73 GP338 track driver swap question

Whereswade

Whereswade

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Aug 25, 2014
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Location
Hammond, WI
Swapping out a "new", as in different, not completely cratered, driver on my 73 GP338. Do I have to take all the bogies off, or can I get away with the one closest to the front? Never done anything like this, soaybe that would be a good question, as well. What is the best way to do this?
 
A few answers ,,, 1st thing , you need to remove front axle ,,, good news , you don't have to touch chain case...
Lock on the brake ,, remove speedo drive , then large nut from RH end of axle ....
release brake ,,, loosen off the track tension completely ... and it will be loose enough to
tuck up into the front cavity of tunnel and leave just enough room to slide out and in the axle with sprocket on...
I read it in tech book and have done it with my TW433... removing front set of bogies will add a bit of room...
To remove axle ... remove three bolts holding the RH end (nut already gone) and pull off the housing,, normally
pulls off easy because of all the nasty black grease from factory..
GRAB the axle and yank it out of the chain case ... it fits into a splined coupler that should be sealed from the chain case oil...maybe a drop..
Sometimes need to persuade with a short punch (2x4) and hammer from opposite side...
http://www.boats.net/parts/search/Yamaha/Snowmobile/1973/GP338/TRACK DRIVE/parts.html
item #3 is the coupler.... nice design...
It is always a challenge to tuck the track up out of the way even when rear axle was removed... patience
It takes a BIG socket to remove the RH axle nut.. but not much torque ,,, It the greasy one in my rack... about 1 3/8" I think
Borrow one rather than buy one as you may never need it again ..
Reverse these steps and realign the track .. maybe measure bolts before removing them...
Books always show this job with sled on its LH side but normally hang the back up.
Found that working on a bench and then raising back is easier on my back especially while stuffing the axle
back in ... bit of oil on splines for next guy in 30 years..
Good luck .. hope I didn't leave any step out ...
.
If for any reason you wanted to remove chaincase ??? do it with axle out
Ron
 
Replied on vsca as well ... and indy bosch says about 1 hour .. i'm old and slower and book says 29mm wrench
which i think i used a 1 1/4 six point socket.. shows an offset wrench in tech book .. might even be in tool kit ??
If you clean the brg support , remember which 2 holes fit the speedo drive for correct angle.
Ron
Your 74 sl will be same .. newer sleds were wider and enough room to take cover off chain case but the plug in spline
was a great idea ,,, left the rest "shakin in their boots"
Saw you list ,,, we were ahead of our time letting a CAT in with the yamahas...
 
Well, the cat started it, at least. In fact, when I grew up, a friend had a Jag, but I was always enamored of the Yamahas, especially the VMax 540.

Again, I can't thank you guys enough! These sites just rock.
 
Ok, got the jackshaft out. NOW, I can't seem to be able to remove the "pins" on each side of the idler wheel. Hints? Can those be replaced with cotter pins?
 
Sorry , hadn't checked here in a while .... if you hadn't solved this problem ,,, need to hold axle firmly over a heavy anvil type object,,
find or make a blunt punch ,, a few good strikes , square on and with out fear of hitting your self with a 16 oz hammer....
Other than that ,, grind off outer pin , remove idler , grind off inner pin ,,, find a proper size flat punch (8mm??) and drive what is left
out of the axle .. a bit of lube the day before might help as well..
...
A well anchored vise will work as an anvil leaving just enough gap to let pin out bottom... don't bother just squeezing between jaws.
Ron
 
Actually, this is the 74 SL, the GP is running and the kids have had her out on the yard for the first snow. It's gone now (the snow) but it's running nice! I just ordered an aluminum track driver from Leon Koch at Vintage Yamaha. While I'm under the hood, I've taken out the exhaust and sanded the rust off, hit it with some muffler weld for the pinholes and cracks, and shot it with VHT primer and White VHT manifold paint.
image.jpgimage.jpgimage.jpg

I just picked up a trailer, so I'll likely take it to a car wash and spray it down, get all the crude out of it. The seat has some cracks that have been sewn loosely, they aren't what I'd call waterproof. I've got a vinyl repair kit that I'll try on some of them. I'm Just giving it some TLC before I get the driver back in.
 
Actually, this is the 74 SL, the GP is running and the kids have had her out on the yard for the first snow. It's gone now (the snow) but it's running nice! I just ordered an aluminum track driver from Leon Koch at Vintage Yamaha. While I'm under the hood, I've taken out the exhaust and sanded the rust off, hit it with some muffler weld for the pinholes and cracks, and shot it with VHT primer and White VHT manifold paint.

image.jpg

I just picked up a trailer, so I'll likely take it to a car wash and spray it down, get all the crude out of it. The seat has some cracks that have been sewn loosely, they aren't what I'd call waterproof. I've got a vinyl repair kit that I'll try on some of them. I'm Just giving it some TLC before I get the driver back in.
 
Some day I need to find a 74 SL and covert it to fluid drive . the early sales brochures show a rear fuel tank , bogie version ,,, as well as the parts catalogs
BUT I have never confirmed any one having one ... As if they intended to and then used the GP chassis with mid fuel tank and sliders instead...
The bolt pattern is likely the same for chain case and need to use a TL engine because of crankshaft end for the cog drive...
Hard to find a sound chassis due to salt damage etc...
Ron
ps I presume that paint takes heat ?
 
Seems to. It's the VHT ceramic coating. I hit them with a few coats of blue after I took those pics. I've had it running a few times, but it runs the fuel
Out of the line between the squeeze bulb and the carb, then dies, so I ahvent gotten it up to temp yet.
 
Newer in line primer bulbs need to relaxed with no side force against them ... pry's the fitting loose..
Is that the problem you are describing ???
Also Yamaha uses a slightly bigger line and 1/4 needs to be new to expand over it .. maybe a split end
Ron
 
I think that IS the problem. I'ce picked up some new 1/4 clear and black So I'll replace that when I get out there again. Being as its -11 without windchill, and my garage isn't completely insulated (have to finish the ceiling!!) it gets cold right away when the torpedo shuts off.
 
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