39 ford
 

what is a good gear ratio for my 39 ford to drive it on the highway I think the rear end now is 378 thanks

Re: 39 ford
 

First Look under the rib of the banjo near the flange where it connect to the torque tube..It should be stamped: 9-34 or 9-37. 11-39 would be 3.54.If it is in fact 3.78 (9-34)you could run a larger tire like a 700X16.

Re: 39 ford
 

I think it depends on your area. Around here we have a lot of hills so I prefer the 3:78. Allows good acceleration from a stop, hill climbing power and decent top speed.
If your highways are for the most part flat and you'd like to go a bit faster than the 3:78 will allow, the 3:54 is a good choice. But, remember you still have to stop and steer so 70mph while possible with the 3:54 may not be prudent to (fully) utilize.

Re: 39 ford
 

I have found 3:54 to be a good ratio while changing your transmission gears to 29/15 gear combination. I have this ratio in tudor sedans and it handles well on moderate hills. I haven't ran it in the mountains.

Re: 39 ford
 

The difference between 65 and 75 mph is significant when it comes to steering and stopping ability. 65 seems to be the sweet spot in that area at least with my car. These cars were not designed to run 70-75 mph. In my opinion, for what it is worth you need to find the best gear/tire combination that will make it run comfortably at a safer speed. If you need to stop fast at 75 mph you might need an escape plan.