H55f 5th gear issues.

[bj70cruzer]

I have a bj70 with a h55f gearbox it had a issue of 5th gear popping out on deceleration and grinding each time i tried puting it back it so i rebuilt the trans mission with new bearings seals and synchros for 3rd 4th and 5th gears.

5th gear got brand new syncro spring pins ans dog gear it drove great for about a year until i noticed it started to pop out of gear on deceleration down hill.

Then started to gwt worse and if the gearbox is left in 5th long enough while coasting on flat ground it will pop out of gear aswell.

It how ever does no grind so the synchros are still good.

Does this seem like a detent spring issue?
I took it out and looks fine but im not sure how long its supposed to be?

What is a permanent fix for this issue? What causes it to pop out of gear?

Thanks

 

[roscoFJ73]

Detent spring for sure. My 61 series was doing exactly the same thing. On long trips, have a bungy cord handy to slip over the gear stick with the other tied under the dash.
The detent spring also has a small metal ball about 3mm in diameter, was that there also?
Its popping out because the gears will not stay meshed unless there is some "detent" pressure holding it in. Under load the gears are tight against each other, but coasting they are not. Hence, it jumps out of gear.
For some reason, its mainly 5th that does this.

Ive broken the detent spring on my Triumph bike twice. Does exactly the same thing and I had to ride hundreds of klms home with my foot holding the shifter in gear. it has one spring for everything

 

[SimonTrick]

Ive had a similar issue (5th popping out) for a few years now but it seems the syncro is now also shot and finding it extremely difficult to engage 5th gear unless i double clutch or rev match (lots of grinding happening). How difficult is it to replace the 5th syncro and replace the detent spring? Would a syncro suitable for a HZJ75 be fine to use?

 

[Hulsty]

Not difficult, remove the transfer case, extension housing and you have acccess to all the 5th gear parts.

 

[bj70cruzer]

I have solved my issue of 5th popping out.

5th was not fully enaging maybe only 60% on the dog teeth. To fix this i put the fork in the press and bent it 1.5mm outwards.

This gives full enagement and no longer pops out of gear.

 

[SimonTrick]

Is there a way to tell what type of spline i would have? 34 or 38 tooth, fine spline, long shaft etc? I know there are a few variations on this... its a 1985 BJ73