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Bronchole
07-06-2005, 03:54 PM
350X cracked case repair?

New to the board here, but not new to 3 wheelers.

I have a 85 350X that had the frame cracked. I figured this out while tracing down the cause of the puddle of oil under the trike during storage. Cracked thru the vertical frame tube over the foot peg, broke both upper motor mounts (over the head) and there were a few other cracks in the frame elsewhere.

The problem is that when the frame is cracked thru the motor becomes a structural member, aluminum doesn’t like this type of load!

The left/center case (the one with the drain plug in it) is cracked around the motor mount bolt. The crack is very small and is not thru to the edges. It is in the middle of the casting. I only noticed it because I can flex the frame of the trike and see the oil bulge from the crack.

From what I have read at here on a few threads I found when SEARCHING it sounds like I can VERY easily have this case repaired by a competent weld shop. I have already disassembled the case out of the motor and I am looking for any information necessary to have this repair done.

My questions are:

Do I have to remove the couple bearings and the cylinder studs for the weld shop to perform the repair?

What is the best way to clean the oil from the crack and the rest of this case prior to welding? I have come to understand that the cleanliness of the aluminum is key in the success of welding aluminum. I do have access to an ultrasonic cleaner with alcohol in it. The tank is large enough to submerse half of this case at a time.

What is the best way to see the extent of the crack? If it was steel I could do a magnaflux, but I don’t think that’l work on aluminum.

If the crack is indeed not going out to the edge (both ends of the crack end prior to breaking out to the edge of the case) should I drill a small hole at each end of the crack to keep it from progressing prior to having it welded up?

Thanks for any help you can offer.

Dan

sblt500r
07-06-2005, 09:32 PM
the studs can stay but the bearings might be no good after the case is welded. depends on how big the crack is and how hot the case gets. plus after the welding and grinding the bearings might get aluminum in them. easier to change them now then after the engine is all together. when i weld cases i always change the bearings anyway, in both halfs. its 20 years old. its cheap insurance.

grind a V where the crack is and then clean it. grind it as deep as you can see the crack. wire wheel the crap out of it. and then use your ultrasonic cleaning tank.

i don't think you would have to drill the holes. i've never had a crack grow when it was being welded.

and the less work your welder has to do the cheaper it will be for you.

hope this helps ya.

Bronchole
07-07-2005, 12:34 AM
Thanks, I appreciate the tech help. I'm from the 4WD Bronco world so mostly I'm used to things being made of STEEL!