Muncie Drive Gear - advice needed
 

Okay, so a few years ago, I had bought a rebuilt Muncie from Ed Hartnett and to detail it the way I want, I pulled the tail housing and side cover for refinishing. It has a 7 tooth plastic drive gear with the metal clip and for the combo I will be running I need to change it out for an 8-tooth 1.84 diameter.

Should I replace it with the plastic gear or the press-on steel drive gear? I realize the plastic gear is a weak link, but from what I've read, it is only is an issue if the speedo seizes. If I go with the steel gear, any issues pressing it on the output shaft using the input shaft as the support in a hydraulic press?

The plastic gear isnt the weak link the clip is. and as you know you need to pull the tranny to replace it.
The metal gear solves this problem. It must be heated not hammered into place and placement is forward on the gear area on the shaft for drivers side cable. Or rearward on the gear area on the shaft for passenger side cable.

True the clip is the weak link, but since the clip is only used with the plastic gear....anyway, so the metal gear cannot be pressed on and must be heated? The Speedo drive is Pass-side and my intent was to place the metal gear in the same spot as the existing gear, correct?

The metal gear can be pressed but heating allows it to drop into place easily. use some masking tape for a stop. Once it cools its locked.
And yes same placement as plastic gear.

Thanks Steve...appreciate the insight and I intended to mark the position of the plastic gear, but simple tape is a good idea. What temp do you suggest heating the drive gear...and my intent is to do so in an oven...not a torch ;)

I use a propane torch and needle nose Vise Grips. A torch wont hurt it, a good sizzle with a wet finger. Not red hot.

Thanks Steve, much appreciated...I'll give it a whirl.

Don't do this. The input shaft does not / will not support a thrust load from the rear output shaft. All the thrust will be taken up by the front and rear bearing if you do it this way.

The propane torch trick works great. I would probably just use a plastic gear. Millions in service without issue.

[QUOTE=novadude;1389454]Don't do this. The input shaft does not / will not support a thrust load from the rear output shaft. All the thrust will be taken up by the front and rear bearing if you do it this way.

This is good to know and I certainly don't want to cause unnecessary damage....very much appreciated.

Use the steel gear, not a big fan of the torch method, I use a piece of 1 1/4" pipe about a ft. long and tap the gear into place, make sure the taper on the I.D. bore goes on first...

Been doing it that way for over 30 years...

Hope this helps... Crash

agree!!!!!!!!!!!!!!!!!!!!!!!!!!!

"not a big fan of the torch method"

Me either. Plan is to use the oven I use for powdercoating, heat soak the gear to 450-ish which should be plenty and then tap into place with a section of iron pipe.

I really appreciate everyone's input...and especially the "don't do this" parts.

What's wrong with the torch method? It's worked flawless for me every time. The gear is really soft, and I was always worried about dinging up the teeth if the pipe moved on me.

Heat / torches are used to install press fit hubs onto shafts in industry every day for good reason. More than one way to skin a cat though....

To the OP: If you are heating to 450 deg in an oven, you probably will not need the hammer - just pliers. It's not that tight of a press fit.

Torch is how its done. Same as starter ring gear. But some like to do it the hard way.

AND another method I have used is to set the gear on a 100 watt light bulb for about 15 minutes ... pick it up with a pliers and drop it on the shaft ... TAZ

If you use 1 1/4" pipe its the correct size and will not damage the drive gear...

The steel drive gears are a very close interference fit, doesn't take much effort...

By the time you get the torch out and lit, I'd already have the gear on the main shaft...

It just seems like a big production for a simple task...

Hope this helps... Crash

Update: Success...steel drive gear installed.

I preheated the oven to 500 degrees, then heat soaked the drive gear for 30 minutes. With swift action normally reserved for a trained Olympian, I positioned the gear on the output shaft and in one fluid motion, placed the iron pipe "driver" over the shaft and tapped...almost nothing. Tapped again...absolute nothing. Tapped it off and I got maybe 20-30 thou engagement. Okay, on to plan B. Fired up the torch, took it to a nice dull red and it literally slipped on without any coaxing. Actually had time to check the position without being rushed.

Lots of ways to skin a cat, but heating the gear in an oven to 500F just wasn't quite enough. If the output shaft were out of the trans, I would have preferred to press the gear on, but the torch method definitely worked for me.

Bottom line -- ya' got it installed ... TAZ