Ford Muscle Cars Tech Forum banner

1 - 20 of 23 Posts

·
Registered
Joined
·
4,977 Posts
Discussion Starter #1 (Edited)
This article is offered as a reference on how to swap an input shaft with the transmission remaining mostly assembled. Although I am making a special type of swap, a stock input shaft can also be replaced this way. Because it is possible to get some parts out of alignment badly enough that the transmission will require a more complete disassembly, these procedures are recommended only for those who are familiar with these transmissions and are willing to assume such risk.

If you would like more information on how to further disassemble a toploader or want to know how to upgrade the output shaft, I suggest this companion tech article: http://www.fordmuscle.com/forums/transmission-articles/487117-31-spline-toploader-output-shaft-conversion.html

After being to the track numerous times, I was able to tune my suspension until my car could pull quite hard at the tree. Unfortunately a by-product of hitting the tires so hard was that I overpowered my small block toploader 4 speed transmission, specifically the stock 1 1/16” input shaft. While investigating some poor, notchy shifts I discovered that I had twisted the input shaft. After deciding that it might be a fluke, I installed a second small block input shaft and it too got twisted on its 2<sup>nd</sup> trip to the track.



There was no doubt that it was time to take some serious action.

The logical thing for me to do (besides buying an expensive racing transmission) was to install a big block based 1 3/8” diameter input shaft, similar to what Ford put behind its 428CJ and 429Boss cars. Unlike the original big block input shafts found behind the big block, the aftermarket variety is made physically longer for usage behind a small block and so it is a direct replacement:



Note the much larger diameter of the new shaft. These large diameter input shafts are available for both the wide and the close ratio transmissions and they have 10 course splines just like the original big block stuff. You will need to ID which ratio you have before ordering parts. The easiest way is by counting the number of teeth on second gear, which is the third gear that is visible from the front of the transmission. See circled area:



A wide ratio transmission has 31 teeth and a close ratio will have 28 teeth on the circled gear.

Other parts that are required for this conversion include a new larger input bearing retainer (snout), a toploader gasket set with a new snout seal, a new larger ID throwout bearing, a larger ID splined clutch disk, and a special modified clutch fork. It is possible to reuse the old original front bearing, but I recommend installing a new one while you have the input shaft as this is a frequent wear item. Here is a photo of all the parts that were replaced in this project:



To do the big input conversion on a small block or 390 toploader, you will need to modify your small block to match the BB throw out bearing that is required. To my knowledge, Ford or the aftermarket does not make the required fork and one must be created using two different forks. I illustrated how to do this in this tech article: http://www.fordmuscle.com/forums/tech-exchange/482330-modifying-clutch-fork.html

Note the CD—it was included with some parts that I bought from Toploader Heaven and it is by far one of the best references for novices who are interested in rebuilding there own toploaders. Much of it is step by step and there are more than a hundred assembly pictures included. The clutch disc and the reproduction clutch fork that I modified were sourced elsewhere.

I also recommend a few tools to do this swap. A good set of retaining pliers to remove C Clips and either a brass hammer (or punch) should be used when you need to tap on parts:



Lets get to work. First, remove the transmission from the car. It will need to be drained of all its gear lube.

With the transmission fully drained and lying on the workbench, remove its top cover. A toploader gets its name because you access the internal parts through the top of the case. Use an adjustable wrench and put the transmission into neutral. Next, remove the 5 bolts that hold the tail shaft housing to the main case and carefully slide it off the output shaft:



At the front of the transmission, remove the 4 bolts that retain the front bearing retainer to the main case. Note that you can also see the end of the countershaft in the following photo:



Note that the front bearing retainer has a divot that faces down to aid drainage. That will be important for reassembly:



Roll the transmission over so that the top case opening is now facing downward. From the front of the transmission main case, again locate the end of the countershaft.

With a suitable hammer and punch (brass preferably), drive the countershaft into the case approximately ½-¾” and NO FURTHER in this manner. Next, carefully push the countershaft all the way through the rear of the main case using a dummy shaft. DO NOT try to remove the countershaft without a dummy shaft or the countershaft’s needle bearings will scatter. This is a very bad situation and it will more than likely require a much more complete transmission tear down in order to make the repair.

My dummy countershaft is a simple piece of PVC pipe with an overall length of 8 ¾”. It has a .830” OD which is less than the countershaft’s .890” OD. Since it is shorter than the cluster shaft, it allows the cluster to drop in the case, thereby giving clearance so that the input shaft can be removed without disturbing the needle bearings found in the counter gear. Here is what my dummy shaft looks like next to an old countershaft:



Once the dummy shaft has been fully located inside side the cluster gear, roll the transmission so that the top opening is again facing up. Here is what the dummy shaft looks like once it has been installed in the countershaft and the countershaft is dropped slightly:



Now you can carefully pull the old input shaft forward out of the case. There will be 15 roller bearings located inside the input shaft and some of them may fall into the case. They are large enough to fish out with a long skinny magnet. The brass blocking ring may pull out also:



The bearing is held on the input shaft with a C-Clip and you must remove it. If you are going to reuse your old front bearing, remove the C-Clip and have the bearing pressed off if it does not slide off on its own.



When I remove a bearing from an input shaft, I use an old disguarded toploader case and a block of wood to drive the shaft out of the bearing:



REASSEMBLY:
Clean all the parts to get them ready for reassembly. Scrap any gasket remains off with a razor blade. Now it is time to install the bearing on the new input shaft. Again I use an old case for reassembly. I place the bearing in the case the opposite way than it is normally installed. Then I heat the bearing with a low wattage heat gun or hair dryer for 20 minutes. Use a low setting as you do not want to overheat the bearing. The heat allows the inner hole in the bearing to enlarge slightly which allow the input shaft to be installed by hand. Be sure to spray the machined area of the input shaft (where the bearing gets installed) with some type of lubricant before shoving it in:





Alternately, you could have the bearing pressed on in a shop or you could have the part of the input shaft that the bearing rests on turned down slightly so that it can be installed by hand without other tools.

Reinstall the bearing retaining C-Clip. Next it is time to install the 15 roller bearing on the rear side of the input shaft. Smear the outer race with some heavy wheel bearing grease and shove the individual bearings into the back of the shaft. I also put a layer of grease on the topsides of them:



Reinstall the brass blocking ring inside the transmission case. It has 3 notches that will match 3 synchronizer keys:



Now carefully slide the new input shaft assembly into the case, watching that the roller bearings and brass blocking ring remain in place. You may need to wiggle the output shaft slightly, but don’t go to extremes.



Carefully roll the main case back over so that the top opening is facing down again. Look inside the countershaft holes to ensure that the dummy shaft is still retaining the countershaft roller bearings. You may need to roll the main case a little more in one direction or the other to ensure that the dummy shaft is aligned with the holes in the case. You may also need to move the thrust bushings slightly to get them realigned. Getting all these things aligned is the hardest part of this swap and is why I recommend that this swap be performed by someone who is knowledgeable of these transmissions.

For reference, here is a picture of an old brass thrust bushing and the case boss that it gets keyed into:







If you can clearly see the dummy shaft on both ends, it is time to reinstall the countershaft. It is installed from the rear of the transmission case:



By keeping it butted firmly against the dummy shaft at all times, it can be pushed by hand until the shaft meets the front of the case. Work slowly to keep the needle bearings and thrust bushings in their place. Once the countershaft contacts the inner front of the case and the needle bearings and thrust washers are in place, finish drive the countershaft with a piece of brass until it is seated in the case with the roll pin being located within the rear case boss:



If you haven’t done so, install a new seal in the front bearing retainer. It will install in the same direction as the old seal in the old retainer.

Next install the new bearing retainer on the front of the transmission with a new gasket with the aforementioned divot facing down. Be sure that the paper gasket divot also faces down too. I recommend using a Teflon pipe sealant on the threads of the 4 retainer bolts.



Now it is time to reinstall the tailshaft housing using a new gasket. This is also time to replace the rear seal and to inspect the yoke bushing that is found within the tailshaft housing. I also use Teflon sealant on the 5 bolts that retain the housing to the main case. To help with alignment, I suggest placing a driveshaft yoke on the tailshaft splines prior to tightening these bolts.



Now it is time to test your work. First, use a crescent wrench to move the transmission through its gears. You may need to spin the input or output shaft slightly for the gears to fully engage.



Next test the new throw out bearing on the bearing retainer. It should slide freely. If not, take a strip of emery cloth and polish the retainer. Slide the new clutch disk onto the input shaft. It to should also slide freely. If not, you should locate all burrs and file them off until the disc slides freely:



Finally, test your pilot shaft bearing for fit. Normally you will not have an issue with it.

It is easy to tell which toploader has been modified:



The good news is that with this modification I no longer need to worry about twisting an input shaft. I was able to complete the season with several new personal bests without worrying if I was going to get “shafted” again.
 

Attachments

·
Registered
Joined
·
4,520 Posts
The best kind of "How-to"; Done safely, quickly and with a big time short cut. The fact that it is an "Upgrade" - even better.

I've always been a believer in replacing any part that breaks, fails orisn't "quite" strong enough - any time you have to disassemble it.

Great tech article, great post!
 

·
Registered
Joined
·
152 Posts
Wow GREAT article, would I be wrong in assuming this works on a 3speed toploader also? Just curious, I need to make the 4speed swap already lol but need to go through this trans one more time
 

·
Premium Member
Joined
·
91 Posts
EXCELLENT post Dennis! I'm guessing that twisted shaft is a 2.32? I had the same problem in 1984 and resolved it the same way......and it's still together! Mark
 

·
Registered
Joined
·
4,977 Posts
Discussion Starter #6 (Edited)
Thanks Guys. I am glad that this article is appreciated.

Beowolfe: I am happy that you see the benefit of taking this shortcut. This way it takes maybe an hour max to do the swap, whereas removing the shift rods/forks and output shaft assembly could easily double the work.

66racer: Not sure about the 3 speed as it has been over 30 years since I had one apart. I would guess that the principles are the same though since they also load through the top.

ford88: The input shaft, bearing retainer, seal, and gasket set came from Mark at Toploader Heaven. The throw out bearing came from Summit and it is a McLeod unit. The BB throw out bearings are actually a 2 piece assembly. A typical roller bearing plus a holder for the bearing. Both are required. Most parts houses only carry the replacement bearing itself.

There is no factory specific fork for this conversion and I had to make one. Basically I combined a small block fork with a reproduction big block 428CJ fork (that is pictured above.) That is the subject of a second tech article which should be published in a few days. I will reference the fork article in the input article when its available.

quickshift: Glad to hear that others have done the input swap successfully. My tranny is a 2.78 wide ratio.
 

·
Registered
Joined
·
7,408 Posts
Excellent Article!

I'll probably be upgrading the input shaft... and probalby the main/output shaft on my car as well.

You probalby don't want to hear this, but I've never twisted an input shaft, but did break the main/output shaft! It broke within the tailhousing, and took it out at the same time... I hope that was a 'fluke', and you don't have a similar issue.

The best dummy shaft I've used is a piece of 7/8" wooden dowell rod. It fits perfect.

Thanks, and good luck!
 

·
Registered
Joined
·
4,977 Posts
Discussion Starter #10
Excellent Article!

I'll probably be upgrading the input shaft... and probalby the main/output shaft on my car as well.

You probalby don't want to hear this, but I've never twisted an input shaft, but did break the main/output shaft! It broke within the tailhousing, and took it out at the same time... I hope that was a 'fluke', and you don't have a similar issue.

The best dummy shaft I've used is a piece of 7/8" wooden dowell rod. It fits perfect.

Thanks, and good luck!
Thanks Mike.

I actually wanted to replace my output shaft over the winter but time and $$ seem to be running out.

Hmmm, IIRC FatNFast had the same issue with the output shafts and like Mike, he uses nitrous too. Is this some weird occurrence that occurs mostly in the giggly gas world??? ;) :D
 

·
Registered
Joined
·
1,153 Posts
I just think once you get up to a certain HP level, you begin to find limitations of all equipment stock or High performance parts. It's a viscous circle. You get your drivetrain to hold the power you have, then you go for more power and start breaking stuff again. LOL. I've candy caned input shafts, broke output shafts, axles, yokes, you name it! If it could be broke I broke it! hehe. Like I said in my article on the C4, after all the money I had spent over the years keeping a 4-speed in mine...I could have bought a Lenco or Liberty Transmission. You will always continue to find the weak link. That's Racin'. Output is next. Now that the input is not going to give, you'll just keep transferring the weak link on back.
 

·
Registered
Joined
·
64 Posts
EXCELLENT thread.

We need more on the older transmissions. A lot of good info. I recently rebuilt my 3 speed toploader and it's a bear to dig up info on these transmissions. Those needle bearings are a pain to dig out of the case if they drop out of the race ;). Have you ever rebuilt one of the 3 spd. toploaders? One thing I couldn't figure out with my rebuild was how loose the output shaft bearing should be? On the 4spd. it seems to be a pressfit into the case. On the 3spd it seems to be a drop in into the case? any thoughts on this? The rebuild manuals really don't seem to adress proper case tolerances and bearing sizes.

On a side note a decent source for aftermarket gears for both the 4spd. and 3spd. toploaders is TransStar. It took me 4 months of searching to find this source. It seems that the rebuild shops around here regard parts sourcing, for internals, as some sort of proprietory secret. Maybe some of you could donate your vast experience and start some sort of sticky for toploader parts sourcing. It sure would be appreciated and well used. Of course I referenced all the high profile sources like 4speedtoploaders.com, 5speeds.com and toploaderheaven.com. . Although these sites have a lot of the gearing and hard parts it has been impossible for me to source individual parts like needle bearings, detents, detent springs, and case plugs.
 

·
Registered
Joined
·
7,408 Posts
One thing I couldn't figure out with my rebuild was how loose the output shaft bearing should be? On the 4spd. it seems to be a pressfit into the case. On the 3spd it seems to be a drop in into the case? any thoughts on this?
On a 4-speed, both the front and rear bearings press fit onto the input and output shafts, but slide freely into the case.

On the last couple I did, I chocked the input and main shafts into a large drill press and used sanding cloth on the shafts until the bearings would -just- slide on and off for easier assembly/disassembly.
 

·
Registered
Joined
·
64 Posts
On a 4-speed, both the front and rear bearings press fit onto the input and output shafts, but slide freely into the case.

On the last couple I did, I chocked the input and main shafts into a large drill press and used sanding cloth on the shafts until the bearings would -just- slide on and off for easier assembly/disassembly.

I take it that this convuluted contraption is only used to pull the bearing from the shaft and not from the case?

 

·
Registered
Joined
·
7,408 Posts
I take it that this convuluted contraption is only used to pull the bearing from the shaft and not from the case?
Yes. That bearing is pressed onto the mainshaft, not the case. The problem with removing it, is that long mainshaft! Most pullers will not work with that long shaft in the way!

Traditionally, the front and rear main bearings... the ones at the front and rear of the case... are removed before the transmission is dis-assembled. There are ways around it, but that's the way it is traditionally done. Special tools are needed since that long shaft is in the way.

Dennis showed how to remove the input without removing the front bearing first by dropping the cluster gear. Maybe he'll share how he removes the rear bearing. :) There's a small town Ford dealership two miles away from my house, so I would just run down there and let them use their tool. (different than the one shown) They are friendly, and I know a lot of them, so it would generally cost me from between $0 and $12 to get them both pulled off... as it didn't take them but a couple minutes.
 

·
Registered
Joined
·
4,977 Posts
Discussion Starter #16
Special tools are needed since that long shaft is in the way.

Dennis showed how to remove the input without removing the front bearing first by dropping the cluster gear. Maybe he'll share how he removes the rear bearing. :)
Nothing special needed to remove the rear bearing either, but you must do a complete disassembly of the case.

Drop the counter gear and remove the input shaft as above. Next remove the shift forks, trunions, springs, and shift rails in order to remove the complete output shaft assembly out of the case. Reverse gear can remain in the case. Remove the countershaft. Then remove the C Clip that holds the bearing on the output shaft. Set the casing on end and put the whole output shaft back into place. Using a block of wood and a big hammer, hit the end of the output shaft which will drive the bearing off the shaft similar to what was done with the input shaft.

To reinstall that bearing, I put the assembled output shaft back into the case and use a 6" piece of heavy pipe as a slide hammer to drive the bearing into place. The pipe must be able to go over the output shaft and yet only contact the inner race of the bearing. After the bearing starts on the shaft, you can set he bearing partually in the case, ensuring that it is sticking out maybe 3/8" from where it normally would rest up against the C Clip that fits around the outer diameter of the bearing.

It really does work and be sure to use a little lubricating spray on the shaft and the inner race before driving the bearing on. If I have gone this far, I normally remove the needle bearings out of the countergear, clean them up and reinstall them with a grease packing then put the dummy shaft back in. The grease helps keep the needles in place and it is much, much easier later on when it is time to install the countershaft in the counter gear.
 

·
Registered
Joined
·
192 Posts
Thx Dennis111, great article. Didn´t know they had BB inputs for SB´s. I also broke an output shaft first. I hope Woodys and Jaysrecipes don´t brake the input, or i kinda hope they do ... ;)
 

·
Registered
Joined
·
4,977 Posts
Discussion Starter #18
Thx Dennis111, great article. Didn´t know they had BB inputs for SB´s. I also broke an output shaft first. I hope Woodys and Jaysrecipes don´t brake the input, or i kinda hope they do ... ;)
Thank you Mosse.

Yep, your right--the new combo just might break the bank. ;)
 

·
Registered
Joined
·
6 Posts
Hey looking and pleading and searching i need a 3 spd overdrive toploader like come in the granada any leads any help would be appreciated??????
 

·
Registered
Joined
·
4,977 Posts
Discussion Starter #20
Hey looking and pleading and searching i need a 3 spd overdrive toploader like come in the granada any leads any help would be appreciated??????
They are pretty common. Lots of them turn up on ebay and FEandgoingbroke (on this board) has/had one for sale in the pacific northwest. Hopefully you posted your request in the wanted ads of this site.
 
1 - 20 of 23 Posts
Top