850T gearbox issue

[lucky]

.

Hello Friends,

I just recently bought a '74 850T is quite nice condition, meaning that it seems to have lived indoors for the last 50 years, with no rust or obvious signs of abuse.  However it does have an issue, it takes two or three attempts to change up into 2nd or 3rd gear.  No problem with 4th and 5th and no problem changing down.

Having read up on this on the forum, and having checked easy fixes like the shifter lever fouling the frame, everything points to a broken return spring, which apparently requires removal and at least some disassembly of the gearbox.  This is an area I have never had to go into yet, even though this is my tenth Guzzi.

It may not be smart to do so, but it does run quite well if I am patient with those upshifts, so I could ride it gently and infrequently and leave it as a project for next winter.  I do have a couple of Loops and a 1400 California so it would be a doable exercise in delayed gratification. I am somewhat intimidated by going into the box, but maybe I shouldn't be.

Now here's the other thing, I have a '74 Eldorado parts bike with a very dodgy motor but quite possibly an okay gearbox.

So my question is, will the '74 Eldorado 5-speed box bolt straight onto the '74 850T?  Or are there complications?

Good to know what my options are before I plunge in . . . so thanks for any thoughts!

[pehayes]

Where are you located?  Put it in  your signature line.

Its not the return spring.  That spring is binary.  It either works or it doesn't.  The purpose of the spring is to return the shifting lever to its central, rest location after each shift.  If the shift lever is returning to center position in 4th and 5th shifts, then the spring is working.  I would change the lubricant or just put some miles before tearing into this.

Patrick Hayes
Fremont CA

[Antietam Classic Cycle]

So my question is, will the '74 Eldorado 5-speed box bolt straight onto the '74 850T?  Or are there complications?

The speedo cable and drive is angled more to the right than that of the 850-T, so it may interfere with the frame.

Fix the 850-T transmission. https://www.thisoldtractor.com/guzzitech.dk/gb_en_complex-technical_gearbox-rebuilding-pictures.html

[lucky]

Where are you located?  Put it in  your signature line.

Its not the return spring.  That spring is binary.  It either works or it doesn't.  The purpose of the spring is to return the shifting lever to its central, rest location after each shift.  If the shift lever is returning to center position in 4th and 5th shifts, then the spring is working.  I would change the lubricant or just put some miles before tearing into this.

Patrick Hayes
Fremont CA

Very good - that is very clear - I have indeed just changed the lubricant so I will put some more miles on it and see if there is improvement.

I am in central Ontario, Canada, so am only now welcoming the onset of riding weather.  Thank you

[lucky]

The speedo cable and drive is angled more to the right than that of the 850-T, so it may interfere with the frame.

Fix the 850-T transmission. https://www.thisoldtractor.com/guzzitech.dk/gb_en_complex-technical_gearbox-rebuilding-pictures.html

Thank you, Charlie

[wirespokes]

With the older, heavy flywheel, bikes, it helps to preload the shift lever. When ready to shift, load the shift lever taking up slack, start backing off the throttle, then pull in the lever and shift.

I think preloading the lever helps by slowing down the gears making them easier to mesh.

The shift drum probably needs to be shimmed. They tended to be poorly shimmed from the factory.

[JoeW]

Shifting from second to third requires putting the 1-2 shift fork in the "neutral position" and then moving the 3-4 shift fork to third. The shift return spring has an adjustable bias using the bolt on the back of the trans. Not knowing what year T, is it one down and the rest up or the other way around. I can't say which way to move the lever. If you loosen the 17mm jam nut, you can adjust the bias by turning the 14mm head bolt. These adjustments are made in minute increments. When you rotate that 14mm bolt, you can see the shift arm move up or down. It just may not be centering properly. Also, it's a T, with that Rube Goldberg shift linkage that moved the shifter from right foot to left. If there is a lot of play in that linkage, that should be addressed.

[lucky]

Shifting from second to third requires putting the 1-2 shift fork in the "neutral position" and then moving the 3-4 shift fork to third. The shift return spring has an adjustable bias using the bolt on the back of the trans. Not knowing what year T, is it one down and the rest up or the other way around. I can't say which way to move the lever. If you loosen the 17mm jam nut, you can adjust the bias by turning the 14mm head bolt. These adjustments are made in minute increments. When you rotate that 14mm bolt, you can see the shift arm move up or down. It just may not be centering properly. Also, it's a T, with that Rube Goldberg shift linkage that moved the shifter from right foot to left. If there is a lot of play in that linkage, that should be addressed.



That’s great, Joe. I have high hopes that the adjuster will sort it out. Just waiting for it to stop snowing! 😹