MTFCA Forum

I don't have history on car, bought rolling chassis from a hot rodder, Working on a 26-7 transmission, upon disassembly found needle bearings (kaydon kn 162016) used in shaft rather than bushings, (drum side came apart during disassembly) both had discolored with heat. my plan is to replace needle bearings with similar and reassemble with clean good surfaces. triple gears will be rebushed due to wear, new drum lugs etc. is this modification ok or do i need to replace shaft?
Thank you for your replies and advice

I have come across that also, did not think it was a great ideal?

A big caution regarding needle bearings in that location. The main shaft is not hard enough to all allow the use of needle bearings for that application.
Eventually the shaft surface will begin to fret and spall due to the contact stresses from the needle bearing contact. There is very little radial load on the shaft, so it might be marginally ok, but it is very poor engineering practice. My suggestion is to install the stock bronze bushings, and bore / hone them to .002/.003 clearance. Needle bearings are wonderfull in many ways, but running them on an improperly hardened shaft will eventually lead to failure.

This has been tried time and again over time. Using needle bearings in the driveline and transmission and even in the triple gears.
Using original style bushings seem to always work out the best overall. The fun projects new style bearing for the drive shaft is a winner in my book though. I wouldn’t put together another one without using one of those. Now that’s a real improvement that does work.

This has been tried time and again over time. Using needle bearings in the driveline and transmission and even in the triple gears.
Using original style bushings seem to always work out the best overall. The fun projects new style bearing for the drive shaft is a winner in my book though. I wouldn’t put together another one without using one of those. Now that’s a real improvement that does work.

I was,a bearing applications engineer for .many years and would never recommend this bearing in that application for many reasons. Stay with the original design.
Art Mirtes

Needle bearings have no place in a Model T.

What Dan and others said. You are asking for trouble and there will be no perceptible advantage. Use bushings.

Actually I need to take exception to the comment regarding needle bearings in place of bushings in the triple gears. I recently pulled apart a transmission built almost 20 years ago with my needle bearing conversion in the triple gears. This the 1st opportunity I have had to inspect the parts after extensive use. You can clearly see that there is no wear on the pins. This is a case of needle bearings being applied to a properly designed and heat treated shaft.

Dan

that is a super opportunity to evaluate the efficacy of your new design...congratulations on how beautiful it still looks. Any idea of mileage?

The roller contact on the pin is very impressive. The bearing fit up must have been perfect and the engine oil must have been changed frequently.
It would be interesting to know the mileage.

We maintain the gear bore and the pin diameter on these to +/-.0002" per the manufacturers specs. Not sure of exact mileage on this one, but the car it was in belongs to a very active touring group in So. Cal. The reason for pulling the transmission was to replace the Turbo 400 clutch discs that were worn out. We have well over 100 of these conversions out in the world not including the new triple gears that we offer with the needle bearings and this is the 1st opportunity I've personally had to inspect a set after 25 or so years producing them. Needless to say, we're pleased with the condition of the parts. Unfortunately, I don't have a milage to report.

I may have to consider the idea of the original posting, as the last run of “floating transmission shafts” I had them “gas nitrided” , so they are about 50 rockwell hard. Not quite as hard as desirable for needle roller. I might get one case hardened just to try. The engine will be about 60 hp at 4,000 rpm!

I am now convinced that the triple gears are a good application for needle bearings. I am wondering what needle bearing is used, does the pin have to be reground to a special size, does the gear bore need to be resized, and what is the resulting mounted radial play.

Are one or two bearing assemblies used in each gear. Seems like two would be better if the width allows it.

I am willing to bet that the gear noise in low and reverse is considerably lower than usual.

Art Mirtes

Art M wrote: ↑

Thu Apr 29, 2021 12:53 pm

I am now convinced that the triple gears are a good application for needle bearings. I am wondering what needle bearing is used, does the pin have to be reground to a special size, does the gear bore need to be resized, and what is the resulting mounted radial play.

Are one or two bearing assemblies used in each gear. Seems like two would be better if the width allows it.

I am willing to bet that the gear noise in low and reverse is considerably lower than usual.

Art Mirtes

Art,

I'm sure Dan will clarify, but I believe the needle bearings are used along with new pins, made especially for use with the needle bearings.

Stock pins are not reground. The pins are carburized chrome nickel alloy steel made specifically for this application. Attempting to reuse a pin of unknown alloy and heat treat is just asking for failure in my opinion. We have never really measured the radial play, as I said above we maintain the gear bore and shaft size to manufacturer's tolerance. My guess is the radial play is considerably less than .002". Play is almost imperceptible when the gear is on the pin. I have made some of these with a larger bearing that requires a much larger pin, which works well to salvage a flywheel where the pins have come loose and damaged the pin bore in the flywheel. I'll have a set of gears with me at the Tulare Swap meet this weekend in space K23.

Hey Dan. Sent you an email about your AC Brake Equalizers. Dave