gears

[Marauder108]

Today i went to a friends house and was talking to his dad about gears. I told him i was thinking about 4.10's. he said that if i were to put them in my car i wouldnt be able to drive on the highway at more than 55 or i would blow my engine. I though that computer tunes would change the rpm for the new gear set up so you can still drive like normal. is this not true?

[RF Overlord]

Your friend's dad is WAY behind the times.

In the late '60s and early '70s, cars had 14" wheels, 2- or 3-speed transmissions, and cast iron pushrod motors that topped out at 5,000 RPM. A car like the MM with 18" wheels and an overhead-cam engine that loves to rev is an entirely different animal. You cannot compare the two. Steve Babcock, the programme manager for the Marauder project at Ford has repeatedly said that the MM was originally supposed to have 3.73s or 4.10s from the factory, but it was nixed by the bean counters due to CAFE.

Many of us have 4.10s and the car loves them. Of course, your top speed will be slightly reduced, but how often to you drive over 120 MPH? If you do that regularly then you should leave the 3.55s in anyway.

[fastblackmerc]

I've had 4.10's in my MM for over 60k and I frequently drive over 55......

[F8LBITEva]

Also when properly programmed for the 4:10's the car will cruise only a few RPM's higher than stock therefore not wasting that much more fuel. Im getting them for my car this spring.

[CobraSVT657]

obviously your friends dad hasn't read any car magazines for the past 20 years... I bought my MM from Oklahoma and drove it back 1000 miles to Ohio.. cruise control set at 70mph and still got 21-23mpg with 4.10's and 3500 stall.

[Dennis Reinhart]

Also when properly programmed for the 4:10's the car will cruise only a few RPM's higher than stock therefore not wasting that much more fuel. Im getting them for my car this spring.


300 RPM at 65 MPH to be exact thie first mod you should buy is a Xcal 3 I have the Ford gears and bearings in stock as well as the Xcal 3 it comes with free shipping.

[SC Cheesehead]

4.10's at 55 mph = less than 2,000 rpm.

4.10's at 70 mph = just over 2,200 rpm.

Like FBM said, over 60K on the odometer running 4.10's in my car with no issues, and virtually no impact on mileage.

Installation is all upside, and no downside, IMO.

[Blackened300a]

Today i went to a friends house and was talking to his dad about gears. I told him i was thinking about 4.10's. he said that if i were to put them in my car i wouldnt be able to drive on the highway at more than 55 or i would blow my engine. I though that computer tunes would change the rpm for the new gear set up so you can still drive like normal. is this not true?

My Uncles 1965 442 has a 4spd and he had the bright idea to put 3.90's in it. Bad idea!, it would be a rocket off the line and roast the tires through the first 3 gears but it would rev way too high at 65mph. We dialed it back to 3.55's and it was a huge improvement. The guy is right in that 4.10s with a old school 4spd would be undrivable. With the gearing of the trans along with the lockup convertor, you could run 4.30s and some members even ran a 4.56 and still have a drivable car. You'll need a tune to calibrate the speedo and trans schedule for the new gear ratio.
4.10s are the way to go. Contact Sparta performance for a set of gears and a install kit.

[fastblackmerc]

4.10's at 55 mph = less than 2,000 rpm.

4.10's at 70 mph = just over 2,200 rpm.

Like FBM said, over 60K on the odometer running 4.10's in my car with no issues, and virtually no impact on mileage.

Installation is all upside, and no downside, IMO.

Well....

No impact on mileage????

Makes the car more driveable.

You'll want to get on it more! "That's what she said!

[rauder88]

As others have already stated 4.10 are safe for out cars with a tune to correct the trans shifting and speedo. I still get 24 mpg highway. I just cant keep my foot out of the gas to get decent mileage out of a tank. These cars are way more fun to drive with gears.

[jflave]

And the 18 in. wheels help with all the above. :)

[SC Cheesehead]

Well....

No impact on mileage????

Makes the car more driveable.

You'll want to get on it more! "That's what she said!


As others have already stated 4.10 are safe for out cars with a tune to correct the trans shifting and speedo. I still get 24 mpg highway. I just cant keep my foot out of the gas to get decent mileage out of a tank. These cars are way more fun to drive with gears.

Yeah, need to add a qualifier relating to impact on mileage.

Also, need to include the "wife factor." When my wife's in the car, my mileage is usually better...;)

[MrBluGruv]

My Uncles 1965 442 has a 4spd and he had the bright idea to put 3.90's in it. Bad idea!, it would be a rocket off the line and roast the tires through the first 3 gears but it would rev way too high at 65mph. We dialed it back to 3.55's and it was a huge improvement. The guy is right in that 4.10s with a old school 4spd would be undrivable. With the gearing of the trans along with the lockup convertor, you could run 4.30s and some members even ran a 4.56 and still have a drivable car. You'll need a tune to calibrate the speedo and trans schedule for the new gear ratio.
4.10s are the way to go. Contact Sparta performance for a set of gears and a install kit.

My dad owned a '67 4-4-2 with a 4-speed. He had 4.30 gears in it, plus like a 750cfm 4-barrel. I don't remember him saying he ever had drivability issues at speed, but I didn't ask much about that. He did say, however, he could turn a flat 13 with it in the 1/4. :D

[SC Cheesehead]

My dad owned a '67 4-4-2 with a 4-speed. He had 4.30 gears in it, plus like a 750cfm 4-barrel. I don't remember him saying he ever had drivability issues at speed, but I didn't ask much about that. He did say, however, he could turn a flat 13 with it in the 1/4. :D

Back in the day I remember some guys putting in mechanical O/D units, IIRC, they were like a secondary gearbox behind the transmission, that enabled racers running low gears to run at highway speeds at ressonable RPMs and then shift the unit into a 1:1 drive at the track. Car Craft or Hot Rod ran a tech article on them in the late 60's - early 70's.

[Blackened300a]

My dad owned a '67 4-4-2 with a 4-speed. He had 4.30 gears in it, plus like a 750cfm 4-barrel. I don't remember him saying he ever had drivability issues at speed, but I didn't ask much about that. He did say, however, he could turn a flat 13 with it in the 1/4. :D

Long tube headers + No tach= Swearing you're turning 5K by the sound of the engine through the exhaust.
I thought it was a blast to drive with all that low end torque but hes 30yrs older then me so we find different things cool. :D

[MOTOWN]

Back in the day I remember some guys putting in mechanical O/D units, IIRC, they were like a secondary gearbox behind the transmission, that enabled racers running low gears to run at highway speeds at ressonable RPMs and then shift the unit into a 1:1 drive at the track. Car Craft or Hot Rod ran a tech article on them in the late 60's - early 70's.

are you referring to gear vendors o/d units?

[DOOM]

but how often to you drive over 120 MPH? If you do that regularly then you should leave the 3.55s in anyway.


My 3.55's aint goin' anywhere! ;) :coolman:

[SC Cheesehead]

are you referring to gear vendors o/d units?

Yep, that or a unit very similar to it.

It's rough getting old, CRS... ;)

[SpartaPerformance]

Everybody here is correct. The 4.10's is a great gear for these vehicles. Many members here have driven many highway miles with 4.10's, and the engine RPM is very low and "cruisable" <-- that a word?

[SC Cheesehead]

Everybody here is correct. The 4.10's is a great gear for these vehicles. Many members here have driven many highway miles with 4.10's, and the engine RPM is very low and "cruisable" <-- that a word?

If it ain't, it oughta be, Tommy! ;)

[guspech750]

I'm having my 4.10's installed in two weeks. Can't wait!!


Sent from my iPhone
Go White Sox

[Marauder108]

wow thanks for the info

[GreekGod]

My Uncles 1965 442 has a 4spd and he had the bright idea to put 3.90's in it. Bad idea!, it would be a rocket off the line and roast the tires through the first 3 gears but it would rev way too high at 65mph. We dialed it back to 3.55's and it was a huge improvement. The guy is right in that 4.10s with a old school 4spd would be undrivable. With the gearing of the trans along with the lockup convertor, you could run 4.30s and some members even ran a 4.56 and still have a drivable car. You'll need a tune to calibrate the speedo and trans schedule for the new gear ratio.
4.10s are the way to go. Contact Sparta performance for a set of gears and a install kit.

I had 4:57 gears in my '66 Galaxie w/C6 auto trans, 428 4V. Like driving around in 2nd gear, but speedo needle would still disappear below bezel (over 120 mph). Very drivable with 3 to 5 miles per gallon, & 14 second 1/4 mile times.

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