50 hp crankshaft swap

[fishheadfrog]

Will an 89 50hp force crankshaft work in an 86 50hp force?

 

[Faztbullet]

Re: 50 hp crankshaft swap

Sorry but no as the 87-89 models use different upper bearing...

 

[fishheadfrog]

Re: 50 hp crankshaft swap

It would be nice to just swap bearings out, Is that even possible.

 

[tater76]

Re: 50 hp crankshaft swap

Yup... the upper bearing can be replaced, but has to be pressed off and on by a shop. You can replace the 89 bearing with one similar to the 86. I buy mine from my local NAPA autoparts store. Bring it to them and they will match it up. The only difference may be a slot on the side of the bearing that lines up with a roll pin in the block. This just locks the bearing keeping the outer race from spinning in the block. The new replacement I buy from NAPA never comes with this slot, but an air die grinder wheel is the perfect width

I usually pay a half hour shop rate as it only takes them 15-20 mins to do it. Oh, and the cranks are the same

 

[fishheadfrog]

Re: 50 hp crankshaft swap

Thanks guys!
I broke my crankshaft; thinking i spun a bearing, I took it apart and there it was a nice clean break.
There was no metal chips or anything inside. The sides of the top piston got a little scratched up; but the cylinder walls look good. A little cash and a trip to the machine shop is gonna get her back in the water. It looks as if it was a casting defect in the crankshaft itself is what caused the problem.

I think i will give the 89 shaft a try and hope for the best.
Anyone know where to get new rings for this thing?

 

[Faztbullet]

Re: 50 hp crankshaft swap

Oh, and the cranks are the same

If they where the same it would use the same bearing, the crankshaft OD for the 1989 is (1.375) OD and the 1986 is (1.181) OD. Two things snap cranks: excessive rpm and flywheel balance.

 

[fishheadfrog]

Re: 50 hp crankshaft swap

Thanks Fatzbullet!
For now i can only get my hands on the 89 crank. looks as if ill be shopping ebay.

 

[tater76]

Re: 50 hp crankshaft swap

I have seen two different types of top crank bearings used on 50hp's One is the older style clamshell like caged bearings, and the other a sealed unit. I have replaced the newer sealed units with the older style. My best advice would be to take it to a parts store and have them match it up if it will in fact not sit in the block correctly or if the 89 is indeed larger. The bearing that will work is actually out of a Ford rear end, and will be around $25-$30 out the door. Like I said before, it can be done.

 

[fishheadfrog]

Re: 50 hp crankshaft swap

Just like faztbullet said the shafts are different and can not be swapped out!
So would a 35hp crank from a Chrysler work?

 

[tater76]

Re: 50 hp crankshaft swap

You gotta think out of the box on the bearing for a minute. You can go to a bearing supplier/auto parts store and find a bearing that has the correct crank shaft diameter of the 86, and an outer race that will fit inside the block. The only other concern would be the cone of the crank end fitting the flywheel correctly, and thats easy to check. Do you have the block apart?

 

[fishheadfrog]

Re: 50 hp crankshaft swap

The block is apart and ready to go back together
Just waiting on a shaft. I do have the 89. The flywheel
Will not fit it and the shaft is about 1/2 inch too
Short witch may cause problems as well.
Is it possible? To have the shaft on the 89 machined??
To match that of the 86??

 

[tater76]

Re: 50 hp crankshaft swap

Had a feeling you might say that. seems that 89 is a year of many transitions in ALOT of the Force motors. I am a cheapskate by nature, and that is why I mentioned what I did. I hate seeing folks spending money on parts that could be reused or altered, and thought my advice may help. If you were close I have a good 85 crank with a new upper bearing, but shipping would be a bear

 

[fishheadfrog]

Re: 50 hp crankshaft swap

I too am a big cheapo....lol
I found an old 55hp Chrysler and did my 86 rebuild. Its all back together now and ready to go. with that said, I went ahead and took the 89 shaft to work and had it machine and then put the bearing on it and it works in the 55 block very well. i guess if a person wanted to they could in fact make it work but would have to use the newer type ignition and flywheel.
the price of doing this is not cost effective with the machining though. Maybe it would be if someone had the parts laying around.
I can text pics if anyone would like to see what the 89 shaft looks like in the 55hp block if interested.

 

[tater76]

Re: 50 hp crankshaft swap

See... a little ingenuity and sometimes things work out. The ignition swap is pretty easy, but like you said, its not really cost effective unless you have the parts laying around. I did swap out an 1985 50hp ignition to my 1973 55hp Chryselr though, and it still runs excellent after two years of service! However, the 89 is different as you stated, and would require a different flywheel, stator, trigger etc.. I would love to see the pics! PM me and I will give you my number.