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ford racing 4.09 gears at the strip

SK17

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Hi all. I have a 2016 automatic with most major bolt ons and drag radials and dyno tune and suspension components but stock cam and stall. I'm currently running 3.55 gears and 275/40/18 Nitto NT555r2 drag radials (26") I bracket race in the summer. Turn about 12.30 on a really good day. I want to run 3.91 gears for a better take off and E.T. What do you think?
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Dave2013M3

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How many RPMs are you now when you cross the stripe?
 

K4fxd

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Need to know Mph and tire size.
 

Cory S

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If you're leaving now on the 4.17:1 1st gear, a 4.09 won't work well without a 28"+ tire.

The shock on the leave, will throw everything off, and you'll likely get wheel hop and accelerate slower to the 60'. That's a 17:1 SLR........ Great for rock crawling, but not for drag racing.
 

LxMike

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4th gear will be good till about 114-115 mph with stock rev limiter, But like Cory mentioned it will throw off your launch.
 

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SK17

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If you're leaving now on the 4.17:1 1st gear, a 4.09 won't work well without a 28"+ tire.

The shock on the leave, will throw everything off, and you'll likely get wheel hop and accelerate slower to the 60'. That's a 17:1 SLR........ Great for rock crawling, but not for drag racing.
Cory S, I'm a little confused at your post. I'm currently running 3.55 gears. I leave off idle. I'm running 26" nittos and trap 112mph.
 
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SK17

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4th gear will be good till about 114-115 mph with stock rev limiter, But like Cory mentioned it will throw off your launch.
LX Mike. My rev limiter is set a tad higher I believe with the dyno tune I obtained. What do you mean when you say it'll throw off your launch?
 

K4fxd

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K4fxd. I run a 26" nitto nt555r2. I trap 112 mph
You will trap about 6900 RPM in 4th gear

Cory S, I'm a little confused at your post.
He is talking about overall first gear ratio. You will 60 ft quicker leaving in 2nd gear with the 4.09's
 
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SK17

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If you're leaving now on the 4.17:1 1st gear, a 4.09 won't work well without a 28"+ tire.

The shock on the leave, will throw everything off, and you'll likely get wheel hop and accelerate slower to the 60'. That's a 17:1 SLR........ Great for rock crawling, but not for drag racing.
Cory, I do have upgraded suspension components. I get no wheel hop on 3.55s. I'm running an automatic compared to a stick with a high rpm clutch drop, but I only leave off idle, I don't even footbrake it up in rpms at all. I do this to have consistent launch rpms every time. I also run a detroit tru trac for the strip. If you still think I'll have problems with the 4.09s, do you think a 3.91 gear ratio would be a nice compromise?
 
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SK17

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Hey all. I edited my original post to include more details. Thanks for the replies and thanks for the private conversations I was in. I still am looking for some more input from fellow drag racers. If I go to 3.91/4.10 gears, I'm confident I won't spin on take off and I'm well within staying in 4th gear at the stripe. After talking to some of you, the issue of shifting into 2nd gear before the 60' mark came up. My question is, why does this hurt anything? My E.T should still be better which is what I want, and although my 60' might suffer a little do to shifting, I'd still be launching faster which adds to the fun factor which is what I'm looking for.

Thoughts please,

Jason
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