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Rocker spindle oil way feed

Submitted by peter_cooper on Tue, 08/01/2019
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Commando

Not sure if this a new issue.

Stripped down the head on my '73 Commando/Combat.

When I removed exhaust rocker spindles discovered that oil feedway from pump>head>rocker spindles does not align with oil feed slots on the spindles when set with locking plates.

Locking plates position the oil feed spindle slot at horizontal and oil feed hole in the head is about 30 deg north of horizontal.

As a consequence it is hard to imagine how any oil is getting to internal oil way of rocker spindle.

Is this a batch flaw or design from day 1? I need to check if same issue on my cast iron head Model 7.

So is there a known solution or do I just machine locking plates to ensure spindle oil feed slot aligns with oilway in the head?

It may make for good oil pressure but very poor lubrication of rockers on spindles as evidenced by notable abrasion on spindle shafts where rocker arms rotate at 5000+ rpm .

Any suggestions appreciated.

Peter

Submitted by john_holmes on Tue, 08/01/2019

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Early bikes using low pressure feed rocker need the holes aligned so the oil has an easy route to follow to maintain flow, high pressure rocker feed on later bikes including the Commando need to have the holes mis-aligned or the oil flow is too much and the head gets swamped with oil. 

Submitted by john_neely on Wed, 09/01/2019

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John is that correct as i have lined up the oil ways on my 73 (yet to be started) commando so it is free flowing using the RGM rocker lock caps which allow this.

Submitted by alex_arthur on Thu, 10/01/2019

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15k miles ago I rebuilt my 850 Mk3 Commando and discovered this same oil feed alignment issue. On Les Emery's advice I opened up the oilway in the head to give a clear feed to the rocker spindle by careful work with rat tail files and a Dremel. The bike has now done many high speed and low speed miles and I have never seen any evidence of oil swamping the head. I would have thought that the rocker spindle oil way will act as a flow limiter (given that the drilling in the head is similar diameter) so it is probably a more logical move to ensure the oil has an uninterupted path to the rocker? 

Submitted by john_holmes on Thu, 10/01/2019

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To clarify.

The oil route to the rocker spindle should be unhindered, but the rocker spindle itself should have its feed drilling to the rockers at 180 degrees to the drilling's in the rockers so the oil flow is restricted at that point. To do this the holes in the rocker spindles point outwards from the centre of the head. 

Submitted by peter_cooper on Thu, 10/01/2019

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Alex, your experience and lack of catastrophic consequences is good to hear and much appreciated.

In addition to the restriction of spindle oil way the orifice on oil feed banjo bolts are a significant flow limitatiion.

From your psoitive experience I will  get my Dremel out and enhance the lubrication cooling of rockers.

Peter

Submitted by ashley_cutler on Thu, 10/01/2019

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Connect the oil feed pipe, leave the spindle plates off, start the bike if you dare  - something tells me you won't need to modify anything when you see how quick the oil is delivered. Likewise those that have installed the spindles the wrong way have covered many miles trouble free  Not ideal but it still works. The oil pump is very good at what it is designed to do, most probably having more capacity than what it needs for the Commando's.

 


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