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Joined: Sep 2011
Posts: 48
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Sep 2011
Posts: 48 |
I'm not far away replacing the 4.11 torque tube with the a 3.55 I've had for some time. The 3 speed is currently out of the car. I'm wondering if there a way to change the speedo gearing to accommodate the change in rear axle gearing. I tried searching for previous threads about this, but nothing popped up. Thanks in advance.
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Joined: Nov 2002
Posts: 7,472 Likes: 26
ChatMaster - 7,000
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ChatMaster - 7,000
Joined: Nov 2002
Posts: 7,472 Likes: 26 |
I know a ratio adapter can be added, but I recently ran across an Ebay add for a car that had the change and it stated that the correct gears were installed in the transmission for the ratio change. I am not aware of speedo gears being available for the standard three speed transmission with a 3.55 gear set. I am also doing the 3.55 changeover so am interested in knowing if speedo gears are available for the transmission.
Steve D
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Joined: Oct 2004
Posts: 535
Oil Can Mechanic
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Oil Can Mechanic
Joined: Oct 2004
Posts: 535 |
Yes and No! I don't know anywhere you can buy ready made gears for the 3.55. However, I have modified the 1950 Powerglide driving gear to fit in a three speed transmission. A good automotive machine shop can do the modification, or you can do it yourself if you have a small metal lathe. Remove the Powerglide speedo driving gear from the front half of the u joint. Then modify this gear to be the same thickness and inside diameter as the speedo driving gear you are taking out of the three speed. Use the 11 tooth Powerglide speedo driven gear in place of the 9 tooth. Enjoy!
Last edited by chevy50jim; 07/20/16 02:14 PM.
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Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
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ChatMaster - 25,000
Joined: Jan 2002
Posts: 30,701 Likes: 141 |
One of the Chev. truck parts vendors advertises adapters. May be Carters. You need a 15% reduction.
Also wasy to calculate the 15% while diving (60 indicated = 69 MPH) as an example but the odometer will be off also.
The adapters run abbout $75.
Just do a search "speedo. adapters" on Bing or google
Last edited by Chev Nut; 07/20/16 03:11 PM.
Gene Schneider
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Joined: Sep 2011
Posts: 48
Shade Tree Mechanic
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OP
Shade Tree Mechanic
Joined: Sep 2011
Posts: 48 |
Thanks for the info. I now have a direction to investigate. Thanks again
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Joined: Nov 2002
Posts: 7,472 Likes: 26
ChatMaster - 7,000
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ChatMaster - 7,000
Joined: Nov 2002
Posts: 7,472 Likes: 26 |
Wouldn't that be a 15% increase?
Steve D
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Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
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ChatMaster - 25,000
Joined: Jan 2002
Posts: 30,701 Likes: 141 |
The speedometer will read 15% slow. The adapter would increase the speed.
Gene Schneider
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