Manual transmission?

[2+2GT]

OK, that gear is toast. You'll have to look it over VERY carefully, the sychro may be damaged as well.

D.Hearne is right, that trans has the short 390 input shaft, and the output shaft and housing are too long for your Mustang. I'll be easier to sell and start over than to fix all that.


New Rear shaft $180.21
New Tailhousing $283.50
Input Shaft $164.86
Second Gear $110.88

These things get expensive real fast when they need repair.

 

[firemansam]

that i see... hmm well thanks for the info guys...

 

[firemansam]

What were the possible spline counts on those shafts for those modles? i have a picture of my input shaft and i can count like 5 or so splines... I have a source for transmission parts at a good deal but dont know what to tell him on the specifics for a new input shaft and output shaft...

 

[D.Hearne]

Nearly All Ford manual trans inputs were 10 spline. The 390 transmissions got the smaller 1-1/16" diameter input, but with a shorter front snout like the bigger, big block input had (1-3/8" x 10 spline)

 

[firemansam]

i have decided that it would be worth my while if just for the knowledge and experice to rebuild this tranny and convert it to work in my car... what i am trying to figure out is what parts i will need, I am aware of these particular parts:

The longer input shaft 1 1/16" diameter
the shorter tail shaft (length?)
the shorter tail housing
and of course a new second gear and synchs...
as well as new bearing and seals

did i miss anything and what are the specs on the tail shaft that i need?
also, i have the opportunity to convert to a wide ratio from the close that this one is. that being said since i dont have my rear gear set yet can i run the close ration and a certain rear gear and still be fairly streetable? (i am lookin for nothing worse than my truck which is 2k at 70) plannin on some 17" wheels and sensible rubber on them. also if i switched to wide ration what would be a good gear ratio? i was figuring just as a guess before all this to run around a 3.50...
thank you guess for all the help so far! and for all that is to come, i know yall can help me figure this out haha!

 

[dennis112]

Unless you plan on road racing there is no negatives to converting to a wide ratio toploader. The lower gear is beneficial for initially getting the vehicle rolling. The gear spread is nicer and each gear above first pulls longer during acceleration compared to the close ratio.

I like fast shifting a close ratio but that is because the gears are spaced close together. You still have to get the vehicle initially rolling in order to get to the fun zone. Also, if you ever plan to haul fat chicks or go to the drags, the wide ratio is much, much better.

A Mustang uses a 14" long tailhousing and the main shaft for these is 24" long. In most cases a common 28 spline main shaft will suffice, but there is a 31 spline shaft that is 100% interchangeable if you get the accompanying tailhousing, and driveshaft yoke. You should not need this unless you plan to drag race. Also, to go up through the shifter hole, you will need a tailhousing that has mounts the shifter on the rear. The top tailhousing in this photo has the proper location (it came from a 65/66 mustang

The tailhousing shown on the bottom is one of David Key's universals. It has multiple shifter locations.

A 3.50 gear would be a nice street choice and you will absolutely love it with a wide ratio transmission. Even if you don't change gears right away, the wide ratio will work fairly well with the lower numerical gears that your automatic car probably came with.

 

[2+2GT]

did i miss anything and what are the specs on the tail shaft that i need?
also, i have the opportunity to convert to a wide ratio from the close that this one is. that being said since i dont have my rear gear set yet can i run the close ration and a certain rear gear and still be fairly streetable? (i am lookin for nothing worse than my truck which is 2k at 70) plannin on some 17" wheels and sensible rubber on them. also if i switched to wide ration what would be a good gear ratio? i was figuring just as a guess before all this to run around a 3.50...
thank you guess for all the help so far! and for all that is to come, i know yall can help me figure this out haha!

The 289 High Performance came with the close ratio and 3.50 diff. IIRC, so did the BOSS 302. You'll be fine.

As for reconfiguring your trans, you'll end up with what you want, it'll be in top shape, and you have satisfaction it's done right, and of course bragging rights.

Any decent supplier can get you the stuff you need to reconfigure and rebuild the trans. I use Glazier Nolan. They could even send the stuff to the sandbox, if your crazy enough to do it there.

 

[D.Hearne]

Believe me, you're better off selling it than trying to convert it. The longer tailshaft is also the mainshaft, you'll have to replace the input shaft, mainshaft and tailhousing. The mainshaft's going to cost you big bucks. David Kee has all these parts David Kee Toploader Transmissions, Inc.

 

[firemansam]

I have been lookin at the Tailshaft housein from david kee... was most likely going with it, and i have found a main shaft for about 150 (the 28 spline 24 inch) all in all internals to rebuild as is looks like about 500 and then the tail shaft for 300 or so still not bad for the experience that would come with it and at about the same price as buyin one already built... but then i am not right in the head and tend to take the hard way some times just cause i can! but thanks for the info i will be sure to post some stuff on it when i get home and get to work on it! (i am not crazy enough to try to do it over here! shipping the beast back home would break me and i make really really good money! haha)

 

[D.Hearne]

Well if you've got the parts, go for it. They're not hard to take apart or assemble. But you will need good instructions on how it's done. David Kee includes the old instructions from the 1964-1970 Motor Repair Manual with his kits. I've done two and used the instructions and everything went smooth as silk. I will recommend not mixing gears from different trasnmissions though, the gears wear in together and if matched with ones from a different unit, will result in excessive noise (I had one such sound like I had a supercharger under the hood) No special tools are needed to do one. Just a hammer, punches and snap ring pliers.

 

[firemansam]

by mixing gears you mean what? like swapping a second gear for a new gear without replacin all the gears or swapping in a new gear from a wide ratio to the close ratio without swappin all of them? i am not following you. but i will definately see about gettin the instructions from him! i am not scared to read directions when i do something! i just dont let people see me do it! haha

 

[firemansam]

Also, would i need to change the cluster gear if i were changing from the Close ratio to the Wide? any other parts i would need to change? i am sure first second(its broke so its gotta get replaced already) and third maybe but 4th will still be a 1:1 right?

 

[D.Hearne]

I meant swapping gears of the same ratio. They tend to wear in together and dropping in a newer gear or one from another transmission will result in gear whine. And, yea, you'll need to change all gears going from close to wide ratio, cluster gear included. You will basically be replacing everything in going from long to short shaft and close to wide ratio. The only part you're going to reuse is the main case and a few small parts.

 

[firemansam]

ok cool i am good with that! thanks for your help D.

 

[D.Hearne]

Oh, and you asked about 4th gear, that's integrated with the input shaft, so you're already changing that too by going to the longer input. Make it back safe. Got a son who's been over there a couple times with the Marines.

 

[dennis112]

To swap from close to wide, or vice versa. Replace the 2nd, 3rd, and 4th (AKA input shaft) gears. Replace the cluster gear too. Four items, that's it.

Every thing else---1st gear, the sychros, brass blocking rings, the output shaft, shift rods, case, tailshaft, tailhousing, reverse gears, shift forks, bearings, seals, etc are all the same irregardless of ratio. If you happen to buy a new cluster, then consider matching it with a new 1st gear so that they better mesh together. If you buy all new gears, then plan on buying new sychros too. I have had good success over the years with used gears if they appear serviceable.

The relative ease of swapping ratios plus the 40+ years of these thing being in the field often means that the ID tag is worthless when identifying what a particular tranny currently is (and will fit) in this day and age.

 

[firemansam]

dennis thanks! I agree that there is no garuntee as to what is actually in there but given that second is already shot i will go ahead and replace it all and pick either the wide or close (still debating) but likely go wide!

and D. I want to thank your son for his service! Wish i had of had the drive to join up when i was young like so many of my friends but i am doin what i can by fightin fire for them while they are serving!