Drive Shaft Issues 50 Merc

50 merc

50 merc

Member
I went to change the rear seal on the trans tail stock on my 50 merc last night and I had to hammer the drive shaft out. It is the first time I have ever had to do this to a drive shaft. The splines do not look dammaged on the trans or the yoke. The outside of the yoke does have a wear mark on it that is fairly signifigant and the one side of the u joint is very stiff. I feel that the u joint some how has something to do with this over a long period of time. So now my question is does any body know here I can get a new yoke? Or should I be scouting around for a used one?
 
Check Speedway Motors. They have a few types of driveshaft yokes in their catalog. I don't ha ve their catalog handy or I would get you a page and item number. Good luck.
 
The yoke slips in and out with movement of the rear suspension so it's hard to imagine that it was frozen in place. If it's scored I'd bet the bushing is also badly worn. I'd get a new yoke, tailshaft bushing, seal, and u joint.

I got a NOS yoke on a popular online auction site for $35. I haven't seen them elsewhere, but someone here will probably chime in.
 
if you tried to remove the shaft whith it hanging down on the diff. end it will be hard to remove as the leveregd weight bineds it . reinstall it hold as level as possable & push & pull it in & out see if it binds then
 
I had the drive shaft sitting on a jack stand to support it while I was removing it. 51 Mike you mentioned the bushing in the tail stock. Is it difficult to replace? I have seen them on the Macs website so I know now what you are talking about just not how to replace it
 
First of all, I highly recommend you get a service manual. It's not hard, but it can be tricky. I'll assume you have an overdrive ******. I have a '51, so bear with me if your's is a little different. Obviously you have to remove the tailshaft housing, there's no other way. Drain ****** oil. Support the ****** from the main section and remove the rear mount and cross member. Disconnect speedometer cable, OD governor, OD cable and rail switch if you have one. Unbolt tailshaft housing from main housing and wiggle it off. Beware of the uncaged roller bearings in the one-way clutch. Count them and don't lose any!

On top of housing is a small rectangular cover, about 1/2 inch by 2 inch. Remove it and look inside. Spread "C" clip tangs inside with flat blade screwdriver while pulling tailshaft out.

You need to drive out the old bushing. I split mine with a small sharp chisel and folded it out. Drive the new one in with an appropriate driver like a wood dowel and be careful to line up the oil weeping hole. Clean any burrs or other defects with a fine file. Test fit yoke. Install seal. Reassemble in reverse. You have to retain the roller bearings in their cage with either heavy grease (which I used) or a thin rubber band (I read about). They say the rubber band will later disintegrate and do no harm.
 
Thanks Mike Just what I did not want to hear...lol I think perhaps I am now going to wait until the snow flies and pull the trans right out and do the clutch and everything else at once. Not a big problem as this is my wifes car. We still have a couple of Kustom's we can cruise around in. We just bought the car because the price was right and it was original car from the west and unmolested as of yet. Other than the paint. I would have preferd the original Patina black laquer. And to think I just got all of the bugs worked out of the engine, carb and distributor. All is good ya gotta love the hooby.
 
In the days, when we were flat rating work, we would just drive the bushing up on the tail shaft and install the new one behind it. As long as there is enough tail shaft for the bushing to ride on it will never give any problems. Never did this on an overdrive unit so it might be too short?
 
Before you replace the bushing you might inspect all the parts as best you can. The tail shaft is 1.175" with 16 splines that are relatively square and the fit is pretty close. A little rust in there would jam it up easy. Clean the slip joint out with a wire brush & solvent and try the fit again. If it slides good and there isn't much looseness with the bushing, just lube it up well and put it back in service.

Kerby
 
I guess I will go home and play some more tonight, and I will try and clean up the splines. You never know it may just work. When \i checked the tail shaft for play It did not move very mutch maybe 1/16 to 1/8th of an inch that was it.
 
I'd probably do the same, that is until winter anyway. I knocked out the job in an evening. Wear on the bushing will likely show up in driveline vibration because the yoke will "orbit" around the tailshaft.
 
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