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#1 |
Registered User
![]() Join Date: Jan 2018
Location: Northern CA
Posts: 588
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Gear Vendors Overdrive
After getting my Jimmy on the road, I was a bit concerned as to the drive-ability of the Truck.
I had rebuilt the motor, stroked it to a 383, and rebuilt both front and rear axles, as well as the 350 transmission. Additionally, I installed Tru-trac posi units in both front and rear. Since I was going with 33" tires I thought 410 gear ratio would be the best. After I finished I wasn't totally happy with trying to go 65 mph as the motor was rotating a bit above 3000 rpms. I contemplated going with the overdrive transmission, but my transmission guy talked me into keeping the T350. He said they're just a great old (strong), transmission. I began to look at the Gear Vendors for an overdrive unit. I probably had about a 50/50 response as to those saying it would work, and those saying it wouldn't work due to the short wheel-base. Finally, I decided to take the plunge and just see for myself if it would work. Then followed it up a Tom Woods driveline. These guys were super helpful and gave me guidance on rear end shims (6 degrees), and built a short driveline with a CV joint on the front end. Happy to say, the Jimmy performs flawlessly! No vibration and most importantly, I can cruise along at 70-75 mph with no problems at all. The motors just cruising along now. The only problem I have now is that I'll probably have to install one in the step-side! Anybody have apprehensions with going this route need not worry. It will work! Gear Vendors themselves are very helpful and can't say enough about Tom Woods drivelines! Pat |
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#2 |
Carpe manana
![]() ![]() Join Date: Dec 2010
Location: Eau Claire, WI
Posts: 12,391
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Re: Gear Vendors Overdrive
Great info. Thanks for posting. Pics when possible please.
__________________
1972 K5 CST Highlander Blazer: http://67-72chevytrucks.com/vboard/s...d.php?t=708547 1972 K20 Cheyenne Super: http://67-72chevytrucks.com/vboard/s...d.php?t=528308 ![]() |
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#3 |
Registered User
![]() Join Date: Jan 2018
Location: Northern CA
Posts: 588
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Re: Gear Vendors Overdrive
Here you go!
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#4 |
Carpe manana
![]() ![]() Join Date: Dec 2010
Location: Eau Claire, WI
Posts: 12,391
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Re: Gear Vendors Overdrive
Very nice. How do you operate 4wd then if the GV unit services just the rear axle?
__________________
1972 K5 CST Highlander Blazer: http://67-72chevytrucks.com/vboard/s...d.php?t=708547 1972 K20 Cheyenne Super: http://67-72chevytrucks.com/vboard/s...d.php?t=528308 ![]() |
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#5 |
Senior Member
![]() Join Date: Feb 2010
Location: Harrah, Washington
Posts: 323
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Re: Gear Vendors Overdrive
With GV you use overdrive in 2 wheel drive only
__________________
71 Blazer 4X4 (unmolested, all original (including paint) 74,000 mile barn find) 67 Camaro RS SS (unmolested, all original (including paint) 81,000 mile barn find) Keith Riel |
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#6 |
Carpe manana
![]() ![]() Join Date: Dec 2010
Location: Eau Claire, WI
Posts: 12,391
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Re: Gear Vendors Overdrive
Is there a switch then to activate the OD as desired?
__________________
1972 K5 CST Highlander Blazer: http://67-72chevytrucks.com/vboard/s...d.php?t=708547 1972 K20 Cheyenne Super: http://67-72chevytrucks.com/vboard/s...d.php?t=528308 ![]() |
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#7 |
Moderator
![]() Join Date: Dec 2012
Location: ON, Canada
Posts: 2,159
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Re: Gear Vendors Overdrive
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#8 |
Senior Member
![]() Join Date: Feb 2010
Location: Harrah, Washington
Posts: 323
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Re: Gear Vendors Overdrive
My buddy had one of these a while back. His used an actual old school dimmer switch on the floor in the stock location to activate the overdrive.
__________________
71 Blazer 4X4 (unmolested, all original (including paint) 74,000 mile barn find) 67 Camaro RS SS (unmolested, all original (including paint) 81,000 mile barn find) Keith Riel |
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#9 |
Carpe manana
![]() ![]() Join Date: Dec 2010
Location: Eau Claire, WI
Posts: 12,391
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Re: Gear Vendors Overdrive
Thanks - I didn't realize the overdrive had an "on/off" switch so to speak. Doesn't seem like a bad way to go - probably less fuss involved than the 700R4 swap we did in my K20.
__________________
1972 K5 CST Highlander Blazer: http://67-72chevytrucks.com/vboard/s...d.php?t=708547 1972 K20 Cheyenne Super: http://67-72chevytrucks.com/vboard/s...d.php?t=528308 ![]() |
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#10 | |
Registered User
![]() Join Date: Jan 2018
Location: Northern CA
Posts: 588
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Re: Gear Vendors Overdrive
Quote:
Fortunately, I'm happy to say that this meets and exceeds my expectations and makes the Jimmy much more enjoyable to drive. It is designed to operate while in 2 wheel drive. Doesn't seem to be a problem to me as I can't ever remember needing to go over 40 mph, or so while in 4 wheel drive. The on/off switch works pretty darn good. Should I want, or need an additional gear, I just turn the unit on and utilize my pull switch. Pat |
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#11 |
Senior Member
![]() Join Date: Mar 2003
Location: Colfax-California
Posts: 8,553
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Re: Gear Vendors Overdrive
Drive shaft looks too short to me. How far does it go into the back of the GV
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#12 |
Registered User
Join Date: Feb 2012
Location: Ruskin Florida
Posts: 4,561
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Re: Gear Vendors Overdrive
Interesting. I also cannot say enough about Tom Woods. Great company! When I installed my NP203 splitter and 1 ton axles they hooked me up. Pricey but absolutely no vibrations. They also suggested the Flat Furd flange for the NP205 and a bolt on the flange Cardan Joint (Spicer of course). Built in 2000 and still works great.
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70 swb 4x4 406sbc 700r4 203/205 d60/14blt locker yadda yadda http://67-72chevytrucks.com/vboard/s...88#post6935688 Yeller 72 Blazer 2wd conversion project "No Daggum Money" http://67-72chevytrucks.com/vboard/s...d.php?t=550804 LS1-T56 3.73 LSD super budget build Blanco-2014 Sierra SWB https://67-72chevytrucks.com/vboard/...d.php?t=810350 |
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#13 | |
Registered User
![]() Join Date: Jan 2018
Location: Northern CA
Posts: 588
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Re: Gear Vendors Overdrive
Quote:
The inside of the housing bottoms out at 3". So the end of the yoke is held back about an inch so there's plenty of room for "sliding" movement with suspension activation. Pat Last edited by Ptjsk; 09-13-2020 at 10:03 AM. |
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