Mega Score - Gear Vendors OD

[chevymike]

I happened to be on FB Marketplace doing some random searching Saturday night and ran across an ad for a almost new Gear Vendors OD unit. Made deal to meet up Sunday afternoon and drove 2 1/2 hours north and 280 miles round trip. This thing is mint and almost had zero use. Guy installed it on his '63 Chevy 4x4 and found out with the gearing and tire size, he didn't need it. I need to swap the adapter out for the NP208 as it has the NP205 one now. This is the exact unit I was looking for, with the fixed output yoke. Also came at a good time as I found my driveshaft has a little bend to it and was causing my vibration at 45mph and higher. I was going to have to get that fixed but now I will just get the new driveshaft to work with the OD unit. Totally stoked!!!

 

[shotty]

Nice score! Why the fixed output yoke?

 

[chevymike]

Nice score! Why the fixed output yoke?

Allows me to run a slip spline driveshaft and if I am ever out and have some issue with the rear end or u-joints I can pull the driveshaft and/or axle shafts and be able to use the front wheel drive to get me out. With a slip yoke, you can't remove the driveshaft and drive it. Just read about a guy on IG who had a rear u-joint failure and had to use chain to make a sling, to keep the driveshaft in, so he could limp it to a safe spot off the highway.

 

[chevymike]

Well, I was able to pick up the NP208 adapter from Gear Vendors (they are local to me) and did the mechanical install on June 27th. Got the measurements for the new driveshaft and picked that up from the shop on July 2nd. Spent a few hours on the 3rd and 4th doing in the wiring and fluids and got to test drive it. I am very happy overall with this system. In autodrive it works very much like a 4 speed auto. 1st-3rd work just like they did but when I get up to 40mph, it engages the OD. When I slow down, it disengages at 25mph. In normal driving, you don't even think about it. I do have a override foot switch so I can turn it off/on and use it to split gears. It was nice pulling up a hill near me where I could have it in 2nd over (think 2.5). 2nd gear is too low and 3rd gear is too high. This puts me in the middle, which was nice. I do have a vibration I need to sort out that occurs between 2000-2400 rpm's. Yoke angles are within spec so not sure what the problem is. Here are some pics and a video of it.

Old parts





New adapter, driveshaft and installed

 

[cruzer747]

foot switch so I can turn it off/on and use it to split gears. It was nice pulling up a hill near me where I could have it in 2nd over (think 2.5). 2nd gear is too low and 3rd gea

I do have a vibration I need to sort out that occurs between 2000-2400 rpm's. Yoke angles are within spec so not sure what the problem is. Here are some pics and a video of it.

going faster than 50mph is nice aint it!? Anywho, hope you get your vibration sorted. Maybe try mounting a camerato record what is happening to the driveshaft/od/tcase at that moment to help sort out the problem, good luck!

 

[shotty]

Been looking in to this a bit and it seems a few people do get vibrations. I know one guy even narrowed it down to the gear vendors device input by removing his rear drive shaft and confirming it still happens when driving around in front wheel drive. Something to consider trying.

 

[Curtisje]

I removed my gear vendors unit. It was shuddering while decelerating. It was on the M1008 truck when I got it. I won't be fixing it or using it again.

It was nice driving on the interstate with overdrive.

 

[chevymike]

I had checked my driveline angles and thought they were in spec but after talking to Gear Vendors and the driveshaft shop, it appears they are not. It was too hot this weekend to play with angles but I think I am going to need to drop down my transfer case mount to get the front u-joint in spec. I used the Spicer driveline operating angles page to find my angles Rear operating angle is 2.5* and the front is 5*. Both places said I should get those numbers within 1* and try to keep max operating angle below 3*. Hope to play around this week.

Spicer Driveline Operating Angle Calculator

Measure the angles of each component in your drivetrain, then use the Spicer Driveline Operating Angle Calculator to find the operating angle of each u-joint in your drivetrain.

spicerparts.com

 

[Curtisje]

I had checked my driveline angles and thought they were in spec but after talking to Gear Vendors and the driveshaft shop, it appears they are not. It was too hot this weekend to play with angles but I think I am going to need to drop down my transfer case mount to get the front u-joint in spec. I used the Spicer driveline operating angles page to find my angles Rear operating angle is 2.5* and the front is 5*. Both places said I should get those numbers within 1* and try to keep max operating angle below 3*. Hope to play around this week.

Spicer Driveline Operating Angle Calculator

Measure the angles of each component in your drivetrain, then use the Spicer Driveline Operating Angle Calculator to find the operating angle of each u-joint in your drivetrain.

spicerparts.com

I wouldn't drop the t-case. I would purchase either 2 degree or 3 degree wedges. I did drop the t-case before and then you have to adjust the transmission shift linkage too. And maybe your transfer case doesn't want to shift properly anymore.

But it's your decision. Just sharing my experience. Good luck.

 

[Sharecropper]

Mike what about the possibility of running a double Cardan at the top? I’ve never done this before so I don’t know. Are those Cardan joints rated for continuous duty?

 

[chevymike]

I wouldn't drop the t-case. I would purchase either 2 degree or 3 degree wedges. I did drop the t-case before and then you have to adjust the transmission shift linkage too. And maybe your transfer case doesn't want to shift properly anymore.

But it's your decision. Just sharing my experience. Good luck.

Ah, never even thought about all the linkage. Talking to both companies, it seems the 5* operating angle is not recommended as it was recommended to be at 3* or less. Being this is the front u-joint, I am not sure how I would decrease that angle without dropping the back of the GV/transfer case. I was originally thinking 3* wedges for the axle until I talked to the two companies.

 

[chevymike]

Mike what about the possibility of running a double Cardan at the top? I’ve never done this before so I don’t know. Are those Cardan joints rated for continuous duty?

I have been thinking more about this. I had done this on a Jeep Cherokee when I did an SYE kit. Never had a problem with it and I think the Cardan joints are rated for continuous duty but I'll do more research. Biggest downside is the cost of having the shaft redone but I guess if it worked, in the big picture it's not that big of a deal.

 

[Sharecropper]

I have been thinking more about this. I had done this on a Jeep Cherokee when I did an SYE kit. Never had a problem with it and I think the Cardan joints are rated for continuous duty but I'll do more research. Biggest downside is the cost of having the shaft redone but I guess if it worked, in the big picture it's not that big of a deal.

You might consider speaking with Tom Woods in Utah. He may provide an opinion on the Cardan. I’ve purchased all my driveshafts from him for years and never had an issue.