swapping fifth for economy?

vristang · Apr 25, 2005

I finally pulled the 408 this weekend. While the motor and trans are out, I would like to look into swapping out fifth gear for better economy.
Does any one have links for gear retailers? I will be doing this myself, as I do not trust many shops anymore.
Any one swapped fifth and have a story to share?

Thanks guys!

vristang · Apr 25, 2005

One more question. A friend I have since lost contact with used to have a calculator for gears, tire sizes, speeds, rpms, etc. This was flat, cardboard, and about 8" in diameter. Does anyone know what I am talking about, and where I can get one?

vristang · Apr 26, 2005

Not one response!???

Maybe I should ask what shifter I should put in my car. Car RamRod got 23 responses last I checked.

Are you guys turning RICE on me!?!

I guess I'm on my own

5.0Droptop · Apr 26, 2005

may not be what you wanted but here is a chart,

http://www.50tech.com/articles/pictures/GearRatioCharts.jpg

vristang · Apr 26, 2005

Thanks.

Not exactly what I was looking for but it does help.

Car RamRod · Apr 26, 2005

vristang said:
Maybe I should ask what shifter I should put in my car. Car RamRod got 23 responses last I checked.

relax. not too many people change gears for economy. just be patient.

5.0Droptop · Apr 26, 2005

I think mustangworks.com has several calculaters for tires and gears etc.

vristang · Apr 26, 2005

Car RamRod said:
relax. not too many people change gears for economy. just be patient.

Hope you didn't take any offense RamRod. But I have had a few responses since the rant! And nothing before the rant.

I don't see why more people don't consider swapping out fifth for economy. It won't affect performance at the other gears, and cruising will be more enjoyable.

Car RamRod · Apr 26, 2005

vristang said:
Hope you didn't take any offense RamRod. But I have had a few responses since the rant! And nothing before the rant.

noo problem. but btw, sometimes when you rant it just annoys people and they dont answer. but it workd here so rant on lol. gl

jrichker · Apr 26, 2005

I don't recall seeing an option to change 5th gear. Evidently, no one else does either.

See http://www.hanlonmotorsports.com/ or http://www.ddperformance.com/index2.htm for parts to see if it can even be done.

vristang · Apr 26, 2005

Thanks for the replies and the links.

I am looking into it further.

Car RamRod · Apr 26, 2005

have you considered a t56 swap?

runningmole · Apr 26, 2005

Car RamRod said:
have you considered a t56 swap?

What he said

vristang · Apr 26, 2005

Last I checked the t56 was kinda pricey. Not quite in the budget for another year or two.

I have found a book which states that the lowest fifth gear (in production cars) was .625 and that it is only offered in the '84 V8 and the SVO trannies. Unfortunately the book only covers Mustangs. What I have seen on the t56 is that it has a .62 sixth gear. Not really cost effective if you just want to improve cruising economy.

Car RamRod · Apr 26, 2005

Im guessing this is out of ur budget, but you could always get a lower ratio rear, and a t56. that would lower rpms while cruising, but the extra gear would make up for the loss in rear end ratio. food for thought, but yeah money dont grow on trees.

vristang · Apr 26, 2005

Car RamRod said:
Im guessing this is out of ur budget, but you could always get a lower ratio rear, and a t56. that would lower rpms while cruising, but the extra gear would make up for the loss in rear end ratio. food for thought, but yeah money dont grow on trees.

Good Point. Here are my thoughts

I currently have 3.27gears. If I drop down the rear end gears to 3.08 or lower I will gain fuel economy, but also lose performance in 1, 2, 3, and 4th gear. I want to swap fifth out so that I will maintain the performance in 1-4, but get better fuel economy in a gear that is basically only good for cruising anyway. I had the car up to 125mph once and still had room left in 4th gear!
After driving the 408w for a short time I think I could actually cruise at about 1100-1500rpm. I'll have do to some algebra to find the fifth gear ratio I would like, I guess.

vristang · Apr 26, 2005

I just did the calculations. I was not able to measure the tires so I had to calculate the tire diameter from the rpm I used to run at 70mph. Tire size came out to 26.62", which seems reasonable.
In order to run at 70mph with 3.27 gears I would need a fifth gear ratio of .519.

Anyone know where to find it?

Car RamRod · Apr 26, 2005

gl on that one

vristang · Apr 26, 2005

There is hope!

The T56 is available with a 6th gear of .5

Jkstang78 · Apr 27, 2005

Here are a few more places.
http://www.g-forcetransmissions.com/default.htm

http://www.ttcautomotive.com/English/home/home.asp

swapping fifth for economy?

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