G model Secondary Gears -- anyone?

[dpep]

Has anyone ever worked on the secondary gear mechanism for one of the G models?

Last fall I was riding one of my 850s when the rear wheel just suddenly locked up. Black strip on the pavement, brown strip on the shorts but I was able to luck out and keep it vertical.

I got it home to a corner of the garage and have just now gotten around to trying to fix it. I was able to shift through the gears at the time it happened; just no go when I let out on the clutch. So problem not in transmission. I can turn the rear wheel a wiggle bit back and forth and the shaft going into the enigine wiggles; problem not in hub or shaft. That leaves the secondary gear which makes sense. This engine I just swapped from a wrecked parts bike. It had a frontal collision with a car. The front end was of course toast and I wasn't going to chance any frame parts. But the engine was not involved in the impact and I assumed it would be o.k. It was low mileage compared to the 130,000 on the engine it replaced.

I can't know but I suspect that a sudden stoppage of the rear wheel in the accident caused secondary gear damage. It is something that would not be a consideration with a chain driven bike.

There is a plate on the side of the transmission case by the secondary gear location. I removed the bolts but the plate no move. I could get it to twist a couple of degrees but that's all. Time to check the books. I did not like what I read.

It appears that to access the assembly I will at least have to loosen the case bolts which has me wondering about possible leaks along the seams later. And the instructions for doing the work involve some specialized tools I do not have. And every book starts the secondary gear section with the warning that this work should only be done by an authorized service facility....essentially that it is both critical and tricky.

I am now wondering if it is even practical to salvage what otherwise seems to be a good engine, What if the amount of work and/or risk and/or expense involved added up to more than I could buy a decent running 850 for? Can I trust anyone, myself or "authorized" mechanic, to fix this problem in way to be sure it won't happen again and at a cost that makes sense?

Whatever feedback I get from this forum is my answer. If no one here has repaired a secondary drive, there is no way I go any further. I'm not much of a wrench to begin with.

[waterman]

Don,
I have worked on a secondary on a G model. Unfortunately for you it was a 650g. In my situation, I had a bevel gear twist on the shaft. I am pretty sure that this was a latent Previous Owner problem manifesting itself since I had purchased that bike the previous fall. Another squid trying to emulate stunters I am afraid. Here is a pic of my bevel gear.

http://s200.photobucket.com/albums/aa36/eboyer/?action=view&current=PICT9161.jpg

Anyway, back to your questions. After a quick glance at the microfiche for a 81 850g it appears that your secondary may be easy to get at and replace; the 650 needs the cases split. It looks like the four bolts on the side may come out and then the drive bevel gear with shaft can be removed out the side of case, at least in theory. Appears as if there is a metal shim gasket and then an oring inside to seal.

As for the real questions of should you do this (or have someone else), I would have my doubts. It obviously can be fixed, but you will likely need to find a donor set of bevel gears (replace as a pair is best). Next you run into the fun of measuring gear lash and finding the correct sized shims to set lash, etc. Finally, if the cases needed split, the fun of reassembly.

I would also be hesitant about this particular motor, even fixed you may consciously think about is it going to lock up again. I know I am a little leary about the one I put back together.

This leads to the next alternative, a different engine. They did make a ton of 850s, someone here probably has a decent one rotting in their garage sitting on the shelf. I passed up on an 850L for 200 in Feb 2008 since I already have a full garage, amongst other things.

[Zooks]

Pull the rear wheel, swing arm and rear shaft and you can get the bevel gears out without splitting the cases. It takes a bit of wiggling to get the gears out past the frame but it can be done without splitting the cases. With the rear out (and the side cover removed) you should be able to see what the damage is using a torch (flashlight). If it's badly damaged inside, you can decide from there what to do next.

I suspect you have a piece of metal in there 'locking' up the gears. You should be able to clean it all out and just replace the bits you need. The gears have an O-ring to stop oil from leaking out, make sure you replace this.

You will need to adjust 'backlash' when you re-assemble or it will whine on deceleration, very loudly (ask me how I know). This can be done by following the manual step-by-step.

I would basically only split the cases if you absolutely have to.
Good luck. We are here to help.

[SqDancerLynn1]

You can get the secondary gears out without removing the engine, Remove the swing arm, gear shift lever & cover. IT will take a lot of persuasion to get them out. It's a semi press fit. If they are bad? You need to replace them with GS850 parts GS1000 is different & will not fit

[TheCafeKid]

Don, I have NOT done this myself, but have suffered thru the listening of secondary whine long enough to make me want to do it. If you DO go thru with it, a pictorial would be SWELL for us shaftie owners. I have the basic idea of how to go about it, but simply havent gone thru with it. The GK i just picked up from Grandpa has a good deal of the "lash whine" as did my 1100G, and it drives me absolutely nuts. But mine comes on acceleration and constant throttle. So I dunno if pulling them apart will solve this, or if its simply the mileage.

At any rate, I know you are versed in the ways of the GS Jedi, but did you check the secondary drive oil level? When Steve and I rebuilt his sons 850G, somehow we either didnt put enough in, or it leaked out from somewhere or something, but Steve had the rear lock up on him much the same way (Only, right in front of a COP! Luck lucky...hehe) At his place, while he was working on a set of carbs, I pulled the rear wheel and what not apart looking for any damage. I found none, so he suggested putting it back together and running the bike in gear on the centre stand to see what happened. I did so, and sure fire, it locked up after a bit of running in fifth gear. This time, i could hear the racket from the secondary drive getting louder, right before it froze. I pulled the filler cap on the secondary box and looked in it with a "torch" heheh, and found it was dry as a bone. I filled it with the required amount of hypoid gear oil, fired it up again and ran it in gear on the stand. Never happened again. Steve has since ridden it, and its never given him problem. I do believe there is a weep hole on that bike somewhere for gear oil to get out if its overfull or something like that? Or a breather hole? Maybe when you laid her down, it leaked enough out to cause your problem. Just something to check before you go pulling her apart all the way...

[Nessism]

Won't hurt to pull them out and have a look. I've seen sets for sale on ebay so that's one option.

[SqDancerLynn1]

Use the gears from the old motor ! If you can't find a set of gears local I think i have a set. Don't worry about adjustment. Get the shims from the replacement set, KEEP them seperate & use them as is.

[Zooks]

I pulled the filler cap on the secondary box and looked in it with a "torch" heheh, and found it was dry as a bone. I filled it with the required amount of hypoid gear oil, fired it up again and ran it in gear on the stand.

Watch it!!! Smart arse (ass).

Why call it a 'flash' light when it doesn't flash?????

You 'mericans sure do talk funny.

[TheCafeKid]

Watch it!!! Smart arse (ass).

Why call it a 'flash' light when it doesn't flash?????

You 'mericans sure do talk funny.

Not as funny as my grandparents on me dads side. They came off the boat from Ireland over here. They used to speak Gaelic when they didnt want anyone to know what they were saying. Tough language, but it sure sounds nice

[rustybronco]

Why call it a 'flash' light when it doesn't flash?????

You 'mericans sure do talk funny.

Because at one time they had a button on them that you could make the "torch" flash. it was used to signal via morse code.

come to think of it can you cut or weld with yours?

[argonsagas]

Watch it!!! Smart arse (ass).

Why call it a 'flash' light when it doesn't flash?????

You 'mericans sure do talk funny.

Yep, they DO talk funny, but some 'mericans just love to flash, such as this one at the Mardi Gras:

http://www.salomonarts.com/images/lod/thumbnails/mg.flasher.jpg

[dpep]

Thanks to all for the replies. It sounds like it is something doable, but I will only attempt it as a long range project over the winter. I guess the worst case is I just end up with a parts bike. I am curious to see what is in there that caused me all the grief.

[jonr]

Don,

I have done this same procedure before, and I did not have to split the cases. However, I only replaced the output shaft that turns the drive shaft. I did have to loosen a few bolts in that area of the case, but this relieved enough clamping pressure for me to get the unit out.

I did not try removing the assembly with the engine in place for I feared it could not be done. I removed everything like the rear wheel, swing arm, etc., but then I removed the motor mounts and use ratcheting straps (suspended from the ceiling joists) to lift the engine a few inches. Then I turned it clockwise (looking from the top down) about 5-10 degrees so that the output shaft assembly was facing me and clear of the frame. I had to rig up a pseudo-slide hammer to withdraw the assembly, but it worked like a peach.

One out, you can take the entire assembly apart sans pulling the bevel gear off the shaft. If that is shot, find a used assembly and re-shim for backlash as stated in previous posts.

I think I have my pictures/post of this somewhere. Looking, looking....
Found it: "Stuck" removing secondary drive unit - 1100G

Ignore the second image of the old assembly destroyed. I did all that before I figured out the slide-hammer thingy. That's evidence that prying it out was a bad idea. Had I followed the good advice before I went medieval on it, it would have been relatively unscathed.

I'm quite positive you can do this with little fanfare. However, the surprise you find when you pop it out may end your quest abruptly. If the mating bevel gear is chipped, then you'll be splitting the cases or parting it out.

Jon

[rustybronco]

Has anyone ever worked on the secondary gear mechanism for one of the G models?

I am now wondering if it is even practical to salvage what otherwise seems to be a good engine, What if the amount of work and/or risk and/or expense involved added up to more than I could buy a decent running 850 for? Can I trust anyone, myself or "authorized" mechanic, to fix this problem in way to be sure it won't happen again and at a cost that makes sense?

Whatever feedback I get from this forum is my answer. If no one here has repaired a secondary drive, there is no way I go any further. I'm not much of a wrench to begin with.

No I have not replaced ether the drive gear (side of the case) or the driven (rear of the case, drive shaft attaches to it) but I have built up a lot of rear axles in cars.
there is a specified pre-load that is measured by rotating the pinion with an inch-pound torque wrench on both assemblies, the pre-load should stay about the same if you are re-using the shims that came with the assemblies, if you are just replacing the bearings and races.
getting the bearings off the gears may be a problem, unless you have a tool to put under the bearing and a press to remove the bearings and replace them.
you will also have to make/get a driver to remove/install the bearing races.

have you considered getting a good used set of gears assemblies (drive and driven) from another 850? by doing that you would have only to figure out the proper shim depth for each (drive and driven) and save the headaches of the rebuild process.

[Zooks]

Because at one time they had a button on them that you could make the "torch" flash. it was used to signal via morse code.

Ah, thanks, that's interesting. I always wondered about that.

come to think of it can you cut or weld with yours?

A torch is technically a 'source of light'.