4 spd Transmission question

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acarlson
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Location: Dahlonega, GA

4 spd Transmission question

Unread post by acarlson » Sat Aug 12, 2017 11:11 am

Now that my engine is running I have a transmission question. I have an LM '66 4 speed. I replaced all of the seals and gaskets on it - including the side cover gasket. I put it all back together and put a small rod through the shift pin and I can shift through all the gears and reverse. With the engine running the yokes spin in opposite directions from each other - which I think is normal. So here's my question. With the engine off, if I shift the tranny into any forward or reverse gear, should I be able to turn the yokes by hand on either side if the differential ?

Alec
1965 Regal Red Corsa 4 Speed Turbo Convertible

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bbodie52
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Re: 4 spd Transmission question

Unread post by bbodie52 » Sat Aug 12, 2017 7:13 pm

The differential allows you to turn one yoke or the other independently, even if the transmission locks the input drive gear (as long as one wheel i off of the ground). The differential spider gears allow one wheel to rotate independently. If one wheel loses traction (on mud, ice, etc.) it will allow one wheel to spin, while the other wheel receives no power and will not be driven at all. A Limited Slip (Positraction) differential helps compensate for this fault. (With the wheels both off of the ground, manually turning one wheel in one direction will cause the opposite wheel to turn in the opposite direction. If you have a limited slip differential, both wheels will turn in the same direction). The videos below will explain the principles behind the function of a differential...





BE SURE TO ONLY FILL YOUR DIFFERENTIAL AND MANUAL TRANSMISSION WITH GL-4 GEAR LUBE. GL-5 gear lube will damage the "yellow metal" components in your manual transmission. The Corvair transaxle shares gear oil between the manual transmission and the differential, so the gear lube must be GL-4 in both.
Pennzoil GL-4.jpg
Pennzoil GL-5.jpg
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible

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acarlson
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Location: Dahlonega, GA

Re: 4 spd Transmission question

Unread post by acarlson » Sun Aug 13, 2017 9:36 am

Thanks Brad - you told me exactly what I needed to know. I didn't understand why I could turn both yokes when the tranny was in gear. In the '66 gearbox, all the shift linkage is attached to the side cover. I was concerned I may not have reinstalled the cover correctly. However, once I blocked the driver side yoke the passenger side would only turn if I was in neutral. This is what I was expecting all along. Now I know. Thanks again ! :ty:

Alec
1965 Regal Red Corsa 4 Speed Turbo Convertible

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