Doug Wilford, can you help me?

[Jerry Chafton]

Hi Doug,
I am needing help adjusting the shift on a 6 speed 100B engine. To make a long story short this bike shifted better than any Sachs I have ridden after rebuilding the engine last year. It was as near perfect as these engines get. The last time I rode it I could hardly get it into second gear and when it did it jumped out. The more I rode, trying to figure it out, the worse it got. Jumping out of all upper gears.
I found nothing loose or broken regarding the shift mechanism.
I tried adjusting and can't get it back where it was.
Can you help? I really need to call you and go over the process. Please contact me at [email protected].
Thanks,
Jerry

[Ron]

Hi Jerry,
Hopefully Doug will give you some real expert advise, but it seems to me its under shifting.
Loosen the travel stops and swing them away.
Then check to make sure when your shifting into 6th gear with the shifter held "up", your not holding pressure against the fork in the selector shaft.
The selector shaft must be completely in 6th gear and the selector fork should have a bit of wiggle room.
Do the same in 1st gear with the lever "down".
Assuming everything is shimmed correctly internally, the only external adjustment you have is the eccentric screw in the selector shaft, which simply moves the selector fork in and out.
Once you find a balance between 1st (shift pedal held down) and 6th (shift pedal held up) you can re-set the travel stops.
That's how I do it. Hope it helps.
Ron

[Jerry Chafton]

Hey Ron,
Thanks a bunch for the reply. I have been everywhere with the selector adjustment with no results. I will try the 6th gear method today. As posted eariler the Sachs shifted perfectly (as perfect as a Sachs can get)and for no reason it went south.
I don't feel it is a shimming problem because it was so good until now. I do have a lot of play up and down in the selector lever but see no shim notes regarding this. The screw pin that holds the lever in place is tight and shows no wear, (the screw coming thru the case at the rear).
I have not yet dismantled the selector lever to check for wear in the cam bolt. I'll try your method first and get back to you.
Again,
Thanks a bunch and hope it works...

[brian kirby]

Jerry, did you put a new selector key in it? If so, was it a repop or one of JP Morgens keys? If it was one of the repop keys, they are (or at least a batch of them were) garbage and it is probably worn causing the jumping out of gear. Ernie had 3 or 4 BREAK all with less than 5 hours time on them a few seasons ago destroying the transmissions. If it is one of those repop keys you should consider yourself lucky it wore out and didnt break. Ernie has 2+ years on his JP Morgen keys with zero issues.

Brian

[Jerry Chafton]

Hi Brian,
Thanks for the input. I used all the original parts except the clutch pressure plate(which was missing) and some shims. All components were in great shape as this unit had been in storage since 1983.
What part are you calling the key? What other parts might be worn and cause this. I just tried the 6th gear adjustment method that Ron had recommended.
I removed the cover(for the 22nd time, ha ha) removed the clutch pak to access the stops and loosened both. I had good slack while holding down on the shifter in first gear but in 6th gear it was binding so I adjusted until I got slack in the fork and rechecked 1st and still had slack there. I put everything back together and now it will not go into 1st at all. It sounded like it was going into second but jumped out as soon as I released the clutch. Basically, no gears.
Thanks again and keep the ideas coming..
Jerry

[Larry Perkins]

I bet you need a selector key.

Larry P

[brian kirby]

Yup, I think you need a new selector key, its the part that threads on the shaft and moves to transmit drive to the gear. My bike is similar to yours but not as bad. When I got it, it shifted better than any other Sachs I had ridden, but over the course of 18 months of racing it started getting harder and harder to make clean shifts. It never popped out of gear, but was noticeably more reluctant to make a clean shift. The key will get worn where in engages the gear and get kind of pointed instead of kind of flat which will cause it to pop out. You can replace it without splitting the cases, Ernie has a writeup on how to do it, but most people split the cases.

Brian

[Jerry Chafton]

Hey guys,
You are probably right, I took the entire shift assembly out tonight and inspected each piece. Not much wear anywhere and like I said earlier I have been at about every adjustment angle possible with no results. Could the key shear off or break all at once? Because that is the way it happened, maybe a little mis-shift a day or two prior but I blamed that on my grandson not shifting properly. He kept telling me it was not shifting the same but this all happened within 2 or 3 miles of riding at the most.
Brian, I don't see how that key could be changed without splitting the cases but I would certainly like to have Ernie's approach. Can you connect for me? And where do I get the good J P Morgen key?

[brian kirby]

Jerry,

The selector keys can break all at once, but it usually locks up the transmission and breaks gears when it does. Here is a link to Ernies step-by-step how-too with picture links.

http://www.pentonusa.org/forum/topic.asp?TOPIC_ID=8981

Not sure how to get ahold of JP, but I know Ernie has ordered stuff from him, others may also know how to get in touch with him.

Brian

[Larry Perkins]

Search here in the For Sale section under JP's name and it will bring up a bike he was selling with a phone number.  If you don't find it that way let me know and I will dig it up.

Larry P

[Jerry Chafton]

Well, that process is certainly interesting. I haven't decided yet which way to go. I am leaning towards splitting the cases just to determine if there is any damage to the gears. I have the bike sold but will not sell  it until I am sure there is no damage and all is good. I didn't have any luck finding JP thru the search feature. The pictures are certainly helpful, thanks Brian and  Ernie. I wish I understood the mechanism a little better but I did not disassemble this when I built the motor. Shame on me.
All help is greatly appreciated.
Thanks,
Jerry

[Larry Perkins]

I spelled JP's name wrong.  It is spelled with an e-JP Morgen.  (415)822-1315 should get him.  I would split them and take a peek at everything if it was me and there wasn't a race looming soon.

Larry P

[Ernie Phillips]

[email protected]

I doubt that the selector key is the problem.  However, if you are going to replace it, go with the JP Morgen product.

The whole shifting thing is weird on Sachs; you move foot up and down which rotates selector shaft assembly which in turn activates the selector boss which has a slot in it that acts like an inclined plane which is hooked to the selector rod via an adjustable, multi-piece shifting lever.  The selector rod pulls or pushes on the selector key through a horse-shoe shaped device called a shift fork (not to be confused with a shift fork from a drum type shift device).  As the selector rod moves back and forth as directed by your foot movement, the selector key aligns up with slots in the main shaft and corresponding gear.  When everything is good, the selected gear is "locked" to the main shaft via the key ... and away you go.  Easy as pie!

Based on your description of having a great shifting engine and in a day's ride it got worse and worse ... the selector key should degrade that rapidly.  If it were my engine, I would not split the cases until a determination has been made that the shift gizmo is adjusted and functioning properly.  Move the eccentric stops out of the way.  Adjust shifter.  Make small changes.  Even with an extremely worn key, it should shift positively.  Shift slow and deliberate.  If you get it working in all gears, both up and down and then try to shift at "race speed" and it doesn't perform, then look at replacing the selector key.   It can be done without splitting the cases.

Oh, don't forget that you should use the tool that holds down the selector boss.  It should be shimmed to limit axial movement.  If the selector boss is free to move up and down on the selector shaft ... well, you are just wasting your time.  I know.

Also, check the play (radial and axial) of the lay and main shafts.  If they are loosey-goosey then you got other problems as well.  The slot in the selector boss and fit of the shift lever, adjustable eccentric is important too.  When these contraptions were brand new, shifting was marginal.  After 35 years .... it can be a challenge..  


Ernie P.
Chattanooga, TN

[joe novak]

My Uncle Ollie used to say, "We can all sit around and talk about what might be wrong with it, or we can take it apart and find out for sure."  And yes, he showed me how to install the selector key without splitting cases...  Let us know what you find when you open the cases.  Even if the transmission is not adjusted correctly, or if the selector key is worn, it should not jump out of gear, not go into gear, or miss-shift he way you have described.  Several highly knowledgeable people have offered excellent advice on your specific transmission problem.   The photos by Ernie demonstrating the installation of a selector key without splitting cases are very well done.   Joe

[Jerry Chafton]

Boy, you guys are a wealth of information. Sounds like you have all been there, done that. I think these tranny shifting problems is why I always raced the KTM versions back in the day. I remember well the problems my buddies had with the Sachs trannys.
During my many attempts to adjust this out I did get the shift fairly good at one time. It would go into gear if I rode slowly and did not accelerate hard once in gear. It would get all gears. The more I adjusted the worse it got. I made adjustments at the rate of about .005 movement at a time and measured each time. When I went back to that point of best shift it continually jumped in and out of gear, even in the higher gears. What I did not do during this operation was leave the stops backed off. Could I have been defeating my adjustment by retightening the stops each time?
I have taken a break from this frustration for a while but will continue in a few days.
Thanks for all the input, I will certainly let you all know the outcome.
Jerry