Final Drive ratio, will a 3.25/1 be too steep ??

[bschulze]

OK, please visulize a 1953 V8 with 3-3/8 x 4 inch, triple 97's on an Offy in a 1928 model A pick up.

Low profile tires, 16 inch spokes. An isky 3/4 cam also.

An S10 5 speed with a high gear .87 overdrive. I'm putting a 9 inch Ford rear end in it.

I have a chance to buy a 3.25/1, 9 inch drop out gear set for $200 out of a F150. Do you think the 3.25 would be too high a ratio for just bopping around town and and highway travel to get there??

I would appreciate your experiances shared.

Thank you,
Bob Schulze, Council Bluffs, Iowa

[HDowse]

The 3.25 with the .87 OD gives a final ratio of just under 2.83. Use this calculator and plug in your values to see what RPM you’ll be turning at a certain speed. The tire diameter is the outside diameter of the tire not the wheel size. I suspect you'll have enough HP to use that setup. If you do go that route, let us know how it works.
http://www.advanced-ev.com/Calculators/TireSize/

[alanwoodieman]

depends on two things--weight of vehicle and first gear trans ratio. I have the same ford truck rear end in my 3/4 ton truck with a 28 tooth cluster (auto) and it can be a little hard getting started off on a hill in traffic. I had the 3:50 rear gear before this and really should go back to it but I do like the higher highway speeds

[pistonbroke]

With the overdrive I would go with 3.50. It will work much better in town and a lot more fun to drive. Just a FYI I would have went with the ford 8" . Much lighter rotating mass as well as the entire drum to drum weight. you will not brake one with a flathead. It sounds like you have a sweet setup regardless, Tim

[40cpe]

Some of the S10 5-speeds have a 4.06 1st gear. If you do have a 4.06 first gear and a 3.25 rear, you will have a 13.195 to 1 low gear compared to a stock ratio of about 10.66 to one. If you go with a lower ratio (higher numerical) rear, the low gear will be even worse. With a .87 fifth gear you will be at about 2205 rpm at 65MPH assuming a 28" rear tire. In my opinion, the 3.25 would be the better ratio.

[Ggmac]

Sponsored Links (Register now to hide all advertisements)

Are you using a stock cam ? Diameter of tires would help with answering your question.
Do you have or plan to drive where they have hills/ mountains ?

[Tim Ayers]

Originally Posted by Ggmac

Are you using a stock cam ? Diameter of tires would help with answering your question.
Do you have or plan to drive where they have hills/ mountains ?

Looks like he mentioned an Isky 3/4 cam. I'm assuming Max1, but would like to know as well.

[Old Redneck]

Mt buddy put a set in a 40 Ford 2 door sedan and they were very nice. Super nice on the Interstate and no problem on the hills. I think I am going to try a set in my 32 Stock V-8.

[36coupe]

What revs do flatheads like to cruise at?
Can they run at 3000rpm all day or is 2500 a better speed?
What’s redline on a stock flathead?
Not trying to hijack the thread but it is kind of relevant to the question.

[pistonbroke]

I had a set of 3.00's with a fresh all stock 255 in my 42 pickup with 6.00 16's. It was way to much gear and a real dog unless you were doing 60mph or better on flat highway. It didn't do the clutch or the rebuilt three speed any favors. Looking back I wish I had gone with 3.50's. Tim

[Ol' Ron]

Not really, But why? 3.5/3.7 would make it more fun to drive. But, I live in Vermont!!!!
Gramps

[tubman]

Originally Posted by 36coupe

What revs do flatheads like to cruise at?
Can they run at 3000rpm all day or is 2500 a better speed?
What’s redline on a stock flathead?
Not trying to hijack the thread but it is kind of relevant to the question.

I find that anything over 2700 RPM and the engine seems to be "unhappy". 2300-2500 is optimum with a stock (Mercury 1CM) cam.

[Bored&Stroked]

You have a light car, so you'll probably be just fine - especially with a .87 OD. Are you sure the OD is that ratio? I've never seen that ratio in a T5 . . . but there is a first for everything. I've installed special road-race OD gear sets with a ratio of .80 - but that is as close as I've seen to your listed ratio.

What is your 1st gear ratio?

[Pete]

You guys sure like to lug an engine.

[V8COOPMAN]

Originally Posted by Bored&Stroked

You have a light car, so you'll probably be just fine - especially with a .87 OD. Are you sure the OD is that ratio? I've never seen that ratio in a T5 . . . but there is a first for everything. I've installed special road-race OD gear sets with a ratio of .80 - but that is as close as I've seen to your listed ratio.

Dale ...... What's one lousy digit among friends? All joking aside, this fairly comprehensive list (seen in link BELOW) does show quite a few of the early
"S"-truck, wimpy-assed T5s as having an .86 for an O/D ratio.

http://www.britishv8.org/Articles/Bo...T5-ID-Tags.htm

Of course, the majority of these all have the weenie gearsets with the worthless 4.03 or 3.76 1st gear ratios. And remember, MOST T5 gearsets won't allow you to just swap-in that sort of an O/D gear pair without swapping-in an appropriately matching, wimped-out gearset.

The MAIN gear, the FRONT gear on cluster, as well as the O/D gear pair figure into the formula to compute the OVERDRIVE ratio using number of teeth on gears for computation. O/D computation formula BELOW:

Number of teeth on front of cluster gear, divided by the number of teeth on MAIN (Input) gear, times number of teeth on SMALL O/D gear, divided by number of teeth on LARGE O/D gear, equals O/D ratio of 5-speed transmission.

Coop


.

[Bored&Stroked]

I do like the .80 OD gear set - have installed it in the Cobra-Z version of the T5 (Ford motorsports transmission with the 2.95 gear set). We have that transmission on a road-race Fox Body - with a 3.73 rear. We spin the 331 to 6500+ and still it takes a long track to be able to use the OD at all.

[Pete]

Originally Posted by Bored&Stroked

I do like the .80 OD gear set - have installed it in the Cobra-Z version of the T5 (Ford motorsports transmission with the 2.95 gear set). We have that transmission on a road-race Fox Body - with a 3.73 rear. We spin the 331 to 6500+ and still it takes a long track to be able to use the OD at all.

I have the same gear set (#202) in my T5 that is in the model A 2 door.
8 inch Ford rear end with 4.10 gears.
Actually it is the short throw shifter and the 3 drops of carbon tet in the ATF that makes the car go so fast.
That alone is good for 10 mph.

[cadillac512]

Originally Posted by pete

i have the same gear set (#202) in my t5 that is in the model a 2 door.
8 inch ford rear end with 4.10 gears.
Actually it is the short throw shifter and the 3 drops of carbon tet in the atf that makes the car go so fast.
That alone is good for 10 mph.

[Westernswede]

If you live in Iowa that should be perfect. I just need a post count of 9 before I can PM to buy parts. Thanks, I got another one.

[bschulze]

I checked with a buddy that has a T5 chart. Checked the tag on the trans and it charted out as :
3.97 1st,
2.34 2nd,
1.48 3rd,
1.00 4th,
.79 5th.
so top gear is .79. I was off a bit .