H55F 1st/2nd synchro wear questions (3 Viewers)

[HZJ75 FARMER]

H55F pulled from a wreck, condition unknown, doing a rebuild job.

Trying to make a judgement about the condition of the synchros on 1st and 2nd.

FSM says 1st gear minimum 32.5mm, but I have 30.8, and 2nd gear minimum 38, but I have 35.4mm.

A new 1st/2nd synchro is about $800 AUD. It's not part of the rebuild kits, so are they not regularly replaced?

Will a new synchro really sit that much higher?

I thought the grooves in the brass would be worn away if it was worn out? Maybe not?

Does all the wear occur to the brass, or will the gear be worn also, and therefore a new synchro may not do much?

When pressing down by hand and attempting to turn, they do exert a nice grip to the gear, but is this any indication?

Do you all just use the factory specs to make your judgement, or do you have other methods?

 

[Eurasiaoverland]

The 1st/2nd synchroniser hub looks fine to me. Are you sure you are using the correct manual? I'm not sure, but they may have changed the hub in the update which the H55F got sometime in 1985.

I replaced mine, but it was wear on the index teeth that led me to change it, not wear on the bronze synchronisers.

 

[HZJ75 FARMER]

I thought it was the correct manual. I'll have to check.

I haven't had to make judgements on synchro rings. If you didn't have any specifications to work with, how would you do it? Is looking at the grooves, and feeling the grip/brake effect normally what you would do?

 

[Eurasiaoverland]

I would just go by looking - from the pictures shown there is very little wear - the grooves on the synchroniser ring are still sharp and the engagement surface on the gear looks fine too. If it was worn down by a millimetre or more it would look pretty trashed. You can look up pictures of the new parts online for reference,

 

[HZJ75 FARMER]

The 1st/2nd synchroniser hub looks fine to me. Are you sure you are using the correct manual? I'm not sure, but they may have changed the hub in the update which the H55F got sometime in 1985.

I replaced mine, but it was wear on the index teeth that led me to change it, not wear on the bronze synchronisers.

Looks correct to me.

 

[HZJ75 FARMER]

I thought there would be dozens of people here who have rebuilt these and had to decide what to do about the synchros?
Maybe not?

 

[JuanJ]

Hello,

In old age, an H55F slips gears. Wear and tear.

Chances are your transmission lived a hard life.

If the measurement is outside FSM tolerances, the synchros need replacement.

In newer transmissions, Toyota modified the design and added a feedback mechanism that made a click when shifting gears. It helped with wear and tear.

I would bite the bullet and replace the synchro.





Juan

 

[sadam_husain]

Did you get to drive it and see how the gearbox felt before pulling it out of the wreck? I've had quite a few H55F's and other than a weak 5th gear they are a pretty tough gearbox so only do what you need to before putting too much money into it, I had one really worn one that would pop out of second and reverse but I still drove on it for about 17-18 years like that untill I lost all the oil into the transfercase and melted all the syncro's, good luck with your rebuild mate

 

[Eurasiaoverland]

That will be the correct manual.

Those synchros are enormous and I'm very skeptical that it is so far out of spec when (from the pictures I can see) there is no wear.

It's not unknown for the FSM to contain errors, or sections which have not been correctly updated.

 

[HZJ75 FARMER]

Did you get to drive it and see how the gearbox felt before pulling it out of the wreck? I've had quite a few H55F's and other than a weak 5th gear they are a pretty tough gearbox so only do what you need to before putting too much money into it, I had one really worn one that would pop out of second and reverse but I still drove on it for about 17-18 years like that untill I lost all the oil into the transfercase and melted all the syncro's, good luck with your rebuild mate

No unfortunately it was a non-runner so I didn't have a chance to drive it.

What was the cause of popping out of second and reverse?

 

[JuanJ]

What was the cause of popping out of second and reverse?

Hello,

It is common in an H55F transmission with old age. Wear and tear.





Juan