gear ratio

walts 66 · Post by **walts 66** » April 25, 2010, 11:15 am

Hello, been a while since I have been to this forum. Too busy trying to get my small painting business started. Anyway, I'm having a rear built for my 66. It has a 240 with a cam and fore barrel carb. T18 trans The rear is a Dana 60 with 354:1 gears. I'm going with a ford 9" and I'm not sure what gear ratio to use. I would like it to be a bit higher ratio for highway and mpg. Any thoughts Tks.

Uncle Skip · Post by **Uncle Skip** » April 25, 2010, 12:18 pm

3.25
U@ss

walts 66 · Post by **walts 66** » April 25, 2010, 12:43 pm

I was thinking 325 But what about 300 a little to high

fmartin_gila · Post by **fmartin_gila** » April 26, 2010, 7:23 am

I kept the 3.70 in my 62. Installed a T5 and is now comparably to a 2.70 and the 223 still does good at highway speeds.

Fred

BarnieTrk · Post by **BarnieTrk** » April 26, 2010, 10:06 am

walts 66 wrote: I'm having a rear built for my 66. It has a 240 with a cam and fore barrel carb. T18 trans The rear is a Dana 60 with 354:1 gears. I'm going with a ford 9" and I'm not sure what gear ratio to use. I would like it to be a bit higher ratio for highway and mpg. Any thoughts Tks.

Is the gear change the only reason you're wanting to change the rear out?
If the Dana is in decent shape, I wouldn't change it.

walts 66 wrote:I was thinking 325 But what about 300 a little to high

Do you plan to do ANY towing or significant hauling with this truck?

If so, your 240 needs the additional gear for the torque to get you going.... If you had a 300-I6 or a larger V8, you may be able to live with a 3.00 gear, but I'd bet you'd be REALLY be disappointed

with a 3.00 gear behind that 240; -- even considering the granny gear in the T18.

If the Dana is in good shape, and the planned truck use is just as a daily driver, with maybe some light hauling in its future, then I'd suggest you leave the Dana, and switch out the T-18. While Fred's idea to go to a T-5 transmission is a good one, unless you happen to locate a good one for cheap, I think you would spend less $$ if you went to a T170 Series 4 speed Transmission.

They are commonly referred to as a: 4spd/OD T170FT (Code-RTS). They are a top-loaded 4 speed with 4th being overdrive. It has an aluminum case and shift tower. They are found in Ford F100-F250 light duty trucks from 1984-85, also known as a TOD (Toploader or Top shift Over Drive (meaning the shifter is on the top - rather than the side). They came in many 2 and 4 wheel drive trucks and were mostly put behind 300” 6cyls and 302 V8s. You would likely want to get the T170FT transmission bracket/crossmember if possible and have your driveshaft modified or a new one made, but both tasks are easy enough and cost little $$.......

Just my 2 cents,
BarnieTrk

walts 66 · Post by **walts 66** » April 26, 2010, 11:44 am

Well I was going to keep the dana until we took it apart. The gear cluster barrings are so bad the diff. was moving side to side and tore the housing up. I can go with a new dana from moser but I like a higher gear ratio. I'm going to take some long trips and it's my daily driver. I don't haul much or tow and gas is not going down .

BarnieTrk · Post by **BarnieTrk** » April 26, 2010, 1:03 pm

Ahh,,,,
Well, one good thing about switching to a 9" rear, is that switching gears isn't as difficult as with the Dana.

If you do the rear end switch with the 9" and it has a good/used 3.00 gear, try it for a while.
If you determine that the gear is too low, you can locate another good/used center carrier section already set up with the next gears you'd like to try ( 3.25, 3.50 or ?? gears). Just pull the axles out, drop the driveshaft and then pull out your center section and slip in the next trial center section, re-attach the driveshaft and push your axles back in and run it a while to see if you like it better.

Make sure that the two center sections have the same 28-spline side gears so the axles will be compatible.
You can exchange the driveshaft yokes between the two center sections if need be......

Good Luck & keep us posted on your progress!
BarnieTrk

walts 66 · Post by **walts 66** » April 26, 2010, 1:18 pm

Tks BarnieTrk I should have it put in, in the next week or so I'll let you know.