Speedo Gears
Thread Starter
Racer
Joined: May 2004
Posts: 301
Likes: 2
From: Boca Raton Fl
Speedo Gears
Changed the rear end to 3:36 from 4:11
My speed-o is about 6 to 7 mph off at cruise speed
Which color speedo gear now works with this rear end?
Has anyone made a table chart of gear ratios and colors (number of teeth)on the speedometer gear for reference?
Tried the search and found none
Thanks
My speed-o is about 6 to 7 mph off at cruise speed
Which color speedo gear now works with this rear end?
Has anyone made a table chart of gear ratios and colors (number of teeth)on the speedometer gear for reference?
Tried the search and found none
Thanks
Racer
Joined: Mar 2004
Posts: 292
Likes: 2
From: Plumas Lake CA
Do a google search for "speedometer gear calculation". Go to the 7th or so selection down, "speedometer gear, speedometer gear selection Ford, GM, Dodge, 700R4". Open that up. They have a speedo gear calculator in there too. I'd post the link directly, but I don't know if they are a supporting vendor here.
Burning Brakes
Joined: Jan 2006
Posts: 957
Likes: 6
From: Burlington wisconsin
TCI Performance has a nice calculator for these gear ratios and associated speedo gears.
Changed the rear end to 3:36 from 4:11
My speed-o is about 6 to 7 mph off at cruise speed
Which color speedo gear now works with this rear end?
Has anyone made a table chart of gear ratios and colors (number of teeth)on the speedometer gear for reference?
Tried the search and found none
Thanks
My speed-o is about 6 to 7 mph off at cruise speed
Which color speedo gear now works with this rear end?
Has anyone made a table chart of gear ratios and colors (number of teeth)on the speedometer gear for reference?
Tried the search and found none
Thanks
Thread Starter
Racer
Joined: May 2004
Posts: 301
Likes: 2
From: Boca Raton Fl
For a rear 3:36 do I need a brown, pink, yellow, blue, red or whateve gear?
Is there an easy answer or are these calculators the only way
Does a 68 vette have 6,7, or 8 drive teeth?
RPM's per mile?
How the heck is this measured accurately
I think I'll just buy all the colors and change out until I find the right one... Heck there are only about 13 of them and at $8.99 each....
NOT!
Is there an easy answer or are these calculators the only way
Does a 68 vette have 6,7, or 8 drive teeth?
RPM's per mile?
How the heck is this measured accurately
I think I'll just buy all the colors and change out until I find the right one... Heck there are only about 13 of them and at $8.99 each....
NOT!
Burning Brakes
Joined: Nov 2006
Posts: 954
Likes: 40
2022 C3 of the Year Finalist - Modified
superdad60:
Can you tell more details: manual or auto? Did you change the all rear end or just the pinion & gear? Did you change rear tiers?
6-7 mile deferent it's too little because you change the ratio by 22% so the speed deference should be higher.
I had original 4.11 with M21 & the color is orange 25 teeth.
I made the opposite 4.11 to 3.36 and bought an adapter of +20% to correct the speed reading.
See also this thread:
http://forums.corvetteforum.com/c3-t...for-4-11s.html
Avner
Can you tell more details: manual or auto? Did you change the all rear end or just the pinion & gear? Did you change rear tiers?
6-7 mile deferent it's too little because you change the ratio by 22% so the speed deference should be higher.
I had original 4.11 with M21 & the color is orange 25 teeth.
I made the opposite 4.11 to 3.36 and bought an adapter of +20% to correct the speed reading.
See also this thread:
http://forums.corvetteforum.com/c3-t...for-4-11s.html
Avner
Le Mans Master
Joined: Aug 2006
Posts: 7,426
Likes: 1,559
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Gear colors
The AIM is the Assembly Instruction Manual, it shows you how all the parts were put together at the factory, you can get one from any of the sponsers.
3:36 Stick drive gear natural(steel) 8 teeth driven gear brown 18 teeth.
3:36 Auto drive gear brown 15 teeth driven gear Blue 38 teeth. PG.
3:36 Stick drive gear natural(steel) 8 teeth driven gear brown 18 teeth.
3:36 Auto drive gear brown 15 teeth driven gear Blue 38 teeth. PG.
Last edited by Peterbuilt; Mar 25, 2009 at 12:40 PM. Reason: typo
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Drifting
Joined: Sep 2006
Posts: 1,259
Likes: 2
From: MS
superdad, you need to know what DRIVE gear is on the transmission
output shaft before you can pick a DRIVEN gear. GM used two different
size DRIVE gears from 68-70 and then another size from 71-up.
Do you know what DRIVE gear you have?
What year is your transmission?
Do you know the FACTORY ORIGINAL axle ratio?
For 68-70, one DRIVE gear was normally used with 3.08, 3.36 & 3.55 and
another with 3.70 and 4.11 so knowing the original ratio will probably tell
us what you have provided everything is original.
output shaft before you can pick a DRIVEN gear. GM used two different
size DRIVE gears from 68-70 and then another size from 71-up.
Do you know what DRIVE gear you have?
What year is your transmission?
Do you know the FACTORY ORIGINAL axle ratio?
For 68-70, one DRIVE gear was normally used with 3.08, 3.36 & 3.55 and
another with 3.70 and 4.11 so knowing the original ratio will probably tell
us what you have provided everything is original.
Thread Starter
Racer
Joined: May 2004
Posts: 301
Likes: 2
From: Boca Raton Fl
superdad, you need to know what DRIVE gear is on the transmission
output shaft before you can pick a DRIVEN gear. GM used two different
size DRIVE gears from 68-70 and then another size from 71-up.
Do you know what DRIVE gear you have?
What year is your transmission?
Do you know the FACTORY ORIGINAL axle ratio?
For 68-70, one DRIVE gear was normally used with 3.08, 3.36 & 3.55 and
another with 3.70 and 4.11 so knowing the original ratio will probably tell
us what you have provided everything is original.
output shaft before you can pick a DRIVEN gear. GM used two different
size DRIVE gears from 68-70 and then another size from 71-up.
Do you know what DRIVE gear you have?
What year is your transmission?
Do you know the FACTORY ORIGINAL axle ratio?
For 68-70, one DRIVE gear was normally used with 3.08, 3.36 & 3.55 and
another with 3.70 and 4.11 so knowing the original ratio will probably tell
us what you have provided everything is original.
1968
4:11 original
1968 Muncie - not sure if close ratio gears but 4th gear is 1:1 of course
Drifting
Joined: Sep 2006
Posts: 1,259
Likes: 2
From: MS
Ok, you should have the small 1.76 8-tooth drive gear and this drive gear
uses the larger driven gears.
Chevy used the same 25 tooth Orange driven gear for both the 4.11
and 3.36 but with the 3.36 they used ratio adapter 6477966 to correct
the speedometer.
You say your speedo is OFF, which way, slow or fast?
I was gonna say you need the 20 tooth 3860343 Blue gear but want to
see what you have now should be more than 6-7 mph difference
between 4.11 and 3.36
Do you know what color driven gear is in there now?
uses the larger driven gears.
Chevy used the same 25 tooth Orange driven gear for both the 4.11
and 3.36 but with the 3.36 they used ratio adapter 6477966 to correct
the speedometer.
You say your speedo is OFF, which way, slow or fast?
I was gonna say you need the 20 tooth 3860343 Blue gear but want to
see what you have now should be more than 6-7 mph difference
between 4.11 and 3.36
Do you know what color driven gear is in there now?
