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Hi guys! I would like some help with choosing another gear ratio for my cougar, it currently has 2.75 wich is good if i go highway cruising but i very rarely do.

I mostly drive around town, little bit of street racing and a little bit of track use.

 

I would like some help on what to choose, my neighbour has a 66 fairlane with almost the same setup cleveland as me (his is a little more agressive) and he runs 3.70:1 and is very pleased.

 

Completely new to swapping out ratios so if there is any additional info you need to help me, let me know and i will provide. Thanks.

1972 Mercury Cougar XR-7 2dr hardtop

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Odmark,

 

It maybe good to install a 3.25 to no more than a 3.50. What is your transmission? FMX or C6?

 

mustang7173

Thanks,

mustang7173 🇺🇸

"Courage is being scared to death but saddling up anyway" -- John Wayne

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Odmark,

 

I would be good if you have an AOD installed. Alot of the mustangs with AOD's had the 3.55 gears installed. You will tach up wards of 2800 to 3000 or higher rpms with that gear cruising around 60 MPH. . Now, your off the line acceleration will be greatly improved. I would probably go with the 3.25 to round out both scenario.

 

Ok - Lets hear it from other forum members.

 

mustang7173

Thanks,

mustang7173 🇺🇸

"Courage is being scared to death but saddling up anyway" -- John Wayne

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Odmark,

 

I would be good if you have an AOD installed. Alot of the mustangs with AOD's had the 3.55 gears installed. You will tach up wards of 2800 to 3000 or higher rpms with that gear cruising around 60 MPH. . Now, your off the line acceleration will be greatly improved. I would probably go with the 3.25 to round out both scenario.

 

Ok - Lets hear it from other forum members.

 

mustang7173

 

Actually, the majority of 5.0 Fox bodies with AODs came with 2.73, 3.08, or 3.27 (special order). That's why I'm not so worried about swapping my 3.00s out since I went with an AOD. ;)

 

http://www.allfordmustangs.com/forums/5-0l-tech/219774-what-stock-gears-1989-mustang-5-0-a.html

Eric

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Highway speed rpm really dont matter that much since i almost never drive like that. But as you say it could be nice to have the ability to do so as well.

 

Still 2800-3000, could be worse :D found a brand new 3.50:1 for 100 bucks now. Lots of people in Sweden seem to have 9" gears laying around haha

1972 Mercury Cougar XR-7 2dr hardtop

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I have 3.50 ratio gears in my car and love it, the car has great low end and mid range response. My car rarely sees the highway so these work very well. I changed them out from 2.75's and noticed a big difference in performance. My vote is 3.50.

351w - Ford racing GT40X 178 cc aluminum heads - Ford racing(crane) 1.7 roller rockers - Comp Cams 280H magnum cam .544" / .544" lift - ARP hardware - hedman longtubes - magnaflow exhaust with X pipe - Duraspark - MSD digital 6al box - MSD TFI coil - optima red top battery - tuff stuff 140 amp alternator - weiand stealth intake  - edelbrock 1406 600 carb  - march pullies and brackets - Be cool fan controller - derale electric fan - FMX trans - motive 4.11 gears - traction lok - lakewood traction bars.                                            

 

 

 

 

 

 

 

 

 

 

 

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I am going with a 3.70 but I also have a T-5. Had an FMX in it before I would not go over a 3.50 with the FMX.

73 Grande H Code. Headman long tube headers, T-5 Transmission, 3.70 Traclok, Lowered 1" all around, Aussie 2v heads w/ 2.19 intake, 1.71 exhaust, screw in studs, full roller cam 608/612 lift 280/281 duration LSA 112, Quick Fuel 750 CFM double pumper, AirGap intake.

 

- Jason

 

 

082-hot-rod-power-tour-2017-1970-1970s.jpg

 

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I would not go over 3.50 unless you have an OD tranny.

-john

(jbojo)

351C 4V cc heads, 10.5 : 1 CR, 290 Herbert cam, Flat top forged pistons, forged connecting rods, Atomic efi,

C6 with Gear Vendor overdrive, 3.89 Tru Trac, Hooker Super Comp with 2 1/2" Pypes Exhaust.        

 

Some Mod pictures can be seen at: [button=http://www.7173mustangs.com/forum-garage?filterxt_uid=2026]Bojo's Garage[/button]

 

 

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I ran 2.72 and 3.25 and now a 3.50. When I had the 2.72 and 3.25 the car was a daily driver. The 3.50 is fine around town and it will work on the highway but your engine will be revving. This wasn't so bad on my 21 mile commute to work. Your cougar may even be more comforatable since it probably doesn't have glasspacks and such.

 

I did findally put an OD unit in the car and still have th 3.5. I do love being able to go into OD on the highways. My gas milage improved 20% or so too.

 

For you I would say 3.25 will be fun and better on the highway. The 3.5 will be funner. You mention track use. Are we talking road course or straight line.

3.50 for the straight stuff but it might be better 3.25 for a road course. You are going to find breaking the tires loose is easier with a 3.50. This means you won't be able to get in it as early on a road course which means less fun.

 

Careful with that street racing... there are a lot of innocent people around.

'Mike'

73 Convertible - 351C/4V CC heads/4bolt/forged flat tops/comp 270/rhodes/mallory unilite/tri-power/hookers/glasspacks/c6/3.50 limited slip/Gear Vendors/Global West sub frames, strut rods and shelby style traction bars/ Rear sway bar/tilt steering (not original)

 

Pics of modifications included in: [button=http://www.7173mustangs.com/thread-1973-convertible--3335]My Garage[/button]

 

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I've got a C6 in my 71 (no AOD), went from 3.00 to 3.50, very happy with the choice. Gets off the line much quicker and can still cruise at 70MPH with no excessive RPM's. I believe it's only a couple hundred RPMs higher at 70. Would have stuck with the 3.00 if I used it as a daily driver, but the fun factor is worth the swap since I don't.

Jim

 

M code 71 Mach 1, 351 4V Cleveland, Ram Air (not factory), C6 Trans, 3.5 rear

 

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3.70 in mine, lot of fun on the street, too low for extended highway use.

 

You can play around with gear ratios, tire sizes, and RPM with the spreadsheet here, to see what you can expect:

http://www.7173mustangs.com/thread-tire-sizes--11566

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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The AOD also has the same gear ratios as the FMX, but adding the final drive of .67:1. Based on the combination of the AOD final drive gear and the rear axle 3.00s, I'm anticipating something around 1750-1800 RPM on the highway (@ 65 mph).

 

The '89 5.0 my AOD came from (along with everything, including the stock Torque Converter) had 2.75s (it was an LX 5.0 'vert). That's why I keep saying I shouldn't have any problems using the stock TC with my combination, when everybody seems to think higher stall speed TCs are needed. It really is almost a direct swap.

 

Plus, if the 351C-2V was ever capable of doing a burnout with an FMX and 3.00 rear gears with only 245 hp, I'm pretty sure there shouldn't be any issues in that department with the 400-ish I believe I have now. :whistling:

 

That being said, I think the general consensus of going with 3.25s or 3.50s will definitely build-in a lot of fun, but anything numerically higher will definitely kill the top-end.

 

I remember when I went from 2.73s to 4.10s in my Jeep - I can't even make it across the intersection now without grabbing second... I can climb the side of a building with it, but the engine's definitely screaming at-speed on the freeway.

Eric

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I am running 3.73's with my c4 and love them. On the highway I am turning 2800-3000 at 65-70 mph. Drove mine 5 hours to Carlisle all ford nationals a couple years ago with no troubles.

If you have found 3.50 gear for $100 locally, I would say jump all over that especially since you wont have to wait on and pay for shipping internationally.

Kevin
1971 Mach 1

408C Stroker - C4 w/3,000 stall - 8.8" Rear w/3.73's - Disc brakes all way around.

 

 

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I am running 3.73's with my c4 and love them. On the highway I am turning 2800-3000 at 65-70 mph. Drove mine 5 hours to Carlisle all ford nationals a couple years ago with no troubles.

If you have found 3.50 gear for $100 locally, I would say jump all over that especially since you won't have to wait on and pay for shipping internationally.

 

I can't believe you're running a C4 behind that monster of yours. :D

 

I think he jumped on the 3.50s and is going that direction. ::thumb::

Eric

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I am running 3.73's with my c4 and love them. On the highway I am turning 2800-3000 at 65-70 mph. Drove mine 5 hours to Carlisle all ford nationals a couple years ago with no troubles.

If you have found 3.50 gear for $100 locally, I would say jump all over that especially since you won't have to wait on and pay for shipping internationally.

 

I can't believe you're running a C4 behind that monster of yours. :D

 

I think he jumped on the 3.50s and is going that direction. ::thumb::

 

Built right, a C4 will take a hell of a pounding!! And weighs considerably less than a C6. Down the road i'm going to be looking for an OD tranny, probably a beefed up 4r70w. But my car had a c4 in it when I bought it so that's what I ran with. My buddy built it for me and it shifts HARD. Its pretty impressive. Broader did all the valve body work to it and its a great little tranny. Might be a different story if I could ever get it to hook up. But for now , it works!! :D

Kevin
1971 Mach 1

408C Stroker - C4 w/3,000 stall - 8.8" Rear w/3.73's - Disc brakes all way around.

 

 

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I am running 3.73's with my c4 and love them. On the highway I am turning 2800-3000 at 65-70 mph. Drove mine 5 hours to Carlisle all ford nationals a couple years ago with no troubles.

If you have found 3.50 gear for $100 locally, I would say jump all over that especially since you won't have to wait on and pay for shipping internationally.

 

I can't believe you're running a C4 behind that monster of yours. :D

 

I think he jumped on the 3.50s and is going that direction. ::thumb::

 

Built right, a C4 will take a hell of a pounding!! And weighs considerably less than a C6. Down the road i'm going to be looking for an OD tranny, probably a beefed up 4r70w. But my car had a c4 in it when I bought it so that's what I ran with. My buddy built it for me and it shifts HARD. Its pretty impressive. Broader did all the valve body work to it and its a great little tranny. Might be a different story if I could ever get it to hook up. But for now , it works!! :D

Well... there it is. Ain't nuthin' wrong with that at all. ::thumb::

Eric

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No one has mentioned tire size, but it is important to consider.

 

a 26" tall tire with a 3:50 gear will turn nearly the same RPM at any speed as a 28" tall tire with a 3.89 gear

 

You need to decide on your tire size and your gear ratio together and in conjunction with the level of engine modification you intend to perform

http://www.7173mustangs.com/gallery/1_01_07_15_8_53_18.png

 

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!

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Ooh - good point! ::thumb::

 

I sharpen it regularly

http://www.7173mustangs.com/gallery/1_01_07_15_8_53_18.png

 

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!

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I think th 3.50 is a good ratio for more aggressive driving/drivers and that 3.25's are slightly more civilized for those that have mistakenly grown up.

 

That is why I have 3.89's lol ;)

http://www.7173mustangs.com/gallery/1_01_07_15_8_53_18.png

 

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!

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