For the shift lever retainer. Anyone happen to know the exact size of these? The nearest guess I have is they are number 6. Thanks in advance, Steve
Last edited by sstock; 05/05/20182:26 PM.
1953 Chevrolet 3100 261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done In the DITY Gallery Video of the 261 running
1964 GMC 1000 305 Big Block V6, sm420, the next cab off restoration
The two pins in the top cover that engage slots in side of shifter lever ball? In my experience they’re not tapered pins but stepped pins, the smaller diameter then riveted in the top cover.
Thanks Grigg, you are right, I just removed one. Now to try and find a source to replace them.
1953 Chevrolet 3100 261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done In the DITY Gallery Video of the 261 running
1964 GMC 1000 305 Big Block V6, sm420, the next cab off restoration
If you are sure that the grooves in the ball are not the problem, just use the proper size roll pin. Available everywhere. You may want to get longer than needed. May be easier to work with. Drive in to proper stick out and cut off outside to flush. The hole size vs pin size is very important to tightness. If there is a "step" involved, drill the snout to fit the roll pin. Gotta be real careful with that hole. +/- .003 tolerance for tight fit. Post a pic of the pin you removed (cleaned up and good lighting)
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
I once replaced the pins by drilling the holes larger for a “roll pin”. In hindsight it wasn’t the best idea, not much or any more difficult to replace them properly like original.
I believe I’ve seen a kit to rebuild/replace the pins. Otherwise you could easily make some on the lathe or even with a file and a drill if need be.
What is wrong with a roll pin? They are sold by PartsMike for this purpose I believe. Just two roll pins for $5. If it works, it works. If poster can find a kit or original Pins. Good.
Wouldnt you know it, I come in from the garage after working on this very thing and read this. I had already drilled it to accept a 5/16" roll pin. Thanks for the link I will order a couple of these for the next one though.
Thanks George!
Last edited by sstock; 05/06/20181:17 PM.
1953 Chevrolet 3100 261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done In the DITY Gallery Video of the 261 running
1964 GMC 1000 305 Big Block V6, sm420, the next cab off restoration
Perhaps later models were a slip fit. Just double checked the original ones in my 51 GMC and they are riveted over, and recall the same on the 52 when I replaced them.
Roll pins are hollow, and brittle since they're spring steel. One overly-energetic shift can break a pin off and drop the broken piece down the shift tower where it will go through those expensive gears like a meat grinder.
Other than that, a roll pin fox is quick, easy, and WRONG! "Other than the iceberg, how did you like the trip on the Titanic?" Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Breaking strength of 5/16 roll pin (McMaster-Carr) Breaking strength is breaking strength, brittle or not.
The stock pin, .25 Dia, even if it's 120,000 psi shear strength, (which it ain't) yields at around 5900 Lbs. Also, the fact there is little or no radius at the step, it has a stress riser built in.
If the roll pins is considered technically brittle: Brittle, in the strength of materials world, does not necessarily mean it has lower strength. Mostly it connotates to higher strength.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
Breaking strength of 5/16 roll pin (McMaster-Carr) Breaking strength is breaking strength, brittle or not.
The stock pin, .25 Dia, even if it's 120,000 psi shear strength, (which it ain't) yields at around 5900 Lbs. Also, the fact there is little or no radius at the step, it has a stress riser built in.
If the roll pins is considered technically brittle: Brittle, in the strength of materials world, does not necessarily mean it has lower strength. Mostly it connotates to higher strength.
I think what Jerry is getting at is that a roll pin has a specific function, which doesn't include the way it is being used here specifically. However, once the shifter arm is in its saddle and the spring, cup and retainer hood is on, isn't its only function is to keep the assembly together and centered? The shifting action seems to be not connected to these roll pins or guides.
Last edited by sstock; 05/07/20182:03 PM.
1953 Chevrolet 3100 261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done In the DITY Gallery Video of the 261 running
1964 GMC 1000 305 Big Block V6, sm420, the next cab off restoration
dougs, you have to get a cut off wheel and cut the peened over portion on the outside, then 1/8"punch to knock it out outside to in. With the replacement nos ones George found, they would have a slight interference fit and would have to be put in from the inside, then some how retained in place then peened over. Anyone have any ideas how one would do that without knocking it back out? BTW, thank you all for your input, much appreciated.
1953 Chevrolet 3100 261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done In the DITY Gallery Video of the 261 running
1964 GMC 1000 305 Big Block V6, sm420, the next cab off restoration
You could make a little threaded jack to fit inside the tower and lightly press/support both pins (pushing them outward) while peening/riveting the outside ends. Backing up the opposite side with a heavy hammer while riveting the other side with a lighter hammer would also remove some stress from the cast iron tower. Same could be down with a bar/block of steel fit in between both pins if it were just the right thickness, or few pieces stacked to right thickness.
Or with cover removed rivet one pin at a time using the horn of an anvil or something similar to support the pin from inside.
A roll pin does not have a specific function. They are used in hundreds of ways. This being one of them. I don't want to step on anyone's toes, but we must try to be semi accurate. The best fix is an actual pin made for that. If a person can get it installed, good luck. If not, maybe a roll pin. You can not peen over a solid pin while in the truck. If you take the top off, it may be possible to install an original pin. I don't know how it's supposed to be installed.
It is called a fulcrum pin. A sort of pivot for the ball and anti rotation for the stick. The shape of the ball keeps it centered. The spring and bayonet cap keeps it retained.The nose of the stick keeps it from rotating also. If pins had no function, they would not wear out. If the roll pin is correct size and installed in the correct size hole, it will work. Slot facing up. The particular fix is a decision for any user.
1. Genuine original pin. 2. Roll pin. 3. Donor tranny top 4. Home made pin 5. Any other pin that works and can be installed.
I think the top is a machined casting, so be careful.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
IIRC, I grinded off the heads of the fulcrum pins and they slid right out. Make sure to stuff a rag down in the shifter hole so they don't fall inside the trans. Look for some rolled steel pins of the appropriate size at your local hardware store. If needed you can drill out the fulcrum pin holes to accept a slightly larger pin. The rolled pins are also sold by Novaks. They are SM420 experts.
Be advised, nothing you can do will make the shifter feel as snug and tight as a new car shifter. There'll still be alot of play but it shouldn't flop and slop around quite as bad after your new parts are installed.
I think staking on the outside with a chisel, three places, is a better way than peening. Less force on pin. I really think a roll pin is the answer.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
Bart, I hear and understand everything you say, and it makes sense. I have rebuilt 4 of these sm420s now and I have only seen one of the many cores I have looked at with bad pins, subsequently this one had been operated with a broken shift lever spring. So thinking this caused the pin to start to eat away. It has a beautiful top loader so right now I am on your item #2 and the roll pin is installed and I'm going to run it.
1953 Chevrolet 3100 261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done In the DITY Gallery Video of the 261 running
1964 GMC 1000 305 Big Block V6, sm420, the next cab off restoration
1953 Chevrolet 3100 261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done In the DITY Gallery Video of the 261 running
1964 GMC 1000 305 Big Block V6, sm420, the next cab off restoration
1953 Chevrolet 3100 261 cu inch, sm420, 3.55 rear, torque tube still,omaha orange, still 6 volt, RPO green glass, side carrier spare, all done In the DITY Gallery Video of the 261 running
1964 GMC 1000 305 Big Block V6, sm420, the next cab off restoration
I like that the best also. Super good idea. I hope the metal is viable enough to hold good threads. He did use thread locker. The double nut/jamb nuts is just a way to tighten the screw. Then stick out & nuts get cut off. You can see on the threads where he used pliers. That works too. I'm just trying to get in on the act. Your roll pins will be just fine.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
Better ideas do come along. Without them we wouldn't have Okie Bushings.
This issue is just a metal pin sticking out of a transmission cover tower. Any way you can get a metal pin to stick out, and function, is A.O.K. DIY repair without a machine shop is what most of us are looking for. Fixing in place is even better.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
