General Category > Bike Builds, Rebuilds And Restorations Only
Sessantacinque GT rehab (V65 GT), frame crabbing, gear box, transmission
huub:
sounds like the shift spring is on its way out.
a pretty common fault with these.
the spring is cheap, but unfortunately the box needs to come apart to change it
nice project for the winter....
Pescatore:
I guess I could have a bad one.
The spring broke some time ago, so I started this project.
I had it replaced, the part came from Stein Dinse.
The shifting was bad from the first day I got it running again.
I've read that it could be installed backwards, but I don't think the
shop that did the work would make that mistake.
Perhaps the shop didn't test the shifting after a dry assembly.
And I didn't think of it until I put it all back together.
Chuck in Indiana:
--- Quote ---Perhaps the shop didn't test the shifting after a dry assembly.
And I didn't think of it until I put it all back together.
--- End quote ---
Sounds like you will get to do it, now. :smiley: There is obviously something wrong. Fortunately.. it's a 2 hour job to get to it on the small block.
Pescatore:
I finally resigned to the fact that I can't fix the shifting problem
from the outside. So I crabbed the frame again.
It was painful to do, thinking about all the care I took to
reassemble it.
On the bright side, I couldn't believe how filthy it was after
a few hundred miles on dry roads last summer.
I wish the rear fender went down below the swing arm.
All clean again.
Pescatore:
With the gear box on the bench I confirmed the same shifting issues: it went into 1st and 2nd, then to get to 3rd I had to shift up,
tap down a bit and then up again.
I adjusted the cam screw a bit, but the pattern was not changing, nor improving.
I decided to take advantage of this great forum and contacted Scout63 for advice. He was extremely generous in lending his time, his knowledge,
his shop, his tools, his grease, his mineral spirits, a ham and cheese snack and most importantly his confidence. He didn't show hesitation in opening
the box and, like a kid wanting to learn to ride a bike but afraid to fall, I inhaled all the confidence and dove in.
Look at these beautiful trees with flowers on them!
But I am getting ahead of myself.
I am also grateful for many posts I found on this forum. Just search for "gear box" many stories came up from others who repaired their gear box.
There is also a write-up by Nick Webb referenced in many posts and here it is again:
https://www.thisoldtractor.com/guzzitech.dk/gb_en_complex-technical_gearbox-repair-breva-750-pictures.htm
Nick refers to a Wildgoose post where all the work was also discussed among two other folks who had similar problems. Unfortunately that
post was deleted. I am not able to track down Nick for questions, but Muzz is on this forum (thank you Muzz).
As well as factory training videos:
http://thisoldtractor.com/moto_guzzi_technical_training_videos_eng.html
Also, while this other write-up is for big blocks, many tips and ideas can be leveraged, so thank you John Noble for this:
https://www.thisoldtractor.com/guzzitech.dk/gb_en_complex-technical_gearbox-rebuilding-pictures.htm
In the process of researching and opening the box we realized that, even though special tools are useful, there are ways around it. That was one
of the obstacles I was creating in my head. A pneumatic or electric impact wrench will do, if you can accept a compromise in re-assembly (read on).
With an impact wrench, you don't need to undo the nut on the input shaft. This is the dreaded 10Kgm torqued nut, in the middle of the picture.
The only reason for removing that nut, barring any bearing or seal damage, is so that you can use the shaft and its gear to hold the lay shaft, under
the clutch housing. That would be using the gear on the right side of the picture below to mesh with the lay shaft gear on the left. Then, you need the special
spline shaft holder tool to undo the nut on the lay shaft. Even though I saw the videos and did plenty of reading, it didn't click until I did this work.
I guess I am not the sharpest tool in the shed.
So, the first step in opening the box is to remove all the allen screws on the inside of the clutch cover and pop it off.
BTW, the picture above shows the clutch push rod. I put that in later and it should be removed before you start opening the box.
The next step is to take that impact wrench and unscrew the nut on the lay shaft. Remember to pry open the punch in the lip of the nut!
Here is a zoom in:
...more to come.
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