Rear End Gear Ratio Recommendation

[mryahoo]

Hi All,

I just pick up a 1967 GTX. The car has it's original 440, hemi 4-speed transmission and Dana rear end with 3:54 gears. While the 3:54's throws you back in the seat a few inches off the line, it tachs about 3500 rpms at freeway speeds. A friend recommended 2:79 (automatic ratio), but I'm unsure how that ratio would be behind a 4-speed. Since I'll being showing the car and doing a lot of freeway driving, the 3:54's are not practical. Any input would be greatly appreciated!

Rich

 

[1badgtx]

Even though my gtx is a auto car I went up to 3.55...Most high performance cars came with 4.10s..The best way to go to have the happy medium is a 5 speed tranny...Then you have the best of both worlds...If you put in the 2.79 It,ll be better for the freeway but your gonna lose that off the line umph..Just my two cents..
Petty Blue 67 gtx

 

[Meep-Meep]

I spent a lot of time with 3.0's and a 4 spd in a 68 Mustang GT and it's fine, however I don't think a 2.79 ratio is available for the Dana 60. 3.54 I believe is as tall as it gets. I have a similar issue with my current 69 RR project (4 spd with Dana 60) and my approach to keeping it freeway friendly was to buy the Passon OD gear set for my tranny. If I install 3.70's in the Dana my final drive, factoring in the .8 OD ratio, will be 2.96. Keeping your 3.54's you will end up with 2.83:1 in OD. If you don't have a really tall tire and are good at not torturing the clutch on take off that 440 will have plenty of beans to get you going. The gear spread of the Passon tranny plus the tall rear end gears will allow you to spend plenty of time in each gear!

 

[Cranky]

Hi All,

I just pick up a 1967 GTX. The car has it's original 440, hemi 4-speed transmission and Dana rear end with 3:54 gears. While the 3:54's throws you back in the seat a few inches off the line, it tachs about 3500 rpms at freeway speeds. A friend recommended 2:79 (automatic ratio), but I'm unsure how that ratio would be behind a 4-speed. Since I'll being showing the car and doing a lot of freeway driving, the 3:54's are not practical. Any input would be greatly appreciated!

Rich

The 3.54 was pretty much it as far as a highway gear goes. Dodge had a 3.08 available in the early Diesel pickups but I'm not sure what all has to be done to install this ratio.....

 

[lockerjesse]

It's possible 3.07 Dana 61

Depending on a competent differential mechanic in your area. Find a 1966-early 1970 Ford F100 with a Dana 61 3.07 gears and Powr Lok option (it will have "61" cast on it) they are 5 lug diffs and use the axle thrust button but shim stack instead of spanner adjuster on axles. Differential will have "use limited diff. Lube only" and ratio tag on cover. Late 1970 could come with Trac Loc and will not work. Next buy a set of 8-3/4" weld on housing ends and perch mounts. Transfer your 23 spline Powr Lok side gears into the Ford Powr Lok which has 30 spline side gears. You can retain the thrust button set up for stock set 7 wheel bearings on your axles or do not install the thrust button for Green bearings. Also for extra cash buy a set of cut to fit 8-3/4" axles and retain the Ford Powr Lok as it has the exact same 30 spline as mopar 8-3/4 and Dana 44. Transfer your brakes and Yoke over (may have to buy a conversion U-joint and use Ford yoke if splines are different) and store your Mopar Dana, you now have a street cruiser Dana on the cheap. Only draw back is no pinion snub mount.

 

[mryahoo]

Wow Locker, that was extremely informative - Thank You!

Rich

 

[Cranky]

Now all you have to do is find that 66-70 pickup. I've had only one go through my shop in all the years I've been messing with cars etc. Needle in a haystack man. To get that rear, you had to special order the truck with it and not very many did that. You'd have better luck finding an late 80's Dodge diesel pickup with that 'street' ratio and going from there.

 

[69rtse4spd]

gears

70 Charger, 440,.030 over, auto, put 3:73 in the Dana 60 got tired of the 4:10s in the 8.750. So far love them, I to will put 4-spd in, on waiting list for Passon OD. gear set.

 

[383man]

If you can fit it you could also just go to a taller tire. Ron