F350 Gearing choices...

[Ford F834]

Ok I under stand on the pump as it must be driven inside off the input shaft.

If I did go with GV OD I would not be starting off in 1st OD but shifting to it once moving then to 2nd.

I would run a 2sp rear button/knob on the side of the stock shifter like they do on 2sp rear trucks.

I drove one and it was easy to use.

As for splitting all the gears going up or down I don't think it would be worth it as some of the ratios would be so close why bother? It would be one of them things once driving and tested you would know if you wanted to split or not.

Then again if GV said not good when down shifting might have to rethink this.

The only thing I did not like with the Ranger unit was needing to cut the stock trany front bearing retainer and then not being able to go back stock with out needing to find another.

I also did not like the 2nd shifter handle, had one in a Toyota LC and was a pain if you wanted to split gears.

Now if you can fit it with an electric type motor that was fast enough, and used the 2sp knob might be a way to go?

Thanks for the information.

Dave ----

Dave, my GVOD was hooked up behind the close ratio T19 diesel transmission. I operated it with a push pull gear splitter switch as you described. And you called it. Splitting gears was completely worthless. The ratios were redundant on the close ratio trans and all you did was loose momentum while shifting. For me it was just an overdrive. On a regular wide ratio transmission it might help some, especially if you were trying to tow with it, but for regular use I think you would find yourself just using it as an overdrive. The DNE shift switch (if you have the original wiring) is a little deal that clamps onto your turn signal lever. I’m sure it could be run by a push pull if you have the solid state controller with the motor timer as well. This is how it looks:

What exactly are your gearing goals? I know I have a transfer case for a creeper gear, but I’ve been very happy with my close ratio T19 and tall axle gearing on my straight six.

[FuzzFace2]

Dave, my GVOD was hooked up behind the close ratio T19 diesel transmission. I operated it with a push pull gear splitter switch as you described. And you called it. Splitting gears was completely worthless. The ratios were redundant on the close ratio trans and all you did was loose momentum while shifting. For me it was just an overdrive. On a regular wide ratio transmission it might help some, especially if you were trying to tow with it, but for regular use I think you would find yourself just using it as an overdrive. The DNE shift switch (if you have the original wiring) is a little deal that clamps onto your turn signal lever. I’m sure it could be run by a push pull if you have the solid state controller with the motor timer as well. This is how it looks:

What exactly are your gearing goals? I know I have a transfer case for a creeper gear, but I’ve been very happy with my close ratio T19 and tall axle gearing on my straight six.

Goal is little less RPM at high way speeds, here that is 70+, legal is 65-70.

Rush hour stop n go so thinking a split gear and let it idle so no need to hit brakes or clutch.

The truck, 300 six/T18/2.75 rear gear for now. It will be a back up to pull my car trailer when needed, guessing a weight of 5K give or take some.

It is all just dreaming / planning for now as the truck is not even on the road yet to see how it does as it sits.

Sorry for the high jack and thanks for the information.

Dave G.

[Ford F834]

Goal is little less RPM at high way speeds, here that is 70+, legal is 65-70.

Rush hour stop n go so thinking a split gear and let it idle so no need to hit brakes or clutch.

The truck, 300 six/T18/2.75 rear gear for now. It will be a back up to pull my car trailer when needed, guessing a weight of 5K give or take some.

It is all just dreaming / planning for now as the truck is not even on the road yet to see how it does as it sits.

Sorry for the high jack and thanks for the information.

Dave G.

You are not hijacking Dave, just participating 🙂. After all I did ask the question about your project, and since I own both straight six and diesel I can assure you that they both like the same gearing and this conversation is very relevant.

When I bought my ‘81 it had a T18 and 2.75’s in its 2wd form. It had 31x10.5 R15 tires... but in reality the 31’s are more like 30” new and mine measured 29”. The combination wasn’t bad, at least running around empty. 2nd gear starts required a little more clutch slipping than I am used to, and for even a steep driveway I would use granny. Any kind of hauling or towing and I’m sure you would need to use granny 1st a lot...

I can’t comment about highway characteristics with the 2.75’s because it had a bad bearing and I never went above ~45mph. However, I switched to 3.00 gears and 235/85R16 tires. By the math this is almost identical to the 2.75 and 29” worn down 31’s. I’ve had it up to 75mph and it does great minus the steering not feeling as tight as I want for freeway speed. But the optimal/sweet spot with my combo is 64-67mph per my gps phone speedometer app. Originally I was going to add the GVOD to this truck and run the DNE2 on the diesel. But after driving it I think .78 would be too much, especially since Arizona isn’t very flat. If you are following my logic, you are in my same boat if your tires are close to 29”. Don’t know if that helps at all...

The close ratio is really excellent with the straight six, especially for towing. For the price that GVOD’s go for, you might consider a diesel T19 with a transfer case on it as a creeper. Depending on your tire size, that with a 2.47 rear center section might be more functional than an add on OD. Just another angle to think about.

[Ford F834]

You are not hijacking Dave, just participating 🙂. After all I did ask the question about your project, and since I own both straight six and diesel I can assure you that they both like the same gearing and this conversation is very relevant.

When I bought my ‘81 it had a T18 and 2.75’s in its 2wd form. It had 31x10.5 R15 tires... but in reality the 31’s are more like 30” new and mine measured 29”. The combination wasn’t bad, at least running around empty. 2nd gear starts required a little more clutch slipping than I am used to, and for even a steep driveway I would use granny. Any kind of hauling or towing and I’m sure you would need to use granny 1st a lot...

I can’t comment about highway characteristics with the 2.75’s because it had a bad bearing and I never went above ~45mph. However, I switched to 3.00 gears and 235/85R16 tires. By the math this is almost identical to the 2.75 and 29” worn down 31’s. I’ve had it up to 75mph and it does great minus the steering not feeling as tight as I want for freeway speed. But the optimal/sweet spot with my combo is 64-67mph per my gps phone speedometer app. Originally I was going to add the GVOD to this truck and run the DNE2 on the diesel. But after driving it I think .78 would be too much, especially since Arizona isn’t very flat. If you are following my logic, you are in my same boat if your tires are close to 29”. Don’t know if that helps at all...

The close ratio is really excellent with the straight six, especially for towing. For the price that GVOD’s go for, you might consider a diesel T19 with a transfer case on it as a creeper. Depending on your tire size, that with a 2.47 rear center section might be more functional than an add on OD. Just another angle to think about.

More reading and price checking is showing that I had an unrealistic estimation of gear swap costs. It is much more that I thought, perhaps in the $2,000 ballpark for quality gears bearings shims and seals, plus labor from a reputable shop. The front axle alone is ~$600 in parts. Selling the overdrives wouldn’t be enough.

Buying a set of used axles would actually be cheaper, but front D60’s are hard to find. I am also leery of used take-outs, at least in this part of the country. Without rust cancer in the equation, people don’t often junk a 4x4 F350 unless it’s been wrecked or beaten to death. Used axles can turn out to be a snake bag.

Doing the gear swap work myself has crossed my mind, but it’s still somewhere around a grand in parts, and another huge time consuming detour that’s way out of my comfort zone. I don’t mind learning, but it’s been nearly 5 years since I parked the truck for rebuilding and the last thing I need is another road block to completion.

Practicality is pointing towards the wide ZF and GVOD option, just because it’s the easiest... but there is another drawback to it that I forgot to mention. The unit sticks out quite far from the transfer case mounting face, and in my opinion should really have more support than just the flange bolts. For most applications this may be acceptable, but for the kind of torque my engine will make this looks like a liability.

The way the GVOD is constructed there is no easy way to attach a cross member like Justin did for his DNE2.

This brings me back to the remote mount transfer case idea. This is another expensive route, but l believe it would be less than new gears. It would require fabricating a cross member/mounting system for the transfer case and customized shift linkage. This can be tedious and time consuming, but not as critical as learning to set up gears. Do you think I could mate the DNE2 to the NP205 with a double cardan or would I need some slip?

[Gary Lewis]

More reading and price checking is showing that I had an unrealistic estimation of gear swap costs. It is much more that I thought, perhaps in the $2,000 ballpark for quality gears bearings shims and seals, plus labor from a reputable shop. The front axle alone is ~$600 in parts. Selling the overdrives wouldn’t be enough.

Buying a set of used axles would actually be cheaper, but front D60’s are hard to find. I am also leery of used take-outs, at least in this part of the country. Without rust cancer in the equation, people don’t often junk a 4x4 F350 unless it’s been wrecked or beaten to death. Used axles can turn out to be a snake bag.

Doing the gear swap work myself has crossed my mind, but it’s still somewhere around a grand in parts, and another huge time consuming detour that’s way out of my comfort zone. I don’t mind learning, but it’s been nearly 5 years since I parked the truck for rebuilding and the last thing I need is another road block to completion.

Practicality is pointing towards the wide ZF and GVOD option, just because it’s the easiest... but there is another drawback to it that I forgot to mention. The unit sticks out quite far from the transfer case mounting face, and in my opinion should really have more support than just the flange bolts. For most applications this may be acceptable, but for the kind of torque my engine will make this looks like a liability.

The way the GVOD is constructed there is no easy way to attach a cross member like Justin did for his DNE2.

This brings me back to the remote mount transfer case idea. This is another expensive route, but l believe it would be less than new gears. It would require fabricating a cross member/mounting system for the transfer case and customized shift linkage. This can be tedious and time consuming, but not as critical as learning to set up gears. Do you think I could mate the DNE2 to the NP205 with a double cardan or would I need some slip?

I'm not surprised about the price of differentials - they are expensive. And, you might want to upgrade with Detroit Tru-tracs or somesuch, and that adds another $1500 or more.

To support the GV box, what about sandwiching a 1/4" plate between the tranny and GV unit? It is a question of how long the splines are and if you'll have enough engagement. But you could fashion a cross-member to both support the box as well as keep it from twisting.

As for an NP205, I think you could use a double-cardan joint. But, beyond that I don't know as I've not done anything like that.

[85lebaront2]

More reading and price checking is showing that I had an unrealistic estimation of gear swap costs. It is much more that I thought, perhaps in the $2,000 ballpark for quality gears bearings shims and seals, plus labor from a reputable shop. The front axle alone is ~$600 in parts. Selling the overdrives wouldn’t be enough.

Buying a set of used axles would actually be cheaper, but front D60’s are hard to find. I am also leery of used take-outs, at least in this part of the country. Without rust cancer in the equation, people don’t often junk a 4x4 F350 unless it’s been wrecked or beaten to death. Used axles can turn out to be a snake bag.

Doing the gear swap work myself has crossed my mind, but it’s still somewhere around a grand in parts, and another huge time consuming detour that’s way out of my comfort zone. I don’t mind learning, but it’s been nearly 5 years since I parked the truck for rebuilding and the last thing I need is another road block to completion.

Practicality is pointing towards the wide ZF and GVOD option, just because it’s the easiest... but there is another drawback to it that I forgot to mention. The unit sticks out quite far from the transfer case mounting face, and in my opinion should really have more support than just the flange bolts. For most applications this may be acceptable, but for the kind of torque my engine will make this looks like a liability.

The way the GVOD is constructed there is no easy way to attach a cross member like Justin did for his DNE2.

This brings me back to the remote mount transfer case idea. This is another expensive route, but l believe it would be less than new gears. It would require fabricating a cross member/mounting system for the transfer case and customized shift linkage. This can be tedious and time consuming, but not as critical as learning to set up gears. Do you think I could mate the DNE2 to the NP205 with a double cardan or would I need some slip?

Ok, a few items, first damn the GV unit looks like a Laycock Denormanville overdrive. For support, make a yoke that will fit the front bolt pattern of the GV and brace it to the transfer case, two wexaples, Chrysler engine to transmission braces and Chevy truck engine mount to a cast aluminum torque converter cover.

For a remote mount transfer case, go look at some military 2 1/2 or 5 ton trucks, they had a remote transfer case as did the old M37 Dodges. I do not remember a slip joint on our 5 tons just a double u-joint stub shaft, but I think they had solid engine mounts. If the GV output is a slip yoke then that should cover it, alignment will be fairly critical however.

[Ford F834]

Ok, a few items, first damn the GV unit looks like a Laycock Denormanville overdrive. For support, make a yoke that will fit the front bolt pattern of the GV and brace it to the transfer case, two wexaples, Chrysler engine to transmission braces and Chevy truck engine mount to a cast aluminum torque converter cover.

For a remote mount transfer case, go look at some military 2 1/2 or 5 ton trucks, they had a remote transfer case as did the old M37 Dodges. I do not remember a slip joint on our 5 tons just a double u-joint stub shaft, but I think they had solid engine mounts. If the GV output is a slip yoke then that should cover it, alignment will be fairly critical however.

Thanks for the input guys…

 

Gary, the plate idea is a good one, but I don’t know if the loss of spline lap would work unless I could find or make a longer coupler. The GVOD shaft is quite short. Bill, I will have to examine it again, but my recollection is that the ribs of the adapter housing won’t really allow me to bolt anything around the front side of the GVOD bolt circle. It is a real pill. There just isn’t a good way to get a hold of this thing. Maybe it is strong enough, but it makes me nervous. I want to do away with the two piece drive shaft and carrier bearing, so there would literally be nothing aft of the transmission mount to support or stabilize the driveline, and ZF’s have been known to break there. Bill, you are correct. The GVOD is essentially a Laycock P-type overdrive. Below are some pictures that should help illustrate what I am up against.

If I do the remote mount transfer case idea, The DNE2 does not have a slip shaft output. It is fixed. The NP205 would also be fixed. However, the DNE2 does have case bolts that can be used to mount a cross member to it, and the 205 must be mounted to a cross member by design. I think joining them with a double cardan could work, but they would have to be exactly aligned as you said. Perhaps a short slip shaft would be better? There are no heavy military trucks in my yards to look at for transfer case donors. The other problem is that Ford seems to be the only one to use a driver side drop, so all of the GM, Dodge, and International Harvester NP205’s have the front shaft output on the wrong side. Pretty much has to be from an early Ford High Boy if I want to go that route. That is why Ford units tend to have much higher prices than the others. They are expensive, but not unobtainable.

[Gary Lewis]

Thanks for the input guys…

 

Gary, the plate idea is a good one, but I don’t know if the loss of spline lap would work unless I could find or make a longer coupler. The GVOD shaft is quite short. Bill, I will have to examine it again, but my recollection is that the ribs of the adapter housing won’t really allow me to bolt anything around the front side of the GVOD bolt circle. It is a real pill. There just isn’t a good way to get a hold of this thing. Maybe it is strong enough, but it makes me nervous. I want to do away with the two piece drive shaft and carrier bearing, so there would literally be nothing aft of the transmission mount to support or stabilize the driveline, and ZF’s have been known to break there. Bill, you are correct. The GVOD is essentially a Laycock P-type overdrive. Below are some pictures that should help illustrate what I am up against.

If I do the remote mount transfer case idea, The DNE2 does not have a slip shaft output. It is fixed. The NP205 would also be fixed. However, the DNE2 does have case bolts that can be used to mount a cross member to it, and the 205 must be mounted to a cross member by design. I think joining them with a double cardan could work, but they would have to be exactly aligned as you said. Perhaps a short slip shaft would be better? There are no heavy military trucks in my yards to look at for transfer case donors. The other problem is that Ford seems to be the only one to use a driver side drop, so all of the GM, Dodge, and International Harvester NP205’s have the front shaft output on the wrong side. Pretty much has to be from an early Ford High Boy if I want to go that route. That is why Ford units tend to have much higher prices than the others. They are expensive, but not unobtainable.

Bill called that one right - Laycock de Normanville. Well spotted!

On the support, I agree that you wouldn't have enough spline engagement with a plate between them given the shortness of the input shaft. Bummer.

Any support you do is somehow going to need to be isolated with rubber. What if you had a cross-member above or below the unit that had a tranny mount on it, and a big C-shaped piece bolted to that. The C would be cut out to miss the case but get the top or bottom two studs of the interface between the overdrive and the spacer.

I'm thinking two studs would be enough to provide support as well as keep it from twisting due to torque.

[85lebaront2]

Bill called that one right - Laycock de Normanville. Well spotted!

On the support, I agree that you wouldn't have enough spline engagement with a plate between them given the shortness of the input shaft. Bummer.

Any support you do is somehow going to need to be isolated with rubber. What if you had a cross-member above or below the unit that had a tranny mount on it, and a big C-shaped piece bolted to that. The C would be cut out to miss the case but get the top or bottom two studs of the interface between the overdrive and the spacer.

I'm thinking two studs would be enough to provide support as well as keep it from twisting due to torque.

I've worked on enough of them to know (a) what they look like and (b) how they work. If it was being used with an automatic, it could be pressure sourced from it.

[Ford F834]

Bill called that one right - Laycock de Normanville. Well spotted!

On the support, I agree that you wouldn't have enough spline engagement with a plate between them given the shortness of the input shaft. Bummer.

Any support you do is somehow going to need to be isolated with rubber. What if you had a cross-member above or below the unit that had a tranny mount on it, and a big C-shaped piece bolted to that. The C would be cut out to miss the case but get the top or bottom two studs of the interface between the overdrive and the spacer.

I'm thinking two studs would be enough to provide support as well as keep it from twisting due to torque.

I like your thinking Gary. I am even eying the four rear studs that join the halves of the overdrive as possible points to mount a bracket.

I am leaning toward using the GVOD just because it is the path of least resistance. I don’t like it the best, and I am afraid once it is in place I won’t feel like replacing it with something else... but I am also leery of making so many obstacles for myself that the project will drag on several more years. This October will mark year 5 of being torn down which is absurd and ridiculous. This option needs nothing except a rear drive shaft because of the frame chop.