It goes back to the root of who we are. It's part of the core of our souls. It was the drive of the earliest shade tree mechanics. It's in the makeup of every motorhead. I'm talking about the desire to do-it-yourself. We all know the deep satisfaction that comes from successfully tackling a project we've never done before. We take great pleasure in being able to say, "I did that myself." for most of us, there is also the need to know the job was done right. After all, no one cares as much about your project as you do.
Of course, things have changed a lot since the early days. We need a lot more than a box of basic hand tools today. There's more specialty equipment and special skills needed now. Who would have ever dreamed that some of us would be tuning our musclecars with a laptop computer? whatever skill level you possess, there will always be things that are best left for a professional. Still, there are a lot of basics that will always stay the same, so we want to take you back to those basics and show you one of the things that most anyone can do.
For you old timers, this will be a good review of something you might not have done in a while. If you are new to Mopar muscle, this may be just the thing to get you started down the road of a very satisfying hobby.
To help you identify what...
To help you identify what we're going to be working on, here is a photo of a freshly cleaned and ready to rebuild four-speed. a Hemi four-speed has 18 splines on the input shaft, while the more readily abundant small-block and not-so-high-performance big-block versions have 23 splines.
We put the word out we were looking for a back-to-basics-type project we could detail for our readers, and John Balow, owner of Muscle car Restorations, was quick to respond with the offer of an A-833 (Hemi four-speed) rebuild. He was kind enough to wait for us to get out to his Chippewa Falls, Wisconsin, shop so we could follow one of his expert technicians through each step of the teardown and rebuild.
Probably the best advice we can give you is to take your time and to carefully notice how each part or subassembly goes together. Keep everything in order as you go and especially keep all the slider assemblies together until you are ready to replace whatever you need to. if you do one at a time you'll have the other one for a reference. It's also a good idea to take some photos just in case you need to step away from the job for a while.
Zumbrota Bearing and Gear in Zumbrota, Minnesota, supplied the parts necessary for this rebuild. They also provide countershafts for the cluster gear and can rebuild the input shaft to good-as-new condition.
Another service Muscle Car Restorations takes advantage of is their transmission dyno. They are able to thoroughly test a transmission, simulating in-car conditions, so when it's finally installed in your car you know it will work perfectly.
The first thing you'll want...
The first thing you'll want to do is to remove the side cover, so you can take a close look at everything inside and make sure your transmission is repairable. Check for broken teeth, worn shift forks, damaged engagement teeth, and so on. You can't see everything this way, but if you do find a damaged gear, you might want to get what you need before you start so the loose parts don't have to sit around.
One thing to take note of...
One thing to take note of is the shift forks are not the same, so don't get them mixed up. The bottom one is for the 1-2-gear slider, and the top is for the 3-4. Check for excessive wear on the contact surfaces, but unless they have been abused, these rarely need to be replaced.
This is the order that you...
This is the order that you need to follow to remove the reverse detent ball. Unscrew the cap and then remove the spring. Then, using a magnet, pull out the ball. Finally, you can unscrew the tube. If you try to take the whole assembly out at once, you'll drop the detent ball into the case. Note the reverse light switch above.
Removing the input bearing...
Removing the input bearing retainer will uncover the snap ring that holds the input shaft in place. The input shaft and bearing can be pulled out the front, but often it's easier to tap it into the case and remove it with the main shaft.
The first step in removing...
The first step in removing the main shaft is to unbolt the tailhousing and rotate it to uncover the countershaft. The small key is supposed to keep the countershaft from rotating, but as you can see by the out of place key, this shaft has started to turn anyway. This could be an indication of bad bearings.
First, knock the counter shaft...
First, knock the counter shaft out from the front of the case to the back. When you do, the cluster gear will drop down enough to disengage from the main shaft gears so you can pull the whole assembly out the tailshaft end of the housing.
This shot shows you the main-to-cluster...
This shot shows you the main-to-cluster shaft relationship. Notice there are thrust washers on both ends of the cluster. Make sure that you recover them.
The reverse gear and shaft...
The reverse gear and shaft rarely need to come out. Unless there is obvious damage, just leave it in place.
The input shaft, which is...
The input shaft, which is also Fourth gear, simply slides off the end of the main shaft. The roller bearings inside the input shaft ride on the very end of the main shaft.
Remove the snap ring to slide...
Remove the snap ring to slide the 3-4 slider and Third gear off the front of the shaft. The rest of the gears slide off the back of the shaft.
The main shaft is held in...
The main shaft is held in the tailhousing by a snap ring that fits into a grove in the rear main bearing. You'll need to hold it open while you or a friend taps the main shaft with a soft hammer to pop the bearing out of the housing.
The rear bearing has a snap...
The rear bearing has a snap ring, but it's also pressed onto the shaft so it's best to find a shop to help you press it off the shaft. The bearing holds First gear in place, so it slides right off with the bearing. Note the grooves for the speedometer gear just above the bearing.
Just one more snap ring and...
Just one more snap ring and you can pull the 1-2 slider and Second gear off the shaft. The straight cut gear attached to the 1-2 slider is for reverse. The main shaft in these transmissions seldom need replacing, but still check each bearing surface for any damage.
The kit from Zumbrota Bearing...
The kit from Zumbrota Bearing and Gear comes with everything you need to return your transmission to like-new operation. The countershaft is an extra-cost item, but in our case it was a good idea to replace it.
Don't forget to replace the...
Don't forget to replace the seal inside the bearing retainer.
OK, now you are ready for...
OK, now you are ready for main shaft assembly. It's just the reverse of disassembly. But before you start sliding all the parts back onto the shaft, be sure to smear high-temp grease on each of the machined surfaces that the gears/sliders ride on.
Check/replace the driveshaft...
Check/replace the driveshaft yolk bushing before replacing the tailshaft seal.
You might need an extra hand...
You might need an extra hand here. Install the main shaft into the tailhousing by wiggling the bearing into place while holding the snap ring open. Now is also a good time to place the tailhousing gasket in place, so you don't forget it when you slide the main shaft into the case.
The 3-4 slider slips on next....
The 3-4 slider slips on next. The main and input shafts are now ready to be installed into the case.
The countershaft has a long...
The countershaft has a long spacer that separates the double set of roller bearing that support each end of the cluster gear. Make sure the key slot is toward the rear.
Here's a tip that will save...
Here's a tip that will save you some frustration. As soon as you are finished cleaning the case, glue the cluster gear thrust bearings to the inside of the case with some adhesive-type silicone.
This next step is one that...
This next step is one that can test your patience and even be a little intimidating, but it's really not too tough. There are two sets of roller bearings supporting both ends of the cluster that are separated by a spacer. Using regular high-temp wheel bearing grease, stick the first set into the end of the cluster and then push them far enough down with the spacer to make room for the next set. Put in another set of rollers followed by another spacer. Be generous with the grease. Make certain to put the long spacer in behind the first set before you grease the rest of the rollers into the other end. If you are using a new countershaft, cut the old one to the same length as the cluster and push it into the cluster so that it's flush on both ends. This will hold the bearings in place while you are installing everything into the case. Then, you can use the new countershaft to push out the old, and everything will stay put. If you are reusing your old shaft, slide it into place after the bearings are greased in just to make sure everything is in place. Then, slowly pull it out and carefully put the cluster in a freezer for a while. The extra cold grease should hold the bearings in place while you are juggling the cluster and main shaft in the case.
The input shaft has just one...
The input shaft has just one set of rollers. Grease them in place the same as the others, and then tap the input shaft partway into the case. You may need a little extra room to line up the main shaft. Once the main shaft is in place, you can install the snap ring and tap it all the way in.
Everything goes into the case...
Everything goes into the case in the reverse order it came out. Set the cluster into the bottom of the case, put the main shaft in, making sure it engages the input, and then lift the cluster into place and finally slip in the countershaft. Don't forget the key before you tap the shaft in flush with the case.
Now you can rotate and bolt...
Now you can rotate and bolt the tailhousing in place and drop in the shift forks. Did you remember the new tailhousing gasket before you assembled everything?
Generously squirt everything...
Generously squirt everything with gear lube. Move the sliders back and forth in order to get some oil under them as well. Also lube up the input bearing before you bolt on the bearing retainer. Rotate the shaft a few times, engaging each of the gears, including reverse, to make sure everything is working smoothly.
The only thing left is to...
The only thing left is to install the side cover and reverse detent assembly.
There you have it-all ready...
There you have it-all ready to go into your car.