Here's the story- (Grab a cold one cause it's long - LOL)
I have a 75 that I picked up last year in project shape. It had no motor and no trans installed but came with both. The trans was an auto 350 and the engine had been rebuilt but not run. Engine is bascially junk - they turned the crank .10 but did not camfer the oil holes so the bearings have scored grooves in them, they punched it out .30 which is okay looking, the heads were rebuilts from a 305, the cam looks stock. Needless to say I have torn it all down and will build it to my design (450hp+) range.
So after getting into it this far, I decided "Full Frame Off" - of course.
I was going to go automatic 200R4 or 700R4 - but I started researching and following the T5 swap threads here.
So now it will be a manual. I started collecting parts thru various sources.
I have a 93 Mustang T5 tag#13-52-208, and the brake+clutch pedals, 2 bellhousings (one hyd one manual), a 11' flywheel and shifter.
The rear end was the stock 2.73.
I just picked up a really nice 4.11. (I had a 4.11 and a BW Super T-10 (2.54 1st gear) in my 67 Camaro back in the 70's and I just loved that launch. So I am changing it to that along with new 3" half shafts and solid ujoints. Rear end will be totally done over.

Now the question (finally! -I know)

I want the HP but I also want the fuel economy of overdrive.

I know that ideal 1st gear total is 10-1 and with the 4.11 that means somewhere around 2.43 for the trans 1st gear. The T5 I have is a 3.35 1st gear and the lowest that I find stock in a T5 is 2.95.
Now a M-21 or M-22 or a Super T-10 would put me in the 2.20 - 2.54 1st gear range but they are 4 speeds with a 1.0 4th gear.

I do not want to go big bucks but am not opposed to changing either a 4 speed into an overdrive setup. There are companies online that will supply a .83 (?) 4th gear replacement. That is one option - anyone done this?

Or I could stick with the T5 as is but will be shifting real quick out of 1st. Total 1st gear ratio would be 13.77

Or I could change the first gear ratio in the T5 to 2.95 which is still 12.13 total 1st gear ratio.

Okay guys! Jump in and tell me what you think is my best choice. Please do not add suggestions like a TKO550, Kiesler, etc.

Thanks for your input!

Peace
Bman

 

ttt

 

I found that a set of 3:55 diff gears with your T5 first gear worked great in my 79! You still have to shift pretty quick, but no matter what you run you will be out of 1st pretty quick.
Bernie

 

Thanks Bernie,
BTW I followed your T5 project - one of the reasons (along with Norval and Sly) that I am contemplating this. I had almost pulled the trigger on a 700R4 from Maddog Lou in FL.

What was 1st gear in your T5 with your 3.55 diff? 2.95 or 3.35?
2.95 gives a 10.47 final and 3.35 gives a 11.89, which is pretty high over the ideal 10-1.

So - should I dump the 4.11 idea for the street? go with 3.73?

What's your suggestion?

Txs again
Bman

 

Mine was 3:35 in first. For the street with that first gear the 3:55 diff gears was great still gibving me 2000 at 70 in 5th gear. If you are going to drag the car You might want to consider 3:73s. But if I was wanting strictly a drag racer I would go with a built 2004R auto.
Bernie

 

Txs Bernie,
No I will not really be going to the races. I just like the muscle car feel of a stick shift.
So your suggestion would be for a "street" car and economy cruiser to drop the 4.11 if I keep the T5 and go no higher than 3.73?
Txs for your time.

Bman

 

No problems! I had excellent performance with the 3:55s and went from 16 mpg to 21 mpg on trips!
Bernie

 

Live with the short 1st gear. I did for many years. Yes I had to shift about 1/2 way across the intersection but it sure made for a quick launch and it sounds great to hear a car start off and rev out so quick.
The tranny is very desirable. I don't know if it needs the double adapter plate or not but a quick measurement will tell. Actually the double plate is easier because the mounting bolt at 1 or 2 oclock is a problem with the single plate and no problem with double.
After 1990 the gear quality was better and were a little stronger. I did a 94 a few summers ago with Carguy4sure and the double adapter and it was easy.
With 4.11 and a .68 overdrive you have about 2.9 on the open road of 2200 at 60 and 2500 at 70 and a wicked out of the hole 1st

 

Thanks Norval.
I knew that I could count on you for advice.
I have the 7.18" shaft which I believe requires the single plate adapter.
Appreciate your time
Bman

 

I am currently running 3.08 gear in the back and I love it.
I can lay as much ruber down in first, spin them a bit in 2nd and even chirp them in 3rd. And with this set up I am turning approx 1900 rpms in 5th at 70 mph.

 

Thanks Sly,
I guess with a 3.35 1st gear almost any rear end in the 3.00 range will be quick.
Back to the drawing board I guess.
Anyone else have a suggestion? Maybe list what you have in your T5 and your rear end.

Peace
Bman

 

I have responded many times on this forum to T5 questions. I know that there are several huge threads in regards to putting T5's in Vettes, that in fact I've added my opinions to.

Basically as I mentioned before. I don't understand the exercise in putting Ford units in GM cars when there are GM T5's. All the Ford units have the 3.35 1st gear UNLESS you have the aftermarket Motorsport or 246 or 251 model. Both never issued in a Ford Product.

The 3.35 ratio is weaker compared to the 2.95 ratio, but for a normal driver it will be fine. You can get .83 OD & .73OD sets for the 3.35 since the stock 3.35 comes with a .68 OD. People have made up these adapter plates to mate the Ford unit to the GM engine. Oddly if you just stick a GM unit in the car which has a longer length shifter you'll probably be about 1/2" farther back then the Ford with the adapter. I don't know if thats good or bad since I never did a conversion. What I can tell you is that the Ford units are 19.5" from the front face to the shifter centerline and the GM Camaro / Fbody units are 21".

Here is the problem. These conversions to me are always small budget conversions. So if your not willing to spend $400 to $600 to add different gear sets in the unit, keep what you have and make it fit!

 

Thanks Paul for the input.
I have read almost every T5 thread that I could find before posting this.
The opinions presented by most members was that the Ford T5 was much stronger than the GM T5 which is important if going to tie it to a 400+ motor. Also the shifter location was more desirable.
As I am still in the planning and parts accumulation phase I'll take your points into consideration. Thanks for your time. I'll be contacting you when it is time to get what I need.
Again thanks to ALL members of CF.

Peace
Bman

 

Here are some pics of my install.
Bernie

 

Bernie,
Awesome pics! Really close detail.
Thanks a lot. I know some people think that this subject gets beat to death, but some of us are still in that stage and extra info helps.
Txs again.

Bman

 

Bman,
If you decide to go this route, we will help all we can! Good luck with your mods!
Bernie

 

Actually not true....if my opinion matters.... When Comparing GM world Class factory V8 units to a Ford Factory V8 WC units. Most importantly only these comparisons can be made with NEW transmissions.

Factory Fords are all 3.35 1st gear with a .68OD

The GM's are 2.95 1st gear with a .63 or .73OD.

You can look for yourself on the Tremec website to see ratings of 3.35 boxes versus 2.95 ratio boxes.

see http://www.ttcautomotive.com compare model 260 to model 251.

Anyway are you buying new? Probably not. You want my opinion? Most used units are junk and its hard to compare how a used unit's life factor may out live anothers...

Adapter plates. Doesn't using an adapter plate stick the Ford shifter back where the GM shifter is... or am I missing something here?

The Ford Input is 1 1/16" diameter 10 spline. The GM input is 1 1/8" diameter by 26 spline..... uh which do you think is stronger? Oddly I've seen many Ford inputs twist but never a GM, but this can't be true...because the member opinion's on this forum say the Ford is stronger... sorry.

The Ford MOTORSPORT unit that everyone looks for has the identical part # gears internally of the GM box!... except that it has a 10 spline smaller diameter input! The Cobra boxes with the pocket bearing inputs are rare and don't seem to offer much of a strength increase anyway.

If you haven't taken a look

Go to http://www.5speeds.com/benchcam

Use the streaming cam and allow the active X control to be downloaded. I guarantee you that although the place is absolutely a disaster zone you will see more T5 parts than anywhere else including the so called "elite" dealers.

 

The reason that most people have used the Ford T5 over the Chevy T5 is that you can easily identify a Ford T5 as being out of a V8 by referencing the serial number, and there are places on the web that tell you what each ford S/N's specs are; and I have seen ford T5's with different first gear and overdrive gear specs. If you didn't see a chevy T5 pulled from a V8 car you can't be sure it is built to a V8 engine's specs. I went with a local Mustang salvage supplier, bought a used T5 and never had a minutes problem with it. If you aren't going to race it you won't hurt it. I agree, using a chevy T5 is a lot easier, but finding one is a lot harder.
Bernie

 

Other than being able to distinguish a world class from a non world class. ALL GM V8 transmissions that came in F-Body V8 cars had a 26 spline input , GM case BOLT PATTERN, exact length input as a Muncie and a shifter centerline 21 inches from the front face. That simple. If its a 14 spline, not a V8... if it has a Ford pattern and 26 spline not a V8 .... it the shifter is located 11.5" from the front face not a V8.

I'm sorry but the Ford's you see with different OD sets and gear ratios other than the 3.35 V8 and over the counter 2.95 ratio .... well are not V8 transmissions.

Also note something IMPORTANT. If you are going the Ford route stick to later 1986 transmissions and up. The 1985-mid 86 WC T5 has a weaker gearset that was replaced in late 1986 due to 3rd gear failures.

 

The bottom line is I installed a Mustang T5 for less than $1500 that worked perfectly and so have many other forum member running as much as 600 HP; all with no problems. I would have much rather gone with a chevy T5 but couldn't find one in a V8 car. The few that I had heard about were much more expensive than the one I bought for $550.00. There are no issues here. I, like most of the others here, went the ford T5 route because they are available, cheaper and are reliable. The first gear wasn't an issue with me, in fact, it was a blast 'cause it would light up the tires anytime I wanted and the .68 overdrive allowed me to go from 16 highway MPG to over 20. Again, I would have rather used a chevy, just couldn't find one I knew was from a V8 car and the adapter plate was easy to make and install.
Bernie