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Regear Rear End
#11
(01-29-2019, 07:45 AM)Jeff73Mach1 Wrote: I'm running 3.89 gears-it is too much even with a tall tire for all but the most idiotic of drivers such as myself.

3.50 or 3.70 would be decent compromises.  (" gears are also available in 3.60 and 3.64 ranges which would also be a nice compromise.

9" carriers fit all gears ratios-unlike some other designs that have different carriers depending upon the gear range.

I would encourage you to upgrade ujoints and yokes while you are at it, and if budget allows,  axles.  It is all easier when it is apart.

I have 3:89's in mine also. They were in the car when I got it. I don't have my motor back yet but it will be behind a TKO 600 with a .64 5th gear (Motor should be around the 450-500HP range). Most of my local driving I'll see a high of 45-50MPH so I'll be spending most of my time in 4th but if I need to head out on the highway I'll be good to go. I'm also concerned about how useful or useless my 1st gear will be...
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#12
Following this thread with interest. A useless 1st may mean different things to people. Useless can mean that the gear is so short that you end up using 2nd most of the time to move the car from a stop. However, useless can also mean that it is hard to get the tires to spin. Therefore, is useful somewhere in between? I bet we get many different answers.

Edit PS: I have a TKO600 and should be close to 500hp. I drove it a little with the 3.00 gears open differential. I was able to easily spin the tires just by pressing the gas pedal. I decided to move up to a 3.50 gear, tracloc and 31 splines in a Strange center section. We will see how it drives.

        [Image: 20160929_171923_edit2_small.jpg]

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump
4-wheel disc brakes
[+] 1 user Likes tony-muscle's post
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#13
(01-29-2019, 10:58 AM)tony-muscle Wrote: Following this thread with interest. A useless 1st may mean different things to people. Useless can mean that the gear is so short that you end up using 2nd most of the time to move the car from a stop. However, useless can also mean that it is hard to get the tires to spin. Therefore, is useful somewhere in between? I bet we get many different answers.

Edit PS: I have a TKO600 and should be close to 500hp. I drove it a little with the 3.00 gears open differential. I was able to easily spin the tires just by pressing the gas pedal. I decided to move up to a 3.50 gear, tracloc and 31 splines in a Strange center section. We will see how it drives.

Hey Tony, my setup when done will be similar to yours. What ratio is your 5th gear in your TKO?
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#14
(01-29-2019, 11:16 AM)73\ mach 1 Wrote:
(01-29-2019, 10:58 AM)tony-muscle Wrote: Following this thread with interest. A useless 1st may mean different things to people. Useless can mean that the gear is so short that you end up using 2nd most of the time to move the car from a stop. However, useless can also mean that it is hard to get the tires to spin. Therefore, is useful somewhere in between? I bet we get many different answers.

Edit PS: I have a TKO600 and should be close to 500hp. I drove it a little with the 3.00 gears open differential. I was able to easily spin the tires just by pressing the gas pedal. I decided to move up to a 3.50 gear, tracloc and 31 splines in a Strange center section. We will see how it drives.

Hey Tony, my setup when done will be similar to yours. What ratio is your 5th gear in your TKO?

5th is 0.67

        [Image: 20160929_171923_edit2_small.jpg]

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump
4-wheel disc brakes
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#15
(01-29-2019, 10:58 AM)tony-muscle Wrote: Following this thread with interest. A useless 1st may mean different things to people. Useless can mean that the gear is so short that you end up using 2nd most of the time to move the car from a stop. However, useless can also mean that it is hard to get the tires to spin. Therefore, is useful somewhere in between? I bet we get many different answers.

Edit PS: I have a TKO600 and should be close to 500hp. I drove it a little with the 3.00 gears open differential. I was able to easily spin the tires just by pressing the gas pedal. I decided to move up to a 3.50 gear, tracloc and 31 splines in a Strange center section. We will see how it drives.

With a 3.25 rear-end I assumed that with 450 horsepower there is limited torque below 3,000 RPM, which means riding the clutch to start moving from a dead stop, unless you rev it to around 4,000 and release the clutch, which can be fun, but not appreciated when you're at a crosswalk at a busy intersection.

With a wide-ratio toploader 4,000 RPM in first would equate to around 35mph.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#16
The 1st gear is useless as in I start from a stop in 2nd all the time, didn't know bigger gears would be the same. I just get worried when cruising down the street 30 mph and the engine sounds like its at 4000 rpm. I'm keeping the normal size tires and they do bust loose easy in any gear but I will upgrade axle shafts and u joints since I've already done it like 10 times between my 2 Jeeps. I had it wheel dynoed with 450 HP and 430 ft/lb torque, I'll have to get the sheet uploaded to here. I've actually never had it on the freeway always cruise easy, but I do dump the clutch sometimes around ricer kids in their jap cars.
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#17
Are you 100% sure it still has the original 3.25 gears in it? Sounds like they may have been swapped out for taller gears already. I would not go numerically any lower than 3.25. Mine had the original 2.75 gears in it and it was a dog.

'73 Grandé 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.

'73 F code convertible. Bright red. Needs total restore. (IE HOT MESS)

- Jason
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#18
No idea guess I'll look up how to determine which gears are in there when I open the case up
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#19
(01-29-2019, 06:22 PM)icejawa Wrote: No idea guess I'll look up how to determine which gears are in there when I open the case up

Or you can raise the rear end, turn one tire a full revolution while counting how many turns the driveshaft makes.

        [Image: 20160929_171923_edit2_small.jpg]

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump
4-wheel disc brakes
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#20
(01-29-2019, 05:39 PM)icejawa Wrote: The 1st gear is useless as in I start from a stop in 2nd all the time, didn't know bigger gears would be the same. I just get worried when cruising down the street 30 mph and the engine sounds like its at 4000 rpm. I'm keeping the normal size tires and they do bust loose easy in any gear but I will upgrade axle shafts and u joints since I've already done it like 10 times between my 2 Jeeps. I had it wheel dynoed with 450 HP and 430 ft/lb torque, I'll have to get the sheet uploaded to here. I've actually never had it on the freeway always cruise easy, but I do dump the clutch sometimes around ricer kids in their jap cars.

Wow... 450hp in a chassis dyno is very good power. Is that a 351 or stroked?

        [Image: 20160929_171923_edit2_small.jpg]

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump
4-wheel disc brakes
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