The Stovebolt Site Forums The Shop Area Driveline Input shaft nut number/availability

A friend has an old garden tractor that appears to have a '38 or so 3 speed tranny that's been adapted to fit. The nut that holds the input bearing to the shaft is shot and I'm trying to find a new one. There are many out there for the SM420 4 speeds, but I don't know if this is the same size. Any hint as to where I might find a replacement or if the SM420 nut will fit the old 3 speed top loader.

Thanks,

Stuart (atomarc)

If you've got a local machinist that might be the best bet. Cutting a new nut would be a quick job for someone capable.

Chevy Master Parts Book lists "Transmission main drive gear bearing retainer nut" as part # 591150, with the same part listed for all 3 speed transmissions from 1937-54. Description says 1 3/8" - 12 left hand thread. The illustration calls it "nut and slinger". The 4 speed uses a smaller nut.

Same part is used on GMC 3 speed transmissions of the same years.

Given the size, not exactly something you'd find on the shelf at your local Ace Hardware, but given the many years of use there ought to be an old tranny laying around you could liberate one from.

As Bill says, 1 3/8" - 12 Plus, they have many other sizes once you determine what you need.

EDIT: Sorry, didn't catch the left hand part. That'll put a kink in things.

Send me the old one to use as a pattern- - - - -I'll make one for you.
Jerry

Gents,

Thank you for all the leads and ideas. I have the ability to make one myself in my shop but wanted to buy one if I could. I actually found that GM part number, and it's obtainable, but the fellow with the old tractor (Gibson) has found more problems with it and has decided to stick it in the corner and deal with it another day.

Again, thank you for your valuable input, and have a nice Christmas.

Stuart

Turns out GM used this part on some transmissions into at least the 1970s. Google 591150 nut and you'll find a bunch of them. The first hit I got also had this special flat wrench needed to properly tighten the nut

Grind a couple of flats on that slinger and use a big Crescent wrench to remove/replace it. It still does the same job, and you don't need to mess with that flimsy wrench.
Jerry

... but you'd need a left handed crescent wrench.

(Bill Hanlon....that is just wrong........)

I tried to get some financial backing for a new tool for use by mechanics that service cars using both inch and metric fasteners 5 years or so ago, but couldn't find anyone interested. Maybe someone here would back me?

Bill, I do have amongst my conversation pieces this unicorn by diamond, but the pliers are not metric.

That's OK as long as the adjustable wrench is metric.

There was a day, when I worked for a BMC dealer, that I was faced with Whitworth, SAE/USS, and metric fasteners all on the same car, 70's era MGs for example and Saabs with Triumph engines and SU carbs.

So when American mfgrs. went metric, I was ready for them. It turned out that Whitworth wrenches worked on the even-numbered metric bolts. I have long wondered what went on when they chose the bolt head sizes. They could have followed suit with the European and Japanese makers, but no... Was Snap-on in the background making sure we all had to buy new tools?

The welding instructor at the high school where I taught auto mechanics for 20+ years said he had a good idea to supplement his retirement income. He was planning to sell an assortment of precision calibrated metric hammers- - - -to public school administrators! He figured he would probably make millions! Anyone who has ever been an "educator" will probably understand that one very well!
LOL!
Jerry