Stripping Short Stroke Manx Cam Box

Hi
Have decided to get the my 1955 Manx running and need to replace a push rod bush and it has been 20 odd years since I last did it.

My problem is I cannot get the side cover off?
I have removed all the nuts and washers around a dozen off (it said in my old manual that there 9 nuts, but there is more than that), and cracked the joint about 0.020", but it will not move any further, I can't remember having this problem before.

One problem could be the damaged bush could be holding it, but I doubt that because the cover looks to have moved evenly in the small amount it has moved, and I can still move the bush.

The bush was damaged when a push rod fractured, grabbed s chunk of bush and loosened the bush in the cam box .

Have I forgotten something?

Best Regards
Burgs

Could be dry in there, and things sticking.
Try turning it over, as much as possible, and wiggling the cover.

Twelve studs and two small dowels, one at each end. Cam bearings that locate in the outer cover are roller type, and are free to slide in or out of the outer races. If for any reason the bearings stick in the outer races, the camshafts can come out with the cover. It might just be that the outer cover is sticking on one or more of the studs, and to remove the studs with the cover still in place would be a very difficult job. Even if broken parts of the pusher or bush are floating around inside the box, there is nothing they can foul up on that can jam the cover and prevent removal.

The picture shows the roller cam bearing in a Summerfield early development cambox (see large diameter flat top pusher)

Hi Rohan and Snotzo
Thanks for the photo reminds me what is in there as I remember, I had these box apart heaps of times with no problems just a bit too long ago.

The flat push rod is interesting, with what looks like an early short stroke 40M profile on the cam, peaky.

I have sprayed the whole lot with WD40 and will let it set a while to penetrate before the next attempt.

The bush is still in one piece just a biggish gouge in one side where the broken pushrod caught, guess it tried to kick sideways.

I thought as soon as the sealer let go it would simply just slide off like it used too!

Let you know how I get on after the weekend.
Best Regards
Burgs

You probably just need to wiggle it off those dowels,
gently give it a try ?

Hi Rohan
Got the best I me and sat down and looked it over with my super glasses on and found the problem, now need to but my engineering hat on and work how to fix it!

What it appears likely to have happened is that the push rod has managed to turn the sleeve somehow when it craked or visa versa???

Inlet, if you look inside you can see the sleeve sitting correctly but in the second photo of the exhaust you can see the sleeve has turned and must be locking the outter case against the housing :shock:?




I will sleep on it for a little while?

Best Regards
Burgs

Hi
All good combination of sealant on the studs, the seat for the nuts worn and closed the magnesium up onto the studs and the outer bearing sleeve turned and jammed on the housing, like Rohan said a little bit more careful force in the right places.

Had to tap the bearing housings out of the cover as the cover was coming off was the trick, move a 1/2mm tap, move tap etc.
While i have it apart I will renew all the bearings and shafts as I think that there is excessive play which has resulted in cam wear and pushrod failure due to hammering.

It is the first time I have had the outer bearing races out of the side cover, so was surprised to find the cover had been machined at some stage and the bearing race was sleeved on the OD to suit. I might reverse this by sleeving the cover, Loctite it in place and making the sleeve a sliding fit so the magnesium cover doesn't fret. It has to be able to move to allow adjustment on the end play for the camshafts.

I last raced the Manx in 1994 (20 years 3 months) when the pushrod broke and I removed the cambox had a look and threw the whole lot in the corner until now, (7 moves of house since) I was surprised to see everything is still covered in a good layer of oil. The oil I was using at the time was BelRay racing oil.

Thanks
Best regards
Burgs