[Fot] Overdrive issue

[Larry Young]

Tony,
We were out racing at Hallett this weekend, so this is the first chance 
I've had to check emails.

I've only been into about half a dozen overdrives, and I have never seen 
a problem with that top hat bushing.  Sometimes they are fairly loose in 
the housing.  I would just replace it with one from your spare.  You 
might want to use a little sleeve retainer to make sure it doesn't turn 
in the alumimium housing.  Your other problems I've seen before.  The 
washer under the sun gear is almost always broken.  It is interesting 
that the original overdrive manual says to have a sun gear  float of 
0.014 to 0.020, while later manuals say to use 0.008 to 0.014.  These 
numbers don't even overlap.  I've wondered whether they changed it to 
help reduce the impact on that washer and alleviate the breakage.   I 
found a lot of inconsistencies like this when I was doing those 
articles, so be careful which manual you pick up.  You should have no 
problem replacing all these parts.  You'll have to take one of the 
planet gears off to replace the thrust washer, but that is not a big 
deal.  I agree, it is amazing that it was still working.

Do you have a overdrive pressure gauge?  Do you have a large or small 
accumulator.  The large accumulators are best for racing.  You can check 
the pressure with a good half inch drill motor and the pressure gauge.  
I've got mine set up to run about 530 psi with a large accumulator.  
I've heard other people go up to  600 or 650 psi, but I really don't 
think that is necessary. I really get a kick in the pants when I shift mine.
Larry

Tony Drews wrote:

>I thought you might be interested in my continuing OD saga.
>
>Thanks to all for the excellent advice!  I took the OD mostly apart 
>and documented my findings on the overdrive page I created:
>http://www.tonydrews.com/Overdrive/overdrive_problem.htm
>
>What's amazing is that the OD worked just fine at the last race.  If 
>you look at the pictures on my OD page, you'll be amazed that it 
>worked at all (I was anyway).
>
>Also, Randall sent me a PDF of the Laycock A-type overdrive manual, 
>so I posted it on that same web page, along with links to Larry's 
>excellent tranny and OD articles.
>
>- Tony Drews
>
>At 10:10 PM 3/30/2007, Tony Drews wrote:
>  
>
>>   I  drained  the  oil  from  my tranny and found a couple of disturbing
>>   pieces in the oil.  They are from the overdrive.  With Larry's rebuild
>>   instructions in hand, I ordered the parts that looked likely.  Earlier
>>   this  evening  I  took  the  overdrive  off of the tranny to begin the
>>   process  of  replacing  those  thrust  washers.   However, the problem
>>   wasn't  what  I thought it would be.  It turns out that there's a "top
>>   hat" bushing in the "pump housing" that the eccentric that runs the OD
>>   oil  pump  rests  against.   You  can  see it in the background of the
>>   exploded diagrams of the factory manual and Moss catalogs, but there's
>>   no  little  number  and  arrow pointing to it.  There's no part number
>>   listed with Moss for it.
>>   I've  got  pictures  of the OD / broken part and of another OD with an
>>   intact part in it on my website at
>>   http://www.tonydrews.com/Overdrive/overdrive_problem.htm .
>>
>>    
>>
>
><snip>
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