Home | About | Links

GTO Main | GTO Trans swap | Muncie Rebuild

Jeeps | Minibike

The Muncie Rebuild Page 

Muncie M20 with Hurst Comp Plus shifter

NOTICE!!  This Muncie Rebuild is now moved to a new domain:  www.SquidsFabShop.com  You'll have to go manually and type in the new address since GeeeeeOHCiteeeeez dot calm won't let me link out.

On the main page, there is a link to this muncie transmission rebuild guide.  It should have no problems with exceeding bandwidth, so it won't shut you off like this one might.  This geocities website will be taken down in the near future, so update your bookmarks.

This page is meant to help those considering a Muncie 4 speed rebuild who have never opened up a Muncie 4 speed before.  I was in this situation and found good information hard to find on the ‘net. Mainly a lack of good visual documentation.  Well, I think I know why; it's darn hard to do a rebuild AND take a bunch of good pictures AND put it on a webpage. Here's my attempt:

I picked up a 1967 Muncie at a swap meet.  I didn’t really know what to look for so I just checked for broken parts.  The info I found on the internet helped me ID what I was looking at during my search.  It was important to me to find a late 60’s tranny since it has the larger countershaft pin, correct spine count (to match my 67 vintage parts) and speedometer output on the driver side.

I paid $350 for it and yes, it was too much.  I ran into some old timers who said they remember buying Muncies at swapmeets for 25 bucks.  Sheesh.

To start:

Get a manual.  I simply have an old Chiltons manual which lays out the whole process in very basic steps.  It’s got a grainy exploded view so I found a nice exploded view here: www.autogear.net  Go to the literature section, scroll down and you can download a great PDF file of Muncie parts with an exploded view. Study this exploded view. As you look at it, it may not all make sense, but when you actually tear down the trans, it will all come together. Manual transmissions really are very cool mechanisms.

Some tools I found necessary: A small punch set, a brass drift set, and a “gorilla” class snap ring plier. A 2 jaw puller is needed, and of course various hand tools.

Someone recommended a supplier of muncie parts to me so I sent some emails and decided to go with them. Bob at www.fourgeartrans.com was very helpful.

Tear it down!

I didn’t follow any particular course of action, but just went carefully. Here are the main steps:

 

Destroyed reverse idler gear

Figure1: Reverse Idler gear and shaft. Like the broken teeth?

 

first and second gear with rear bearing

Figure 2. This is the midplate with 1st and 2nd gear and it’s syncro assembly (hub/slider/and brass rings). Reverse is hangin' off the back there. 3rd/4th synchro assembly and 3rd gear are already removed.

 

Rear bearing snap ring removal

Figure 3. Arrow shows back snap ring.

Cluster Gear Anti Rattle plate removal

Figure 4. Rattle gear taken off. Notice rivet on top after being punched out. Spring underneath is removed too.

 

Now the main case should be bare.

Take a look at all the itty bitty parts. Time to wash ‘em and the case too. Time to determine what you need to do a good rebuild. My gears were in good shape, although the engagement teeth on third gear were a bit rounded off. The engagement teeth are the little “nubs” on the sides where the cone shape is. See Figure 5. The sliders grab these teeth when the gear is engaged. If they’re rounded off too much, the gear will push the slider off and back into neutral. Reverse gear has no synchro, hence no little engagement teeth.

Figure 5. Black arrows show the engagement teeth. These are in good shape. Brass synchro (otherwise known as the blocking ring) is installed over the cone portion of the gear.

 

I didn’t want new gears so I talked to the Fourgeartrans guy and he recommended Torque loc sliders. These help keep your gears engaged especially if your gear’s engagement teeth are a bit worn. Normal sliders are straight splined. Note the Torq-loc splines. On the left is the destroyed original, and on the right is the Torq-Loc. See figure 6.

Figure 6. The original was in pretty bad shape (left). Torq-Loc slider on the right.

I sandblasted all the case parts since they were really stained and dirty. I tried chemicals, but the finish was still stained and ugly. I used fine Olivine blasting sand. Lot's of work but it looks good.

I repaired a stripped hole in the tailhousing with helicoil, and also fixed a hole in the tailhousing from a long bolt used on the shifter mounting plate. I used JB Weld epoxy to seal it up. This is good stuff!

Figure 7. Blasted case on the left, pencil showing hole in tailhousing on right. Nothing a little judicious use of JB Weld won't take care of.

 

So get your rebuild kit and let’s get started on the….

 

Rebuild!

Figure 8a. Synchronizer assemblies. 3rd/4th is to the left, 1st/2nd is to the right. Hubs are already inside the sliders. Finger points to hub extension. The analogy used frequently is the assemblies stacked together look like “a hamburger bun” as you look at it.

Figure 8b. This detail shows the spring holding the key in place. The spring holds all three keys in. It is the same on the other side. Note the orientation of the keys.

Figure 9a and 9b. Correct orientation of synchro assembly to be installed.

Figure 10a. In the foreground we find on the left: 1st gear sleeve, to the right one beating shalilly, and in the middle one steel pipe. Figure 10b is the pipe pressing the sleeve down to the hub. Make sure you tap it down all the way.

Figure 11. Blocking ring is in the synchro assembly (align the 3 notches in the blocking ring with the keys in the synchro), and first gear is about to settle in.

Figure 12. Snapring locates bearing. Make sure the bearing is facing the right way or it'll be sticking out of the midplate.

Figure 13. The midplate isn't pressed on yet here, but you can see the locating lip of the midplate is facing down. This will register it with the maincase when the time comes....

Figure 14. Still not fun trying to wrestle this sucker on even with the right tool.

Figure 15. Notice the old input shaft nut as a washer for banging on the speedo ring.

Figure 16a. 3rd gear is being slipped on. Cone toward the front. Figure 16b. Now the synchro assembly is being placed on. Make sure to tap it on all the way.

Figure 17a. Here is the front snapring installed. Notice that it says T-10 on the slider. T-10s and Muncies share many common parts. Figure 17b. Your assembly should look like this!

Figure 18a. Case and countergear. Figure 18b. You can see from the edge on down: thin washer, roller bearings, thin washer, roller bearings, thin washer, and yep, the big long spacer is in there. Same for the other side.

Figure 19a and 19 b. Thrust washer being installed on front of case.

 

Figure 20. Note the orientation of the pin notch.

Figure 20. Front reverse idler thrust washer and gear (not installed yet in photo). They'll be loose until the rest of the guts are insalled.

Figure 21. The input shaft is ready to have the bearing cage and roller bearings place inside.

Figure 22. This is the whole shebang. The 3rd 4th synchro is slipped over to engage the mainshaft (4th gear position) to help hold the input shaft on for the next step.

Figure 23a. The midplate has been tapped on. Figure 23b. Bolt the whole thing on to seat the silicone. Also note the reverse idler has been installed. It'll still be a bit loose until the rear of the pin is seated in the tail housing.

Figure 24. The shim is being used to shoe horn the lever past the spring loaded ball bearing. Shown here, the reverse lever shaft still needs to be pushed toward the outside of the case about 3/8 of an inch.

Figure 25. Tailhousing installed.

Figure 26. Here is a detail of the shifter forks installed in the shifter plate.

The finished product. Kinda ugly isn't it? I am going to do a final scrubdown and maybe clear coat it.

This was a very rewarding project and it really isn't that hard.

This is my first cut at putting down the whole procedure so if you see anything amiss, I'd appreciate any feedback. See my About page to get my email address.

 

Views since November 2004:

Counter

 

Home | About | Links

GTO Main | GTO Trans swap | Muncie Rebuild

Jeeps | Minibike

 

Dave Miles

October 10, 2004

Hosting by WebRing.