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ET: Engine (Twin) Front EXH follower spindle on the piss ET30/3 ( a cure)

Vincent Brake

Well Known and Active Website User
VOC Member
Hi all, i thought to share this:
As mostly all these follower spindles are a bit on the piss, relative to the CAM spindles, due to the fact they have a thread to postion, at one side and a hole on the other.
The cams wear unevenly and a bit more valve clatter there. Never liked it, so the head starts to work.....

Finally after my 5th casings repair i saw that the hole into the casing is rather deep, say 3/4 or so (it will differ of course).
This will provide more thrust than a normal spindle hole:D

So i reamed (or hone'd ) it out clean, than made up an hardend axle, 0,02 mm interf. fit, and honed a follower acordingly (no interference fit;)) lenght 47 mm.
One side i made in a thread M5 and after assembly of the follower and axle, plugged it with a bronze thread part glued in place.
M5 12.9 bolt in,



Vincent 2018-08-04 14.53.56.jpg

Nigel Spaxman

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VOC Member
It is nice to see how other people fix things. Mine was wrecked there the thread stripped, I guess it is typical. so I tapped it out one size bigger, bushed the hole back to standard, and made a special spindle. That put the thread really close to one of the through bolt holes. It was so close I filed the head of the through bolt so that it had a prong that fitted into the notch in the new spindle to prevent it from coming unscrewed again. Looking at the picture of yours I can't understand why there doesn't seem to be a through bolt hole anywhere near the front rocker spindle hole. I have an early B, did they change the location of some of the bolt holes?


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VOC Member
VOC Forum Moderator
Nigel, yes the crankcase through bolt in that area changed to a shorter stud that screws into the timing side crankcase just like the one between the cylinder barrels.


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VOC Member
Had to do all shafts there certainly on butchered Argentinian B-Raps , some with individual sizes, but found a face reamer at a useful size for restoring good holes. The obsolete imp. thread on the new front ex follower spindle I retained, just made an oversize shaft on it, no big problem once you accept this thread. Provided the tread in the case is allright , better keep it, less work to do. While dealing with the box of troubles I did not keep the valve lifter design, but it is a fiddly job like in my photo but I am positive with it.
Vincent, your boring operation on the followers looks impressive, I guess you had to balance the lot well for 3000 rpm. Or it would have gone out the window into the next county ? Better get yourself one of the hf spindles for that type of operation, way less of nerve wrecking and nice for fitting components in micron dimensions. You cannot do minimal feed in a turning operation, unlike with grinding. I mostly fabricate a mandrel with an alu cylinder that gets a strip of abrasive glued on with instant glue. Easy to replace when blunt and wide choice of grits. Works great and not critical for vibrations , useful for through holes. There are hf spindles from 48 mm , up to 60 000 rpm at 1000 Hz. I like the Danfoss converters 5000 series. Had air power spindles long time ago , clamped in the Multifix lathe holder, but I hate noise , high air waste and oily too. Sure, CBN hard turning is great, but when you have to deal with bores or shafts with holes or gaps in them the finish may look unacceptable from hard turning, so grinding is unavoidable.
My setup for the crank pin hole in the one piece crank web was allright and proved perfect when trueing the crank - but ONLY for veeery low speeds on the lathe. Finish grinding for great surface roughness was no big deal once the lot was trued perfectly on the lathe plate. Maybe I had better honed the DRO mill positioned pin hole instead for good finish but did not think of this at the time.

hf spindles:
65 mm spindle
48mm spindle set



air grinder for roller follower:

Horex prewar.JPG
Last edited:

Vincent Brake

Well Known and Active Website User
VOC Member
Thx Vic.
Looking good, and no i would not be able to reach 150m/min to use CBN. With that flywheel.......
I do them cnc round milling with a carbide mill. Toolroom Mazak FJV.
But i use 30 mm main axles with about 0.1 mm interf fit.
I have done it now 3 times each max run out at bearings position 0.01

But a little hole/ intermittend cut, in it makes no problem, if you stay at a depth of 0.1 mm each cut.

I forgot about the spindels.
But will get one.
Do you really watercool them?



Well Known and Active Website User
VOC Member
So you got extra main shafts pressed in ? A lot easier to do for sure, but I prefer one piece crank webs with main shafts, that is why I had to place a big spacer under the crank on the lathe plate. For trueing up the assembled crankshaft I place it on veeblocks at bearing places and test on extreme ends for runout. So I can see EXACTLY what the crank does in the engine, no guesswork like with setting the crank "between centers" . My cranks were allright as shown in youtube earlier.
Yes, the warer cooled spindles get plain water from a tap, just a very small trickle is all you need and after use just blow it dry with air. But only needed in lengthy operations really. Would not want air cooled types, quite noisy I guess at 30 000 rpm I guess.
Another matter: I´d laser weld the oil hole in the follower shut. This oil hole is just as bad as holes in a cam lobe when on the lifting lobe segment. You don´t want a hole in a place with high loads as you spoil the oil film with breaking the oil wedge from any hole ! I do not believe in the logic of oil supply from the pushrods running down from rocker oiling and getting to the follower oil hole - most unlikely to me, thinking of the very fast moving rockers and followers rather flinging any oil off before reaching the cam. Better look for a lot more oil into the cam spindles instead.


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