Author Topic: 4.10 and speedo accuracy  (Read 3055 times)

aaronz28

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4.10 and speedo accuracy
« on: July 26, 2009, 02:21:38 AM »
my car originally came with 3.73 rear... i now have 4.10s and can't seem to get the speedo accurate..

anyone know of the correct componants to get it spot on??  the trans is coming out this week, so if I have to change the gear on inside the trans... now is the time..


anyone??

Thanks

Aaron

JohnZ

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Re: 4.10 and speedo accuracy
« Reply #1 on: July 26, 2009, 02:05:05 PM »
Mine had 4.10's from the factory, and had a 25-tooth orange speedo gear; one of those should take care of you.
'69 Z/28
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aaronz28

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Re: 4.10 and speedo accuracy
« Reply #2 on: July 27, 2009, 01:24:22 AM »
thnks John, thts what I have in it now, and it is off... so i must have the different drive gear inside the trans.

thanks

Aaron

jmcbeth

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Re: 4.10 and speedo accuracy
« Reply #3 on: July 28, 2009, 01:03:03 AM »
Jerry rebuilt my transmission and put the correct gear in the transmission. My speedometer is correct. Jerry will know which gear to use.
John
1969 Camaro Z/28 RS
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70L34

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Re: 4.10 and speedo accuracy
« Reply #4 on: July 30, 2009, 11:59:21 PM »
I don't mean to hijack, but I would also be interested to know the correct gear for 4.56 gears, and whether it requires a reduction adapter.

68Zproject

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Jerry@CHP

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Re: 4.10 and speedo accuracy
« Reply #6 on: August 03, 2009, 01:36:47 AM »
There are also different drive gears that are on the main shaft.  Think they are six, seven and eight tooth.  That is where the problem lies.  Not all variations are available.

Jerry

aaronz28

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Re: 4.10 and speedo accuracy
« Reply #7 on: August 03, 2009, 09:59:36 PM »
This is getting confusing...

i've now read that there were 6,7,and 8 tooth drive gears,,, but also read that there were 9 tooth drive gears...

and then others (like Liberty's Gears) say that there were only two... and they had 7teeth, but you could get two different Diamters which would change the speedo calibration...


can anyone confirm exactly which drive gear (the one pressed onto the output shaft of my Muncie)  to work with Stock 15inch wheels/ E70x15 tires.... 4.10 rear gears???

JohnZ's car came with an orange (25tooth) speedo gear.... so that much I know....

which gear shoudl I have pressed on the output shaft to make this combo accuate???

MAny thanks

Aaron

KENSTOY1969

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Re: 4.10 and speedo accuracy
« Reply #8 on: August 05, 2009, 10:03:42 PM »
I'm not sure how accurate you're trying to get.  If you use the approach below it will take into account all the variations that have been discussed.  The key is driving 60 miles an hour only.

Time a 10 mile drive on the highway using the mile markers as your measure doing 60 MPH consistenty.

Then use the following calculation for the "# Teeth Needed"

# Teeth                            # Teeth
on Gear Now                      Needed                                           # teeth on gear now X 600 (seconds)
-----------------------   =   ----------------------        or   # teeth needed = -----------------------------------------------------
Time in seconds                 600 seconds                                       time in seconds for 10 miles at 60 MPH
for 10 miles at
60 MPH

Use the listing below to determine which color gear you need.

From the National Parts Depot Camaro Catalog
Red - 21 teeth
Blue - 20 teeth
Green - 22 teeth
Black - 23 teeth
Orange - 25 teeth
Yellow - 24 teeth
Purple - 17 teeth
Brown - 18 teeth
Neutral - 19 teeth
Silver - 22 teeth