After some research, I've decided to not swap my 86 460/C6 van to a E4OD and instead go for a Gear Vendors overdrive. So powertrain gurus and people who have installed GV overdrives before, I have some questions!

1. Just how "bolt on" are they anyway? The website makes it seem like you barely need to do anything besides have the driveshaft shortened. However, reading around, I've seen that some people need to replace the whole transmission output shaft which requires disassembly of the whole C6!
2. I have a 2WD C6 with the longer tail housing. I THINK the 'full disassembly required' people have 4x4 versions. Is this correct?
3. Do you really need the $500 automatic control rig? It's a solenoid shift, if I just rig up a switch and promise to only engage it in forward 3rd on the highway, is that all there is to it?

Thanks in advance!

 

...bump...

Nobody? Oh boy, looks like I'm in for an adventure

 

Sorry man I don’t know anything about it. And apparently no one else here does eother

 

The GV tail shaft housing is a long one. So you should be good with your 2wd C6. The 4x4 C6 is the short out put shaft which would require a complete tear down to replace. I believe on 4x4's the GV unit bolted to the back of the transfercase or possibly a divorced unit.

 

I don't know (yet) but am planning on a Gear Vendors OD in my '97 F-250 (460 and E4OD with 4.10 gears). So I'm interested to know what you find out.

My understanding is that the Gear Vendors replaces the tailshaft housing on the trans in a 2WD application (and replaces the rear output housing in a 4WD application, but we're not really talking about that here). Converting a trans from 2WD to 4WD 9or back) involves replacing the tailshaft and tailshaft housing, which requires a full disassembly of the trans.


So if the Gear Vendors requires a new tailshaft I'd be pretty sure it would require a full trans disassembly to install it. But if it mated with the original 2WD tailshaft, then it might just be a bolt-on R&R.

 

I have a DNE2 bolted to my c6. Genscripter has a GV unit.

As far as installing the unit, you unbolt the tailhousing from your c6 and bolt on the GV tail-housing adapter. Then bolt the GV to it. Measure for the driveshaft. My DNE2 didn't use a slip yoke like the c6, so I purchased a new driveshaft from a shop locally.

As far as the shifting of the GV, I am not sure. My DNE2 is stupid simple and can be shifted with a simple 12v switch. I think the GV is a little more complex, but not sure if you can't make your own harness.

I am sure someone will jump in.

So what made you choose the GV over the E4OD? Just curious cause you can get a rebuilt/durable e4od and a stand alone controller that eliminates a lot of the issues people have with the e4od. Plus you get a locking torque converter that is going to give you a mpg boost.

If $ wasn't an object I would swap out my c6 for an e4od and keep my DNE2 as well for double OD. I could run 4.10's or 4.56s so I could tow a house and still have lower cruising RPMS than I have now........the best of both worlds.

 

Interesting thread.... which got me to thinking (and I'm genuinely interested, this isn't meant to be sarcasm or trolling): what's the planned benefit of this? Higher top end speed? Improved gas mileage? What would be the expected MPG improvement?

If for MPG, and taking the above numbers into account, how many miles would it take with the projected fuel savings at today's gas prices (or even adjusting higher considering we're currently close to an all-time adjusted dollar low-price-per-gallon) to break even on purchase and installation costs?

I hate the 12mpg I get with my E350, and lower cruising RPM's would be nice on long trips, but I don't think even the late model E150's higher geared rear ends won't get any better than.... what... 18mpg? I know over 65mph my MPG's drop almost logarythmically (is that a word? maybe "exponentially" or "drastically"? Or maybe just "like a rock". ).

If the numbers work out to be promising, I'd be interested in your seeing your results.

 

I have found a number of benefits. Here you go.

1. I track all my fuel and have found that there is an MPG different. It probably raised my average MPG about 1-2mpg. In all hwy situations I have gotten as high at 19mpg. Prior my highest was about 17mpg, but peak #'s isn't where I saw most of my gains. It used to be that if I cruised above 65 my mpg would tank bad. With the OD there is staill a drop, but not nearly as bad. I also used to see mpg #'s in the 13's fairly often, now I rarely see anything below 15mpg. Think that it evens things out and makes it more forgiving. If I had a locking torque converter I would probably see much more benefit from the lower RPMs.

2. It made road trips much nicer. My van is an diesel, so the cab was pretty loud. The drop in RPMs made it easy to listen to the radio and talk, so that was a big plus. Drivability.

3.As far as $ payback. Buying a new GV would take forever to get the payback. I purchased my DNE2 used back when fuel was $4 a gallon and I was driving 30k miles a year. With those #'s my DNE2 paid for itself in 1-1.5 years. With the drop in fuel prices and if you don't put a lot of miles on it will take quite a few years (if ever) for you to make the $ back. However, it makes the miles you do drive much nicer.

There are tons of variable that affect MPG and people will argue all day if dropping the RPMs will increase your MPG. The answer is "It can in the right situations". In mine it did.

This is why I said I would like steep gears with a locking torque converter and double OD. The steep gears benefit in towing and can increase your city MPG by making it take less energy to get going. The double OD would allow me to drop my RPMS more at hwy speeds while the locking torque converter would eliminate the slip that I see from my c6 at low rpms. I did replace my stock converter with a low stall diesel on to help, but it still is not the same as a locking one.

 

My answer is still theoretical as I haven't even definitely decided to do a Gear Vendors yet. But my thoughts:

My F-250 (460 / E4OD) has 4.10 gears and could easily pull much taller gears, probably with better mileage and less engine noise. But I don't want to reduce the GCWR (or pay to regear 2 axles), so I'm not willing to consider changing axle gears.

If the overdrive bumped my mileage from 10 mpg up to 12, at 10,000 miles / year and gas at $2.50 / gallon it would save me a little over $400 / year in fuel. Nothing to sneeze at, but not going to give a quick payback either.

Even though money is money, it still feels different depending on what you're spending it on. A year after dropping $3000(?) on a Gear Vendors I wouldn't really miss that money anymore. But for a long time I'd feel better about driving my truck if it cost less to operate, polluted less and didn't have to stop for gas as often. Is that a completely rational argument? Not really, but it's still real.

 

Whew, this is what I was hoping to hear, and it lines up with the research I've done on other forums.

 

Going to an E4OD swap seemed like a lot more major surgery and fabrication - driveshaft, transmission crossmember, speedometer drive, etc. and on top of that the aftermarket controller. I talked it over with my mechanic who handles this rig, and his transmission house, and we came to the conclusion that an OD will get basically what I want done with the least pain - possibly even able to do it all myself, which I like

Never welded driveshaft before, but I have a TIG welder and a lathe... and the truck has a 2-piece driveshaft with a center hanger bearing, so it looks super easy to just chop and reconnect that instead of the long aluminum one.

 

I'm primarily after less strenuous cruising. Being able to go faster than 60 on the highway without running the engine at 3000+ revs would be nice. I've never, and am unlikely to, tow entire universes and continents with it.

The difference between 9 and 11 mpg to me is almost nonsensical anyway... I just cannot drive 55 at all!

 

Alright, I just dropped some Franklins on a used GV whole setup. It's coming from a seller on eBay who is going to dig it out of his parts truck, so here's hoping I get something worthwhile

 

Personally I wouldn't shorten a driveshaft myself. It spins at over 2000 rpm and any imbalance will be at least annoying if not lead to real problems. I paid a shop $250 to shorten (including balancing) 2 driveshafts a couple of years ago.

 

If you are having someone else do it, any type of swap that requires some custom work ends up being very expensive due to the labor hours. If you can do the labor and enjoy projects then it can cut the cost considerably.

I would agree with this. I think it was under $300 for my entirely new driveshaft. Maybe you could weld it and then have a shop balance it.