I don't know about you guys but the price for diesel has really made me start considering other options. Right now I get around 12MPG around town and 15 or so at 70 MPH on the freeway (4x4, w 4.10) . Has anybody tried using one of the gear vendors overdrive units yet? I spoke with them today and they said that if my motor was turning 2600 it would bring the RPM down in the 2000 range. Any thoughts or comments would be appreciated!
Thanks

It all depends what you want the truck to do.Flying down the highway,Pulling or economy?I had a 1995 chevy 4x4 extra cab sb,6.5 non turbo that turned 1800 @60 MPH and I could drive just over Nine hours(highway)on one tank.Can't beat that mileage in a full size truck!Alot of factors come in play when mileage is involved(assuming engine is tip top).Speed is a big one!.On this same truck I changed tires and went to a goodyear ats and lost approx 120-150 kilometers range.The ats's were softer and had more rolling resistance(but rode alot better than the AS work tires I replaced).There are alot of combinations you can use.You just have to find the one that is for you.Gear vendor has been around for a long time and from what I hear make a very durable unit.Lowering the RPM's would help the engine live longer and should pick-up a little MPG(slowing to 60 might help too!).If you pull lots keep the 4.10's and put a gear vendor box behind the T-case for economy.The overdrive is pricey but all those extra gears will be cool.If you don't pull at all you may want to swap ring and pinion or whole diff assemblies for lower RPM's.I all comes down to how much you want too spend.Just remember recovering the money you spent on lowering rpm through mileage gains will take a very long time to recover but it will add life to the engine.

:rant: Don't do it, don't even think of adding the gear vendor to your suburban. I tried this already and all I can save is save yourself the nightmare. There unit I feel is not compatible with the diesel 4X4 suburban. Please contact me for the details at thefermdog@aol.com. You will be money ahead and grief to put this out of your mind as an option. Just please trust me on this one and contact me for the details.

:rant: Don't do it, don't even think of adding the gear vendor to your suburban. I tried this already and all I can save is save yourself the nightmare. There unit I feel is not compatible with the diesel 4X4 suburban. Please contact me for the details at thefermdog@aol.com. You will be money ahead and grief to put this out of your mind as an option. Just please trust me on this one and contact me for the details.
Please tell us what happened as quite a few people have asked this question (myself included)

I am also curious. The previous owner of my truck had one on it and besides having to get a new driveshaft, he said he loved it. Cruised at 120kph @2000rpm with a dually and 4:10's! So, what could be bad?:confused:

In my suburban it created severe driveline vibrations that myself two other driveline shops and an overdrive installer couldn't correct. Gear vendor couldn't figure it out either after two solid months of over the phone help. Go to this link and read more about it.

http://forums.thedieselstop.com/ubbthreads/showflat.php?Cat=&Number=2505296&page=0&view=collapsed&sb=5&o=31&fpart=2&vc=1

I want to clarify this, I'm not saying that the gear vendor won't work in any application. I have driven other trucks with them(all two wheel drive) that drove great and the gear vendor worked great, thats why I got one for myself. I'm just putting in my 2 cents worth and warning that it does not seem compatible with the 4X4 diesel suburban. The only other 4X4 diesel suburban that I could find with one on it was for sale on e-bay. The ad said the unit had just been installed less than 2 months ago, but he would not comment on why he was selling. I personally feel that he had the same problem as me.

I spoke to the previous owner of my truck again and he said that he too had some horrible vibration issues at first. He ended up spending a fortune on custom driveshafts before he got it tamed down. Might have to look at the US gear one.

I am not really interested in trying any other overdrives at this point. The main reason I got it was like CRASHLY origanally started this thread with, I wanted to improve my milage. But it didn't really help enough to justify(18 up to 18.5). And as far as driveshafts go, that wasn't my problem(even though I did go through 4 of them to get the driveshaft part taken care of). My problem was a vibration on the input side to the gear vendor, I could remove the driveshaft and drive the truck on the front axle in FWD and I could still feel the vibration. It was not as bad but still there. And my major problem is I think the vibration screwed my transfer case(Censored ), because now even after removing there unit I have a vibration in the truck and before installing there unit my truck rode as smooth as any gas powered truck and some cars out there. I just want them to honor there word and do the refund like they said they would.

Crashly;

I have a very simular set up on my C-2500 as you Maxitork, ect and I changed to 3.42 and tow 5,000 regular and 25-27foot Travel Trailers from Arizona to Montana in the winter and the truck does a good job. Switching to 3.42 would be less costly and simpler to use and not have to mess with drive lines and all that junk. I also ran my truck at TDP Pull Off and it pulled about the equivalent times as 4.10 geared stock 6.5's have. So unless you pull heavy and alot consider switch gears. I also have a friend that had a gaser Subarban with the GV unit and he loved it for the first year then he sold it with the truck when he bough a newer one.

Just another thought, If these gear vendors are so bad it seems to me there would be a lot of them on E-bay from unsatisfied people. I have been keeping my eye on Ebay for a couple years for one and rarely see one on there.

Just my thoughts

I surely hope that mine is an isolated incidence. But today I finally was contacted by gear vendors, some people off of the dieselstop website called them and I received a phone call from them. And they are going to honor the refund like they said they would. I was not trying to say that they are a bad product, as I stated earlier I have driven other vehicles with them and loved em, I just wish that I had not run into the customer service problem that I did.

I installed a used gear vendor unit in my suburban in May of this year. My best tank during our vacation to the east coast was about 18.5 mpg running at 75 mph with the A/C off and outdoor temp around 70. I would say that my average tank is about 17 mpg but I drive faster now with the GV than I did before. I do have a noticable vibration between 45 and 50 mph but I haven't been motivated to try to trouble shoot the problem. Putting the GV in my truck required cutting out a section of the cross member and bolting on a steel plate (purchased from GV) across the bottom of the cut out area.

I thought I should add that I make my living as a vibration analyst (industrial rotating equipment, mostly large process fans) and from the get-go I always assumed that all that overhung mass from the transmission to the output yoke of the GV is simply resonant at whatever speed the output shaft is turning when running between 45 and 50 mph. The fix for this, I believe, is to build what we call a "dynamic absorber" and somehow attach it to the GV. A guy I work with once overhauled the manual transmission is his early Ford Mustang many years ago. He left some sort of useless looking thing-a-ma-gig that was bolted to the outside of the transmission off when he re-installed it in the car. On his test drive he had a terrible vibration at 30 some mph. He bolted the thing-a-ma-gig back on (which we now know was a dynamic absorber) and the vibration went away. I have the equipment and the software to design and build a dynamic absorber. When I get time and can figure out a way to mount one to the GV I'm going to give it a try.

Gear vendor feels that my vibration is the transfer case(np241) that is actually vibrating not there unit. It is interesting to find out that somebody else is having the same exact vibration that I was having, 2100 rpm input to the gear vendor (45-50). The wierd thing of my vibration is that it was constantly changing, but the worst and most consistent at that point in direct. Does your suburban also have the np241(manual shift) in it Ax Subman? Have you ever tried shifting the gear vendor in at 40 or so and seeing if the vibration changes?