truck I'd just past) and went on a bit further; the truck turned up a driveway so I started to pull off the road to see if I could figure out what had happened.

Upon slowing down, I couldn't shift out of 4th down to 3rd, neutral, or any other gears. The xmsn was stuck in 4th gear.

I made the rest of the trip using only 4th and 4th/overdrive. To keep the engine from "pinging" when taking off, I dialed back the timing as much as the vernier adjustment on the distributor would allow. Interestingly enough, I was still among the quickest away from the stoplights when taking off in 4th gear!

My brother lived only a few miles from my parents, and I knew he had enough of the right tools to pull & teardown the gearbox. When he got home, not only could he not park his MGB in the garage, I was standing there ready to have him help me pull the gearbox out of the car. I had already determined the problem by taking the side cover off and seeing the springs & balls had escaped from the #3-4 synchro hub (same component you're having issues with).

After getting the xmsn apart, a trip to the Ace Hdwr for some generic springs (as mine got mangled trying to force the lever back to 3rd) and a tube of Silicone sealant, being as Ace didn't stock Healey xmsn gaskets.

The cause, it seemed, was that the synchro ring for 3rd gear was just a bit shallower than the one for 4th, allowing the outer ring too great a travel (as the inner hub could move closer to 3rd gear) letting the balls & springs escape.

I swapped the 3rd synchro ring for 4th, and the gearbox was good until I retired it for too many cavities (tooth decay) on the 1st gear segment of the laygear.

BTW, when you took your xmsn apart, did it have copper sealing washers under the boltheads for the bellhousing?

 

[Johnny]

I found the problem and the problem was ME! If you look at your photos (6th from the top) you'll notice the inner hub has a NOSE pointing up. That part goes into the driven gear in the front. I had it reversed. I'm only glad that in fact it wasn't able to shift into 3rd or 4th, even with difficulty, I may have forgotten about it until I had the transmission in the car. So, all I did was with the case in a vise (Nose part down) was lift out the rear main gear cluster, flip over the 3rd/4th hubs with the longer nose part down into the driven gear and voila! All works just fine now. With plenty of grease in the shaft even the roller pins stayed put when I lifted it out. BTW I discovered when first installing the main gear cluster into the driven gear in front, if you place the rollers with lots of grease, and secured with two rubber bands, around the main shaft you can easily lower the gear set down into the driven gear by yourself pretty easily.

I now have two more questions. The three springs that go down on top of the interlocking balls seem to me to be too short. Shouldn't they be longer and in fact stick up above the case? the ones that came out of the case on my car are the same as the ones used on the hubs?

My second question is the screw that goes into the side of the case to hold the interlocking ball (it's a small square headed bolt) that's associated with the 3rd/4th shaft near the front of the case. To me, this should have a spring behind the ball then the bolt would be pushing against the spring which in turn pushes against the ball. The drawing doesn't show one there, what do you think?

Again, many, many thanks for all your efforts.

 

[Johnny]

Yes, I'm curious to know why too.

I had made a fast shift from 3rd into 4th (after passing on a 2-lane road) and a huge blast of smoke came up through the cockpit
<span style="color: #FF0000"> </span> What caused the smoke???

I couldn't immediately pull over (in front of the truck I'd just past) and went on a bit further; the truck turned up a driveway so I started to pull off the road to see if I could figure out what had happened.

Upon slowing down, I couldn't shift out of 4th down to 3rd, neutral, or any other gears. The xmsn was stuck in 4th gear.
<span style="color: #FF0000"> </span> I'm thinking the fork shaft had to be binding here.

I made the rest of the trip using only 4th and 4th/overdrive. To keep the engine from "pinging" when taking off, I dialed back the timing as much as the vernier adjustment on the distributor would allow. Interestingly enough, I was still among the quickest away from the stoplights when taking off in 4th gear!

My brother lived only a few miles from my parents, and I knew he had enough of the right tools to pull & teardown the gearbox. When he got home, not only could he not park his MGB in the garage, I was standing there ready to have him help me pull the gearbox out of the car. I had already determined the problem by taking the side cover off and seeing the springs & balls had escaped from the #3-4 synchro hub (same component you're having issues with).

After getting the xmsn apart, a trip to the Ace Hdwr for some generic springs (as mine got mangled trying to force the lever back to 3rd) and a tube of Silicone sealant, being as Ace didn't stock Healey xmsn gaskets.

The cause, it seemed, was that the synchro ring for 3rd gear was just a bit shallower than the one for 4th, allowing the outer ring too great a travel (as the inner hub could move closer to 3rd gear) letting the balls & springs escape.

I swapped the 3rd synchro ring for 4th, and the gearbox was good until I retired it for too many cavities (tooth decay) on the 1st gear segment of the laygear.

BTW, when you took your xmsn apart, did it have copper sealing washers under the boltheads for the bellhousing?
<span style="color: #FF0000"> </span> No I don't think they were copper, are they supposed to be? In fact, I didn't have any washers under the heads of the bolts, I thought that was odd. I'll check later.

 

[Randy Forbes]

The selector shaft springs are definately longer than the synchro hub springs, like by double.

 

[Randy Forbes]

Forgot to answer Q2...

There's no ball or spring under the square headed plug; that's for access to drop the two (2) interlocking balls in.

In my (transmission) case, the plug was slotted and DID NOT want to be removed, so I had to put the balls in through the front.

 

[Johnny]

Forgot to answer Q2...

There's no ball or spring under the square headed plug; that's for access to drop the two (2) interlocking balls in.

In my (transmission) case, the plug was slotted and DID NOT want to be removed, so I had to put the balls in through the front.

Now I understand, there's 5 total balls and 3 much longer springs. I guess the plug as you say is just to drop them in. Whoever worked on my transmission last put an extra ball in under the plug plus the 2 interlocking ones.

I figured the springs had to be much longer, I'll see if my local hardware store has any the right size. I'm still trying to see how anyone could have destroyed the 1st gear,reverse gear and the laygear so bad. The transmission had to have some work done on it as all the gaskets were new plus inside was so clean, other than all the shavings from the destroyed gears. Maybe it was due to the wrong length springs? I also noticed on the reverse gear shift fork plunger seems really hard to depress in, is this normal? I can push it in using the vise and a socket but should it be really that hard?

Oh, Randy, my book says to use plain lockwashers under the bolt heads for the bell housing, why use copper washers??

My next step, wire the square headed bolt heads to the shifting forks.

Again, many thanks for all the help.

 

[Randy Forbes]

Johnny, those detent ball springs, along with the springs inside the synchro hubs, are what keeps your transmission from popping out of gear (and from being unduly hard to get into gear). You're going to want to be sure you have the correct tension on those detent balls.

I replaced all those springs with new ones during my recent rebuild. Moss Motors supplied them to me.

If you still want to go the hdwr store route, I can measure the wire diameter, number of coils, and the free length of my old ones (heck, I'll even mail them to you).

Yes, the reverse plunger is VERY difficult to depress <span style="font-style: italic">on the bench</span>, but you'll have a mechanical advantage when you attempt it fully assembled using the gear lever.

I had found remnants of copper (presumably from a washer) inside the bellhousing holes when I sand-blasted it (prior to the thermal-dispersant polymer coating). Those threaded holes are open to the oil reservoir of the gearbox, so it's possible they could weep oil. At a minimum, I would use a thread sealant (shown below) on those bolts when you attach the bellhousing to the gearbox.

 

[Johnny]

Many thanks Randy but not necessary to measure etc. From your excellent photo I can count 16 coils, the length isn't too hard to determine. A fellow club member has some springs left over I can borrow. Thanks for the offer though.

Good reasoning on the copper washers, I'll get some of those too as I remember a slight leak there around the bolts. Remember mine didn't have any washers.

Glad I talked to you about the plunger. I'll assemble the top part and try shifting.

Many thanks for all your help.

 

[Johnny]

Here's an update for those willing to put up with my incessant questions. I now have the bellhousing attached to the transmission, was it easy, NO. With the transmission upright on the workbench (without the shifter attached) I offered up the bellhousing and couldn't get a tight fit, by twisting and turning I finally got close enough to tighten some bolts. After tightening the bolts the shifter shafts were binding. Something was wrong. I removed the bellhousing and verified the laygear shaft aligned with the bellhousing opening provided to keep the shaft from turning. I noticed it had nicked the aluminum bellhousing. I smoothed out the opening with a dremel tool and now decided to flip the transmission over with the flat (top) of the transmission down on the workbench. Now, while focusing on the shifter shafts the bellhousing slipped right on first time and I had a good tight seal. Taking Randy's advise I used a thread sealant and copper washers and tightened all the bolts. With the transmission once again upright I found I can move all three shafts very easily. Apparently the laygear rod didn't quite align correctly and also the shifter shafts didn't either. Lesson learned, attach the bellhousing with the transmission laying flat (upside down) on the workbench and focus on alignment.

Once again, many thanks Randy. Now, re-attaching the overdrive!

 

[Randy Forbes]

... Once again, many thanks Randy. Now, re-attaching the overdrive!

If you think the bellhousing was fun to attach, you haven't lived until you mate the overdrive with the gearbox!

If you have any problems, you should just give me a call, and I'll talk you through it.

Whatever you do DO NOT FORCE ANYTHING.

The splines in the planetary gear carrier and uni-directional clutch MUST LINE UP PEFECTLY. Rotate the output shaft of the transmission so that the base-circle of the oil pump cam is nearest the oil pump plunger. If you're lucky, the mainshaft will pass right through the two (2) splines (rarely am I that lucky).

Don't forget putting the eight (8) springs in...

When the cam gets close to the plunger, using a long screwdriver, depress the plunger to get the roller up the ramp (some cams are beveled to assist, but not all).

Evenly tighten the nuts on the two (2) long studs to pull the units together, periodically checking for binding (by rotating the tailshaft flange). Install the remaining nuts, tightening them all evenly, and then have a beer!

If you get into trouble, call me: (419) 350 1098

 

[Johnny]

Okay, this is the final response to this thread and here's what I've learned, in a nutshell.

As a novice mechanic I now no anyone that is handy with tools and familiar with auto mechanics (also with a lot of patience) can rebuild the transmission.

You can save a lot of money by asking around for leftover parts. Consult with anyone willing to listen. I purchased an early model (BN6) transmission that had the mainshaft destroyed in the OD. I was able to salvage an excellent reverse gear, and 1st gear with sliding hub both of course are straight cut gears not beveled.

You must have the exact replacement part number thats stamped on the laygear. Use a suitable tool for inserting in the laygear before final placement. Read the shop manual it explains why.

Use copper sealing washers and thread sealant on all bolts and studs to keep the transmission from leaking oil.

Install the OD with the transmission inverted on a furniture dolly with the rear shaft sticking up in the air. Place the cam for the oil pump on the shaft and seated with the lowest part of the cam facing the bottom of the transmission. The OD units weight will help overide the roller cam on the pump. If you can, borrow a main shaft from someone and use it to align the planetary gears in the OD before attempting to install the OD. READ THE SHOP MANUAL, After the fourth try I finally got the hang of it. Use NYLOC nuts with thread sealant on the 8 studs attaching the OD.

Finally, seek help from the Forum on everything!!!

Good luck to all.