[Mgs] Overdrive Diagram

Charley Robinson Charley38 at twc.com
Fri Jan 18 13:50:06 MST 2019


Right on, Max.  This threa piqued my interest so I looked at the MGB 
Driver article and others.  There are as many opinions as there are 
a$$holes still floating around.  Sheesh, it's like discussing politics 
and religion. :-(;-)

CR

On 1/17/2019 5:41 PM, Max Heim via Mgs wrote:
> Are you sure it isn't the gear oil?
>
> The factory has always called for engine oil. There has been a lot of 
> ridiculous debate over precisely what grade of engine oil (personally, 
> I don’t think it matters, but let’s not start that), but there is 
> certainly a large difference in viscosity between say 20W50, and 
> 85W90. The overdrive, unlike the rest of the transmission, uses oil in 
> a hydraulic function, not just as splash lubrication, so viscosity is 
> probably very important.
>
> --
> Max Heim
> mvheim at sonic.net <mailto:mvheim at sonic.net>
>
>
>
>> On Jan 17, 2019, at 11:13 AM, Jack Wheeler via Mgs 
>> <mgs at autox.team.net <mailto:mgs at autox.team.net>> wrote:
>>
>> Does anyone have a good exploded diagram of the overdrive unit used 
>> in a 1971 MGB, that you could send to me?  I am particularly 
>> interested in the pump assembly.  I changed the oil in my gearbox 
>> this week, using EP 85/90 GL-4 gear oil, as recommended in a recent 
>> article in the MG Driver magazine.
>>
>> While the car was up in the air, I noticed a leak around the plug 
>> which holds the pump assembly in place.  So, I removed the pump, 
>> careful to keep all the pieces in the order in which they came out.  
>> I cleaned everything up, and reinstalled the pump assembly and plug 
>> (part number 466-315 in the Moss catalog), with a new gasket.  I 
>> thought I had all of the pieces of the pump assembly (items 62-66 in 
>> the Moss diagram) in the right order when I reinstalled it, but when 
>> I took the car out for a test drive, the overdrive would not engage.
>>
>> In addition to trying to keep the pieces in the order in which they 
>> came out, I also used the exploded diagram in the Moss catalog (Page 
>> 41) as a guide.  The Moss diagram, however, is different than my 
>> overdrive unit.  Moss says their diagram is for cars from 1968 to 
>> 1980, but apparently, some things were changed during that time 
>> frame.  I can't believe the engineers would let anything go unchanged 
>> for 12 years! It looks like the plunger (Moss part number 466-305) 
>> shown in the Moss catalog diagram has a roller on the end of it.  My 
>> plunger does not have a roller on the end of it.  Maybe this will 
>> give you a lead to which diagram I am looking for.
>>
>> So, that leaves me looking for a good exploded diagram of the unit 
>> used in a 1971 model.  Can anyone help with that, or does anyone have 
>> any suggestions as to what I might have done to make the overdrive 
>> not work, when it has always worked fine. Thanks.
>>
>> Jack Wheeler
>> _______________________________________________
>>
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>
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