Gearbox problems

[Srenner]

I'm looking for a little assistance on a gearbox problem. This box was rebuilt 8 years ago by a place that has been around for decades doing American boxes. That said, they also thought it was a 3 speed!

All of the adjustment procedures in the book have been followed, several times.

When attempting to shift into 1st gear, it can lock the gear change lever lever (hey, that's what the book calls it! J50099) BEHIND the selector bar (J50086). It manages to slip the little selector finger out from the slot in the selector shaft, pass underneath the selector shaft, pass up along the outside of where it should be and pop all the way up to have the gear change lever (JA50095) appear to be in 3rd gear. The cockpit shift lever is then jammed in what looks like 1st gear position and the gearbox is locked in neutral, as the gear change lever is no longer inside the selector forks.

It appears that limiting the downward movement of the gear change lever and shaft (J50099/J50097) by placing a washer under the gear change lever (JA50095) prevents this from occurring. But why would it do this?

Also, reverse is extremely difficult to grab, with no "feel" that it is engaging the gear. Most often, the lever will not move into reverse. The reverse lockout button has no "feel", although I can see it works by peering into the small hole in the backside of the shifter. The action of shifting is not smooth and fells quite stiff and "notchy", as if the selector lever lever (J50099) is getting snagged on something. It has a bit of this feel when operated by hand at the gear change lever (JA50095).

2nd gear does not fully engage and pops out out of gear under load and unload. Any attempt to change the length of the of the rod from the column shift to the selector bar change lever (52390) makes reverse easier at the loss of 2nd gear, or a small improvement in 2nd at the loss of reverse.

Both the selector bars (JA54438/JA50086) and the brass fingers are in very good condition and measure out to nominally the same as other sets that I have.

The side cover and all its parts appear to be in good condition and have no noticeable differences from my other side covers.

Anyone have this set of problems before?

Regards,
Scott

[Forumadmin]

You probably do not have the full provenance of the box and thus must suspect either a mixture of parts from different boxes and/or wear on various parts. That said we need to look at the each symptom and try to analyse the cause.
Probably the best bible on gear boxes is that written by Harry Brierley which, if it not already on this site, I will load into the Gallery.
Is the box out of the car now?
Is it in a left hand drive car, as those helping this thread must realise that the linkages will be different?

[Srenner]

James and I just put the box back in the car on Sunday. I solved the locking problem as described by use of a washer, but now we have these other issues.

I do not know the history of this unit. I am unsure if the restoring owner had another gearbox for parts. It is LHD, so 1st is towards the rear and down, with 4th towards the front and up. Reverse is all the way rear and down.

Of my 4 Jowetts, I have three shift patterns: normal RHD, normal LHD (1st on top) and inverted LHD as described above!

[Amy]

Of my 4 Jowetts, I have three shift patterns: normal RHD, normal LHD (1st on top) and inverted LHD as described above!

I can't help on the issues, but that amount of configurations must get hideously confusing!!

(Hello by the way - hope the other gearboxes made it over in your baggage ok... still looking foward to your European trip report... )

[conrod]

The gear operating shaft lever (the one on the top of the gearbox) on a left hand drive Jupiter is slightly different to that of a right hand drive.

Have you got the correct one fitted ?

[Srenner]

Yes, it has the correct lever. I have about 10 NOS ones, also all the same. My parts book makes reference to LHD and RHD, but also says they are interchangeable. The paper tag attached to the NOS ones also has the same notation.

Re: Different shift patterns on the cars: usually not a problem remembering which car has which pattern, but if I forget, the grinding of the box will remind me.