The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1967 - 1972 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 08-13-2016, 01:22 PM   #1
Smokintire70
Registered User
 
Join Date: Jul 2016
Location: Santa Rosa California
Posts: 52
Gear ratio in transmission. Explain please.

I don't know how the gear ratio works in a transmission. Can some one explain it to me like I'm im kindergarten? That would be great. Thanks.
Smokintire70 is offline   Reply With Quote
Old 08-13-2016, 01:55 PM   #2
Alex V.
Registered User
 
Alex V.'s Avatar
 
Join Date: Mar 2013
Location: Campbellsville, KY
Posts: 888
Re: Gear ratio in transmission. Explain please.

The changing of ratios, or how each ratio relates to engine RPM, ground speed, etc.? More specifically, automatic or manual?
__________________
Alex V.
------
1967 C10 Suburban, 350/NP435, Green/Green, PS, PB, HD cooling, charging, shocks, and springs.

1985 GMC C3500 SRW, Sierra Classic, 454/TH400, white/blue.
Alex V. is offline   Reply With Quote
Old 08-13-2016, 02:21 PM   #3
davepl
Registered User
 
davepl's Avatar
 
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
Re: Gear ratio in transmission. Explain please.

Its like your old ten speed bike, but instead of big gears and little gears connected by a chain, it's big gears and little gears meshed together directly. In lower gears the engine can produce more axle torque but at lower speeds, good for climbing hills and pulling boats. At higher speeds that gear reduction goes away until in high gear it's 1:1 (in our trucks) and the rear end is the only gear reduction between piston and tire.

Since you can't stop the wheels while the engine is running, the torque converter allows some slip between the engine and the trans when they two are turning slowly, and then less and less slip as they turn faster, up to about 1500 rpm when there's almost no slip.

Old Powerglides only have 2 gears. Most of our automatics in these trucks are 3 speeds. Later models have 4 or 6 or even 10 speeds these days.

Basic enough? Need more detail?
__________________
1970 GMC Sierra Grande Custom Camper - Built, not Bought
1969 Pontiac 2+2 427/390 4-speed Coupe
1969 Pontiac 2+2 427/390 4-speed Convertible
davepl is offline   Reply With Quote
Old 08-13-2016, 03:43 PM   #4
Smokintire70
Registered User
 
Join Date: Jul 2016
Location: Santa Rosa California
Posts: 52
Re: Gear ratio in transmission. Explain please.

It's a 700R4. So the first gear is 3.06. Does this mean the output of the transmission is basically 1/3 of the engine speed? And 3rd gear is 1.00, meaning the engine speed is equal to output speed of tranny? Also the 700R4's overdrive is .70 so the tranny output spins faster than the engine speed. Is this all correct?
Smokintire70 is offline   Reply With Quote
Old 08-13-2016, 04:40 PM   #5
Bigdav160
Registered User
 
Bigdav160's Avatar
 
Join Date: Apr 2011
Location: Klein Texas
Posts: 3,852
Re: Gear ratio in transmission. Explain please.

Yes!
__________________
My Classics:
'72 K20 Suburban + '65 Dodge Town Wagon
'72 Corvette Roadster +'67 Corvette Roadster
'73 Z-28 Camaro
'63 Ford SWB Uni Pickup
'50 Ford Coupe
Bigdav160 is offline   Reply With Quote
Old 08-13-2016, 05:20 PM   #6
Smokintire70
Registered User
 
Join Date: Jul 2016
Location: Santa Rosa California
Posts: 52
Re: Gear ratio in transmission. Explain please.

Cool thank you guys! It was kinda confusing to me. Glad I got it.
Smokintire70 is offline   Reply With Quote
Old 08-13-2016, 05:20 PM   #7
davepl
Registered User
 
davepl's Avatar
 
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,332
Re: Gear ratio in transmission. Explain please.

Quote:
Originally Posted by Smokintire70 View Post
It's a 700R4. So the first gear is 3.06. Does this mean the output of the transmission is basically 1/3 of the engine speed? And 3rd gear is 1.00, meaning the engine speed is equal to output speed of tranny? Also the 700R4's overdrive is .70 so the tranny output spins faster than the engine speed. Is this all correct?
It is. Also on these later model units there is a clutch that can lock up so that the torque converter doesn't slip -at all- once rolling along at a good speed in top gear, for example.
__________________
1970 GMC Sierra Grande Custom Camper - Built, not Bought
1969 Pontiac 2+2 427/390 4-speed Coupe
1969 Pontiac 2+2 427/390 4-speed Convertible
davepl is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 05:31 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com