1st trip w/ T5
- Thread starter Rapid
- Start date
mdjay
Premium Sponsor
You must have highway gears in the rear and a .64 top gear on your trans. Nice numbers for a 42 year old car
You have some room now to add some rear end gears without too much loss up top.
dlf
New Member
Your results are very comparable to mine. My 66 coupe has a 3.00 differential gear and your rpms appear to be very close to what I'm getting at 70 mph. I'm planning to put a new pumkin in the 8" rear this weekend with a 3.55 and trac loc. I felt that the 3.00 was a bit tall for my engine/trans setup and after much consideration, I decided to go with the 3.55.
ratio411
Founding Member
I had 3.42s with a .50 OD on a previous car, and it did 2000 rpm at 80.
1700 at 80 is crazy low.
You must have 2.79s, right? (and maybe some tall tires too...)
I would think you could jump up to 3.25-3.55 and still get decent mpg.
Dave
1700 at 80 is crazy low.
You must have 2.79s, right? (and maybe some tall tires too...)
I would think you could jump up to 3.25-3.55 and still get decent mpg.
Dave
Thanks, My diif does not have its tag but I do believe that it is a 2.79. I am running 70 series soon to be 60 so that will help and I plan a Tru-track with 3.25 gears as the next project. I have always enjoyed my car but it has really come alive with the new tranny!
iskwezm
10 Year Member
Put some 3.55's or 3.80's and youll think it was new engine you slapped it.
I have 3.80s(soon 4.11's) and drive mine pretty far distances sometimes, but im not worried about gas mileage
How would the 3.50s affect the rpm? If I am turning 1500 at 70 mph with the 2.79
what would I turn with the 3.50? Is there a formula? It is a daily driver with mixed city and highway use and I would like to stay flexable.
Thanks
ratio411
Founding Member
Here, you need to know your tire size and such...
http://www.f-body.org/gears/
I was playing around on there...
If you are running 1700 rpm at 80 mph, and your engine is capable of 6000 rpm...
Then your theoretical top speed is 280 mph!!!
You need more gear...
personally i like this calculator. http://www.mustangworks.com/analyzer.html
if you scroll down there is a gear with tire diameter calculator. It is for the t-5's. I know there are different 1st and 5th ratio's but it gives you a ballpark if you want to enter different rear gear ratio's. Personally i believe the 3.73 rear gear with the t-5 is an awesome combo. so at 80 mph withh 3.73's you would be turning 2600 rpm.
if you scroll down there is a gear with tire diameter calculator. It is for the t-5's. I know there are different 1st and 5th ratio's but it gives you a ballpark if you want to enter different rear gear ratio's. Personally i believe the 3.73 rear gear with the t-5 is an awesome combo. so at 80 mph withh 3.73's you would be turning 2600 rpm.
67 Evil Eleanor
New Member
You need more gear, why not a 4+ with that final drive of .63 or so. I personally like a .82 final and perfer a 370 or 350 (I have both and have learned thru the wallet). The .67 with a 370 is still sluggish in 5th unless you plan to change at about 130 or 140. But thats just me. 
iskwezm
10 Year Member
blown65
Founding Member
Similar threads
