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Buttercup · 10-29-2010, 06:20 PM

I currently have a MileMarker dual range transmission. I have been reading the threads here talking about the GearVendor. I am not too happy with cruising down the freeway at 65 @ 3200 rpm. I don't think things are 100% correct with my setup but am thinking about replacing the MM with the GV. I would like to get in that 2700 rpm range when cruising down the freeway. I am sure it might help save some gas (currently averaging 7.33 mpg after our last trip).
That plus a few other little modifications and I would have a very sweet ride indeed.
So, I am wondering if anybody else more experienced in this area has any thoughts on the subject....

barts · 10-29-2010, 08:23 PM

Quote:

Originally Posted by Buttercup

I currently have a MileMarker dual range transmission. I have been reading the threads here talking about the GearVendor. I am not too happy with cruising down the freeway at 65 @ 3200 rpm. I don't think things are 100% correct with my setup but am thinking about replacing the MM with the GV. I would like to get in that 2700 rpm range when cruising down the freeway. I am sure it might help save some gas (currently averaging 7.33 mpg after our last trip).
That plus a few other little modifications and I would have a very sweet ride indeed.
So, I am wondering if anybody else more experienced in this area has any thoughts on the subject....

If you want to save gas, your best bet is to slow down. Changing your engine RPM isn't going to help that much; certainly the cost of the GV overdrive is going to take a long time to recover.

- Bart

Buttercup · 10-29-2010, 09:59 PM

Ummm, well - we were driving at an average of 62 mph on roads that had 70 and 75 mph speed limits. Going slower is no longer an option I imagine. HWY 40 is fast paced. Slow vehicles are actually a danger on the road.
No, I would like to be able to go at the same speed as we are driving now (generally between 60 and 65) at the same RPMs others are touting they can do at the same speed.

Klatawa · 10-29-2010, 10:13 PM

I installed a GV three year ago and is working out verywell. I have a 1965 suburban with a 350/turbo 350 with 4.10 gears. with out the GV I was running 3100 at 60mph. With the GV I am turning 2500. This works out real well as the 350 is in wheel house at 2500. With the Gv engaged it drops the 4.10 to about a 3.33 ratio. I run in OD most of the time. The GV has a manual and auto option to engage. It kicks in a 40mph and drops out a 20 mph in auto mode. I use the manual switch so I can control when it kicks in. The Burb is my daily driver so with out the trailer I kick it in just over 20 mph with the trailer conected I kick it in at about 45 to 50 mph to keep the rpm up. My gas milage is at 14 daily and from 10 to 11 towing depending on hills.
The GV is on the spendy side at about $2500 with the deep pan for towing and then you will have a drive shaft modification.

Good luck, Dave

ROBERTSUNRUS · 10-29-2010, 11:36 PM

Hi, just for fun I ran a test in my Lincoln the other day. I drove on a long, level, straight street. I locked my cruise control at exactly 45 MPH. I pressed the button for instant gas mileage and got 21 MPG. Next I did the same thing, but turned off my overdrive. I pushed the button for instant gas mileage and got 17 MPG. Four miles per gallon loss at higher RPM at same speed on same street. RPM does make a difference.

Buttercup · 10-30-2010, 07:59 AM

Yea, I recognize it is spendy but the cost is worth not only the improved fuel economy, but also the quieter ride and quite frankly the reliability.
On our last trip, the MileMarker would lose power due to a corroded fuse holder (a problem that will be fixed permanently). When it did lose power, it would shift to low under load. Normally, you take your foot off the gas and shift from high to low and back. The unit clunks either way. But under load the clunk becomes an earth shattering jar. I am sure that this could be very damaging to the unit after a few times.
By all that I have read so fat, the GV shifts smoother and probably is a more capable unit than the MileMarker.

kmpro · 10-30-2010, 08:15 AM

You guys have convinced me about the GearVendor. I have been given one and have yet to install it, but the conversation here is helping me make up my mind. I agree with you, lower RPM will use less fuel and at today's prices that will make some difference. I normally cruise my 310 at 62MPH about 2900 RPM. I am like some others too in that I keep a close monitor on the rearview mirrors when driving where the speed limit is 75MPH. I have some friends who drive that kind of speed, but anyone who has seen a steering axle blowout at that speed knows it is not worth the risk, not to mention the fuel consumption at 75 MPH. Not MOHO smart!! These peeps.
I am going to get busy and install the GearVendor O/D on the Silver Hornet and see what difference it will make.
Mike

Buttercup · 10-30-2010, 08:42 AM

Mike,

Any chance you could document your experience?

Ike T · 10-30-2010, 08:46 AM

Tim,

It would be interesting to understand how a GearVendor OD unit affects transmission temperatures.

In our white box MoHo, overdrive produced 10* higher temperatures (200* vs 190*) as towed our car cross-country this summer. I ran in 3rd gear at a slower speed rather than OD (even on the flats) to keep the tranny temps lower.

Where I am headed with this is would you need to upgrade the aux transmission cooling system if you installed this unit?

kmpro · 10-30-2010, 09:10 AM

Thanks Guys:
OK, I will try to take pics as the mod takes place and post them on the forum. Ike, you brought up something I had not considered. I will see if more aux. cooling is needed for the tranny as well as engine. My engine has a 195 degree thermostat and between that and the thermostatic fan clutch, this puts my engine temp at 220 on the gauge. This is normal temp without climbing grades etc. I would feel more comfortable with engine temp at about 200 but the fan clutch doesn't come in till 220. I use the aux. electric fans to hold the heat down as much as possible, but a 454 just runs on the warm side in my MOHO.

Smartstream · 11-02-2010, 12:58 AM

I just put a gear vendor unit in my Moho and just got back from my first trip with it, 1228 miles. I have to say I love it. Mine is a diesel while it sounds like most of you are running gas.

The first problem is I actually got lower mpg. The coach is so quiet and smooth that I was driving much faster than normal and pushing air costs money. The ride is so improved I don't understand how this coach got to be 28 years old without somebody making this great improvement.

The install was very simple, remove the tail shaft housing, bolt on the adapter housing, shim the coupling, bolt on the overdrive, take some measurements and take your drive shaft to a good shop to be shortened. The control unit and speedo connections are simple plug in, all you need is to run the loom and find a 12V + source and a good ground.

I did remove the parking brake from the rear of the trans and fabricated a disc rotor and caliper set up on the drive shaft. I was having vibration problems with the old unit and decided to try something new, so far all is good. I also added more trans mount support because of the extra weight the diesel puts on the trans mount.

Before the OD the max governed rpm of 3300 produced 67/68 mph. With OD I'm making 65 mph at about 2600 rpm. 75 mph was no problem other than the fuel consumption. Also the trans temp was a few degrees cooler in OD. The only thing I can figure is the lower engine rpm doesn't heat the oil as much.

Good luck, Dan

Buttercup · 11-05-2010, 07:16 PM

Dan,

Thanks for the update. I am wondering how much shorter I would have to make the drive shaft knowing that there is already an overdrive unit in place. Not sure how the MileMarker (now US Gear I think) compares to the dimensions if the GV.

Smartstream · 11-05-2010, 09:17 PM

Quote:

Originally Posted by Buttercup

Dan,

Thanks for the update. I am wondering how much shorter I would have to make the drive shaft knowing that there is already an overdrive unit in place. Not sure how the MileMarker (now US Gear I think) compares to the dimensions if the GV.

Talk to the people doing your drive shaft work. The shop that did mine wanted measurements from center of carrier bearing to end of trans output shaft and measurements to slip yoke and u-joint and a few others. Then they put it all together and came up with a shaft length. Each shop has their own methods but basically measure several times and cut once, fewer mistakes that way.

By the way I heard U.S. Gear is no more, not sure about MileMarker.

Cheers, Dan

Buttercup · 11-05-2010, 09:53 PM

MileMarker was the predecessor to US Gear if I am not mistaken. It is a hard shifting beast unless you know how to get it to go one way or another.

raveson · 11-06-2010, 07:55 AM

My 89 345 was fitted with a gearvendor OD when new according to the logs. The unit died a couple of months ago, so I contacted GV. They replaced the main gear box with a rebuilt for $1,000. I think the price is only for those with existing units. The unit is well worth it's price if you travel much. At 62 mph, I'm running about 2500 -2600 rpms. When set on automatic it kicks in and out at 40mph. I manually turn it off on up-grades. Trans temp usually holds at about 190 degrees, but in traffic with ambient temps in the 90s I do have extra fans to manually turn on to keep the temp down.

choctawmel · 11-11-2010, 04:15 PM

I'll have a 0.75 finely gear if I ever get this 4L80E built and in the Silver Bullet. Guess I kind-a hijacked this tread. But a can of worms is what I've open! http://www.airforums.com/forums/f159...old-69221.html

Smartstream · 11-11-2010, 05:16 PM

Quote:

Originally Posted by choctawmel

I'll have a 0.75 finely gear if I ever get this 4L80E built and in the Silver Bullet. Guess I kind-a hijacked this tread. But a can of worms is what I've open! http://www.airforums.com/forums/f159...old-69221.html

Your final gear ratio my be the same but for us with the origional 3 speed TH 400 the Gear Vendor gives us 6 forward speeds vs your 4 speed. That can make a big difference in the hills.

When do you figure you will close that can of worms and get the Silver Bullet on the road?

Cheers, Dan

choctawmel · 11-12-2010, 01:12 PM

Quote:

Originally Posted by Smartstream

Your final gear ratio my be the same but for us with the origional 3 speed TH 400 the Gear Vendor gives us 6 forward speeds vs your 4 speed. That can make a big difference in the hills.

When do you figure you will close that can of worms and get the Silver Bullet on the road?

Cheers, Dan

That's tough to say. I spend 2 hours at the parts store today just finding a transmission mount that will work.
The brake shoes in the e-brake? After two days of ordering the wrong ones? The parts guy was throwing parts, he was getting so mad.
Did get the right (I hope) e-brake cable. It's got the right ends, just hope it's long enough.
I'm still waiting on the transmission to be rebuilt with the tail shaft housing I search high and low for so I could have the e-brake I can't find shoes for.
Glad I have a dry, warm barn to work on it.
Of course with a th 400 you can use a gear vendor. I had a Allison 545, gear vendor don't work on a 545. I could spend $2000 and rebuild the Allison or spend somewhere around $3500 and have an overdrive/load-up transmission.
Can't wait till I turn the motor into a long stroke 496 (or maybe a 513)
That and I'm crazy!
mel

Auretrvr · 12-29-2010, 05:06 PM

Here's my notes on installing the GV. I like the ability to drop RPM's on the flats and keep the noise down. If I could keep a lighter foot on the gas I would be getting better mileage!

porourke · 12-31-2010, 02:39 AM

We have one on our coach, it was on it when we bought it. A year after we bought it, we took my Daughter and two grand kids from here in Houston to Disney Land in Florida. We kept close records of milage and gas purchases and MPG came in at 10.3 Mpg. Right after we got it we took a trip to El Renio OK. and back and didn't use it because I didnt understand at the time how to. What we got was 8.1 MPG. The main thing I like about it is once turned on Auto its fully automatic. The red Auto light stays on and when you get to the shift point it goes out and the green enguage light comes on. From that point on untill you hit the foot switch to turn it off it shifts from Drive on the chassis transmission to overdrive on the GearVendor unit. You dont have to press a button on the dash or twittle with the chassis transmission shift leaver when you drop below overdrive range. It works with the electronics in the Chevy transmission, This makes for a more pleasent drive particularly on long trips. The only problem I have had with mine is that were the heat exchanger is mounted in front just below the coach batteries shelf it has a tendancy in wet weather to pick up mud. When this happens the temperature gauge for it next to the controler will start creaping up. If you take long trips frequently they are definetly worth it, from a MPG and convince stand point.

Pat