If you like our site, please consider joining our club!
By joining you will help ensure that we can continue to provide this service
JOIN HERE!

R90/6 slipping in low gear

User avatar
Randolph
Posts: 74
Joined: Tue Jan 13, 2015 11:31 pm

Re: R90/6 slipping in low gear

Post by Randolph »

I have to differ with you on the clearance issue. There should be zero clearance between the bearing and that 1st gear rear thrust washer.
The entire shaft, gears and bearings should be assembled as a unit. The unit is inserted into the case THEN the rear cover is installed with proper shimming on the rear bearing to give .05-.1mm clearance with the rear cover.

Yeah, all those clutch parts look pretty sad. I'd replace all of them and the diaphragm spring too.
I hate mission creep, but I'd yank the flywheel and install a new crank seal and an oil pump cover o-ring. There also might be an o-ring on the flywheel.
Besides using a clutch plate centering tool when I put the clutch back in I use a dial gauge to center the pressure ring. See pic. With the clutch bolts just snug I use a cats-claw on a wooden block to lever the compression ring to center it. Yes the clutch bolts are beveled but they DO NOT center the compression ring well. You can reuse the bolts, as well as 11mm flywheel bolts. Don't reuse 10mm flywheel bolts if that is what you have, use new ones. Use a little blue loctite on both.

How did the throw-out piston and parts look?
Attachments
pressure ring centering
pressure ring centering

Bob W
Posts: 5
Joined: Wed Dec 21, 2022 2:21 pm

Re: R90/6 slipping in low gear

Post by Bob W »

Southland clutch in Cal machines the metal plates and relines the disc with thicker material to compensate. About $200. Mine works well.
Bob

User avatar
cbclemmens
Posts: 216
Joined: Sun Apr 25, 2021 2:21 pm
Location: Apollo, PA
Been thanked: 4 times

Re: R90/6 slipping in low gear

Post by cbclemmens »

Randy and I are not going to agree on the end play. That's alright as long as you have 0.05-0.1mm you will be ok.

Bob; There are heat cracks on the plates so I think I"ll replace them. The bike has 154K miles on it. I'm not the original owner so I don't know if it is the original clutch or not. It sure looks like it might be.

Craig

User avatar
Randolph
Posts: 74
Joined: Tue Jan 13, 2015 11:31 pm

Re: R90/6 slipping in low gear

Post by Randolph »

Craig,
INFO:
I'm getting ready to install the "short" 1st gear on the intermediate shaft and I was reading a thread on Adventure Rider with Anton .
The new gear is about 1.5mm thinner than the original and it could cause the 1st gear on the output shaft to interfere with the rear bearing on the intermediate shaft.
If you add shims to the the output shaft between gears you might run into the same type of problem.
Just sayin'....
Randy

User avatar
cbclemmens
Posts: 216
Joined: Sun Apr 25, 2021 2:21 pm
Location: Apollo, PA
Been thanked: 4 times

Re: R90/6 slipping in low gear

Post by cbclemmens »

I am finally getting back to work on this. The new gears had to come from Germany. Just when they got here my wife went into the hospital. A week later, while still in the hospital she had a heart attack and died, so I haven't had time to play with my bikes, for the last couple of months.
Randy;
I am not taking up the excess end play in the out put shaft between the gears. I am taking up the excess end play by putting an extra trust washer between 1st gear and the rear bearing.

Craig

mtblah
Posts: 13
Joined: Sun May 07, 2023 7:22 pm
Location: New Braunfels TX

Re: R90/6 slipping in low gear

Post by mtblah »

Craig , so sorry for your loss ! My condolences .

User avatar
srankin
Posts: 1054
Joined: Fri Jul 14, 2017 8:45 pm
Location: Spencerport, NY USA
Been thanked: 14 times

Re: R90/6 slipping in low gear

Post by srankin »

My thoughts and prayers are with you and your family, God help you in you loss. St.
Owner of a 84, R80RT and 78, R100RS

User avatar
cbclemmens
Posts: 216
Joined: Sun Apr 25, 2021 2:21 pm
Location: Apollo, PA
Been thanked: 4 times

Re: R90/6 slipping in low gear

Post by cbclemmens »

Thank you guys for your condolences.

I just did a final check of end play with the plasti-gage between the outside shim and the bearing. It was difficult because if I heated the case too much the plasti-gage melted. But I think I got this one right. As you can see in the photo, it shows 0.076mm of end play (Haynes says it should be between 0.05mm and 0.10mm). I think I'm ok to finish closing the case up.

Craig
IMG_4764 1.jpg

User avatar
vechorik1373
Posts: 260
Joined: Fri Oct 27, 2006 3:00 am
Been thanked: 15 times

Re: R90/6 slipping in low gear

Post by vechorik1373 »

I have seen this problem before. The greater the load the bike is forced to deal with, (like a sidecar) can cause this "slippage" you speak of. The input shaft has a spring loaded cam arrangement to lessen drive like shock when you suddenly accelerate or de accelerate. #4 and $5 in the drawing can "cam completely over" IF the spring #6 is weak or broken. The symptom you described is from the two parts camming over under load. You looked at your input shaft and did not see anything wrong, but that is what the problem is.

gearbox.jpg
Vech
Technical Adviser, Former owner, Bench Mark Works
662 312 2838 cell 9 am to 4pm CST PLEASE!

User avatar
cbclemmens
Posts: 216
Joined: Sun Apr 25, 2021 2:21 pm
Location: Apollo, PA
Been thanked: 4 times

Re: R90/6 slipping in low gear

Post by cbclemmens »

Vech;

Thank you. I really would have liked to have had your advice before I put it all back together.
(laughing as I type that.) I ordered that spring - it is only $25 - I'll get it in assuming I can get things back apart.

Thanks again.

Craig

Post Reply