Why do I have to shift into 4th in 1/8 mile with 4.10's

M

MustangLife

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Jan 5, 2003

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Chattanooga, TN

Feb 15, 2004

#1

• Feb 15, 2004

• #1

I have 4.10's in my car. And I always have to shift into 4th gear close to the end of the 1/8 mile. If I stay into 3rd, I'm crossing at 6300 rpm's (ouch thats high).

Most people I talk to with 4.10's on sohc stang say they stay in 3rd. But I don't feel good about staying in 3rd at 6300 rpms. My rev limiter is set at 6600. I think I'm trapping 79 -80 mph. I think the lower trap speed is cause of a slow engaging 3rd that I haven't gotten fixed.

mods are in sig.

 

Bone Racing

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Sep 7, 2003

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Feb 15, 2004

#2

• Feb 15, 2004

• #2

just a guess...do u spin alot off the line?

cause if traction is a serious issue...your 1/4 mile becomes longer and u might add a shift

 

stangman

15 Year Member

Jul 10, 2003

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Feb 15, 2004

#3

• Feb 15, 2004

• #3

Bone Racing said:

just a guess...do u spin alot off the line?

cause if traction is a serious issue...your 1/4 mile becomes longer and u might add a shift

Click to expand...

bingo... if you show us your 60's... we'll most likely show ya why

 

Jackie Chan

I didn't read this.

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Oct 17, 2002

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Feb 15, 2004

#4

• Feb 15, 2004

• #4

1/8=stay in 3rd

 

luther1228

New Member

Sep 24, 2003

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Baton Rouge, LA

Feb 15, 2004

#5

• Feb 15, 2004

• #5

i stayed in third with 4.30

 

M

MustangLife

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Chattanooga, TN

Feb 15, 2004

#6

• Feb 15, 2004

• #6

Before I broke my rear end I was getting 1.85-1.90 on nittos at lower rpms launches.

Josh

 

B

BULLITT#828

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Nov 9, 2003

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Austin, TX

Feb 15, 2004

#7

• Feb 15, 2004

• #7

MustangLife said:

I have 4.10's in my car. And I always have to shift into 4th gear close to the end of the 1/8 mile. If I stay into 3rd, I'm crossing at 6300 rpm's (ouch thats high).

Most people I talk to with 4.10's on sohc stang say they stay in 3rd. But I don't feel good about staying in 3rd at 6300 rpms. My rev limiter is set at 6600. I think I'm trapping 79 -80 mph. I think the lower trap speed is cause of a slow engaging 3rd that I haven't gotten fixed.

mods are in sig.

Click to expand...

WHAT?!? Any Mustang equiped with the TR-3650 transmission (2001-1/2 & later) and 4.10 gears (assuming stock height tires) will be travelling at 84.73mph @ 6000 rpms. With your list of mods, I SERIOUSLY doubt your reaching those speeds in the 1/8th mile.

These figure have nothing to do with the amount of wheel spin at the launch, so don't listen to that. If your wheels were still spinning when you went through the traps (fat chance), THAT could effect your need to grap the next gear, but otherwise vehicle speed vs. RPM is only governed by the gear ratios both inside the tranny and the rear end, and the diameter of your rear tires. That's it.

Check out www.bullittarchive.com/Misc/Gears/ for verification.

If link doesn't work, just do a "cut & paste" into your address bar.

Ian

 

M

MustangLife

Active Member

Jan 5, 2003

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Chattanooga, TN

Feb 16, 2004

#8

• Feb 16, 2004

• #8

Well something is wrong. Could it be my 4.10 gear which i got new in box from gef.racing is really a 4.30. I've been thinking thats what it sounds like.

Josh

 

B

BULLITT#828

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Nov 9, 2003

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Austin, TX

Feb 16, 2004

#9

• Feb 16, 2004

• #9

Josh,

Is your car actually hitting the limiter in 3rd when running the 1/4, or are you just shifting because it looks like you're getting close? Remember, stock tachs are notoriously inaccurate (slightly). You may have up to 200 more RPM's to work with than you think you have. My suggestion: If it doesn't hit the limiter, keep your right foot down.

That is a goog point about your new gears pehaps being mis-packaged, but whoever installed them should have seem the ratio engraved into them. Ask your installer (I'm assuming you didn't did them at home).

Ian

 

luther1228

New Member

Sep 24, 2003

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Baton Rouge, LA

Feb 18, 2004

#10

• Feb 18, 2004

• #10

can you run over 110mph in 4th? if so you dont have a 4.30. i never shifted into 4th in the 1/8 with a 4.30

 

downsouthman1

Member

Dec 16, 2003

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Texas

Feb 18, 2004

#11

• Feb 18, 2004

• #11

Yeah if you're forced into shifting to 4th @ the end of the 1/8th mile you must have like 4.56s.