T-5 Conversion from Aluminum T-10

[Shelby_r_b]

Hi,

I've been asking around / going back and forth about doing a T-5 conversion on my 1966 Carryover.

The car has its original transmission, and I have the requisite "popping out of second gear while not accelerating" issue.

I'm kicking around doing a T-5 swap, as I'd love to have the extra gear for highway usage as needed. My previous early 67 GT350 has its original drivetrain as well, and I always dodged getting on highways for fear of winding out the engine or getting passed like I was driving backwards.

My plan would be to remove the original tranny, send it out for repair and save all the original parts.

Please let me know your thoughts / experiences.

Thanks!

[Bigfoot]

I kinda love the 4 speed on a 65-67 with the 3.89 rear.
You don't have to worry about ur 289,....they will rev like that forever.
I drove back from SAAC 33 in my 65 in 85/90 degree heat and had not only a wonderful time but no issues whatsoever. And I was going at a pretty good clip.
Must have been like 300 miles plus.

Oh,...and I drove both ways of course.

5 speed can be fun and I'm not discouraging the swap but don't worry about ur HIPO.
Enjoy
My 2c

[shelbydoug]

The T5 isn't as closely spaced as a T10. The spacing on a T10 is often considered ideal.

What you get with a T5 is a better first gear ratio and an overdrive 5th. I didn't like the gear spacing and went with a Richmond (Doug Nash) 5 speed.

With that transmission first is 3.26 and 5th is 1:1. Gear spacing is modeled after the T10.

What you do to get  the effect of an overdrive in 5th is by dropping the rear end final drive. Depending on exactly how hard you want to accelerate out of first you either go to 3.00, 3.25, or 3.50 rear ratios. Of course you could go to a 2.50 or 2.75 rear if you want to cruise like a Lincoln in 5th.

I have 3.50 s in right now. I have a 3.25 ready to go in. With 3.50s you can almost pull the front tires off of the ground by letting out the clutch normally and nailing the throttle. Tire dealers will love you. You will be in there often for replacements.

Generally speaking, production T5s are not very heavy duty transmissions. They are a bit on the light duty side. You will be ok with a 289 but the more cubes that you load on it, the sooner you will break it.


Nothing is foolproof though. The FIRST time I drove the car with the Nash, I twisted the shift cams off. Seems they were two part and "friction welded" together. No one told me until after I broke them. Then EVERYONE SAID,  "sure, you didn't know?" Some guys can break anything. I get at least an honorable mention on that list. 

You need to use a 1/4" spacer on the original bell with the T5 and you need to finagle the shifter. Other then that it's a bolt on.

The Richmond I used was the Ford 24" length with 31 splines so the driveshaft remained stock.
Depending on which T5 you use you may need to mess with the stock drive shaft.

Incidentally, the Richmond is nice in a GT500 as well.

[Bigfoot]

^^
Douggy laying out the knowledge!

[shelbydoug]

^^
Douggy laying out the knowledge!

I gotta get it out otherwise my head might explode!   

Hope what little knowledge I have helps?

[sfm6s1506]

I did the swap and haven't looked back since. I kept the orig 3.89's and love it. I can rip through the gears and leave the smoke a rolling. It has handled the torque with no issues .
I did the swap 2 years ago. Just my experience with it. Your car do whatever suits you.
Good luck
Jerome

[Shelby_r_b]

Thanks to all for the responses!  And...wow!  Really great information.  To me, this type of information exchange is one of the incredible forum benefits.

And, I'm curious - has anyone switched to a T-5 and later regretted / changed back to the original 4-speed? 

So far, based on some additional feedback, I'm going to drive the car with the original tranny for a while before I make the decision to swap.  Part of me worries about loosing the "feel" of a 4-speed, and not having driven a T-5 before, I'm afraid that I'd make the swap and not know what I'm missing.  The good news is that there are quite a few back roads by me that don't require a speed north of 60 MPH.

...however, this is Texas, so it's not uncommon to be on a single lane road in the middle of nowhere with a 70 MPH speed limit! 

[pmustang]

I have a 66 GT350 and took out the T10 as it was doing the same as yours. I had Orlando Mustang fit a T5WC setup from Modern driveline in the car. I have 3.89 gears. I cannot imagine it being better. Just love it. I also have a T5WC in my in my Shelby Clone. I also sell classic Mustangs here in the UK. To me its the best mod you can do to your car. Requires no cutting/altering of the car and makes is very drivable and hugely lowers the rev's at speed.

And yes you can lite up the tyres at will.

I can probably find the receipt from modern driveline for the conversion if you like.

Also they did struggle with the crossmember supplied by modern driveline and went to another and returned theirs.

Cheers. Peter

[6s341]

I've had a WC 5 Speed in my early '66 for the last 19 years.  Put it in when we couldn't keep the 4 speed from popping out of 3rd...I still have the 3.89 rear end, but a lot more power than the original motor, and it's been great in town, on the highway and on the track.  Feels close enough to stock in the first four gears, but for highway cruising, it dropped the RPMs from around 3500 to the low 2000s at 70 mph...
Cheers!

[Brant]

OK, Ruben. I think that I may have mentioned this to you.

Here's a great chart to compare RPMs and speed based on which tire size, transmission, and rear gear used.

https://www.engineersedge.com/mechanics_machines/transmission-gear-ratio-calculator.html

For comparison, here are the gear ratios for the T10M (close ratio Sebring gears):
1st  2.36
2nd 1.62
3rd  1.20
4th  1.00

...and the World Class T5 currently available from Ford Racing. That is the transmission that you will use if you do the swap.
1st  2.95
2nd 1.94
3rd  1.34
4th  1.00
5th    .63

Obviously, there are tons of other variables that are going to effect the "seat of the pants" feel of the various transmissions and rear gears. Things like driving style, camshaft profile, etc.

That said, this gives you a neat little comparison, and you can spend days comparing numbers! You can thank me later!   Looking forward to the 200 page report!

[shelbydoug]

Good point Brant. I just want to mention that there are other T5 gear ratios available. For instance, the Turbo T-bird transmission has a 4.11 first gear.

I believe that most of the v8 Mustang sourced units are going to have a 3.25 (or in that vicinity) first gear.

Most of the people I know who did the swap used a used Mustang unit from a "junkyard" simply because they are so much less expensive.

The "world Class" mentioned is a higher quality intended for racing abuse that a stock production car normally doesn't see. It would be a great choice.

[pbf777]

     The standard Ford O.E.M. V8 5.0 Mustang installations first gear gear ratio was 3.35:1; post 1986 (?) the terminology of "World Class" was added due to an engineering redesign of the B.W. for the Ford intended production product, as for using T-5 transmissions for other applications (I4 or V6), this would not be recommended for a number of reasons, so don't get tangled up in these "other possible" ratios.     

     As already stated, you would want to use the current Ford Racing product, part #M-7003-Z Tremec ("World Class") Super Duty T-5 (previously as a product from B.W. it was known as the "World Class" "Heavy Duty"), both for it's preferable closer ratio spread as compared with the other T-5s, with the 2.95:1 first gear ratio, which is not that far off in the "feel" of the B.W. T10 ratios of 1st: 2.66, 2nd: 2.10, 3rd: 1.60, 4th: 1:1 (1966?); but even if you do have the version with the 2.36 first gear and associated remainder, as listed in a previous post, I would consider the T-5 ratios as superior for typical street use, particularly permitting the preference for less rear gear multiplication.   

     If you are not wishing to experience the vehicle in it's purest form, as delivered originally, then I would say yes to the conversion to the T-5; as it truly will make your car more enjoyable in overall operation.  The only "rub" (well, except cost) is, it seems in some instances (not all) for proper fitment, it has been necessary to "trim" the shifter opening in the transmission tunnel "some"; seems the result of the cars being the sum of not always accurately bent sheet metal; if this is a Shelby, well, greater efforts may be required to avoid this concern.           

     Scott.

     

[pmustang]

modern driveline sells a shifter relocater but I havent needed it nor have the approx 10 T5 fitted cars that have been through the shop had one.  Seem to remember it being called a slik shift

[Jim Herrud]

... it has been necessary to "trim" the shifter opening in the transmission tunnel "some"; ...

modern driveline sells a shifter relocater but I havent needed it nor have the approx 10 T5 fitted cars that have been through the shop had one.  Seem to remember it being called a slik shift

To put a number on the amount of trans-tunnel-clearance trim required, here's one example: I am putting a Modern Driveline T5z (MD P/N MD-552-0251) with their "Quik Stik Shifter" (MD P/N MD-88-421-204-03) into my '65 Fastback. Even with the shifter relocator, I still had 0.3" of interference with the front of the tunnel opening. I trimmed a 0.4" clearance off the front.  Note that in the distant past, the frame on my car was reported to have experienced a significant collision with a large, hard object. Subsequently, the frame has been extensively massaged and now measures as correct-to-spec. In addition, all my large aftermarket goodies (rack & pinion, headers, etc.) now (finally) fit as intended. Just one data point. Jim

[deathsled]

I have a Ford Toploader four speed with Richmond gears.  Came out of Peter Kutt's racing Hertz.  No popping out of gear issues ever experienced.  Can't bring myself to go to a five speed.  I like to hear the revs way too much.  But highway driving makes me leery of blowing up the engine however Zray has indicated on at least one prior occasion that this is not a legitimate concern.  I have a 5.0 in "the red one" with roller cam and roller rockers.  Came out of a late 80s Mustang set up for drag racing.  Still not issues yet.  Original engine block in my closet (literally).  The ladies are or were none the wiser as it was covered over and sat and sits peacefully on the hardwood floor.  "Happy little engine" as Bob Ross might have said if he painted engines instead of clouds.

Richard E.