Broken Transmission Dog Repair (mystery metal chunk in sump)

[kshansen]

Even if the dog was somehow able to magically perform a half-gainer with a 360 and end up getting into messing gear teeth, you STILL have the clutch pulled in. You hear or feel the transmission gernading itself, so you keep the clutch pulled in until you come to a stop. Or, you start to release the clutch and you feel or hear the transmission gernading itself, so pull the clutch back in all the way, apply the brakes, and come to a stop.
Opposing scenarios are welcome.

Well that's all well and good IF the dog doesn't get caught someplace "down stream" of the clutch but I believe you will find that the clutch is in between the crankshaft and the transmission not between the transmission and the output shaft. So if something jambs up the transmission gears holding in on the clutch will have no effect on the locked up transmission and the rear wheel connection!

As for expecting the broken part to just sit in the bottom of the transmission and play nice. I wouldn't make any bets on it. With all those gears spinning around throwing oil every which way in a vibrating engine not a chance I would be risking, especially not for someone else!

 

[jetmechmarty]

For your consideration:

This broken dog is not an uncommon issue. I'm beginning to believe some of these gear wheels were flawed from the factory. It's always the same gear that breaks. My hypothesis is that the dog in question was manufactured in the wrong position. It broke because it was carrying the entire load. That's my educated guess. I can't find a better reason as to why I've been driving a broken transmission all these years.

 

[TwoManyXS1Bs]

...you will find that the clutch is in between the crankshaft and the transmission not between the transmission and the output shaft. So if something jambs up the transmission gears holding in on the clutch will have no effect on the locked up transmission and the rear wheel connection!

Ditto...

 

[DogBunny]

Thanks for everyone's help and input.

But who knows what shape the tranny parts are in inside that donor motor? Maybe they have broken dogs too? I plan on building up a spare motor from parts bike motors but I want to take a look inside the lower end to make sure everything is OK in there. I also like that idea of stronger XS750/850 triple tranny parts. There just so happens to be a 750 triple in my dealer's boneyard, lol.

Maybe three years or so ago I parted out an XS750 triple. It had no title, and I only spent the time parting it out because I got it for almost free. When it came to the frame, I felt that there was so little interest in this model, and that frames are inherently difficult to sell and ship, that I just scrapped it. The same with the engine. It just wasn't even worth doing any diagnostics on in my opinion. Because of the aluminum content and the weight, I got a decent per pound price for it. I normally will go to considerable trouble trying to get parts into the hands of someone who can use them, but you have to draw the line somewhere.
Well, anyways, I'll probably never part out a 750 triple again, but if I do, I'll harvest the tranny before I scrap the engine. Lesson learned.

 

[DogBunny]

DB, if you want to replace the cam chain guide too, the reasonable thing to do changes. One difficult thing to keep in mind is at the rear there's a piece that's very hard to impossible to remove (my experience with it) that traps the cam chain that has to go before you separate the top end and upper case -- unless you remove the lower case and slip the chain over the end of the crank. If you just want a new transmission, remove case bottom and plop one in is definitely the way to go. Right side gasket can be reused almost forever if it's original. No need to replace seals; replace later from the outside if they leak now.

Okay, I think I'm finally convinced to replace the tranny rather than the top end.

 

[DogBunny]

Well that's all well and good IF the dog doesn't get caught someplace "down stream" of the clutch but I believe you will find that the clutch is in between the crankshaft and the transmission not between the transmission and the output shaft. So if something jambs up the transmission gears holding in on the clutch will have no effect on the locked up transmission and the rear wheel connection!

Ditto...

Yeah, I though that might be the case... Bummer.

 

[DogBunny]

Inspired by 5twins "Flip Stand" (see post #35), I made my own. At first, I was going to copy 5twins'. Then I came upon a useless old XS650 frame that I forgot that I had. "Useless" because I had cut the neck off and sold it with the title. So, I re-purposed the frame into a flip stand.

I started by welding a plate where the neck had been. If not for that, making this stand would have been crazy simple -- just weld an angle iron onto the top of the neck, and trim the bottom of the frame.

It's not as compact or elegant as 5twins', and takes a while to bolt up, but it's okay for a tool that you won't use much.

This wasn't planned, but what I like about mine is that being so long it is very easy to lift each end and raise the engine to a more comfortable height. You will appreciate the height when you are working on the 4 bolts near the dipstick, which are now on the bottom.

The one hiccup is that this bolt -- #14 in the cases assembly sequence -- is blocked by the stock engine mount bracket. It's hard to tell by the picture, but the bolt IS blocked.

So, I welded up this angle iron support to take the place of the left-side rear engine mount triangular bracket. The right-side bracket is still being used. Note that the welds on the angle iron to the frame are bridging a 1/4" gap. Weld the angle iron with an engine mocked up in place to get it right.

 

[DogBunny]

Splitting the cases. A heat gun and two heat lamps (that I use to cure painted parts that are too big for the oven). I tapped on the cases every ten minutes with a hammer and a block of wood. After 40 minutes the cases separated. Easy.

Here's the broken-off dog (red arrow), and what should be there -- green arrow. TwoMany called it correctly in post #17 -- the countershaft 5th gear. However, that picture in post #17 is confusing -- the transmission is sitting in the wrong case half. It should be sitting in the upside-down top case.

This photo courtesy of member wxjmx. It's how he split his cases -- pallet on the ground. I love this picture. I used the same set-up when I split the cases of my donor engine. But, it made me realize that I am way too OCD to split my keeper engine like this. Too much engine rolling around, and too uncomfortable of a working position. And too unstable when the time for torque-wrenching comes. BTW, I used the same heat gun and two heat lamps to split the donor engine cases, but they only took 20 minutes to let loose.

Here's my donor engine after I split the cases. I chose this engine because it had spent too much time with the cylinder and side covers removed, courtesy of a previous owner. If the cylinder is removed, a milk crate makes the perfect stand for removing the transmission, almost like it was made to order.

 

[DogBunny]

At first I was going to copy 5twins' flip stand, and I asked him for a couple of dimensions. He graciously provided the following info and permission to share it:

OK, I'll start out by listing the materials I used - 1" square tubing and 1" dia. pipe, along with various bits of angle and plate. The overall length of the stand is about 18" but the actual length of square tubing used on the base is 16". The distance between the uprights C to C (your dim. A) is 14 1/4" but I think the more important measurement you'll want/need is the distance between the mounting holes on the uprights, front to back. That's 11 7/8". I used 9/16" holes to give myself some play but anything 7/16" or larger will work, anything that would accept a 10mm bolt.

The height of the uprights, from the ground to the center of the mounting holes, is 15 1/8" for the rear, 16 1/8" for the front. The length of the actual upright parts will be 1" less because they're sitting on top of 1" pipe and square tube.

When I built mine, I welded up the bottom "T" base and front upright mount, then attached that to an engine to determine exactly where the rear upright needed to be welded on. The exact location is going to depend on where you placed the mounting holes in the front bracket.

 

[Jim]

My "upside down" splitter/buildup stand is a 4X6 about a foot long with 4 holes for the top end studs. It's actually pretty stable for buildup torquing...