General => Douglas Motorcycles - General Discussion => Topic started by: Hamwic on 17 Jun 2020 at 21:56

Title: M32 Pushrod and Rocker tip Lubrication
Post by: Hamwic on 17 Jun 2020 at 21:56
Hi Chaps,

The M32 strip continues, and today's discovery concerns the lubrication, or lack of it, for the pushrod ends and rocker cups. Previous owners have done a wonderful job with the grease gun on the rocker brasses, but there is apparently no provision for any lubricant to reach the rocker cup or pushrod end.  There is , as far as I can see, little prospect of the oil mist lubrication beloved of early designers, ever getting up that far from the crankcase end. It seems that at least one of the pushrod tips has seized in the rocker, and the outer hardening has parted company with the softer inner and welded itself to the rocker cup.

I think this is recoverable, and a new pushrod tip will be created, but I am thinking of providing a little dribble of oil into the target area. I'm guessing others have already come to this conclusion, so would be interested to hear how this might achieved without swamping the pushrod tubes. Alternatively is the occasional application of an oil can through a suitable port likely to be adequate?

I look forward to hearing your suggestions!

Best regards
Title: Re: M32 Pushrod and Rocker tip Lubrication
Post by: Doug on 18 Jun 2020 at 13:34

On the Dirt Track rocker arm there is a very small drilling from the rocker arm journal (hollow) to the cup. But those run on the bore, upon a rocker spindle shaft. Though it has a grease fitting on the top of the rocker spindle, the design is made for a heavy oil, or a low melting point grease. I wonder if on your K32 someone used grease that did not flow as the designer intended and somehow defeated the purpose? If oil were used, do you see any way that it would work?

Title: Re: M32 Pushrod and Rocker tip Lubrication
Post by: Hamwic on 18 Jun 2020 at 16:39
Hi Doug,

Thanks for your reply. Apart from really filling the rocker boxes up with LMP grease, I can't see a way to keep the pushrod ends lubricated with the current set-up. Similarly the inlet guide won't be getting any help, unless a bit of two stroke mix is added to the petrol, much like a veteran. I think perhaps some kind of external small bore pipework might be required as there won't be any crankcase pressure above the tappets to speak of. What to do with any surplus could become a messy problem, as the pushrod covers aren't a sealed fit at the bottom end as far as I can tell? On a JAP this is achieved by a small bore pipes and crankcase pressure, but the oil eventually gets to go back downstairs - well some of it does! You can see by the discolouration that the rocker ends have been getting pretty hot. More thinking required.

Cheers for now

Title: Re: M32 Pushrod and Rocker tip Lubrication
Post by: eddie on 19 Jun 2020 at 07:10
It would be interesting to see the other rocker and push rod. It looks as if a wrong push rod has been fitted at some time - either in the past (causing excess wear in the centre of the cup), or at present (so that the push rod is only sitting on the unworn rim of the cup). I don't think anything has broken away from either the rocker or push rod - it's just a case of excessive wear due to a mis-match of parts. From what can be seen of the worn push rod, it looks to be of the same construction as those on the earlier dirt track engines - a tubular body with hardened steel ends. On the dirt track engines, these ends are cleaned up internally and soft soldered onto the tubes.
   On the dirt track engines we use in our sprinters, we grease the rocker spindles. Then oil up the rest of the valve gear (push rod ends, valve guides and ends of valve stems) with Castrol 'M' from an oil can. This oil up is done as soon as we unload the bikes ( to give the oil time to penetrate) and this is sufficient to give us a full day's running without re-oiling.

  Hope some of this helps,
Title: Re: M32 Pushrod and Rocker tip Lubrication
Post by: Hamwic on 19 Jun 2020 at 09:25
Hi Eddie,

An investigation with the Dremel reveals that there is indeed half a ball end embedded in the rocker tip, which has now been eased out. The pushrods are steel tube with soldered tips as you describe. There is evidence of prior attention to the rocker ends. I would guess they have been built up with weld, and re profiled, but possibly not hardened in the cup.

Because of the comprehensive covering of most of the moving parts, oil can attention without another access point is not possible, so deciding where and how to provide it will keep me quiet whilst I tackle the rest.
The cylinders will be coming off to day, so lets see what's going on downstairs!

Cheers for now