Overdrive unit

[Martintebbut]

Hi All,

I am new to this. I live in Sydney Australia and I have a 1988 Allegro 32 foot RV powered by a 454 Chev. petrol driving a Turbo (or TH) 400 three speed auto. gearbox. It has been converted to right hand drive to suit Australia's road rules.

I am interested in installing a Gear Vendors overdrive unit to give me a higher cruising speed and lower fuel consumption.

Can anyone give me the benefit of their experience with one of these units? Are they good? Will I have trouble fitting it? Is the cost and trouble worth the end results? Anything else?

Please post response on forum or email me directly on martintebbutt@bigpond.com

Hoping to hear from as many as possible, with even the smallest contribution.

Martin TEBBUTT

[arrowhead]

Hello Martin
I have had a GV in my 33 foot coach with a Chevy and I love it especially on the hills.
However I started pulling a 10,000 lb trailer and burnt it up coming home on a recent trip so I am installing the replacement tomorrow.
The failure was my fault it was simply overloaded.
With my smaller trailer it was just fine
They are very nice to deal with for sevice

Let me know if I can be of further help

Dale

[RV Wizard]

Martin, welcome to iRV2.com. We are glad to have you join us here. I am sure you will enjoy the website and forums. There are quite a few of these units out there and I have not heard of any real problems if used correctly. Take care and keep us posted.

[Gary RVRoamer]

I've been working on and visiting RV-related online groups for over 12 years and have never heard a complaint about the Gear Vendors Over/Underdrive unit. Have heard a lot of praise for it in the same time too.

Now whether it will give you more speed and better fuel economy may be another story. What you get is more gears, including a higher overdrive. That may or may not translate to higher cruising speed, though it should gain you something on completely flat terrain. Your driving style and the terrain will dictate whether the engine has enough horsepower to stay in high overdrive. If it begins to struggle and the rpms fall off a bit, it will downshift and you are right back in the same gear you have now.

Fuel economy gains also depend on your style and the terrain. If you baby it you ought to be able to stay in higher gears and thus lower the RPMs for a given speed. But if you push for more speed you may give that back. Basically it is all up to you, the driver.

[Martintebbut]

Great to hear from you Dale, Mike, and Gary,

I certainly appreciate your responses as there is not much information here in Australia and hardly any American Rv's like mine over here.

Your contributions are reassuring and are encouraging me to go ahead with importing a GV unit.

As my TH 400 gearbox has the parking brake attached I am hoping that this does not cause any complications. Also as the unit will require the shortening of the tailshaft I am hoping that the slight changing of the angle at the front tailshaft universal will not create high speed issues.

Also is there any opinion as to whether it would be overkill to attach an oil cooler to the overdrive?

Any more contributions or comments will also be much appreciated.

Hoping to hear back.

Martin Tebbutt

[blacktie.shooter]

Originally Posted by arrowhead

Hello Martin
I have had a GV in my 33 foot coach with a Chevy and I love it especially on the hills.
However I started pulling a 10,000 lb trailer and burnt it up coming home on a recent trip so I am installing the replacement tomorrow.
The failure was my fault it was simply overloaded.
With my smaller trailer it was just fine
They are very nice to deal with for sevice

Let me know if I can be of further help

Dale

Originally Posted by Martintebbut

Great to hear from you Dale, Mike, and Gary . . . Also is there any opinion as to whether it would be overkill to attach an oil cooler to the overdrive? . . .

Martin Tebbutt

Martin, I've only heard of a couple overdrive failures, including the one above, and they both center around towing a load in overdrive. Also, please note that only one of them was GV; the other was the top gear in a four-speed tranny, right out of the factory. It wasn't even a case of being overloaded, it was too high of an expectation as to what an od could haul.

Driving your car, it's OK to stomp on the loud pedal and steer. Not so with a coach. The bottom line, with any tranny, od-equipped or not, is to pay attention to what is going on with your tach, your engine, and your transmission.

I don't think you need another cooler; just do NOT lug the engine, towing or not. Keep lubricating and cooling fluids circulating by maintaining your revs up in the power range, especially when climbing hills, and even more so with a toad.

If your tranny isn't shifting soon enough to achieve that, shift it yourself. If your tranny is "hunting," i.e., going back and forth between direct and overdrive, it's not comfortable for the load it is hauling. Fix that by locking out the overdrive.

One huge advantage to a gear-splitter auxilliary box like Gear Vendor is the additional ranges it provides between each of the forward gears you have now; maximizing the efficiency of your engine by eliminating the big chunk of rpm that you lose going from, say, third to second, in the middle of a steep grade.

Welcome to the fun world of RVers, and keep us posted from way down there.

[Martintebbut]

Originally Posted by blacktie.shooter

Martin, I've only heard of a couple overdrive failures, including the one above, and they both center around towing a load in overdrive. Also, please note that only one of them was GV; the other was the top gear in a four-speed tranny, right out of the factory. It wasn't even a case of being overloaded, it was too high of an expectation as to what an od could haul.

Driving your car, it's OK to stomp on the loud pedal and steer. Not so with a coach. The bottom line, with any tranny, od-equipped or not, is to pay attention to what is going on with your tach, your engine, and your transmission.

I don't think you need another cooler; just do NOT lug the engine, towing or not. Keep lubricating and cooling fluids circulating by maintaining your revs up in the power range, especially when climbing hills, and even more so with a toad.

If your tranny isn't shifting soon enough to achieve that, shift it yourself. If your tranny is "hunting," i.e., going back and forth between direct and overdrive, it's not comfortable for the load it is hauling. Fix that by locking out the overdrive.

One huge advantage to a gear-splitter auxilliary box like Gear Vendor is the additional ranges it provides between each of the forward gears you have now; maximizing the efficiency of your engine by eliminating the big chunk of rpm that you lose going from, say, third to second, in the middle of a steep grade.

Welcome to the fun world of RVers, and keep us posted from way down there.

Thanks Ken,

I really do appreciate your very informed comment and the time you have taken to give me that info. It is most reassuring to me.

I have had a bit of experience driving heavy equipment and I completely agree with your advice regarding using the gears appropriately and manually selecting gears in an auto when necessary to match the load and the hills etc.

The Gear Vendors appears to get excellent references wherever I search.

Sounds like it will do everything that I need to improve highway cruising and economy and perhaps even a little more with the extra 3 gears. I know that I could also do with another gear between top and second when descending a steep hill and it sounds like the GV will give me that as well.

This has been a great start for me on iRV2. I will try to post some feedback in the months to come when I get the unit and install it.

Martin