Gearbox synchro Woes!

Hello all,

I have split the gearbox and the transfer box as it would not select any gears. Upon inspection the clustershaft had lost a lot of teeth.

After ordering all the gears and shafts i need i an just getting the rebuild compleated and i dont appear to be able to get the snap ring to snap on the grove on the shaft - hopefully the pictures explane what i mean. it appears to be a fraction out!

I do note that the old synchro ring appears to be a little "crushed" when compaired to the new one.

I dont want to force anything unless i should.... but what am i doing wrong, what have i missed!!

The sychro ring is not seating all the way down on second gear. That is going to cause the synchronizer hub to set a little away from the gear. The hub should be right against the gear. It looks like the hub might be backwards.

When you install the snap ring, use something to hold the shaft solidly vertical. Let gravity hold it all down till you get the snap ring on. You should not have to force it. The snap ring groove should be clear.

thats what i thought, when you say the hub should be right against the gear, I have tried the gear both ways and the gap it the same.

If i stand it on its end and let gravity do its job i still cand get the smap ring on!

Something is amiss there Steve. What components are new? The collar that slides on has a "long side". The long end goes on to the front. In the attached photo of a T90, the trans is shifted into 3rd. You can see how the collar, sychro ring and second gear should be fitting together. It is similar on the T84.

Attachment 10159

I’m kinda thinking along with bmorgil it looks like the hub may be in backwards or maybe one of the springs that hold the sliders in is giving you fits, it’s not much from going together tight.

Hello

All the components are new, and all brought from just one supplier here in the UK.

It all feels to tight if that makes sence, i had a quick look at the synchro rings last night and the news ones appear wider than the ones that came out. I will measure them later and see if i am right.

I am baffled!

The synchronizer wears on the inside of the brass ring. As it wears it sets deeper and deeper into the gear. Eventually it sets too deep to function properly or it becomes glazed and galled. I would try using the old collar first. Assemble the main shaft without the synchro assembly, just the collar and second gear. If the snap ring clears with just the collar, it is the synchro ring holding it off for some reason. Either the ring is machined improperly or it is hanging up on the locks as TJ suggested. If the old synchro rings look good, you could give them a try. They need to look perfect on the inside. Little to no wear on the bronze surface. If you can still see and feel the "Lube Ridges" or grooves on the inside and it is clean and free of galling, it is good.

Attachment 10160

If the snap ring wont go on with the old collar and second gear only, the main shaft and/or second gear is improperly machined. Check to be sure the bushing is all the way in second gear and not holding the collar or the gear up.

In your second photo, the sliding clutch looks to be starting to engage the synchro ring in second gear. At the top snap ring end, there are a lot of splines showing on the collar. The sliding clutch appears to be shifted slightly into second. Be very sure something isn't backwards.

Hello All,

firstly thanks for all the replies, i do realy appreciate them all.

I am still a little puzzeled as to what is going on, please see the two photos i have attached showing the synchro on the mainshaft both ways up without any of the collars on and it still wont fit!

Spoke the to the dealer today i got all the parts from and he was just as puzzeled as me!! it looks like i will be taking a trip up to see him with the parts! unless of course you guys and gals spot something that i have done wrong or missed!!

Attachment 10161Attachment 10162

Steve did you try the old parts? If the old second gear and shift collar wont work on the new main shaft, the main shaft is bad etc.. I think you can narrow it down with the old parts. One of the three pieces must be machined improperly or possibly the stack up of all three parts is incorrect.

Hello

The new bits (second gear and SYncrho) line up on the old shift the same as the new shaft!

I will speak to the dealer in the UK, that is puzzled too and wants to sort the probem.

A trip up to see him next this week or the week after is on the cards!!! i am hoping that i have done something wrong that i have missed!!

Keep us advised. I'm very curious to know what isn't quite falling into place.

No worries, i still feel its something that i have done that i have missed to be honest.

It looks like i will be taking a trip up to the dealer to see what we can work out.!

For sure there stevegully, I think your dilemma has everyone baffled. These trannys are about as simple as they get.

Attachment 10191

Good evening, All,

Ok I have had a conversation with the dealer that sold me all the parts, all of the parts he has on the shelve have the same problem!

I must stress that he is a puzzled as me and he has been extremely helpful, so no complaints about his service or follow up care.

However, I took a close look at the gear today and with a straight edge i think the attached photo shows the problem.

Luckly enough I do have access to a workshop that has the capabilities to “shave” off the difference and then it should fit.

We got there i believe!

Steve, the old collar looks like it is in great shape just dirty. If it will clean up and isn't worn, I would just use it.

some of the teeth are pitted, i did think of that, but decided not to!