Re: [lro] Roverdrive vs. High Ratio Transfer Box

From: Peter Ogilvie (roverhi@yahoo.com)
Date: Thu Mar 06 2003 - 13:19:10 EST

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    If you are sticking with the low rider 15" stock
    tires, you need some sort of higher gearing for
    highway cruising. Going to 16" rims and 235/85/16's
    or even 255/85/16 or 33/10.50/15's will help some on
    keeping the highway rev's down. Not enough for long
    trips on relatively flat ground, IMHO. OTOH, larger
    tires will raise the gearing so long climbs on
    relatively steep grades that are common in the
    mountains can require a downshift into 3rd. As Simon
    says, quite steep grades can even require 2nd gear,
    BTDT in my old VW bus.

    The problem with the Ashcroft gears and a stock
    engine, is that it just can't pull 4th gear, even on
    relatively modest hills. Less restrictive on a light
    88 but a major problem in a 109 Stationwagen with 4
    passengers. So you spend a lot of time in 3rd gear
    when stock 4th, which you haven't got, would work. A
    major problem is when you can't hold 3rd with an
    Ashroft conversion. Instead of doing 35-40 in stock
    3rd, you are in 2nd doing 20mph. As TAW said, being a
    motating road block can be dangerous for you as well
    as others when drivers get impatient.

    One thing not often mentioned about the Ashcroft
    gearing is that the ratio is changed on all high range
    gears. Starting off in Ashcroft 1st is supposedly
    close to starting in stock 2nd gear. Just to see if
    I'd possibly like the Ashcroft conversion, have tried
    starting off in 2nd in our hilly local terrain. It's
    not fun getting the truck moving from a stop on a
    hill, even a slight rise. Lots of clutch slipping and
    many driveways would have required low range or a
    running start to get up. That was enough to turn me
    off to the Ashcroft setup.

    None of the above would be a problem with a V8 or a
    Davis GM four. Don't see anyway you can ring enough
    horses out of a 2 1/4 to pull an Ashcroft 4th gear for
    most of my driving. I'm currently running a 2 1/4
    with a Weber 32/36, milled and massaged head and a 2.5
    cam. It has solved the problem of having to drop into
    3rd on most hills but still ain't no torque monster.
    My driving is probably not typical as we have no
    freeways and a max 55mph speed limit. Don't really
    need freeway gearing. Would still love to be able to
    split 3rd-4th gears on the Saddle Road, however.
    Suspect that if I had Ashcroft gearing, even with the
    engine mod's, would spend at least half my driving
    time in 3rd gear. Not an experience I'd look forward
    to.

    For a 2 1/4, there is no way I'd consider the Ashcroft
    gears. An O/D is so much more versatile and should be
    much more pleasant in every day use. One big
    advantage of the RM O/D is that it is supposed to be
    robust enough to be used in O/D even in the lower
    gears. The Fairey and other units are said to be best
    used in 4th only. Kind of defeats the purpose as I
    used 3rd 0/D a lot more than 4th O/D.

    As far as cutting the tunnel. You have to holesaw a
    cut for the O/D shift lever. It's approximately 2"
    diameter. You only need to cut a small x in the
    tunnel cover to allow the shaft through, however. I
    haven't gotten around to reinstalling the O/D so have
    been driving around with the hole in the tunnel. Can
    hardly tell the O/D was there as the small cut in the
    tunnel cover is unnoticable. Might be another story
    if there was an oil slinging leak aimed at the hole,
    however. If you are really anal about the hole in the
    tunnel, take Simon up on his tunnel or look around for
    a spare to make the hole in. Should be easy and cheap
    to find one.

    Good luck with whatever way you decide to go.

    Aloha
    Peter O.

    --- "KURT W. KRAUSS" <kwkrauss@knlaw.net> wrote:
    >
    > Because I was the original post on this topic,
    > thought I'd follow up.
    > First, many thanks for the observations on
    > overdrive vs. hi-ratio
    > t-boxes. My '73 NAS SIII is dead stock - 2.25
    > petrol, 15 inch wheels,
    > leaded head and 18,800 original miles. All smog
    > equipment is intact, as
    > is the Zenith carb, and true to original test
    > drives, it IS a bit
    > "sluggish" - more so than, say the average SII. I
    > don't have plans to
    > "hop it up." It resides in fairly hilly country -
    > Manchester Vermont,
    > where it is infrequently used.
    > Judging by the comments, especially TerryAnn's
    > remarks, I'm inclined to
    > go for the Roverdrive for those times I want to
    > drive it on the
    > interstate. I still am unclear, however, whether
    > the installation would
    > involve any cutting or drilling of the truck (e.g.
    > transmission tunnel)
    > to accomodate the lever to engage the overdrive.
    > Where does it sprout
    > from?
    > Kurt W. Krauss
    > 1973 NAS SIII
    > 2000 Discovery SII
    > 2003 Audi allroad
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