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    D-type O/D relief valve oddity

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A quandary and a study as a result

   This was a spare 3-rail o/d transmission from a 1970 GT6 I had that I decided to rebuild. This was the first time I'd ever tried rebuilding an o/d along with the tranny itself. This page is just one of several quandaries that came up while rebuilding this thoroughly trashed transmission.


valve_assy_order.jpg (9217 bytes)


What the heck is this little ring?  The top shot here shows the way this relief valve was assembled upon initial rip down..I think!  Or should it be assembled as pictured below left.


valve_assy_order2.jpg (15762 bytes)


I could see someone in the past having assembled it as on top at the left here, as it would have stiffened the spring thus stiffening the valve. This would have raised the pressure of the pump 'relief'.

But if it was assembled as pictured at the bottom left here, it would have made the valve release more readily. Correct?

valve_dims1.jpg (25369 bytes)

These are the dimensions of the ring. It's almost the exact size as the seat end of the spring itself.

Now the real problem is I can not find this 'ring' anywhere in any of the photos in any of the catalogs or manuals.


    Do you think this was someone's attempt to 'band-aid' this o/d at one time?

    Do you think I should just chuck the ring (not put it back in at all?

     Does anyone have any idea of the specs for this spring?



....update 6/2004...
Ok, thanks to the many lists, it's now been made apparent that this little washer was added by a past rebuilder to 'up' the pressure a bit as the tranny aged. It seems that adding a 3/16" thick washer, between spring and plug on the relief valve gives about a 20 psi pressure rise on worn pumps.  BUT...you do not want to simply start adding washers if your o/d is not pumping right. Too much pressure can cause as many problems as too little pressure. So you need to get yourself a good pressure gauge to really see what's going on.

...stay tuned.....


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