Overdrive breakage

On Sunday afternoon, I was on my way home in the '53 towing my '22 Jaeger 3HP hit and miss engine. Everything was going fine until I went to shift into overdrive. The lever went into the "overdrive" position, but the overdrive wasn't engaged. I was still in direct drive. Weird. So I tried moving the shifter back into the direct drive position. No go. I didn't hear any grinding noises and wasn't too far from home. So I continued forth. I was thinking what possibly could have happened. I couldn't remember the construction of the OD since I installed mine a couple years ago. The only logical thing was that the shift fork broke and the piece around the shift collar had moved in such a way that I couldn't move the shifter. I got home and did some research and guess what? I'm not the only that this happened to.

Scroll half way down the page.
http://www.public.asu.edu/~grover/willys/od.html

Well, it appears Advance adapters, makers of the new Saturn OD, which is what I have in my jeep, decided to cut corners by using cast aluminum for the shift fork when the original ODs made by Warn had bronze sift forks. So I said to myself, that is definitely the problem. This morning, I got the chance to take it out and looky what I found.



Upon further disassembly. That one worn looking spot on the broken piece is from when I tried moving the shifter back. The fork was probably stuck on the collar and was spinning around. I can see the wear marks on the fork.



Mine appears to have broken at the weakest spot where the material is the thinnest about an 1/8" thick.

I contacted Herm the OD guy asking him if he had any bronze shift forks and his response was, "Advance adapters will replace the broken shift fork at no charge. My shift forks do not fit the Saturn shift shafts."

So, now what I'll do is contact AA and see if I can get a replacement fork to use as a mold and have one of my friends from the antique engine world cast me some made out of bronze. Apparently Warn used bronze for a reason and this must be it!

As you can see, it is a very weak spot in the construction. There is a deep groove that could have material in it to make it stronger.







Now, I know someone will say it, it must have broke because of the load you were hauling!!! Well, it could be and it could not be. I have hauled plenty of things with my Jeep. I have hauled this engine before along with several others. Never had a problem. I have also hauled some motorcycles, with no problem. I have driven the Jeep on several 200 mile round trips with the trailer hauling stuff and never had a problem. I think it is a crap design!

 

I have to agree on poor design. Apparently AA thinks so as well or they wouldn't replace it for free.

 

Looks like there's a little room in the case for some more material at the break. You could add a little clay to that area to thicken it up, when you cast s bronze replacement.

The replacement from AA may already be an updated design.

 

Same thing happened to me, replaced it with a bronze one I had from an older OD[/IMG]
Here is where mine broke[/IMG]
Might be interested in a spare if you are thinking of making several.

 

Looking at the pictures in the article I posted, the shift forks (the aluminum ones) look to be the same as mine. In that article too, he states the fork was updated to a better design. Now, I don't know when mine was made, but it was purchased 10 years after that article was made. So I don't know if AA had a surplus of the junk forks and decided to use them and replace them as they broke or what? I contacted AA 2 days ago and haven't gotten a response yet. I did ask my engine buddy and he said bronze would be much better and he said he can do it. I'll keep you updated.

Yes, I was going to make several up so it wouldn't be too pricey. I'll have to see what is the most cost effective way.

achuto, how long did you have yours before it broke? Mine was 3 years or so.

 

Mine broke about a year after I bought the jeep. I think the PO installed new OD a couple years before I got it but there was an issue once with me being stalled on a steep hill locked in gear and the best way getting it in neutral was using a "little" force on the OD.

 

I don't think pulling a trailer should have anything to do with the fork breakage. Assuming you do use the clutch, there should be no load on it, trailer or no trailer. Forcing it into neutral when the gear train is jammed up is another story, but I know the bronze versions can take that with no problem-at least the one in my my CJ5 survived that. It's been tested more than once thanks to the factory clutch linkage.

I'm going to guess the cost to manufacture the aluminum diecast fork is about an order of magnitude less than the bronze version.

 

Yes you are 100% correct duffer. I think it is a cost issue. I know my clutch is in good operating condition. I just wanted to point out that it wasn't my trailer for all the nay sayers.


Sent from my iPhone using Tapatalk

 

nay sayers? Where?

 

Rick Grover documented this years ago
http://www.willystech.com/wt/homepage/index.html

 

I had the fork fail on my Saturn OD about 6 months ago. It was about 8 - 9 years old when it broke. AA didn't offer me a replacement fork and I also spoke to Herm about using a bronze fork. I got the same answer from him that you did. The new fork I got didn't inspire any more confidence in it than the one that broke. Personally, I avoid doing business with AA whenever possible. This fork failure is very common and should have been properly resolved years ago by AA.

 

Thanks for your reply Posi. Looks like I'll be getting my old fork tack welded together and getting some bronze ones made. I was going to call AA, but after reading what you said, I guess it is a waste of breath.

 

It's worth a call to AA. If you can come up with a bronze version, it would be very popular.

 

I got two new bronze ones in today!!! Now I'll have to bring them to the machine shop to get worked. I had two made because if I wanted to put one in the '49, I would be all set. You know what is funny too? These two plus the shipping back to me was the same price as one new one from AA. So take that AA!




My friend reinforced the area where mine broke. Should have no troubles now!

 

Very nice indeed.

Please when you are done you post a picture of the new and old forks side by side for comparison!!

 

I ended up buying a bronze fork from Herm. sgojpn called me awhile back and told me he had bought a bronze fork and it fit in the Saturn OD no problem. I haven't put my new fork in yet. It's still too cold to work out in the garage here. I'm guessing that getting the roll pin hole in the correct spot will be the most difficult part of machining that casting. I hope you can post some pics after they come back from the shop.

 

The hole for the roll pin actually isn't a big deal. Why? Well, the shaft can rotate that the fork goes on. That was something I checked. The grooves for the poppet ball go all the way around the shaft.

I find that strange that Herm's fit the Saturn. He told me they would not when I asked him. I didn't push the issue because he is the "Overdrive Guy".

I'll post up more pictures when I get further along.

 

Can't you just take a fork into a CNC machinist and have them turn some out in stainless or high carbon steel and get away from the softer metals?

 

That's correct that you can rotate the rail, but your linkage may not line up with the slot at the rear of the shaft unless you have the rail with the rod end connection. Mine has the slot for the linkage. Herm told me the bronze fork wouldn't work on my Saturn as well. I didn't question him about it either.

 

The bronze fork is plenty stout and I imagine the cost to have a one-off fork CNC'd would break the bank.