Gearvendors OD no reverse

UPDATE: Gearvendors OD no reverse

It's the third year now that my F350 has no real reverse and I want to fix that this year (for shure... )
It was not that bad because I helped me out with the good old D60 front axle to drive backwards if needed...

What happened:

Behind my C6 + BW transfer case is a gear vendors overdrive installed. Some day it popped "out of gear" because of an assh*** who was going to hit me so I had to floor it, brake hard and floor it again and that was the moment where it "popped out". I had no forward gear at that time...had to stop...switched the OD off, restarted the engine and then I could drive again - even OD worked fine the rest on my way to work. After work I wanted to back out of the parking lot... put it in "R" and with a LOT of slippage I could back up ("oh no" I thought at that moment ). The second time I tried reverse was completely gone.

I searched the net and found that this could be caused by a broken "reverse band" in the GV OD ?!?
After that I contacted GV (two years ago) and they only wanted me to sell a complete new rebuild unit...and because I'm living in germany and with shipping, duty and taxes this would cost me around 1500-1800€ which is around 1600-1900 $. That's why I avoided it so long.

Do you guys know a better way than to buy the complete unit from GV?
Is there a way to repair it for not so much money?
Or does someone have a unit for sale?

Thanks in advance.
BTW: I like this forum more and more... great people here!

there is no reverse band in the GV. it is a planetary type system that requires hydraulic pressure to work. You're a actually in better shape in sourcing parts for the unit since the original manfacturer is in England. GKN/Laycock is the original designer of the GV unit. you should either be a L series or the latest P series. Post a pic and I can ID it for you.

I know that the planetary / hydraulic system is used for forward "gear" or better said overdrive/direct but to my understanding (what I read about this thing) it has nothing to do with reverse. If I drive normal (forward) everything works like it should (overdrive & direct) but only reverse is not working.



...and no, that's no oil dripping - that was a overdose of Fluid Film on the underbody (but the GV leaks a bit to)

There is a sprague in the gear vendors, but only used for O.D. The powerflow in a gear vendors does not change if it is in direct foward or reverse, it runs through the same side of the cone clutch that is engaged by springs. If you are slipping in reverse you should experience slipping in direct forward.
Now that is said it is much easier to pull the gv unit and inspect or rebuild it then the transmission. If you cannot find parts in Europe try maximum--overdrive for parts. Google laycock for more information, also volvo used the p series overdrive.

My thoughts are you do not have issues with the gear vendors. I feel you have problems in the c6 trans. An easy way to know what gv trans you have is look at the speedometer cable input area. If the fitting in about 2 inches diameter on the gv trans then its the better P series. As posted. The gear vendors has nothing in it that works during reverse gear in the main trans you have in the truck. In fact they are designed to never go into the overdrive when you are backing up the truck. Gear Vendors in El Cajon Ca USA bought the company in Englad a few years ago. They bought everything but the oil stains in the parking lot. So anything you need for their trans will have to be purchased from here in Ca. USA.

If you put the GVOD in direct drive mode, put the transfer case in 4HI, and put the tranny in reverse, how well does it back up? If it backs up "normally", that indicates (to me at least) that the tranny is driving the front axle properly in reverse, and your issue is indeed the GVOD. If the reverse is still lousy, then that indicates that the front axle is NOT being driven properly, and since that cuts the GVOD out of the picture, that would point the compass needle back at the tranny. Just a "dumb guy" way of helping narrow down which unit is the culprit.

Oh, come to think of it, I have read on other threads that the transfer case can fail in a way that forward gears are fine, but reverse is weak/inop. So that's another possibility.

In 4HI and 4LO reverse works fine - no slipping at all. That's how I helped me out over the last years.
The problem must be in the GV OD...

A couple more pictures

Odd that the direct side of the cone clutch slips in reverse but not forward, but stranger things have happened. Wonder if there is not some bearing issues that would let the shaft **** to the side in reverse.

http://www.uniquecarsandparts.com.au/how_it_works_laycock_overdrive.htm
this shows some nice diagrams of how the gear vendors work

I am not 100% sure on this, but it could be that the direct side of the clutch is shot and forward motion in direct is a result of the sprague clutch.
After reading up on this I would say I am 99% sure that this is your problem. With any luck you can just replace the cone clutch, if you have not damaged the clutch surface on the planetary.

Hers what I know of gv failures. If they fail you will NOT have the overdrive effect but.. You can still drive in all the normal gears. Thats the reason I purchased the gv unit. The US Gear over under trans fails and your stuck where it happens. Another note is the gv hydraulic pump that operates the cone clutch only works when the truck speed reaches about 20 mph. So at a stop there is no pressure nor is their any pressure in reverse. You sure seem to want the problem to be in the gv unit so go ahead and take it out.see whats wrong. May as well open up the transfer case too because your that far into it. No better time to inspect the transfer case really. Just might find the problem in there and not the C6 or the gv. Sorry I can't just point out whats positively wrong. I also would not just buy a rebuilt gv either. That would really suck doing that only to find thats not the problem.

icanfixall said:

Hers what I know of gv failures. If they fail you will NOT have the overdrive effect but.. You can still drive in all the normal gears. Thats the reason I purchased the gv unit. The US Gear over under trans fails and your stuck where it happens. Another note is the gv hydraulic pump that operates the cone clutch only works when the truck speed reaches about 20 mph. So at a stop there is no pressure nor is their any pressure in reverse. You sure seem to want the problem to be in the gv unit so go ahead and take it out.see whats wrong. May as well open up the transfer case too because your that far into it. No better time to inspect the transfer case really. Just might find the problem in there and not the C6 or the gv. Sorry I can't just point out whats positively wrong. I also would not just buy a rebuilt gv either. That would really suck doing that only to find thats not the problem.

Click to expand...

Read the page I posted. When shifting and when neither clutches are in contact the spraque clutch applies so the engine does not find a neutral. If the direct clutch is out the sprague clutch will transfer power in forward but not reverse. 1995voyageres is most likely running metal to metal on the direct portion of the clutch, or for some reason the springs applying the pressure on the direct side of the clutch are not doing there job.

Hmmm yeah I think the only way to tell where the problem is is to take the GV OD out and open it.
Is there a possibility that the transfer case can be damaged on the 2WD output side so that only reverse is not working? I know something about transfer cases but not everything...

The C6 is obviously fine because in 4WD reverse works...

Another thing about my transfer case: Sometimes (in reverse...) it pops out. Then I have to shift the C6 to N and back to R and after that it works again. But I'm not 100% sure if the TC pops "out of gear" or one of the hubs. Happens not very often.

Another thing: Last fall I adjusted the rear brakes and lifted the whole rear axle up so both wheels could turn freely. Out of curiosity I put the transmission in R and the wheels began to turn backwards But the slightest amount of braking stopped them even if I stepped on the gas.

1995voyagerES said:

Another thing: Last fall I adjusted the rear brakes and lifted the whole rear axle up so both wheels could turn freely. Out of curiosity I put the transmission in R and the wheels began to turn backwards But the slightest amount of braking stopped them even if I stepped on the gas.

Click to expand...

The more you explain the more it sounds like the gv unit. Pull it off check it out. If the clutch looks fine on both sides check to see if something is holding from applying the direct side of the clutch. Could be physical obstruction in the pistons, or blocked passage way allowing enough oil to escape to release the overdrive side of the clutch but not enough to let the direct side engage.