RE: IML: 'overdrive' details

["Frederick Joslin" <fljoslin@xxxxxxxx>]

I would change the gears in the Ram unless you really need them for towing.

A big part of the overdrive units as I recall is that effectively you go from a 3 speed to a 6 speed. This allows you to put higher numerical gears in your rear end (3.55 for example) for acceleration, but still get good highway mileage.    

----- Original Message -----
From: "Rob McCall"
To: mailing-list@xxxxxxxxxxxxxxxx
Subject: RE: IML: 'overdrive' details
Date: Wed, 26 Jul 2006 22:42:26 -0400


I haven't tried it yet, but I am heavily considering it for my '04 Diesel
Ram and my '68 Barracuda. In the Ram with 4.10 gears, even in 6th it is
turning the motor too high for sustained highway use. It has more than
enough guts, but the mileage drops like a rock. At 55 MPH and below it's
happy. Over 55 and goodbye $$$.

The GV unit allows gear splitting, i.e. 1st gear/1st gear in overdrive,
2nd/2nd overdrive, etc. With the stick shift in the truck, I can see this
being handy. With an automatic, not as handy.

Now the real question is what rear gear ratio do you have now? If you are
still running the stock gears, I do not think you will see much of a
difference in mileage. A 2.94 rear gear in overdrive is the equivalent of a
2.29 rear gear. If you are planning a run to the salt flats, that might be
a good ratio. If you are running 3.55's, it will drop it down to a 2.77, a
nice highway gear ratio. 3.91's drop down to a still highway friendly 3.05.

I have a spreadsheet at work that I was playing around with during lunch(es)
this week calculating RPMs based on MPH, rear gear ratio, and tire diameter.
If I remember to send it home tomorrow, I'll be glad to share it with anyone
who is interested.

Other than cutting the driveshaft, the transmission tailshaft housing is
replaced with the GV adapter and the overdrive unit bolts to it.

Rob McCall
'67 LeBaron, probably 2.94 gears.

-----Original Message-----
On Behalf Of Damian Justice

yessir, you have to cut, or replace the driveshaft. They have
under/overdrive if you are intrested in a quick takeoff followed by high
speed/low rpm. I am only intrested in low r's on the highway. I guess
nobody has tried it yet.






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Fred Joslin