Just purchased this truck couple of weeks ago (87 F250 extended cab 4X4 6.9 with 4spd) and while working on it I noticed a black box 2" X 3" X 1/2" thick under the dash that says "Gear Vendors" on it. Bunch of wires coming out of it. I looked under the truck and it doesn't appear to have anything added to the trans and I thought those units attached to the end of the trans or between the trans and transfer case. Maybe it was on the truck at one time and someone removed it? There is what appears to be a spacer between the trans and tranfer case however there's no wires going to it so I assume that's what it is simply a spacer. My intention was to remove the 4spd and replace it with a ZF 5spd (already have it) however if the gear vendors can be added easily, I may go that route.
GEAR VENDORS
- Thread starter catbird7
- Start date
take a pic of the backside of your transfer case. if you still have it installed, it will be there. post the pic so we can confirm or deny it's existence for you.
icanfixall
Official GMM hand model
Yes... Please take a pic and post it. Not a chance you can have an adapter without a GV behind it.
yup. that's a controller. the GV unit is long gone unfortunately.
here's what a destroyed one looks like....
http://www.oilburners.net/forums/showthread.php?60778-GV-carnage-very-ugly-pics
here's what a destroyed one looks like....
http://www.oilburners.net/forums/showthread.php?60778-GV-carnage-very-ugly-pics
I currently have a running / driving ZF-5spd however it has 306,000 miles on it. Synchronizers could / should be replaced (sota "clicks" a little goint into 3rd), doesn't leak anything. Its attached to a SMF and gear noise is terrible when lugging slow.
Additionally, I have this truck which came with a T-19 4spd.
Which is the better choice,
Rebuild the ZF 5spd and swap out the T-19 or rebuild the T-19 (pops out of 2nd gear) and add the necessary gear vendors parts? I'm looking for fuel mileage and do a considerable amount of highway driving.
I'm leaning toward rebuilding the ZF-5spd however I'm not sure if it's a direct swap. ZF is currently attached to a 7.3 4x4 single cab. Wanting to install into an extended cab 4X4 that currently has the T-19 and it's attached to a 6.9. Will everything bolt together? Driven shaft lengths different?
Additionally, I have this truck which came with a T-19 4spd.
Which is the better choice,
Rebuild the ZF 5spd and swap out the T-19 or rebuild the T-19 (pops out of 2nd gear) and add the necessary gear vendors parts? I'm looking for fuel mileage and do a considerable amount of highway driving.
I'm leaning toward rebuilding the ZF-5spd however I'm not sure if it's a direct swap. ZF is currently attached to a 7.3 4x4 single cab. Wanting to install into an extended cab 4X4 that currently has the T-19 and it's attached to a 6.9. Will everything bolt together? Driven shaft lengths different?
Csm Davis
Registered User
Gear vendors suck, 2000 hp at what torque? Must be 2 or 3 foot/pounds.
icanfixall
Official GMM hand model
Ok... So what do you feel is a better aux trans. With your 16 post count I'm all ears. I do my best to never stop learning so lets see.
Actually, for a 4x4 application, the ZF and the T-19 are the same length, so no driveshaft modifications needed. I can't say with authority that you can reuse the transmission frame crossmember...I did this swap and I swapped crossmembers because I was on a tight timeframe and couldn't risk finding out the hard way that it wouldn't work, but I've since heard that you can use the T-19 crossmember. But, other than the crossmember, the clutch assembly (you need to use the clutch assembly for the ZF, NOT the T-19), and the floor pan insert that goes above the transmission (all of which are bolt-in parts; no welding or fabrication needed), you're good to go
A 7.3L flywheel bolts to a 6.9L without trouble, the bellhousing and transfer case bolt patterns are the same, and the clutch hydraulics are the same.I haven't had any direct experience with the GearVendors unit, but I've heard that they don't take kindly to engine-braking (something I'm VERY aggressive with), and I don't like that they mount behind the transfer case on a 4x4 application...I would like to be able to use the gear splitter in 4 wheel drive if necessary, and the Doug Nash/U.S. Gear unit mounts between the transmission and the transfer case...on the other hand, you can't buy new parts for the Doug Nash units. So, there's give and take going either way...personally, I would put the ZF in, then start looking at auxiliary gearbox options if you decide you want double-overdrive...
Hope this helps a bit...good luck!
jaluhn83
Full Access Member
Personally I would go with the ZF.
I am not real fond of the GV for a truck application, though I'll admit that I've never owned one nor worked with one much, and many have had good luck with them.
GV design was originally a Laycock overdrive built for mid 60's British sports cars and subsequently used on other cars as well. It's designed to give a top end high gear for high speed, ie what you'd want in a sports car and also to be easy and smooth the shift. High load, low speed shifting, etc were not factors in the original design. GV beefed up the design some, but it still shares that genesis.
The GV shifts with a hydraulically/spring shifted cone clutch - hydraulic for OD, spring for direct. The hydraulic pressure is generated by a pump off the input side of the gearbox. Line pressure and volume are thus effected by road speed, which is why it's not recommended to shift into od below a certain speed - something like 35 mph IIRC. Below this it may shift, but could be slower (ie more clutch slippage due to being in between gears) and not have enough pressure (not a strong of a clutch force, slippage under load) Thus, using it as a gear splitter is limited, and you have to be careful lugging down in od. Engine braking too could be an issue in OD, since any slippage will reduce the speed of the input side, reducing pressure, causing more slippage..... Low order probability, but worth considering.
At the end of the day, the GV is good when used as designed - as a selectable extra top end gear under light to moderate load. It's not the best option if you're towing heavy, or wanting a gear splitter.
I am not real fond of the GV for a truck application, though I'll admit that I've never owned one nor worked with one much, and many have had good luck with them.
GV design was originally a Laycock overdrive built for mid 60's British sports cars and subsequently used on other cars as well. It's designed to give a top end high gear for high speed, ie what you'd want in a sports car and also to be easy and smooth the shift. High load, low speed shifting, etc were not factors in the original design. GV beefed up the design some, but it still shares that genesis.
The GV shifts with a hydraulically/spring shifted cone clutch - hydraulic for OD, spring for direct. The hydraulic pressure is generated by a pump off the input side of the gearbox. Line pressure and volume are thus effected by road speed, which is why it's not recommended to shift into od below a certain speed - something like 35 mph IIRC. Below this it may shift, but could be slower (ie more clutch slippage due to being in between gears) and not have enough pressure (not a strong of a clutch force, slippage under load) Thus, using it as a gear splitter is limited, and you have to be careful lugging down in od. Engine braking too could be an issue in OD, since any slippage will reduce the speed of the input side, reducing pressure, causing more slippage..... Low order probability, but worth considering.
At the end of the day, the GV is good when used as designed - as a selectable extra top end gear under light to moderate load. It's not the best option if you're towing heavy, or wanting a gear splitter.
Diesile
Full Access Member
Amen to the above.
Wanna part with that controller?
Black dawg
Registered User
If you already have the zf, I would do that. The GV is nice, and adds some ratios if needed, but is an expensive part that parts arent easily obtained for.
Black dawg
Registered User
There are lots out there holding up fine to real power and real towing. What is your experience with them? There is very little info out there on failures, so I like to get all the info I can.
Csm Davis
Registered User
Well my post count here has nothing to do with what I have learned in the last 35 years of turning wrenches or college. So almost every other option is better in my opinion the best idea would be to go with the over drive transmissions that are out there and can be had for the same or cheaper than the GV unit. They know that the unit is not that strong torque wise. I called to see for a friend who I had told of my troubles, but he couldn't find what he would like better for a 2 and 1/2 ton military truck that has a 135 hp motor, and they wouldn't sell us one. He only camps in it so the max load would be 14,500 and all the low gearing is in the axles. I personally want to keep my transmission package as short as possible to help with drive shaft angles and the only auxiliary unit I really trust is a brownie box in a big rig setup. If someone makes a gear only overdrive unit I would like to see it, there used to be a couple different units made for small vehicles but I believe they have gone away.Ok... So what do you feel is a better aux trans. With your 16 post count I'm all ears. I do my best to never stop learning so lets see.
