Differential gear question
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Senior User
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Differential gear question
guys
how could i find a way to see whats gears i have in the rear end.
i found a video this video. did what the guy did in the video.
i cam up with 12.5 that /10 is 1.25 i know that isnt right.could anyone help me out?
the tag on the axle saids it should be a 2.47
how could i find a way to see whats gears i have in the rear end.
i found a video this video. did what the guy did in the video.
i cam up with 12.5 that /10 is 1.25 i know that isnt right.could anyone help me out?
the tag on the axle saids it should be a 2.47
Senior User
Joined: Jul 2012
Posts: 295
Likes: 1
From: Centerpoint, IN
guys
how could i find a way to see whats gears i have in the rear end.
i found a video this video. did what the guy did in the video.
i cam up with 12.5 that /10 is 1.25 i know that isnt right.could anyone help me out?
the tag on the axle saids it should be a 2.47
how could i find a way to see whats gears i have in the rear end.
i found a video this video. did what the guy did in the video.
i cam up with 12.5 that /10 is 1.25 i know that isnt right.could anyone help me out?
the tag on the axle saids it should be a 2.47
Thread Starter
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Senior User
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He is doing that on a drag racing axle so it has a spindle instead of a differential and he had the opposite side tire spinning too. Make sure you have the opposite side tire chocked so it won't move then do 10 rotations of the tire and divide the pinion rotations by 5 since a differential drives both the tires you half the number of tire rotations if that makes sense. So yours would be 12.5/5 =2.5. So your tag is right and it's a 2.47 since that 0.03 is just error because you took general measurements.
got other question.
right now.with those gears, we have to slip the clutch/ride the clutch to take off.its pretty much like takeing off in 2nd gear.
its a 85 f150 with a 4.9 300 6 pair with a 3spd.
we are looking to put other gear set in.just enough so we can take off with out slipping the clutch and what not.do you know or could you steer me in the right place to start. thanks.
Postmaster
Joined: Nov 2009
Posts: 4,575
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From: Broken Arrow , OK
A shade tree could do it, but rear ends are a little tricky. If it isn't done right you will have gear noise. You tube should have plenty of videos on changing ratios.
You might be able to solve your problem with tire size. A smaller tire will drop the gear ratio.
You might be able to solve your problem with tire size. A smaller tire will drop the gear ratio.
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we are runing the stock tire size.we cannot go down anymore or the truck wont be able to move around on the woods
Post Fiend
Joined: Dec 2007
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From: Lost
Do you have a 9" (front drop out) or 8.8" (rear cover plate) axle? The 9" can be dropped out and a new one installed pretty easy. An 8.8" would be easier to swap the complete axle assembly. Either way, a salvage yard should be able to get you what you need.
For 80-86 & 87-96 (can be used, but minor differences).....
9" ratios are: 2.47, 2.75, 3.00, 3.25, & 3.50 as the most common, and a few even steeper that were used in older vehicles. Last used in 87.
8.8"ratios are: 2.47, 2.73, 3.08 and 3.55, with a 3.31 coming along in the 90's. First used in trucks in 83.
83-87 could be either axle.
That's the less expensive way to go. the more expensive route, is take the truck to a shop and have them regear your current axle.
For 80-86 & 87-96 (can be used, but minor differences).....
9" ratios are: 2.47, 2.75, 3.00, 3.25, & 3.50 as the most common, and a few even steeper that were used in older vehicles. Last used in 87.
8.8"ratios are: 2.47, 2.73, 3.08 and 3.55, with a 3.31 coming along in the 90's. First used in trucks in 83.
83-87 could be either axle.
That's the less expensive way to go. the more expensive route, is take the truck to a shop and have them regear your current axle.
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Joined: Jan 2001
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From: Virginia
thanks man.
got other question.
right now.with those gears, we have to slip the clutch/ride the clutch to take off.its pretty much like takeing off in 2nd gear.
its a 85 f150 with a 4.9 300 6 pair with a 3spd.
we are looking to put other gear set in.just enough so we can take off with out slipping the clutch and what not.do you know or could you steer me in the right place to start. thanks.
got other question.
right now.with those gears, we have to slip the clutch/ride the clutch to take off.its pretty much like takeing off in 2nd gear.
its a 85 f150 with a 4.9 300 6 pair with a 3spd.
we are looking to put other gear set in.just enough so we can take off with out slipping the clutch and what not.do you know or could you steer me in the right place to start. thanks.
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Senior User
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yes even on the road we have to slip it.
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From: Virginia
I thought if you just needed the take off power when loaded, you could swap the tranny out for a 4 speed with a granny. I guess if you are having problems all the time you might need to swap the rearend. Are you sure the engine is running correctly? That old six should be hard to stall out.
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I thought if you just needed the take off power when loaded, you could swap the tranny out for a 4 speed with a granny. I guess if you are having problems all the time you might need to swap the rearend. Are you sure the engine is running correctly? That old six should be hard to stall out.
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From: Lost
I thought if you just needed the take off power when loaded, you could swap the tranny out for a 4 speed with a granny. I guess if you are having problems all the time you might need to swap the rearend. Are you sure the engine is running correctly? That old six should be hard to stall out.
Senior User
Joined: Jul 2012
Posts: 295
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From: Centerpoint, IN
Man I bet. My 95 Ranger with a 3.45 rear gear is a pain, let alone 2.47. Although the tranny 1st gear difference probably makes up for that but yeah I'm sure it's not fun. What tranny do you have? And if you are swapping gearing just go to a junkyard and get a complete rear end with the gearing you want. Most of the time it's cheaper than doing a gear swap.
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Man I bet. My 95 Ranger with a 3.45 rear gear is a pain, let alone 2.47. Although the tranny 1st gear difference probably makes up for that but yeah I'm sure it's not fun. What tranny do you have? And if you are swapping gearing just go to a junkyard and get a complete rear end with the gearing you want. Most of the time it's cheaper than doing a gear swap.
Post Fiend
Joined: Dec 2007
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From: Lost
You'll hate that one even worse than the 3 speed, unless you swap in a lower (higher number) ratio.......
