Gear help
Thread Starter
Burning Brakes
Joined: Apr 2008
Posts: 1,179
Likes: 5
From: Lake Orion Michigan
Gear help
I'm trying to figure out what size gear i have
At 80mph it's turning 1,800rpms....It's an 85 with a 700R trans:o Anyone do the math or tell me the formula for doing it?:o
At 80mph it's turning 1,800rpms....It's an 85 with a 700R trans:o Anyone do the math or tell me the formula for doing it?:o
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
btw, here is the calculator I use:
http://www.f-body.org/gears/
gear ratios for the 700r4 are 3.06/1.63/1.00/.70
I bet you have 2.73s in the back.
http://www.f-body.org/gears/
gear ratios for the 700r4 are 3.06/1.63/1.00/.70
I bet you have 2.73s in the back.
Team Owner
Joined: Dec 2007
Posts: 20,974
Likes: 261
well I see you have bigger rims than stock so that throws off the calculation on speedo, but I have 2.59's in a 1900 auto and I am like 1800 at 70 with stock 17'' rims and stock speedo gear. I think you probly have the same but the bigger rims throws off speedo a bit IMHO not sure if speedo gear was changed or anything else!
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Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
How sure of you one the 80 at 1800rpms...your speedo or tach may be a little off. The best fit for that senario is 2.59s, which to my knowledge, were not available in 85s, only 2.73 or 3.07.
Have someone with a normal car unmoddified car pace you at 70 and see how much the speedo is off.
Have someone with a normal car unmoddified car pace you at 70 and see how much the speedo is off.
Thread Starter
Burning Brakes
Joined: Apr 2008
Posts: 1,179
Likes: 5
From: Lake Orion Michigan
How sure of you one the 80 at 1800rpms...your speedo or tach may be a little off. The best fit for that senario is 2.59s, which to my knowledge, were not available in 85s, only 2.73 or 3.07.
Have someone with a normal car unmoddified car pace you at 70 and see how much the speedo is off.
Have someone with a normal car unmoddified car pace you at 70 and see how much the speedo is off.
P.S. The rearend was rebuilt about 2 years ago but I see nothing about changing out the gears.
Thread Starter
Burning Brakes
Joined: Apr 2008
Posts: 1,179
Likes: 5
From: Lake Orion Michigan
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
Look under the storage lid on the drivers side of the hatch, should be a list of three digit codes there...write 'em down and pm them too me and I can tell you what all your car came with stock.
If the list isn't there, try the other side, or under the center console lid.
If the list isn't there, try the other side, or under the center console lid.