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push rod tube seals........

1660bob

Well Known and Active Forum Website User
VOC Member
My Shadow motor is coming together nicely now.I am contemplating barrel and head fitment,and the pushrod tubes are being replaced with a set of Maughans solid turned stainless items.Very nice too-substantial.

What is the accepted wisdom as regards seals? I have the standard items ET123 upper and ET104 lower.

Certainly, the upper seal seems OK, and with the rigidity/quality of the new tubes,only one washer atop the flange seems sufficient-is there any need for a second one under the flange on top of the nut (or room-given the thickness of the Spares Co. ET123`s)?
Perhaps more importantly, the bottom seal ET104, it seems, cannot be removed without lifting the head? Thus, I want to get this one right first time- the standard hydraulic type seal seems to fit OK, but I have heard mutterings that a tight O`ring is better......which works best? All advice greatly appreciated, Regards, Bob.
 

bmetcalf

Well Known and Active Forum Website User
VOC Member
The die cast motors are supposed to have oversize counterbores, which has been fixed with alloy rings to correct the ID. The standard seals work fine for me unless there is too much ring blowby.
 

davidd

Well Known and Active Forum Website User
VOC Member
Bob,

I am with you on the top seal. The best job I have seen on the bottom is on Robert Watson's bike. He inserted a thin aluminum sleeve with an "O" ring groove. Oil tight and it does not un-install itself when you are pulling the pushrod tubes up to seal the top. If Robert does not spot this, it might be worth a pm to him.

David
 

Vincent Brake

Well Known and Active Forum Website User
VOC Member
H Bob, I use the seals from Neal Videan, the best i have seen sofar, and they proved to be tihgt, at least or the llast 10000km
(obtainable also from vince farrel

cheeriiiiio
 

Marcus Bowden

VOC Hon. Overseas Representative
VOC Member
Grey Flash TT bikes had a different system, which enabled them to be dismantled quickly as top of tube was cone shaped and head lifted straight off, another advantage is that the lower seal could be replaced with out disturbing the head, by releasing the top nut, pushing the tube down, remove the adaptor, slide tube out, replace leaky seal (usually gone too hard) and reassemble, if you require photos and a few measurements let us know.
bananaman
O.S.Rep e-mail will find me.
 

SteveF

Well Known and Active Forum Website User
VOC Member
Could someone who has fitted the Neil Vindean seals ( ET123V3 ) for the pushrod tubes, offer me a hint.
I assume the nitrile ring (has aluminium internally) goes on top of the pushrod tube flange and so between the flange and the head.
I'm a bit unsure about the brass ring, it seems to be chamfered on one side. I am guessing that it should go between the pushrod tube nut, ET127, and the pushrod tube flange, but which side should the champfer be, up towards the flange or down against ET127?

Cheers - Steve
 

Marcus Bowden

VOC Hon. Overseas Representative
VOC Member
Steve, I should imagine champfer up towards the flange to allow for the radius of the flange bending, so sliding seal up tube under flange it should fit flush, fitting other way it will probably hold it off, depends on tube fit.
bananaman.
 

clevtrev

Well Known and Active Forum Website User
VOC Member
Use a standard 18mm x 24mm x 3mm lip seal, but you will need to make a ring to keep it at the top of the counterbore.
 

greg brillus

Well Known and Active Forum Website User
VOC Member
I use "O' rings on most all engines now, I find the original type too inconsistent be it the diameter of the case housing or the tubes which need to be 3/4" diameter if they are good ones, many are smaller than this or not round, and this will promote leaks, also the material can vary from soft to hard. An o ring with a 3 mm cross section works well, I have never had any issues with them coming out, after I tighten the tube nut I massage the o ring down to the base of the groove. I generally smear a very small amount of sealant around the very bottom of each pushrod tube immediately before installation, firstly it helps lubricate and provide a nice sliding fit as the pushrod tube changes angle as it enters the mouth of the crankcase, and it gives a little more sealing ability. I generally use two of the ET 123 One atop and one under the flange of the tube and do not over tighten these, a small amount of sealant smeared on the top tube flange before assembly will help. Neal's seals work ok but are very difficult to remove, as the rubber part deforms with the head temperature and bonds itself into the tube housing, I prefer the original type. Using an o ring on the lower seals tend to sit lower in the housing, so I use a smaller section o ring above it and this visually looks better. I figured if an O ring could handle the case pressures of a race engine, then it should work fine on a road engine, so far this has been the case.
 
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