The Stovebolt Site Forums The Shop Area Driveline Driveshaft configuration

I just bought an SM420 (GM 17 591568 on shifter housing) transmission. Apparently it was the original transmission on my 58 Apache Panel. I thought it would be a simple re and re, but the 3 speed in it now has the slip yoke in the tail shaft, and the new one has the slip yoke in the center of the two part drive shaft by the steady bearing. The overall length of the shaft is wrong (too long) and there is no cross member where the steady bearing should bolt. I guess I can get a new drive shaft made with the slip yoke from the new shaft in it, but it is about $400 to make. It came out of a 58 short box, shouldn't it be the same wheelbase as a Panel? Any suggestions?
Thanks for any help - glad to have such a great site/resource available!

welcome to the garage Ted, check in at the BC bolters threads and you'll find some folks who might give you some 'hands on' help with the project, might even have some parts .... my suggestion is stick with the 3 speed, the granny 4 won't gain you a thing

a 4 speed in a 1/2T any length would be unusual for 58, an option [RPO318] .... takes a special driveshaft according to the assembly manual, and if your truck isn't set up for a steady bearing, it didn't have a 4 speed originally

Bill

Thanks Bill - I will certainly check out BC Bolters to access some local know how! I want to switch to the four speed for a better gear shift position. The three speed was badly converted to floor shift, and I only marginally improved it by modifying a Spectre kit. At least first and reverse are on the left now. But it is still very close to my leg. The granny low and the PTO that came with the transmission are not the draws for me. Where are you located? I am in New Westminster.

Hy Teds58Panel, welcome, as red58 said check out the B.C. Bolters section, we have a pickanick coming up in May.

Comox Valley here, well below the snow line I'd think it would be a lot easier to find the right shift parts to make the 3 speed column shift, not hard to set up

Bill

Bill, that would be my first choice but I have been unable to track the column shift linkage down. I would have thought ther would be plenty around but the only one I found was a wrecker in Idaho who wanted $300!

Thanks for the welcome Shop Shark. I am hoping the Panel will be presentable by then.

If you're talking about the column shift linkage for the three speed, I've got that laying around in my junk pile. Mine's a '48. I don't know if it will fit yours, but someone might be able to figure it out.

Thanks Paul. I put an ad in "Parts Wanted" and someone from Michigan has the linkage. I will phone him today. If it falls through I will check compatibility on yours. Thanks so much!

What is the wheel base of your panel? The drive or propeller shaft for the sm420 is shorter than the standard 3 speed, that has an extension housing. The longer shaft is the same one found on the HD 3 speed, 4 speed, and hydramatic trucks. If you have the 32 truck the longer shaft is split with a center bearing, the 3 speed short shaft is not 2 piece.

It gains you a low gear for manuvering, I think the 2nd in the sm420 is a bit lower too, not so much clutch slipping etc. And I think 2nd is syncronized, and that is a gain.

Before you switch to a SM420, I think you should drive one. You say that having the low first gear doesn't interest you. You will find that reverse is just as slow. Second is synchronized, but it is also slower than a SM318. Unless you plan on pulling trailers, you probably would find a SM420 a nuisance. Again, I would urge you to drive one. If you like it, then I could consider making the change. If the drive shaft has a center bearing, it probably came from a 3/4 ton. Putting in a cross member for a center bearing is no big deal. Or if you can get away with a single drive shaft, make one out of the drive shaft that goes from the center bearing to the rear end, you should be able to have a longer tube put in it for less than $75.00 I have 1700 and 1800 series shafts made for about $60. You probably have a 1300 series which should cost a little less. But $75 should be the max even if you are not a regular customer.

I better check my measurements Truckrolet - maybe I mixed up whether it was longer or shorter. You are absolutely correct - the SM 420 is much shorter than the three wiped with the tail shaft. Do you see any value in the PTO?

the shorter 4 speed with a tail intended for a bolt on "yoke" is the reason a center bearing is used with it, and the rear shaft for the 4 speed is shorter than the one with a 3 speed, you'll have a lot of changes to do to put in a 4 speed, if you even have the correct 4 speed for 58, and if the truck originally had a 4 speed, those items were changed [scrapped] to install a 3 speed

Bill

Crenweige - that sounds like sage advice. I remember putting a wide assembly crankshaft in my Triumph motorcycle in the 80s based on something I read and I never liked riding it as much afterwards. I do have bigger issues to deal with first anyway. If I did switch, would it make sense to put in a taller ratio differential? I thought if I did reverse would be to high, but it sounds like it would be OK.

We pay a lot more for auto stuff up here - maybe I need to shop around if I do get driveshaft work done.

Thanks

Bill, plan A is definitely to find the column shift linkage. There is a lot to be said for taking the path of least resistance!

I found a column shift setup from a fellow stovebolter. But it is off a 55. Am I right to assume a 55 column shift will fit on a 58? It is missing the two piece shifter rods. Will those be difficult to find or fabricate? Finally, is the two piece shift rod assembly for 1st Reverse or for 2nd 3rd?

Thanks so much to all you experts who generously share your knowledge!

Bill, I picked up a column shift assembly. By some insane coincidence I found it in Kansas City and I am here on business! I have to thank you for the pictures you posted on an earlier post abou column linkage. You have saved me hours of work trying to figure out how it goes together.

Cheers!

half dozen pics starting here to help setting it up and checking over/cleaning the box on the lower column

Bill