Need a quick & easy way to figure out gear ratio
#547220
12/06/09 06:43 PM
12/06/09 06:43 PM
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Joined: Jan 2003
Posts: 5,449
Woodbridge,CA
NAS Backyard
OP
master
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OP
master
Joined: Jan 2003
Posts: 5,449
Woodbridge,CA
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I was doing to old car shuffle getting ready to move this project to the other side of the backyard for longer term storage, and I discovered it has a Sure Grip in it I believe. No tags. The yoke is 3 1/2" wide, is that small or large, I can't remember. Anyway I have the car jacked up with the wheels on it and I can turn the driveline. How do I figure out the ratio? I may have to "borrow" this gear for awhile if its a 3:55 It was probebly changed at one point. The car came with a 318/904. Would it be on the fender tag?Thanks
1970 Challenger Ragtop 426 4 speed
1961 Olds 88 2 dr Sedan 394 4 speed GVOD
1968 Pontiac Firebird 428 4 speed
2000 Ford F-150
2002 HD Roadking
1961 Licence Plate collection
1995 Buick Roadmaster
www.nogreenautolaws.com
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Re: Need a quick & easy way to figure out gear ratio
[Re: stumpy]
#547222
12/06/09 07:04 PM
12/06/09 07:04 PM
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Joined: Jan 2003
Posts: 5,449
Woodbridge,CA
NAS Backyard
OP
master
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OP
master
Joined: Jan 2003
Posts: 5,449
Woodbridge,CA
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Thanks stumpy! Looks like it's a 3:55, but it's a small yoke. I may leave it in the shop for awhile and get it running so I can move it around under it's own power.It hasn't ran a in 10 years but it ran when it was parked.
1970 Challenger Ragtop 426 4 speed
1961 Olds 88 2 dr Sedan 394 4 speed GVOD
1968 Pontiac Firebird 428 4 speed
2000 Ford F-150
2002 HD Roadking
1961 Licence Plate collection
1995 Buick Roadmaster
www.nogreenautolaws.com
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Re: Need a quick & easy way to figure out gear ratio
[Re: stumpy]
#547224
12/06/09 08:22 PM
12/06/09 08:22 PM
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Joined: Jan 2008
Posts: 377
Michigan Troll
blk00rt
enthusiast
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enthusiast
Joined: Jan 2008
Posts: 377
Michigan Troll
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any tricks for figuring out gear ratio on an open rear end?
Rob Dunn
1976 Dart Sport 360
2000 dakota RT 408 with 150 nitrous
2013 Dodge Ram 1500 Hemi
2009 Jeep Patriot
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Re: Need a quick & easy way to figure out gear ratio
[Re: blk00rt]
#547226
12/06/09 08:58 PM
12/06/09 08:58 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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Quote:
any tricks for figuring out gear ratio on an open rear end?
Just jack one tire off the ground and rotate the wheel 2 full turns counting how many times the yoke turns...........3:55 will rotate roughly 3.5 turns....
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Re: Need a quick & easy way to figure out gear ratio
#547228
12/06/09 09:41 PM
12/06/09 09:41 PM
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Joined: Jan 2008
Posts: 377
Michigan Troll
blk00rt
enthusiast
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enthusiast
Joined: Jan 2008
Posts: 377
Michigan Troll
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thanks, Ill be doing that this week.
Rob Dunn
1976 Dart Sport 360
2000 dakota RT 408 with 150 nitrous
2013 Dodge Ram 1500 Hemi
2009 Jeep Patriot
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Re: Need a quick & easy way to figure out gear ratio
#547231
12/07/09 12:19 AM
12/07/09 12:19 AM
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Joined: May 2005
Posts: 581
Texas
Texican
mopar
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mopar
Joined: May 2005
Posts: 581
Texas
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Quote:
Quote:
any tricks for figuring out gear ratio on an open rear end?
Just jack one tire off the ground and rotate the wheel 2 full turns counting how many times the yoke turns...........3:55 will rotate roughly 3.5 turns....
1.) Jack the rear end of the car up on stands and place the tranny in neutral.
2.) Spin the draveshaft so that one of the bolts is on the top - dead center...and Mark it (crayon...grease...spit...etc..)
3.) Place a mark on one of the tires (anywhere)
4.) For an open rear end, spin the tire "exactly" two full turns and carefully count how many times the driveshaft goes round. When the tire has made it's second revolution (stop on the same exact "tire" mark)... Determine if the driveshaft has gone around 3.5 times or 2.7 times....or 4 times... etc...
For a posi rear end, spin the tire only once.
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