Which Gears To Choose?

[Mustang Jim]

Well, I've finally had it with my 2.75 gears on my 64.5 coupe. I want to switch to a higher ring & pinion gear (numerically), but I am not sure which to go with. At first I thought about 3.55's, but I am concerned that it might be a bit too much for the 3 speed manual and 260v8. I am now considering 3.25's as it will keep the rpm's down on the highway. A quick calculation shows that a 3.55 gear with 215/70R/14's will put me at about 2800 rpm at 60, while a 3.25 gear will put me at 2550. The car is not a daily driver, but I do want to take it on the highway from time to time without the engine screaming. What do you guys recommend? Will going from 2.75 to 3.25 give me a significant improvement from a standstill, or should I just go for the 3.55's?

 

[allcarfan]

it will give you a good improve ment. 3.25s are good highway gears

Can you tell me where you found that calculator for engine rpm? Dont you have to know what your gear ratios are inside your trans for that to be accurate?

 

[351pacecar]

Even 2500 rpms is alot for cruising with a v8.

I wouldn't personally go over 3.00 with a 3 spd, but then I would stick the 3 spd on a shelf where itll sit safe for originality purposes and then put a t-5 in it so you can acutally use the higher gear ratios.

 

[allcarfan]

2500 rpms a lot for cruising?? Isnt that what a lot of classics 'cruised' at stock?

 

[HistoricMustang]

My personal choice would be 3.55's. I currently have 3.89's for the track but as the car is converted back to street use it will get a set of the 3.55's.

HistoricMustang
www.historicmustang.com

 

[69 302/351c]

I went from 2:79s to 3:55s and I can't wait to drop back to 3:25s. Yes, at 60 it's about 2800 rpm but most of my highway cruising is at 65-70 so the engine noise is excessive to me. Not a race car, just a weekend cruiser.

 

[HistoricMustang]

Jim,

My older brother and I had a brand new 260, 3 speed baby blue ragtop and the girls loved it way back then - especially the homecoming queen!

I have a great photo of me and her at the 50 yard line.

What a great motor and what a great homecoming night. My arch rival had a yellow ragtop with a black top. He struck out and I scored.

Any gear above a 3.25 will do you justice and good luck.

HistoricMustang
www.historicmustang.com

 

[6Stang7]

Can you tell me where you found that calculator for engine rpm? Dont you have to know what your gear ratios are inside your trans for that to be accurate?

http://www.geocities.com/z_design_studio/transmission_vr4_6.html


Yes and no. If you have an overdrive tranny, then you will need to know what the raito of the OD is. However, anything that doesn't have OD, it is safe to assume that there final gear is a 1:1 raito; therefore, your tranny won't play a part.

-Shaun

 

[Mustang Jim]

Thanks for the feedback guys. Though the car is strictly a weekend driver, I want to take it on the highway without the engine screaming. I'm sure I could deal with the 3.55's up to 60mph. Beyond that, well I'm not so sure. Will I get a worthwhile boost going from 2.75's to 3.25's? With the 2.75's, the car is a slug from a standstill, but it is great on the highway. Maybe the 3.25's are the best compromise. I would love to put a t-5 in, but it's not happening any time soon. For now, I'm ok with the 3 speed. Allcarfan, third gear on my tranny gives me a 1:1 ratio. Randy's Ring & Pinion has some good calculators on RPM's, ratios, tire sizes, etc... By the way, I'm going to swap out the center section to do this job as it is just a simple unbolt/bolt in job. I have been looking on e-bay and I have found one seller,McCanes Automotive, that has a number of 8" center sections to pick from in the $250 - $300 range. He's got good feedback. Any recommendations on vendors?

 

[rollin68]

I went from 2:79s to 3:55s and I can't wait to drop back to 3:25s.

3.55s were too much for my little 289, i coud chirp 2nd on command, but turning 4000+ rpms to keep up with traffic wasnt fun, of course this was with a C4 which will turn a few hundered more revs then yer 3 speed to go the same speed. As most of these guys said, if you plan on any highway driving, just get the 3.25s

 

[kyle67]

I've got a set of 3.25 Motive gears and the install kit, new in the box for an 8 inch, that I would love to sell. I'd like to get 175 shipped.
drop me an email [email protected]

 

[FIRE14142002]

http://richmondgear.com/112901.html

THIS CALCULATOR WILL HELP FIGURE IT ALL OUT

 

[66P51GT]

http://richmondgear.com/112901.html

THIS CALCULATOR WILL HELP FIGURE IT ALL OUT

SWEET!