Dremel fix...What to look for

[crazy steve]

Ok, I'm finally getting ready to start putting the SG together, and first on the agenda is to make reasonably sure the motor I'm using is in good shape. I've already run a compression test, going to check the valves, and I want to flip the motor and look at the gears while the motor is still out of the frame.

Not having experienced any gearbox problems yet (knock wood ), how bad will these get before jumping shows up? I don't want to grind prefectly good gears if I don't have to...

[trdriver71]

I don't know but rasputin and I are both interested because we have to do this to our bikes, we were just talking about it last night on exactly what to do.

[motoman]

A bit hard to tell just "looking" Steve. Not that you aren't able to see the dogs on the gear sides, but deciding if wear on end of dogs warrants re-grinding. From my experience with this, if you see any shiny edges on dogs and edges are NOT square edged, myself would pull that lower shaft and square up the dogs with a slight angle so as to dovetail them a bit. Re-peat a same slight matching angle on the slots. Work on both the slots and dogs are done on the load side, so just pay attention to orentation and direction of load side. Way easier to do now than after motor is in.

[crazy steve]

How to do it is shown here: http://www.xs11.com/forum/showthread...4198#post34198

But I haven't actually ran the motor I'm going to use, as the bike was semi-disassembled and incomplete when I got. I've looked at the ones in the above post which was popping out of gear, but wonder just how bad that 'rounding off' can be before you need to worry...

[trdriver71]

rasputin and i were wondering on the slots of the other gear and what angle they would have to be.

[benxs1100]

If it were mine I would just grind them now while you have the motor out rather than wait for it to start popping out. This is way to common of a problem. As far as the difficulty the write-up is in great detail and very easy to follow. The angle of the cuts does not have to be extreme. Just slightly so that they grab each other better. More important than the angle is to just make sure everything is meshing properly when your done. (IE. Make sure all 3 posts are contacting.) It is a much easier task than it looks like.

[FJ111200]

But I haven't actually ran the motor I'm going to use, as the bike was semi-disassembled and incomplete when I got. I've looked at the ones in the above post which was popping out of gear, but wonder just how bad that 'rounding off' can be before you need to worry...

Just do the washer swap.

[jwhughes3]

FJ111200 - is that the one Bob Jones describes

in his book where he thinks they assembled it wrong?

Do you have any pics of what it is supposed to look like?


John

[FJ111200]

Don't know about Bob Jones, but it's well documented on this forum somewhere. Do a search. I've repaired 2 gearboxes by doing the washer swap by the gear cogs and replacing the "star" washer and the roller bearing on the end of the selector drum. Worked for me, no problems since.

[crazy steve]

A bit hard to tell just "looking" Steve. Not that you aren't able to see the dogs on the gear sides, but deciding if wear on end of dogs warrants re-grinding. From my experience with this, if you see any shiny edges on dogs and edges are NOT square edged, myself would pull that lower shaft and square up the dogs with a slight angle so as to dovetail them a bit. Re-peat a same slight matching angle on the slots. Work on both the slots and dogs are done on the load side, so just pay attention to orentation and direction of load side. Way easier to do now than after motor is in.

So if I'm hearing you right, if those edges are rounded even a little this should be done. That's what I wanted to know. I don't really want to grind anything that doesn't need it, but I also don't want any future trouble either; I'm planning on selling this one, and want to be able to tell the new owner the trans is good and not be ignorant or lying. For what it's worth, the selected motor looks pretty good inside (right now, the cams are out for valve adjustment, and only 5 of 8 are just barely too tight) with minimal wear on the chain guides, etc. Not everybody has transmission trouble (I never have on my bought-new '78), so I may have a good one. I'm convinced that most tranny problems are due to sloppy shifting habits and/or abuse...

After I get the top end buttoned up, I'll flip the motor and see what I have.

[DGXSER]

Steve, I have done this fix on several engines now.

First one I did was Thunderstruck and the gears were just barely showing the slip under heavy throttle in upper RPMs. When I looked at the gears, I could have never guessed they looked worn enough to cause a problem.

Here is the 5th gear dogs as they came out of the engine. Little fuzzy but you can see the level of wear and rounding.




And the 2nd gear slots before grinding. You can see on the face of the gear where they have been rubbing across, perhaps from skipping. And in the lower part is 1st gear which also shows some wear across the face, but never skipped on me.



I went ahead and ground all four gears. I also did the dremel fix on Banshee before I ever ran the bike. Even after I thought I had them ground effectively, first would skip when I hit the power badn at 3k, just one skip or so, not alot. I pulled it back out and reground to make sure there was no rounded edges and it now has no skip no matter how hard I hammer it.

In short, if it were me, with the advantage of having the engine on a bench in front of you like that. I'd certainly do the fix now, under those conditions I might even go ahead and split the cases to make the process simpler.

[bikerphil]

I don't want to grind prefectly good gears if I don't have to...

I also don't want any future trouble either; I'm planning on selling this one, and want to be able to tell the new owner the trans is good and not be ignorant or lying.

Steve, JMHO, I'd inspect the trans. and touch up the slightly rounded gears. If they are not badly worn it shouldn't take long. I'd also do the washer swap. Then you can stand behind your work for the next owner, otherwise anything could happen.

[jetmechmarty]

This thread needs a contrarian. I'll do it.

When I pulled mine, they didn't look bad to me. I replaced the four gears and did the washer move. I don't trust the "dremel fix". I say do the washer move, give it a good test ride and sell it with confidence.

For those of you happy with the "demel fix", great. I'm not knocking it, I just don' want it on my bike.

Marty (on Maui or in Maui?)

[crazy steve]

Can't always have bad luck..

Well, life is good. I got the valve shimming done (just pulled the cams.. seems to be the easiest way) so I rolled the motor over and pulled the pan.

Woo Hoo! The shift dogs look perfect! Nice sharp edges on both the dogs and slots, and no sign of any wear marks between the slots. I was told this motor was 'good', but you never know....

Clean the pan up and reinstall, and it's time to start detailing motor for install..

[DGXSER]

It pays to be lucky every now and then. Glad you got to avoid that little treasure of work.