I have the Gear Vendors unit pulled from my Nehpew's truck and cleaned up.
Problem 1: I have the bolts out on my yoke plate, but it won't come out. Is the yoke holding it on?
Problem 2: The yoke on the GV unit is only a 4" job, and my drive line has 4 1/2" yokes. I can have the driveline modified, but will a 4" u-joint hold up to a standard with lots of torque?
Problem 3: The speedo hookup on the GV looks like a GM clamp style. My Nephew's truck didn't use it, instead there is a short piece of speedo cable going to the sending unit which is wire tied to the cross member. I'm guessing that there is some sort of electronic shanigans happeneing to fool the PCM then the overdrive is engaged. Is this right?
Problem 4: What kind of oil do I use, and how do I fill the darn thing?


Answer to problem 3. I found the electronics do trick the PCM

Mark

 

Update:
Pulled the yoke and tapped the bearing retainer off, mounted the GV in my truck, everything cool. That is, until I put my old yoke on my nehpew's truck to pull a measurement for the new driveline. I found a little retaining/spacer collar on his that apparently is there to keep the spline in the GV from coming too far forward. So off it came, corrected the error and have it all bolted back up now.
Anyone want to trade me their 1st gen manual trans electronics for the auto stuff I have?

 

Mark: GearVendors recommends GM Axle Lube SAE 80W-90, part number 1052271. Dealer item. It takes just shy of 2 quarts to refill the unit.

Be sure to drop the pan on the unit (6 bolts) and clean the filter screen that goes in the pan. There is also another small (1 inch X 2 inch) drum shaped screen to clean that is accessed when you have the pan off by removing the round threaded plate that is located near the edge of the unit with a spanner wrench or with 2 punches and a scredriver. I use diesel or gas to clean the pan and screens and then dry them with compressed air.

The fill plug is located on the top right rear of the unit. When you get the GM oil they are supposed to give you a filler spout and tube with the oil. If they don't, ask for it.

Also, you may want to call GearVendors and ask them for the manual for the unit. They also have a network of dealers who can help you with your installation/wiring. I have mine wired with a dimmer switch on the floorboard to manually activate the unit. Hope this helps you out.

John (DH)

 

Thanks John, that helps a ton!

 

I just got the Gear Vendors all hooked up with a temporary manual switch just for testing. At about 40MPH I switched on the OD, NO GO!!! .
I did notice however that I loose engine braking when it is switched on, and when I switch it off while coasting it engages again and everything acts normally. It feels like a band is severly out of adjustment or broken.
Does anyone know about these units????

 

Have you contacted GearVendors? Sounds more like it could be a wiring issue. I am going by memory, but I believe that the manual that came with the unit said that it could not be used with an engine brake, but I could be mistaken.

Is the solenoid that engages the unit working?

Also, do you have the unit wired to the PCM correctly? The unit works with the torque converter lock up. Additiionally, if you have 4WD, and put the truck in 4WD, the unit is locked out until you restart the truck in 2WD.

There are quite a few variables and that is why I would suggest that you call them.

John (DH)

 

Gear Vendors says my unit is toast, and they want $750 to rebuild it.
I asked about rebuild parts and was told that it would cost almost as much to buy the parts as it would to get a rebuild from them with a warranty. I don't like that much.....
I'm going to try a few things to boost the pressure, if it doesn't work, I gotta go back the the two piece driveshaft for a while

 

I checked the oil in the GV unit today, and it's dark colored with lots of shiny little tiny flakes in it. Bear in mind that the $30 bucks worth of oil I put in it two day ago was perfectly clear
Tomorrow morning the unit comes out. Crap!