Help me find out what speed im going after 4.10 install

1

1hot5.0

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Sep 6, 2002

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Surprise, Arizona

Jan 21, 2004

#1

• Jan 21, 2004

• #1

Im getting my 4.10's installed this friday. I would like to know, how off will my speedometer be using the speedo gear for 2.73's? I called a speedo shop, and they said 35%, which is about 15 mph. Does this sound right?

I plan on having a speedometer reduction box made next week.

 

PonyGrl420

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Jun 18, 2002

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SC

Jan 21, 2004

#2

• Jan 21, 2004

• #2

Its not going to be a constant speed difference. The faster you go the more it will be off. Im sure there is a chart on the web somewhere.

 

willys1

Active Member

Dec 2, 2003

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New Jersey

Jan 21, 2004

#3

• Jan 21, 2004

• #3

Thats rite When Im doing 60,my speedo says 85!! I had the same gear change.

 

1

1hot5.0

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Jan 21, 2004

#4

• Jan 21, 2004

• #4

Gulp, I guess I am going to have to stick with traffic, and go by the chart I made.

I used this calculator http://www.slowgt.com/Calc1.htm#RPMInGear to come up with these numbers:

15 mph 1st gear= 2,000 rpm
25 mph 3rd gear= 1,400 rpm
35 mph 3rd gear= 2,000 rpm
40 mph 3rd gear= 2,217 rpm
45 mph O/D = 1,664 rpm

I used the correct gear ratios and my tire size of 225/50/16.

I think I will be ok, I just need to be careful. Thanks guys.

 

willys1

Active Member

Dec 2, 2003

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New Jersey

Jan 21, 2004

#5

• Jan 21, 2004

• #5

I use the tach when Im in traffic,I have an aod,stock 225/55/16 inch tires.and 373 gears,at 60mph Im at2100rpm/70mph-2300rpm/80mph-2500rpm.At low speeds I just wing it !!

 

Asha'man

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Feb 5, 2002

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Denver

Jan 21, 2004

#6

• Jan 21, 2004

• #6

www.hanlonmotorsports.com has a gear ratio calculator that tells you what speedo gear you should have. It's a very easy thing to swap out - disconnect your speedo cable and plug on the tranny, undo the bolt holding that unit in and pop it out. Remove the U-clip and swap gears, replace the U-clip, pop the unit back into the tranny, rebolt, plug in the cable and junk, and you're good to go.

Ash

 

L

leakyfaucet

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Dec 19, 2003

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North Carolina

Jan 21, 2004

#7

• Jan 21, 2004

• #7

Yeah, I did the speedo gear swap. Took about 30 seconds. Saves a lot of hassle. I think the white 21 spline gear is what you get for 3.55-4.10 gears. So it will still be off some, but not that much. The white 21 spline is very very close to the actual speed of a 3.73 gear, however.

 

willys1

Active Member

Dec 2, 2003

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New Jersey

Jan 21, 2004

#8

• Jan 21, 2004

• #8

I got the white 23 tooth for my 373,didnt put it in yet,hope it works with my 410's!!

 

PonyGrl420

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Jun 18, 2002

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SC

Jan 21, 2004

#9

• Jan 21, 2004

• #9

the 3.73 speedo gear helped me out a lot when I had 4.10's. Its still a lil off though, but its a lot better then nothing.

 

willys1

Active Member

Dec 2, 2003

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New Jersey

Jan 21, 2004

#10

• Jan 21, 2004

• #10

PonyGrl420 said:

the 3.73 speedo gear helped me out a lot when I had 4.10's. Its still a lil off though, but its a lot better then nothing.

Click to expand...

How much is it off at 60 mph.?

 

Henceforward

The Avatar Master

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Jul 17, 2001

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Jan 22, 2004

#11

• Jan 22, 2004

• #11

Here is some help with the gear...

http://www.geocities.com/mgnedell/notchback/tech/speedo.html

 

PonyGrl420

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Jun 18, 2002

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Jan 22, 2004

#12

• Jan 22, 2004

• #12

willys1 said:

How much is it off at 60 mph.?

Click to expand...

I dont rember for sure, I havent had the car in a while. I dont think it was that much though like 10-15mph but im not positive

 

willys1

Active Member

Dec 2, 2003

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New Jersey

Jan 22, 2004

#13

• Jan 22, 2004

• #13

PonyGrl420 said:

I dont rember for sure, I havent had the car in a while. I dont think it was that much though like 10-15mph but im not positive

Click to expand...

nahhh,its almost off that much now,its gotta be closer then that!

 

H

HazMat404

Founding Member

May 24, 2002

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Jan 22, 2004

#14

• Jan 22, 2004

• #14

ok...with the 4.10 in and the white speedo gear that is for the 3.73, you will be one mph higher for every 10 you are going. example when going 10mph you will read 11mph. when going 40mph you will read 44mph and when going 90mph you will read 100mph. i had one of my buddies ride next to me and we had walkie talkies and said how fast we were going back and forth and it was pretty much dead on to the 1mph higher for every 10mph you are going. hope that helps.....



its funny, every car i go in thats not mine, i automatically read 1mph higher for every 10 im going. its just automatic right now and dont even think about it

 

willys1

Active Member

Dec 2, 2003

1,004

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New Jersey

Jan 22, 2004

#15

• Jan 22, 2004

• #15

LOL,,,,,thats pretty good!!! I guess thats the best way to do it,if you dont have a dyno!!---Walky Talky's--LOL,,Im not laughing at you,thats just a unique idea

 

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HazMat404

Founding Member

May 24, 2002

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Jan 22, 2004

#16

• Jan 22, 2004

• #16

hehe...we use them all the time to pick on ricers. he has an 01 cobra vert and my car is dead even with him speed wise so we get to have our fun. i got sick of not knowing my speed so i devised a way to get it down perfectly....it almost always dead on when i go by those radar signs by schools and stuff

 

1

1hot5.0

Founding Member

Sep 6, 2002

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Surprise, Arizona

Jan 22, 2004

#17

• Jan 22, 2004

• #17

Thanks for the replys everyone!

I'm just going to get the speedometer box.