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Discussion Starter #1
I am looking at picking up a 89 5.0 Notch, now the owner has put on the 93 Cobra Wheels with 245/55/17 tires all around, he says it is stock gearing in the car but it revs at 1800 rpm in 5th at 100kph (60mph) It is sounding like 373's or even 410's to me? Anyone have an idea? Thanks!
 

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Discussion Starter #3
How many RPM's are you turning on your '89 with 3:73's?
With 16" Pony's and a 205/65/16(Till I get some ET Street Radials haha) I am sitting at 1500 Rpm At 100kph. Would the Rim size effect the rpm that much? Or Factory tach be out?
 

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Could be the tach going bad, i was at about 1900 RPM at 60mph when i had stock gears in my car.
 

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Discussion Starter #5
Could be the tach going bad, i was at about 1900 RPM at 60mph when i had stock gears in my car.
Hmm, My stoch tach says 1550 and my Autometer says 1500 so.. What is the trick to checking the gears without taking off the diff cover?
 

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My stock 2.73's put me at about 1600 rpm @ 100km/h (60mph) with my 17" cobra R's. Closest size to the P225/60R15 is a P245/45R17. I went with a 235 instead just to avoid any clearance issues up front.

Does the 93 Cobra have a larger outside tire diameter than the other foxbodies?
 

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Discussion Starter #7
I made a typo, the 89 Notch has a 245/45/17 tire all around on it. Still revs at 1800 in 5th at 100k I just don't see how my 373's rev that much lower then a stock gear?
 

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Discussion Starter #9

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Discussion Starter #17
Well now I am wondering could my stock tach and auto meter be out if I am only turning 1500 in 5th at 60mph with 3.73's? Or maybe my car doesn't have 3.73's? Time to find out tomorrow.
 

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Discussion Starter #18
I have done high 13's on pure **** 205/65/16 tires, previous owner said he did a 13.7 @ 101 mph with m/t et street radial, saw time slip. A friend of mine has a 00 GTP with 3.3" pulley,full exhaust, ZZP Tune, and more and does a consistent 13.9 @ 99mph at the track and my 89 walks it every time..

Today I checked the rpms in 5th at 100kph it sits at 1600 rpm in 4th at 100k 2600 rpm, I jacked up the rear and I spun the tires to check to see how many times the drive shaft spun, it was hard to keep an eye on both but it look to be about 27 or 28 after the tire did 10 full revolutions. So more or less looking like it has stock gears? I just don't see how the car from a 40 roll can go right sideways without even dumping the clutch just stepping on it makes 1st and 2nd a joke..
 
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