A re-seal gone bad

Rayzors79TF · Post by **Rayzors79TF** » Sat Dec 20, 2008 12:34 am

Ok I dove in head first to replace the blown crank seals on my 79 440 TF. All was going well with the tear down what a surprise. Anyways upon inspecting the crankshaft, I noticed that one rod has alot more side clearence. If I understand the service manual the rod side clearence is .027 max. Well one of mine is almost triple that. I dont know what happened but I dont think thats going to work. :sad:
I have read that a crank can be rebuilt for around 175.00$ which seems fair but way out of my budget. Is it possible to use another good used crank from another motor? If so what other 440 cranks will work (sportfire-Mopar) etc. Also where should I begin the search and what would be a fair price. Thanks for any help. I dont want to scrap my sled.

Post by **Matt** » Sat Dec 20, 2008 1:09 am

You can look for a used crank, but finding one that is 100% good might be tricky. You'll need to get a Trailfire crank - Sportfire is different. Of course, the best option is to spend the money to have it rebuilt.

400brian · Post by **400brian** » Sat Dec 20, 2008 4:10 pm

Send it to Jerome, then you know what you have.

Rayzors79TF · Post by **Rayzors79TF** » Sat Dec 20, 2008 5:28 pm

I tried calling this morning but no answer. I dont understand how this rod ended up with so much side clearence. I do not see any strange wear marks in the case and the pistons show almost zero wear. The bearings seem ok with the exception of one outter oring is wasted. What else should I be looking for.

mwking · Post by **mwking** » Sat Dec 20, 2008 11:47 pm

If you look back about three months in this forum you will see that I had exactly the same story to tell about the crank in my '82 440 Trailfire. When I tore the motor down it was ok, when I checked it before reassembly the pto rod bearing clearance was twice what it should be. The crank wouldn't even fit back in the case. The Trailfire cranks are a weak spot of the motor. What used to happen, back when these sleds were new, was someone would go blasting through some drifts and catch some air with the sled only to land with the throttle open and track spinning on a hard packed trail. The sudden deceleration to the drivetrain would twist the crank. Toymech had a similar thing happen to his '81 440, he was towing another sled when the rope caught and brought him to a sudden halt. The pto end of the crank that started coming apart on me was worn and I ended up getting another parts motor to get a rebuildable crank. I ended up spending more than I planned on the motor for sure, but I know what I've got and it will be reliable.

Murray

Rayzors79TF · Post by **Rayzors79TF** » Sun Dec 21, 2008 3:13 am

That makes sense. So its a fair bet that if I cant find a used good crank this one will not be able to be rebuilt, and I am s.o.l. Or can they be re-pressed to take up the clearences. I can see on the counter weight that it has backed off the rod pin by about .030 or so. I cannot spot any other damage. Do you think it did anything to the cases.

400brian · Post by **400brian** » Sun Dec 21, 2008 3:51 am

You need to talk to Jerome, but I believe the thrust washers can be replaced no problem.
If nothing else is bad, I'll bet he can fix you up.

Rayzors79TF · Post by **Rayzors79TF** » Wed Dec 24, 2008 4:34 pm

I am a hack I admit it. Anyways, I ended up taking the crank to my work and used the press to run the counter weight back down to get the rod side clearences. I resealed the bottom end and checked the run out and it was still well in spec. put it all back together and it seems to run as good as new. gonna go ride it later and see what happens. In the mean while just going to keep my feelers out for a replacment motor. anyone care to take bets.....

Post by **ICCSF 108** » Wed Dec 24, 2008 5:38 pm

Once you had it apart & pressed back together straight??? I would have welded the throws.. I'm glad you got it yourself as long as the crank is straight & the throws are where there suppose to be ( 1 @ BDC & the other @ TDC ) sometimes the money you saved will cost more in the long run if it's not put together correctly..
Just my $.0735 worth

Kenny

Rayzors79TF · Post by **Rayzors79TF** » Thu Dec 25, 2008 3:05 am

I agree it was not the best fix in the book, and if I had another option within my budget I would have taken it. I thought about welding it but if it didnt work down the road at least I would still have a buildable crank once I free up the cash. for that matter I am only out a seal kit for trying. I did ride the sled though for a few hours and it ran great with no strange knocks or vibes. I might have got lucky on this one.