tremec tranny?

[Draco]

For those of you using the Tremec TKO, are you using the 5th gear ratio of .68 or TKO II with .82? I'm just trying to decide and any little bit of advice or comments (some cobraphile must have one!) or pros and cons would help.

Draco

[bran3b]

I have te TKO with the .68 fifth. I love it. I have 3.55 rear gears, which gives me around 2000 RPM at 75 MPH. This might not work well with a wild motor, but it works well with a "streetable" 460. I haven't tried any racing yet, but it should do ok (I think).

I only have 500 miles, so I am sure that someone out there has more experience than me, but I like it so far.

[MistressMotorsports]

I have the .68 gear with 3.73 rears and a 393W motor. For street driving, I find the .68 to be great. It's nice to have the revs so low when cruising at 75 or so. For the road course, the .68 sucks. At Willow Springs I need to grab 5th about half way down each straight. The jump from 4th is so great that the motor really falls on its face. I'm going to change to the .82 jsut for this reason. If I strictly had a street car, the .68 would stay.

Mike Eckhaus

[Draco]

I guess I should add, I'm building a 393 with a 3.50 gear.

Draco

[Richard Hudgins]

Draco,

With a 3:50 gear, I would recommend the .82. Actually, I would recommend it with a 3:73.

The gear split is just too big between 4th and 5th with the .68.

Of course, the JBL will not accept a BB, so my knowledge is limited as to how they might work with the .68. With enough torque, it may be OK.

I think what you have to look at is speeds on the street. 75 mph is the maximum that you will using most of the time. The reality is more like 60-65 mph.

Look at the powercurve for your motor and pick the 5th gear that will let the engine run cleanly for street use.

It has been my experience that a 351 based engine that is worked over at all likes at least 2300 rpm for cruise.

[Jack21]

Same with a T-5/351W. With 3.55 gears, and .80 5th, 75MPH is 2500RPM, which is right where I want it for highway cruise and passing without downshifting.

With taller rear gears, 3.73 - 4.10, you might want to use the taller 5th. The 351 with Cobra type cam and heads does like 2300 RPM or more at cruise.

[coyled]

I went to the .82 and like it. Even on the street, the motor does not lug in 5th. I have a 358ci high hp motor. I run a 3.89 gear. If you like cruising at 70 mph and your motor will lug at 2000 rpm or less than the .68 works great. I do use 5th on the front straight at road america. scott

[SCOBRAC]

5th gear at willow? &^%$$#@!@!!

Best of luck..

[niles]

Does anybody know how, who and what it cost to change a .68 5th to a .80?
thx
gn

[DAVID GAGNARD]

Draco;

I have a Tremec with the .68 fifth gear. Although not in a Cobra here is my setup....3300 pound 65 Fastback with a 351-W with 350 hp,RV cam,484 lift,272 dur. fairly mild,running a 3.00 rear gear in a 9' rear end with 26' tall tires,fifth gear 2000rpms=73 mph on the interstate,motor loves this and so do I for the gas mileage,I drive it a lot on the highway.....Still run 12.90's in the quarter mile at around 105 mph,I shift gears at 5500 rpms and cross the finish line in forth at about 4600 rpms.

I originally ran a 3.50 rear gear but had a vibration problem that was a bad ring and pinion and "borrowed" a 3.00 center section to try and loved it so I stayed with it... Gas mileage went up and still has enough pep off the line to suit me.

If you plan to drive it on the highway you may want the 3.50 rear gear and the .68 fifth in the trans. The tremec has a low 1-2-3 gears to get you going especially in a car 1000 pounds lighter than mine with more hp and torque you want be disappointed.....You will still blow away 95% of the cars on the road with this setup.....

Just my .02 cents.....

David

[mikief]

They're aren't too many of those .8 gearsets left. If you do find em, make sure they're both stamped with Ford PN 1352- something. The Mexican gears don't stand up very long. I was lucky enough to find the last .8 driven gear in Tucson. I love mine. Grab 5th at 130 and only lose 400 RPM!

[coyled]

Niles, its like 650.00 to make the change, which I did. I then broke the tranny, third gear. I have sinse baught the road race version. I would be willing to sell the .83 5th as it is still fine. scott

[Specialk]

who is the best source to buy a Tremec?

[pbrown]

Forte's is a supplier of Tremec and sells mostly to the FFR crowd via the other forum. I haven't had any dealings with this company personally. He offers the standard (.68) and the road race (.83) version.

http://www.fortesparts.com/

[Dwight]

D&D IN WI. I BOUGHT A TKO, BELL, CUTCH, YOKE, EVERYTHING I NEEDED FOR $2100 DELIVERED. I THINK THE TKO WAS $1200. CALL AND TALK TO THEM. THEY HAD THE BEST DEAL OF THE EIGHT PLACES I CALLED.

www.ddperformance.com/

PS I LOVE MY TKO!

[justa6]

I've been using the RR version of the TKO. I've got 4.11 gears and the overdrive is perfect for my combination. Expect the trans to be a little "sticky" when its brand new. We took the car to last years run and gun and couldn't power shift it at all (Brand new). However, since then the trans has really broken in well. Car gets "launched" at between 6-7000 RPM with M/T ET streets on it and they don't spin much. Getting 1.4 60' times out of it with ET's in the 10.8 range. Trans has never missed a gear since it broke in. Overdrive makes running on the street very comfortable. My motor doesn't like to be lugged as its only 274 cubic inches and a V6.

Bottom line is I really like the trans (once it broke in). I'm using GM Syncromesh fluid in it.

[wilf leek]

I have the TKO in my car, using a 408W, 3.31 rear end. The shift quality has improved a lot over the first 6000 miles.

Now that I am used to the car, I wish I had gone for the RR version with the 0.8 fith. Although the car will still pull in fith, it's quite a low rate of acceleration compared to 4th.

At the time I built the car, I didn't know about the RR TKO, wish I had found this forum earlier!

[Chaplin]

Wilf-
I was planning on going with a 3.31 rear and using the TKO with the .68 5th and noticed your last post. Are your complaints about the gearing limited to when you are racing or on a track or do you find it to be a problem for highway driving also? What rpm are you turning in 5th @75 mph (I think that's 120 for you English if my math is correct!).

Thanks,
Mike

[Mr.Fixit]

I have never tried the .8 fifth but have alot of experience with the .68 fifth trannies. With a 3.73 rear end gear. fifth gear is freeway only, 0no traffic. I still prefer fourth most of the time so the motor is in a better rpm range (3K instead of teens). The only other time I get into fifth is after 7000 rpm in fourth, and I still need to accellerate, by then you are going pretty damn fast, so this only really happens on the long straightaway at willow springs, and very rarely elsewhere. But, at those times, I would prefer a .8 fifth gear. But if I'm gonna spend several hundred dollars upgrading an $1100 cheapo "hecho en mexico" tranny, might as well get a better one to begin with. The overdrive provided by the ..68 fifth does what it should, improve freeway milage. You just need 3.55's or more to use it under 75.

[Chaplin]

Mr. Fixit-
Do you think that even with all the torque of a 428 the .68 would be too low (is that right- always the confuse the low/tall) with a 3.31 rear?? I probably will never race, but would use a 5th as a highway cruising gear only? Alterntaively, if you wanted the .68 and used a 3.54 rear do you think the 3.27 1st gear of the Tremec would result in 1st gear being too short and result in excess wheel spin without a lot of usable power??


Thanks,
Mike