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Rocker Arms & Rocker Shaft Assembly

Posted: Mon May 18, 2020 10:00 am
by pgp001
I have just got round to having a better look at the rocker assembly for my spare engine, I have already purchased a new shaft and was going to fit that as a matter of course.
However on closer inspection it looks like the bushes in my pressed steel rockers a past their sell by date plus there is some wear to the pads.

So my two questions are:-

1. Can I stone the pads to remove the wear pockets, and if so how deep can I go before I am through the hard surface.

2. I see in the workshop manual that re-bushing is not an option, I have my own home machine shop so I want to know why I cannot re bush them.

Anyway if reworking these is not an option, where do I go shopping for some new rockers, I see Mini-Spares do the Cooper S forged type but are out of stock, Bull Motif also list these and I wonder if they are the same item. I dont really fancy using the later sintered type, but what do others think ?
Complete reconditioned pressed steel type rocker shaft assemblies are available, but I suspect reconditioning might just mean using old rockers on a new shaft, so I would be no better off, has anyone used one of these recon assemblies ?

Thanks
Phil

Re: Rocker Arms & Rocker Shaft Assembly

Posted: Mon May 18, 2020 10:07 am
by philthehill
Here you go - not a full set though but should get you out of trouble:-

https://www.ebay.co.uk/itm/MORRIS-MINOR ... SwFAtekvyB

Re: Rocker Arms & Rocker Shaft Assembly

Posted: Mon May 18, 2020 10:16 am
by philthehill
Regarding the stoning of the pads - if you have a noticeable recession into the pad I would not even try stoning them - the surface hardening is not very thick at the best of times.

Regarding the bushes in the pressed steel rocker arm - fitting new bushes to the pressed steel rockers raises the possibility of the rocker distorting when pressing in the new bush, also the possibility of the spot welds holding the formed metal breaking or coming loose.

Personally I would not even try fitting bushes to the pressed steel rockers - I have some BMC NOS rocker bushes for the forged rockers which could be adapted to fit the pressed steel rockers plus I am able to ream the fitted bushes to suit the shaft.

The sintered rockers can be obtained new and are a good replacement for worn pressed steel rockers.

Re: Rocker Arms & Rocker Shaft Assembly

Posted: Mon May 18, 2020 10:24 am
by pgp001
Cheers Phil

As I suspected re the bushing etc.

What do you think of the Bull Motif forged rockers, they would actually be cheaper than the partial set on ebay.

Thanks
Phil

Re: Rocker Arms & Rocker Shaft Assembly

Posted: Mon May 18, 2020 10:32 am
by philthehill
You will have to post a link - I have looked on BullMotif web site and can only find reconditioned pressed steel rockers. Also looked on ESM Morris who took over BullMotifs Morris stock.

The bushes rarely wear out it is always the shaft that goes first.

Re: Rocker Arms & Rocker Shaft Assembly

Posted: Mon May 18, 2020 10:49 am
by pgp001
B.M. Link

https://bullmotifminispares.com/2096/fo ... er_12g1221

By the way, I checked my pistons and the three piece oil control ring fit perfectly, so I am going to use those.
I have just had everything in the ultrasonic tank to remove all the tiny bits of swarf etc after balancing the rods and pistons.

Phil

Re: Rocker Arms & Rocker Shaft Assembly

Posted: Mon May 18, 2020 11:00 am
by philthehill
Do the new pistons have the oil dispersal holes at the back of the oil control ring groove. If the holes are not there oil trapped between the rings will build up and go back up the bores and cause smoke.

Thank you for the link - the rockers look good to me.

Re: Rocker Arms & Rocker Shaft Assembly

Posted: Mon May 18, 2020 11:12 am
by pgp001
Hi Phil

No there are no holes actually, there is a long slot round either side, so plenty of room for oil to get through.

I will enquire with B>M> and see if they have those forged rockers in stock.

Thanks
Phil

Re: Rocker Arms & Rocker Shaft Assembly

Posted: Mon May 18, 2020 1:34 pm
by alanworland
Interesting that you don't recommend stoning of rockers, I would also agree that there's not a great deal of case hardened surface to play with.
However, many moons ago before I was aware of how thick (thin!) a case hardened surface was I had all my cam followers surface ground to remove the indentation formed by the cams.
Now having put a further 80k+ on the engine all still appears well!
Perhaps case hardening was specified thicker?

Alan

Re: Rocker Arms & Rocker Shaft Assembly

Posted: Mon May 18, 2020 1:34 pm
by alanworland
Interesting that you don't recommend stoning of rockers, I would also agree that there's not a great deal of case hardened surface to play with.
However, many moons ago before I was aware of how thick (thin!) a case hardened surface was I had all my cam followers surface ground to remove the indentation formed by the cams.
Now having put a further 80k+ on the engine all still appears well!
Perhaps case hardening was specified thicker?

Alan

Re: Rocker Arms & Rocker Shaft Assembly

Posted: Mon May 18, 2020 1:40 pm
by philthehill
pgp001
As regards the non oil dispersal holes - Does the slots you describe carry out the same function as the oil dispersal holes in that it allows oil to be passed to the inside of the piston and back to the sump?

Phil

Re: Rocker Arms & Rocker Shaft Assembly

Posted: Mon May 18, 2020 1:49 pm
by philthehill
Alan
Do you have a side valve engine fitted to your Minor?
You may be right about the thickness of surface hardening.
The base of the cam follower is specially ground to encourage the cam follower to rotate so reducing the possibility of one position pocketing.

Roller tip rockers are the way to go but expensive if purchasing a quality item. I have full roller rockers fitted to my minor.

Phil

Re: Rocker Arms & Rocker Shaft Assembly

Posted: Mon May 18, 2020 2:15 pm
by alanworland
Phil, yes original sidevalve engine coming up to 140k now, rebuilt at 50 something.
As far as I can remember the followers had been rotating ok but had a bad wear dish in them hence the grind which probably only removed 3 or 4 thou but that must be the extent of the hardening. Same camshaft and clearances remain good, and as we know the old sidevalve has to work hard!

Alan

Re: Rocker Arms & Rocker Shaft Assembly

Posted: Mon May 18, 2020 2:25 pm
by pgp001
philthehill wrote: Mon May 18, 2020 1:40 pm pgp001
As regards the non oil dispersal holes - Does the slots you describe carry out the same function as the oil dispersal holes in that it allows oil to be passed to the inside of the piston and back to the sump?

Phil
Yes Phil
The slots are right through to the inside, so will work the same as a series of holes would.

Phil

Re: Rocker Arms & Rocker Shaft Assembly

Posted: Mon May 18, 2020 3:02 pm
by paul 300358
I'm not quite sure what's wrong with sintered rockers as when they wear you can swop them round on a new shaft to get a different part of the face in contact with the valve. Simply put rocker 1 onto position 8, 2 onto 7, 3 onto 6 etc.

I know that the pressed steel rockers were case hardened and the forged rockers were age hardened (2 years IIRC) but are sintered rockers hardened?

Re: Rocker Arms & Rocker Shaft Assembly

Posted: Tue May 19, 2020 6:55 am
by Mark Wilson
A couple of years ago I was advised when calling in person at Minispares that their Cooper style rockers were extremely poor quality and that they had advised their head office to withdraw them. Which may explain them being out of stock. Could the Bull Motif Cooper rockers be from the same source?

Re: Rocker Arms & Rocker Shaft Assembly

Posted: Tue May 19, 2020 8:30 am
by pgp001
I hope not, Iv'e just ordered a set yesterday :o
Do you know what the quality issue was ?
Phil

Re: Rocker Arms & Rocker Shaft Assembly

Posted: Tue May 19, 2020 10:22 am
by paul 300358

Re: Rocker Arms & Rocker Shaft Assembly

Posted: Tue May 19, 2020 10:48 am
by pgp001
There is some interesting information on the reproduction forged rockers here. Looks like they were badly twisted in manufacture.
http://www.theminiforum.co.uk/forums/to ... -a-rocker/

I will be giving mine a very careful inspection when they arrive.

Phil

Re: Rocker Arms & Rocker Shaft Assembly

Posted: Tue May 19, 2020 11:05 am
by Mark Wilson
I can't remember the exact problem, but he was extremely uncomplimentary about them and refused to sell them to me. Whoever made them has had four years to sort the problem, so could be OK by now. 😊