Tremec TKO

I have posted on this topic before...at other forums:

I have been involved in 2 Tremec 3550 installs, one in a 66 and one in a 67 and the one thing I can tell you is these transmissions simply do not fit the early cars unless you are willing to do major modifications.....and I mean MAJOR.

Many companies will try and tell you that they have crossmenbers/kits to install a Tremec properly in an early Mustang without major surgery and the only thing I have to say is that they are all liars.....BIG LIARS.

The proper drivetrain angle for an Early Mustang is 3 degrees. For you to achieve this drivetrain angle the top of the Tremec will be sitting above the tranny tunnel.....meaning the factory welded in crossmember needs to be cut completely out at the top or simply removed and the whole top of the tunnel needs to be removed also. Then a new cossmember, floor reinforcements, and a new top for the tunnel need to be fabricated.

Anyone who tells you that the drivetrain angle is not important is simply misinformed or also lying. For a Tremec to fit in an early Mustang without hitting the bottom of the welded in crossmember without cutting it the drivetrain angle will be somewhere between 5 and 7 degrees and severe problems result including but not limited to the following:

- unfixable driveline vibrations
- short U-joint life
- possible hard ot adjust carbs due to severe angle
- fan to radiator interference on some cars
- hood clearance issues on some cars
- less ground clearance
- possible header interference...especially on power steering cars
- sometimes the exhaust will need to be modified to bolt up again
- if you run an SFI scattershield (like youshould) then the mods are even more severe.

I could go on but I think you get the idea. It is a very doable swap and it can be done properly but the majority of Tremec installs are simply not right. If you are willing to do all the surgery needed or are willing to live with some of the shortfalls of an improperly installed Tremec then go for it.

The engine really needs to be moved back .5 inch to get the best shifter position but that is not actually necessary....but nice, and I moved my engine back and will never run one in the stock location again.

You will definitely want to switch to a cable clutch. You will need an all new crossmember. The driveshaft will have to be shortened also.

Good luck. If I can be of further help let me know.

you might want to look into a Gforce T5 if the above post is completely true (and due to the detail, I'd guess that it is). T5s fit pretty easy and Gforces are pretty tough.

SadbutTrue said:

you might want to look into a Gforce T5 if the above post is completely true (and due to the detail, I'd guess that it is). T5s fit pretty easy and Gforces are pretty tough.

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While T-5s do fit much better than Tremecs they also do not fit without modifications. The single rail shifter built into the top fo the case is the problem. It hits the built in crossmember before proper drivetrain angle is attained. So once again, all the kits you can buy are compromises and you will have too much drivetrain angle. You can overcome this with a T-5 by simply notching the built in crossmember and building your own bolt in crossmember to support the tanny and enlarging the shifter hole in the floor.....unless you don't mind having the extra drivetrain angle. It is up to you....mine is notched with a custom crossmember and I enjoy the factory 3 degree drivetrain angle.

Anyone who tells you that the drivetrain angle is not important is simply misinformed or also lying. For a Tremec to fit in an early Mustang without hitting the bottom of the welded in crossmember without cutting it the drivetrain angle will be somewhere between 5 and 7 degrees and severe problems result including but not limited to the following:

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Wow, from the sounds of it, I had better pull the tranny out of Kingsford.
Guess the last 6 years of trouble free maintence has been just dumb luck.
I suppose I'm getting sick and tired of hearing all these "problems" with the driveline angle. With over 400 HP I've yet to have problems with U-joints or any other alledged problems from not cutting up my tranny tunnel.
The choice is yours

2bav8 said:

Wow, from the sounds of it, I had better pull the tranny out of Kingsford.
Guess the last 6 years of trouble free maintence has been just dumb luck.
I suppose I'm getting sick and tired of hearing all these "problems" with the driveline angle. With over 400 HP I've yet to have problems with U-joints or any other alledged problems from not cutting up my tranny tunnel.
The choice is yours

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You can do whatever you want and feel however you like and just because you don't think you have had any trouble is fine....but your drivetrain angle is WRONG no matter what you think or feel and that is pure fact. If you don't want to do it the right way that is fine. I wouldn't want a Tremec in my car because I wouldn't carve her up to make it fit right.

Ronstang,

How do you actually know my driveline angle is wrong.
Perhaps I did something else to the driveline to correct this horrible situation (you'd think the car would have self-destructed by now, LOL).

Ever think of the possibility of changing the angle of the pinion on the rear end?
Guess its not really so amazing now that my Tremec doesn't have driveline issues, eh.
Of course, I could have cut up my tranny tunnel, but that doesn't make that much sense, does it.

If you lowered you engine and changed your pinion angle then I can see how you could have compensated for the issue....but if your pinion is at more angle than stock don't you have traction issues because of it? I'm not trying to be a smartass....I'm honestly curious....there is always room for learning.

i think i'm going to have to agree with 2bav8 on this one, yes it may cause the u-joints to be at non-ideal angles, but so does lowering the rear end, going over bumps, and just driving in general as the suspension moves through its course. Even if it cuts the life of the U-joints in half, thats still what? 50, 60 thousand miles that they'll last?

also, if you're having carb problems from the extra 2-3* that the engine tilts back i'd hate to see you drive your car on a hill.

i'll agree with the guy that has done the swap and has the miles on it to back it up.


all in the name of good discussion and fun. happy stangin' everyone.

Ronstang,

A nice set of Cal-Trac traction bars help prevent the rear end from wrapping up.
This is very important as it keeps the pinion from rising, which would cause some poor traction (like you're not going to have traction problems anyway from a motor that requires a TKO) among other things .

I'm going to look for some pics of my engine, one with my old T-5 and one with the Tremec installed. Going to be hard to tell from a photo, but basically my point is you're not going to see the motor sitting (much, if any) lower with the Tremec.
Its actually been from my experience that my TKO fits better than my T-5.
I used to kill tranny mounts with a T-5, I've yet to replace one tranny mount with the TKO.

It is completely fine with me that people do whatever they feel necessary but if a person with no experience asks me I am going to tell them all the possible pitfalls of such an install. Some of the problems may never arise and some might but they are possible. I am one who prefers not to mess with things like drivetrain angle. A slight correction in the pinion angle to correct for lowering is one thing but a Tremec installed with a commercially availabe crossmember is going to have about 6-7 degrees of drivetrain angle which is twice the factory spec. I have been there and didn't want to run the car that way so the only answer was surgery and the person whose car it was was fine with it.

I have had problems with drivetrain phasing before and it is most noticeable at high speeds so most people never even realize it. If you guys can successfully run such large drivetrain angles then it would be nice if you could document all the necessary adjustments you have made to compensate because this converstion is way over the heads of the novice and most people will just buy the crossmember, install it, and eventually have some kind of problem and not know the coause.

I am always open to discussion and feel that a day that goes by without learning something is a day you have wasted....so school me.

I agree on the Cal-Tracs....I have run them on a 600HP street big block Mach 1 (500cid) and they are phenomenal. It was just my understanding that large pinion angles, even with traction devices, were problematic.

to get my Tremec TKO to work right in the 67 with the factory clutch linkage we had to cut the tranny tunnel, add a 3/4" spacer to the Dark Horse tranny crossmember, and also add a couple of wedges to the axle.

been working great for 25K miles behind a 400 horsepower 302.

Wouldn't a richmond 6 speed be a viable alternative to the tremec or is it not quite as strong (I thought it was?)

@ SNIPE

RONSTANG is right. The transmission swap in my 67 was
a lot of work too. The driveline angles are extremely important.

It is described everything on my homepage. Unfortunately only into german. (www.mustang1967.de)

Originally posted by Ronstang
While T-5s do fit much better than Tremecs they also do not fit without modifications.

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I guess I have to plead ignorance here. I have not heard the T-5's with aftermarket tranny mounts install at an incorrect install angle. Do you know what angle the T-5 will install at without cutting the upper cross member and shimming up the tranny mount?

I am in the process of installing a Tremec at this time. I am cutting the tunnel for proper drivetrain angle. I would still like to know what problems exist with the T-5 install as I have several friends that have a T-5 and many others that want to put in a T-5. I used to have a T-5 in mine and never saw any problems, but I only had about 300hp and never really drove it hard because the suspension sucked.

It has been a while since I tried to install my T-5 but if I remember the drivetrain angle was 4-5 degrees and stock is 3 degrees. All I know is that I had to notch the built in crossmember and raise the tanny an inch to an inch and a half to get it to 3 degrees.

I don't have any concrete numbers and I don't want to mislead people so I suggest anyone doing this swap go to Sears and get a magnetic angle finder and do the measurements and see for themselves. Put the angle finder on the rocker panel/door sill to get the reference angle and then put it on the valve cover (carb flange is angled to correct for drivetrain angle so don't use it), and the difference between those 2 measurements is the drivetrain angle....and on all the Mustangs I have measured it has alway been ~3 degrees.

The question was installing the Tremec in a 69 mustang. I hear the earlier models were more difficult to install the T-5 and Tremec. Let's hear from the 69 and 70 owners who had done this mod and maybe they can shed some light.

ron: my T-5 went in without an issue with a modern-driveline cross member.

skywalker said:

ron: my T-5 went in without an issue with a modern-driveline cross member.

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I'm not saying it won't go in without issue....I'm saying your drivetrain angle is incorrect. Whether any of the potential downsides of that ever manifest themselves is anybody's guess. My point is that it is IMPOSSIBLE to attain the factory designed driveline angle without cutting the car some. Go measure your drivetrain angle and see if it is 3 degrees. That is really my only point. To me having the proper drivetrain angle is important...as it is to all the poeple who have asked for my help with their installs. Others disagree and that is fine, but not correct in my opinion.