Ford 8" Gear Swap and Traction-loc

[Rmoore45]

Hey guys,

Well, I'm tired of my stock 2.79 gears with my T-5 I'm looking to change out the gears and put in some sort of limited slip. I'm looking for some advice on what gears to use (probably going to be 3.25 or 3.55) but what I really need help on is the limited slip/traction-loc device. Which one is the best and where can I buy it?

If you don't know my car, its a 1967 coupe with a mild 289 and t-5 with .68 overdrive which is my DD. I mainly do city driving so I think that a 3.55 would be a good choice but 3.25's would allow for more highway, but anything will be better than my 2.79's.

Thanks, Ranger

 

[Realmongo]

When I rebuilt my 8", I went with 3.25:1 gears and a Detroit Tru-Trac differential. Take a look at either Summit or Jegs and pick out what you like.

 

[horseballz]

Ranger,
If you are well experienced in differential setup, what Realmongo said is the cheapest way to go. I you're not that experienced, this is the beat "value" on the web:

http://www.ebay.com/itm/FORD-MUSTAN...ries&vxp=mtr&hash=item4d00301905#ht_600wt_985

There are a few others that are $50-$100 cheaper, but few have the great rep that this guy "TJ" has and many of the others use cheaper parts. This guy will even tell you, when you talk to him, that his warranty starts when you start driving the car, not when he ships it. I've not purchased from him yet, but everyone I know (many) has been quite pleased with his work. Here is another helpful link. Scroll to the bottom calculator for manual data entry:

http://www.csgnetwork.com/multirpmcalc.html

HTH,
Gene

 

[chris66dad]

I also went with the TJ unit from ebay.
Add up all the costs, for me it was the best deal. I did not have the tools to rebuild my old 8 inch

 

[69Rcode_Mach1]

I say go for the 3.73s. A lot of the 5.0 guys like them with the T-5, I did. If your T-5 has the 3.35 first gear ratio the 3.55s would work fine, but the drivability is not that different between that and 3.73s. I went with the detroit locker and am very happy. Traction-lok still wears and turns into a peg leg. I never have any sort of tire squeaks or wear in corners. If I gas it, it locks up straight and goes, you can feel it engage. I have zero complaints with the locker on the street. Don't do 3.25s as it won't be a huge difference in acceleration for the money.

 

[PoppyMod]

Hi,
I agree with 69Rcode..., 3.25 is a nice C4 auto gear. With the T5, 3.55 to 3.89 is a nice place to be if mainly a street warrior.
Happy Trails....

 

[Rmoore45]

Thanks for the reply's guys I like this forums advice because most people have had experience with different setups. I'm definitely going to go with the Eaton Detroit truetrac however I'm still undecided on gears. I have 3 major choices, 3.25, 3.40, and 3.55. I mainly do city driving so I'm leaning more toward 3.55s or 3.40s but like I said, I'm still thinking.

 

[69Rcode_Mach1]

Go with the 3.55s bare minimum, with you having a T-5 the 3.73s are perfect though. I recommend checking on the 5.0 section and they will tell you the same thing. The fact that it is a street driver and doesn't see a lot of highway time makes me say definitely go for the 3.73s. 3.73s work great on the highway as well with the T-5. 3.73 with the T-5 and 4.10s with the AOD is the general rule you will find with most the overdrive transmissions our cars are equipped with.

 

[jcode68]

+1 on the 3.73's. That's what I'm running with my T5 (also coming off 2.79 peg leg) and I have zero regrets. Geared just right for the T5 IMO and still have plenty of gear for the highway.

 

[Smitten65]

What I've found is that MOSTLY people with 2.95 first gears in their T5's seem to recommend 3.55 or 3.73 or even 4.10. People with 3.35 first gear T5's TEND to say 3.25, 3.40 or 3.55. Granted, tire size comes into play too. Those with bigger tires tend to recommend gears that are higher numerically. I picked a 3.40 trac-loc to keep first gear useful (3.35 first gear with 215/60/15 tires). It kept my 1st gear ratio at about 11.39 and enough RPM'S in 5th gear to keep from lugging with the .68 OD. That ration works out to 2.31, REAL hiway 'gears'. LOL! Also one factor affecting recommendations seems to be whether the engines are stock, mild or wild builds.

If you do the math, you'll see that mostly, people are falling above 10 SLR to get performance of any kind. Toploaders have either 2.32 or 2.78 first a c4 2.46 so you can see why people want more gear with them but are forced off the freeway with the RPMs that come with 65 MPH traffic if they go too high.

 

[woodsnake]

3.55 at a minimum. I have 3.50 in my 68, with performer RPM cam, (.496/.520) and it is under geared for the high way. I have to downshift to pass anyone, and it lugs at 60 MPH...3.73, or 3.89 would be better, with the OVERDRIVE.