This was forwarded from Rex Minneman:
>Subject:
> Re: Speedometers and Overdrive Transmissions
> Date:
> Mon, 14 Apr 1997 18:15:47 -0700
> From:
> Craig Wiper <craigw@sonic.net>
> To:
> "S. L. Hower" <howersl@ttown.apci.com>
> CC:
> mgs@autox.team.net
>References:
> 1
>
>
>At 08:37 AM 4/14/97 -0400, you wrote:
>>
>> Craig,
>>
>> I wrestled my PC back from my wife. Here's some data that I've compiled
>> over the years regarding the O/D swap.
>>
>> I did a bit of research on the O/D swap and here is what I have found
>> from various sources (Bentley, Haynes manuals and A.B Bonds)
>>
>> There were two types of O/D's fitted to an MGB (D type and LH type).
>> There are two types of LH overdrives ( Black label abd Blue label).
>> The LH O/Ds are interchangeable, but there are some gotchas:
>>
>> The Black label is the 'early' LH; the Blue label is the later (~76 on).
>> The difference between them is the speedo gear *inside* the overdrive.
>> The speedo gears are rare and a royal pain to replace (O/D dissasembly).
>> Black label O/D trannys need a different O/D speedo (1280 vs 1000rpmile).
>> Blue label O/D trannys and non O/D tranny's use the SAME speedo (~76 on).
>> Fitting a Blue label O/D tranny to a pre 76 car requires speedo
>> recalibration (there is no pre 76 speedo that will work).
>> 77-80 O/D trannys have O/D on 4th gear ONLY (the tranny remote tower is
>> different).
>> All MGB's from 68 onward use the same length driveshaft (31 1/8).
>>
>> (this last point has been debated somewhat)
>>
>> Please correct me if any of these are untrue!
>>
>> --Scott
>>
>> Scott Hower --> howersl@ttown.apci.com
>> Air Products & Chemicals, Inc. 'Its better to be silent and
>> 7201 Hamilton Blvd Trexlertown, PA thought a fool than speak and
>> (610) 481-2646 remove all doubt' --A. Lincoln
>>
>>
>>
>Hi Scott. I've placed the donor car's speedometer into my B. It is a
>5321/04 1000. My old speedometer is a 5320/06S 1280. The overdrive is an
>LH
>black label. I get the same results with both speedometers! The speedo
>gear
>(plastic) is a white one w/22 teeth, same as the original which was
>stripped.
>Craig Wiper
>craigw@sonic.net
>http://www.sonic.net/~craigw
>
At 07:31 AM 8/19/98 -0400, Warren Pruitt wrote:
>I have acquired a '76 overdrive gearbox which I am going to install in my
>'70 B roadster and was curious about the speedo difference and the easiest
>way to correct the problem. My understanding is that year gearbox turned
>the speedo at 1000 revs while my speedometer is calibrated for 1280 or 1240
>(can't remember). Can the gears in the gearbox be changed to the earlier
>gears and do both gears have to be changed or just (hopefully) the pinion
>gear? Somewhere I thought I read about a box that could be installed on the
>cable between the speedo and gearbox that could be adjusted as needed.
>Anybody know anything about where these can be found and at what cost? The
>other option is replacing the speedo, but I imagine an instrument that
>matches my current ones are going to be rare.
>
>On a different note, I have a slight pull to the right at speed (it's not
>road crown). I have replaced tires, set alignment, switched wheels,
>replaced springs, shocks, bushings, tie rods, king pins, rear springs, and
>just about everything else except the lower arms (wishbones?). I wish I had
>done this when rebuilding the front end. The car had been hit in the front
>right corner years before I bought it and I am wondering if they were bent
>back a tad then. The original right front tire was more worn than the
>others but not by much. The only other thing I can think of is a
>crossmember problem. Any other reason you can think of or how I can
>determine the actual problem?
>
>Help appreciated!
>
>Warren Pruitt
>1970 Roadster
>warren_p@ls3p.com
>
|