Gear Vendor OD troubleshooting

[ocnorb]

Checked the fluid. It was low.

Added about 20 oz. and then test drive.

No OD. The light comes on (Green Overdrive) and off when I kick the switch, but she doesn't switch. Bad solenoid maybe?

 

[87crewdually]

Jack the truck up on secure ground and put up on jack stands.
For extra caution you could remove the tires too just put the lugnuts back on so your drum doesn't fall off.
Have a Helper bring the truck up to 40mph while using a test light see if you have power and ground to the solinoid in overdrive.
If no power then there is an electrical problem. Possibly just bad connection or bad speed sensor.
If you do have power and ground to the solinoid when activated, unplug the 2 wires off the solinoid and with the truck off put power and ground directly to it and you should hear an audible click. If no click, unscrew it using the correct thin wrench. Disassemble and attempt to notice any sticky or stuck valves or clogged holes. It should look like this. Reassemble with petroleum jelly on the o-rings. After reassembly make sure it clicks when powered up.

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Ideally it would be nice to check pressures but you need to make an adapter and look for 20 psi nonactivated and over 400psi activated at operating rpms at the test port on the bottom of the unit, we'll cross that bridge if we have to go that far.

Post your findings when you get time. Oh yeah 20 oz is alot, it sounds you may have ran it dry unless you have the added sump on the bottom.

 

[RLDSL]

If the solenoid is still clicking, you can replace the orings on that shaft internally in the thing. When they go bad the things can get jumpy then quit If you can't find orings that size, I know a source for them, the guy usually gets around $5 or so bucks shipped for a set.
If the cone clutch is bad, don't wast money on a new one from GV, find a late model 740 volvo with a M46 tranny and yank the laycock P style out of it and use the cone out of that critter, even GV admits the cone clutch in the volvo units is better than the ones they currently make, but environmental issues won't let them make the good ones anymore
Same guy can get hydraulic seals for the bottom end. That's the usual trouble area

 

[Darrin Tosh]

Couple of things:

I have called GV and they sent me a manual for my unit for free. It has a break down of the parts and shows how to disassemble the unit.

It also has a speedometer correction table that shows you what you need for your final drive gear, tire size etc.

I had to get a new gear, different gear housing, and a reducer to correct my speedometer. All of the parts ran about $150. The manual has the part numbers for all of the parts, color of the GM gears so you may be able to get them from GM or another source cheaper.

Let me know what your tire size is and i will look it up for you to see what you need.

It sure is nice to see that my speedo is at 70MPH and knowing that is how fast I am going. Should have done it years ago!

 

[ocnorb]

Some real work, finally!!

Ok guys, first off THANKS to all of you for your help.


I was able to put a voltmeter on the dash hooked into the solenoid. I get:

1. Zero volts with key off
2. 12 volts with key on in overdrive
3. 0.44 volts when it kicks down into "Auto-Drive" (Red light on controller)
4. Zero volts when I kick the floor switch and all lights go out.

I believe this means that the controller is doing what it is supposed to.

Next I put 12 volts directly to the solenoid and it did make clicking noise as it should.

I pulled the pan off next. The drain plug magnet was covered with alot of black substance that feels tarry so when I dropped the pan I was expecting the worst.

It doesn't look too bad. In fact the screen is spot less. There is nothing on the screen at all. Maybe the mechanics that have been changing the fluid have just been too lazy to wipe the magnet off??

My camera went north with the wife for a wedding she is attending, so I have no way to post anything but cell phone crummy pics until she gets home later.

Nest I pulled the solenoid out and bench tested it. It moves a little, but I still can't see through the holes. How far should the inners move on this thing???

 

[ocnorb]

Well, I guess the OD is toast.

Cleaned up the solenoid and pan, put in new fluid and took it for a drive. Still have a one-speed OD.

 

[87crewdually]

With the vehicle jacked up running at 40mph did you try putting 12v to the solinoid? If you can drill and tap you may be able to make an adapter for the test port. IIRC it's 3/8" course thread. Adapt a 3/8 bolt to npt to a pressure gauge to check pressures. At 40mph without the solinoid energized you'll have 20psi. Energized the psi will be over 400psi. The port is the bolt on the bottom that you probably assumed was a drain. You can see it in the pic it's next to the filter. Also were you able to check the filter?

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[RLDSL]

Ok guys, first off THANKS to all of you for your help.


I was able to put a voltmeter on the dash hooked into the solenoid. I get:

1. Zero volts with key off
2. 12 volts with key on in overdrive
3. 0.44 volts when it kicks down into "Auto-Drive" (Red light on controller)
4. Zero volts when I kick the floor switch and all lights go out.

I believe this means that the controller is doing what it is supposed to.

Next I put 12 volts directly to the solenoid and it did make clicking noise as it should.

I pulled the pan off next. The drain plug magnet was covered with alot of black substance that feels tarry so when I dropped the pan I was expecting the worst.

It doesn't look too bad. In fact the screen is spot less. There is nothing on the screen at all. Maybe the mechanics that have been changing the fluid have just been too lazy to wipe the magnet off??

My camera went north with the wife for a wedding she is attending, so I have no way to post anything but cell phone crummy pics until she gets home later.

Nest I pulled the solenoid out and bench tested it. It moves a little, but I still can't see through the holes. How far should the inners move on this thing???

It doesn't have to move all that far but if the orings aren't holding pressure, it won't do a thing, all the clicking on earth won't mean a thing. You need to try to replace those orings on that solenoid First, although things are not sounding good. You can get the orings for a few bucks and eliminate that variable. THat is the simplest cause of a failure to engage. and rebuilding it yourself with a handful of orings is a dang sight cheaper than spending $85 to get a new solenoid from GV

 

[ocnorb]

With the vehicle jacked up running at 40mph did you try putting 12v to the solinoid? If you can drill and tap you may be able to make an adapter for the test port. IIRC it's 3/8" course thread. Adapt a 3/8 bolt to npt to a pressure gauge to check pressures. At 40mph without the solinoid energized you'll have 20psi. Energized the psi will be over 400psi. The port is the bolt on the bottom that you probably assumed was a drain. You can see it in the pic it's next to the filter. Also were you able to check the filter?

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Instead of doing it on jackstands I drove it down the road with the wires hanging out the window hooked up to the solenoid at one end and my voltmeter on the dash.

I didn't know that there was a filter up there. Assumed it was only the screen. Wish I had seen that pic before I put it all back together.

Is the port the bolt that goes up under the solenoid? (Mine has a large finned aluminum pan on the bottom that I don't see in any pics on Gear Vendors website.) EDIT- never mind I reread your post and you had already answered that it was the port!

Maybe I just need to tear it out and get it on the bench or knuckle under and order a rebuilt from GV.

 

[87crewdually]

The finned pan you speak of is an add-on from gearvendors and is a sump to increase the capacity. If your confident I can supply you pics of a similar unit for a guide and you can order a "re-seal" kit from G/V. The kit is around $30 and gives you all the proper o-rings (for everything from the solinoid to the pistons), assembly gaskets and sump gaskets. They will sell you the parts as long as you know what you need. I think they shy away from selling just parts because alot of people try to just throw parts at the units and when they still don't work from mis-diagnosing the people ***** to G/V like it's their fault so they would rather refurb it for ALOT of money. If you got it on the bench apart you can then inspect your conical clutch and replace if necessary.

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Here's some o-ring sizes:

App Qty Nat'l Size ID CS OD
--------------------------------------------------------------------------
Operating Piston 2 214 1 1/8 1 1/4
Speedometer Bearing 1 210 3/4 1/8 1
Pump Plug 1 021 15/16 1/16 1 1/16
Pump Body 1 023 11/16 1/16 13/16
Dashpot Plug 1 024 1 1/8 1/16 1 1/4
Dashpot Sleeve 1 022 1 1/16 1 1/8
Relief Valve Body (large) 1 022 1 1/1/6 1 1/8
Relief Valve Body (small) 1 028 1 3/8 1/16 1 1/2
Solenoid-valve-outside 2 014 1/2 1/16 5/8
Solenoid-valve-end 1 010 1/4 1/16 3/8
Solenoid-valve-stem 2 007 5/32 1/16 9/32


This is a "j" type pic which is very close to a "P" type which is what we have. If your not comfy with yourself doing it I'm in NJ and willing to help you out if need be.

 

[ocnorb]

I've never torn into a transmission, but I am willing to give it a shot.

Maybe we can all learn something?? I will post pics of the process if it will help others out.

It will be a few weeks before I can get to it. Heading out on a camping/fishing trip for this next weekend.

 

[HellzMindPlaya]

So I joined this forum just for this post, hopefully some of you are still around! I just picked up a 1985 F350 DRW Crewcab with a 6.9 IDI, a Bank's Turbo (must be the old one, before the Sidewinder I guess) and a Gear Vendor OD for $1500. The OD didn't work on the way home so I got to drive 50-55 MPH the 70 miles home! Poor Engine got a work out. So I figured out the wiring to the OD because is was very Jerry-rigged and now the light comes on when the truck is supposed to go into OD but the OD doesn't engage. So I checked the Solenoid with a 12 battery and it does click so it seems to be good, I next rigged up a multimeter and went for a short drive and saw that the OD is getting 12vdc when the OD light comes on, so the control box is working as it should. After trying what I figured was the easy test I then moved on to replacing the oil in the unit... I just used some 80w-90 from Napa because I figured I could get the more correct stuff if/when I got the unit working. Not sure if the unit was low to begin with but the stuff that came out was rather dark.

Called up DV and they want $1050 plus $80 freight and $500 core for a rebuilt unit with another 1 year warranty. Not feeling that rich right now so I am coming to you fine people to see what you think my next line of action is. I can add that with everything connected up and the OD light on that when I take my foot off the gas at 45-50 the engine drops to an idle, but with the OD off the engine only drops maybe 300-400 RPM.

Any help will be greatly appreciated.

Trever

Edit: Did the OP ever get his OD figured out?

 

[icanfixall]

I was talking to Gear Vendors last week. They are now the builders of these units. They bought all of the business and machines from the factory in Englad. So they are an inhouse maker ... Much better deal for all of us too.
Do you know if you have the J or the P unit.. The P unit is the newer units and they have the large approx 2 inch speedo head in the tail shafts. The J models have the smaller 1 inch speedo head. If the serial number tag on the side of them has an XR stamped into them they have been rebuilt by the factory...

 

[ocnorb]

Edit: Did the OP ever get his OD figured out?

Sounds like you got a great deal!!

If you look at the picture above- my OD had a worn out clutch (part 61). As luck would have it I found a good used one on Craigslist for less than I could buy the parts.

A year or so later I had it repaired and sold it.

 

[towcat]

if you google up "maximum overdrive" for GV parts, they're a good source for service parts for GV overdrives. I bought a rebuild kit from them for $275 that contained all the necessary bearings and friction materials.