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Collection, Preservation and Display of Old Lawn Mowers

Ransomes Auto Certes

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Just bought a Ransomes Auto certes and I am restoring it. It has the Norton Villiers F12 engine and I have a few questions.

Mower was bought as "won't start" but I found that the exhaust valve was stuck open. This freed off easily so no problem there. There is a weak spark when flywheel is turned over by hand, but thei may well be ok on the pull starter when replaced. However i am wondering if I can check the points essily and if so, what needs to be removed and will I need a special puller.?    Carb needs a new float needle and main jet tubular filter, which is essential as jet has a hole not much bigger than the sharp end of a needle. Are silencers available for these mowers or do I make a new one?. I have all the tools to do the job so that does not scare me. Is a service manual for the engine on line anywhere ? 

This is a good mower all round and does not look like it has done much work, so well worth restoring. I worked in the lawn mower shop for five years from 65 to 70 and well remember the chap who built the hand Certes, a Harry Pitcher, who lived north of Ipswich in Tuddenham, where I lived, and I often gave him a lift to work. Good days and a great bunch of guys in that factory.


wristpin Tue, 23/04/2024

The points may be cleaned and set through the window in the flywheel but to do the job properly you do need to remove the flywheel and you do need a simple puller that screws into the holes provided  - not a legged one that hooks around the rim which can ruin it. The flywheel can be very tight.

Carburettor parts are probably available from Jon Cruse at the Hailsham  Mower Centre or from Villiers Parts.

sparkymike Tue, 23/04/2024

Flywheel is now off but noticed that one fin is missing from the flywheel. Not sure what to do with this yet. Might be able to get a slice of alloy tig welded on to the stub. I don't think it will affect the balance any, but would like to fix it if possible. Can't grumble as only paid a pittance for the machine anyway. What is torque setting for these engines, bearing in mind the alloy crankcase. I have had to helicoil one of the holes so far as a previous owner had bodged in a whitworth bolt that was only holding on the bottom threads as upper threads had stripped out. Contact set /coil look brand new, so some luck today.!!



wristpin Wed, 24/04/2024

Not unusual to find a broken fin.

I think that you will find most of the information that you need on this site but for a start

Head bolts 12ft lbs ft, big end 8, flywheel 30, end cover bolts 9.


sparkymike Fri, 26/04/2024

The Villiers F12 engine is now stripped down and looks to have been rebuilt very recently with new  +.20 piston and rebore. All bearings and bushes look to be new. Bit of luck all round I guess. Only one point is the use of Hylomar or   similar sealing paste. See photo as to reason I never use it. It tends to break off inside and can seriously clog up any oil holes or other important small items. I only use Wellseal which works fine for me and Rolls Royce apparently. Mike.

sparkymike Sat, 27/04/2024

Crankshaft now measured and is within factory limits. Good. I have also removed bottom blade with the aid of an impact driver. All screws came out which is a change from an old Atco I was working on some years ago. The blade as fitted is very flat with no lip, so either it has worn the raised lip off or could it be one of the "scraper " blades. Why were they fitted ? I will take photos later top side and underneath. While I was at RS & J I only came across the normal lipped blades. These were sent to us in bulk , as were the spiral blades for the cutting cylinders, from Tyzacks. The twists in the spiral blades has to be very accurate as the collars that supported these blades were first welded onto the shaft and then blades slipped in afterwards and then they were welded. I spent a few days working out helix angles for a particular mower where they were having trouble fitting the spiral blades and found it was due to the fact that when they calulated the twist, they had not allowed for the small angle that the blade went through as it passed through each collar.

I have to make a silencer for the Certes and am considering a rudimentary press tool to press out each side, which I will then spot weld together. Should be quite a straightforward job. I hope !!.

sparkymike Sat, 27/04/2024

By the way, I managed to get a copy of the F12 maintenence workshop manual from the Villiers man in Braintree, Essex.            Very good comprehensive booklet and not expensive.


sparkymike Sun, 28/04/2024

Is there any advice on sharpening the Certes shaver blade, before I replace it on the machine? I have been checking the rear rolls and one of the grease/oil nipples is missing, maybe broken off. Are these press fit or screw in ? I might be able to remove the bit which is left with a long easyout but will have another look tomorrow.



sparkymike Tue, 30/04/2024

Grease nipples look to be press in type and I might have some somewhere, a legeacy from RSJ no doubt.!!                                 The crankcase is now spotless inside and out so I am starting to rebuild the engine. One thing bothers me, the cam collar that operates the contact breaker does not have much of a cam on it and am wondering if this has worn down a lot. Can anyone give me the dimension across the collar at the cam's highest point. There are two ways of fitting the cam and only one way is correct and should be able to be worked out by TDC. (I hope) There are one or two details missing from the workhop manual, this being one of them. There does not seem to be any mention of the crankshaft thrust washers , or thickness of same.



wristpin Wed, 01/05/2024

The standard Auto Certes blade was flat with a slot machined just back from the front edge , in effect making it lipped but not in the same sense as the lipped blade fitted to a Marquis .  There was an optional shaver blade for the AC but as far as I know it was for fitting by the user and not a factory fit option on new machines .

I’ve not got a cam ring or a dismantled engine to hand but I think that they are symmetrical and can be fitted either way round. In the reassembly section of the Villiers manual it just says refit the cam. No mention of any markings or particular orientation, but I’ll have a look in my “ stores” later in the week.  Early F12s didn’t have thrust washers on the crank and I can’t recall seeing a figure for their thickness when fitted to later versions, or for that  matter,  an end float figure. Gasket sets for the F12 only contained one crank case end cover gasket so it would seem that Villiers were not  particularly  concerned about setting end float.

sparkymike Wed, 01/05/2024

.Re. building up the engine, there are only a few parts inside, before the cover 
casting can go back on.
Crankshaft, conrod, camshaft, gear trough and spring,and the cam followers plus the 
location dowels, if they were removed. 
The gear trough spring should be fitted with open coils to the rear side of trough.
Timing dots are on crank gear and cam gear.
Re. piston fitting, I used a strip of brass around 3/4" wide and a jubilee clip 
to compress the rings. Not too easy a job as the cylinder face has a step in it in
the combustion chamber area. I should have made a stepped brass ring and then it 
would have been a lot easier. As it was, I eased the rings in that area and the 
piston slid in ok. The original lock tab plate was pretty mangled , so made a new
 one from 18 Gauge brass as I could not find any suitable steel in the workshop.
When fitting the side cover casting, care has to be taken to make sure that the
gear trough locating pins are lining up with the cover holes. Apart from that, all
pretty straighforward in that area.
Fitting the valve spring collets are fiddly and you need a spring compressor with
a very thin end. If anything else is used then that gets in the way of fitting that
small slotted disc. (In the manual they quote that part as a peg, maybe an earlier
method of fixing. As with any engine, lubricate all moving parts with engine oil
before fitting.

wristpin Wed, 01/05/2024

I’ve not done it myself but I’ve seen valve springs compressed out of the engine and kept compressed with two thin cable ties . Once back in with their retainers in place , snip the ties. On the subject of retainers, three types have been used - pins through holes in the valve stems, key hole slot retainers and the little horseshoe retainers.

On the subject of gasket cement . New gaskets are usually assembled dry but reusing undamaged ones  just need a smear of heavy grease, but Wellseal does have a lovely ( addictive !) smell !



sparkymike Thu, 02/05/2024

This particular engine has the horse shoe type of valve retainers. Is there a drawing for the clutch two pin adjusting tool.?           I am sure I can soon make one up if someone has the details. I am asuming it is the same as the Marquis tool.?

A photo would be handy as well.




wristpin Thu, 02/05/2024

Cam ring. Found a short block with the cam ring in place. Don’t take any notice of the two centre pops at around 11 o’clock  as someone had been “ playing” and there are various felt pen marks on the stator plate.
The outward face with the centre pops  is smooth and the inner face next to the oil seal has a small step or relief.

If we call the key way as six o’clock the thickest part of the ring 5mm is at about 5oclock and the thinnest at about 8oclock 3.85mm. The largest diameter is between 11 and 5 and is 31.22mm.

All measurements taken with a diy quality digital vernier ( not tool room !!!)

Hope that this helps.



wristpin Fri, 03/05/2024

Cam ring.

Found this one on a scrap “ short block”.  Someone has added the two centre punch marks, but that side faces outwards. Presumably experimenting with the timing as there are various felt pen marks on the stator plate.

The inner side facing the oil seal has the raised edge.

outward facing side

Outward facing.

Inner facing side


sparkymike Fri, 03/05/2024

As a diversion I decided to have a look at the grass box. Several dents which is the norm, they can be all beaten out with care, a fair bit of surface rust that also can be treated. The two sides stamped "Ransomes" are in much better condition than the wrap round centre skin. So I am now considering replacing the centre skin or just re-make the complete box. I have a fair selection of sheet metal tools including pyramid rolls, so not too much out of the question. I then asked myself what would be involved in making new sides as well ? The Ransomes motif could be pressed in a new sheet using a two part lead mould, taken from the old box. The semi circular rib is no problem as I have a rolling tool for that purpose. The original box metal is around 025" thick , so I would probably use 18 or 20 gauge. Anyone else done work along these lines ?


sparkymike Sun, 05/05/2024

Thanks for the photo. I should be able to make one of those ok. I would probably thread the pins instead of welding them in.

Re. the cam, engine is now assembled so can't measure it now, but I did measure over the high and low diameter of the cam before I replaced it and different was around .025" which was more than I had at first thought. My immediate problem is the Siba pull starter. In my infinite wisdom , I took the whole thing apart as it was caked in oil grease dirt etc. but neglected to take a photo of the spring in situ in its housing. A photo showing spring in position would be worth a thousand words !! (And save me a good bit of head scratching) One of the two fibre washers in the clutch part has been replaced with a rubbery type washer, so will replace that. I have made a small jig in order to wind up the spring and wire it so that it can be replaced.  The whole part was painted green, but I thought some of these were painted black or silver ?


sparkymike Sun, 05/05/2024

Now got the pull spring in place, but don't want to cut the retaining wires until sure it is correct . Mike.

wristpin Sun, 05/05/2024

Most Sibas on Villiers F12s that I come across are unpainted in their natural alloy finish but considering their potential age there’s no telling what paint finish they may have collected along the way. I usually anchor the casing to a block of wood clamped in the vice at a comfortable height and hook the fixed end of the spring to its anchor then work it round inside the guides until it’s coiled up and holding itself in place. Strong ish fingers and thumbs with plenty of space around to manoeuvre the loose end of the spring until it’s tamed in the centre. 
Siba parts are getting a bit scarce so I buy what’s around when I see it.


sparkymike Mon, 06/05/2024

I have been checking out and cleaning down the front steel roll. The roll has two machied end caps each fitted on with small counter-sunk screws. These took a bit of shifting, but impact driver (Vessel) worked flawlessly After they were removed I  thought (wrongly) that the spindle would just tap out, but when it did not shift, I then noticed under the grease, a small circlip next to one of the bearings. After removing this, the shaft then tapped out easily. This just left the other bearing in the end of the roll. That tapped out with the aid of a long rod from the other end of the roll.  At one end of the roll there is a small pin in the spindle This locates with a keyway in the shaft hole in the end bracket on the adjusting end of the roll carriage/support tube. There is a hole in the carriage tube  and looking into this hole I could see half of another hole in an inner tube. It looks like that end of the support is removable, but at the moment it is solid. I am thinking that there should be a bolt through, locking the two tubes. Is this correct?. 

wristpin Tue, 07/05/2024

I think that when the inner is free to move in the outer the two holes can be locked with a punch to aid assembly and dismantling. Usually the inner and outer tube and rod are seized solid and take a fair amount of effort, wiggling and penetrating fluid to free them up.

There is a small amount of movement between the two roller spindle supports to allow for alignment  / levelling  when setting the front roller left to right in relation to a bar resting on the rear roller and the cutter unit sole plate. Easier done in the metal than in the 1000 words ! If you can lay your hands on an Operator’s Manual it may explain it better - or even have an image.


sparkymike Tue, 07/05/2024

I now know a bit more re. the steel roll carriage. The two threaded holes at each end are in a 1/2" steel rod that passes right through the carriage tube. On my mower, this was totally stuck and must have been like this for years , due to the amount of rust etc. that came out. I had wondered why the roll adjuster was so tight to rotate.. I tried heat/penetrating oil and brute force to remove the rod but in the end, used a long 5/16" UNF bolt in one of the holes with a tube, and used this as an extractor, which worked a treat. Needless to say, the rod will go back in with some anti-seize on it. The hole I mentioned in previous post might have been intended as an oiler .If so I will fit a push in greaser/oiler in it to prevent any dirt etc. getting in and causing a repeat of the above saga.


sparkymike Thu, 09/05/2024

In the above upper photo, the keyway can be seen in the steel roll spindle hole which engages with a very small dowel in the spindle which stops the shaft from turning. I wondered what the steel rolls were coated with in the factory, but they look to be plain steel, but may have been given a coat of preservative before they were sent to customer. I found a small spacer around 1/2" long that I was unsure of its location,but I now think it goes in the adjusting end of the roll.


sparkymike Thu, 09/05/2024

I now have the cutting cylinder assembly out of the machine and I need to remove the cylinder spindle extension , part no. MBA 4958.        Do I re-fit the chain sprocket and does it then remove with left hand thread, or is it splined ? Machine is a Mk, 8   Mike.

sparkymike Fri, 10/05/2024

I was thinking about how to remove the splined coupling on the cutting cylinder when I had a bit of a brainwave/brainstorm !!   I counted the splines on the coupling and there were six. Searching through my selection of ring spanners (large ones) I found that one fitted perfectly. I fitted it on the coupling, put a piece of ply through the cylinder and gave the spanner a sharp smack with my hand. I nearly fell over backwards when it came off with just the one hit. I have had a feeling that this mower had been through a complete overhaul and then was stood up when the valve stuck open , or the carb jet blocked and the fact that this coupling came off easily seems to suggest that it had not had time to bed down before mower was stood up.


sparkymike Fri, 10/05/2024

I am using the greenhouse for spraying the various parts on my machine. Almost gives a baked finish on a sunny day and the paint dries a lot quicker than in my workshop. Luck for me, the wife has not filled it with new plants this year yet.


sparkymike Fri, 10/05/2024

I have the distance piece for the hight adjuster but that is around an inch and a half long. This other spacer is around  a half inch thick and approx 3/4'' diameter. I will check size and center hole diam and post back. 


sparkymike Sat, 11/05/2024

The spacer is just over 3/8'' wide and the hole is 5/16''.  It came off that front roll somewhere, but I guess all will be clear when I put it all back together. One place it might fit is on one end of the comb bar. I have also cleaned/derusted the bottom block and that has come up nicely. I can well remember these being made when I worked at the factory. The actual block was a good quality angle iron and the ends were welded on in a jig. The ends were either cast steel (not iron) or forged.We had the equipment to do either. I was friends with the chap who bored  out  the bearing housings in the bottom blade end carriages. I used to check them with a dial gauge from time to time. The holes in the block ends were drilled and tapped in the drill bay and the pivots were machined in a lathe. I think the order of manufacture was probably milling first which provided a level base for drilling, lathe work, then boring and finally welding onto the angle iron. It sometimes amazes me that the average person thinks lawnmowers are a pretty rough piece of engineering, but at times we worked in tenths of thousands of an inch.


wristpin Sat, 11/05/2024

There are two “collars” that bolt to the chassis side plates to limit the travel of the front roller,  it as you say, it may become more apparent when you get to the reassembly stage. I’m a bit intrigued about your ring spanner to engage the cylinder drive dog. I’ve had a sort through my collection of old  “ agricultural” ring spanners and found one that fits but doesn’t engage the dog. I usually just use a blunt cold chisel and a lump hammer to give the dog a sharp smack. Works well and not caused any damage yet !


sparkymike Sun, 12/05/2024

I should have added in my post, it is a 3/4 Whitworth spanner and while technically not correct size, it was a good fit on the flats of the extension piece and worked. What do they say, modus operandum or is it neccesity is the mother of invention. If it had been very tight it might have slipped round, but I don't think it would chew the splines up as that part was induction hardened in the works. A better idea would be to weld a long bar on to a scrap splined collar that slides on the adaptor part. That would work any time without any damage. Spent more than an hour yesterday removing the red flaking paint from the cutting cylinder. Ideally I should get my friend who has a vapour blaster to give it the final touch before painting again. That is much kinder to any parts than sand/shot blasting and very good on carbs. The bottom block by the way, was painted red and I think this was from original . It had been overpainted in green, but I am wondering if the Certes bottom blocks were painted red to avoid confusion on the assembly line ? (Different blades than the Marquis) The cylinder bearings, RL5 SKF are like new,and felt seals are good. The thin bearing protector plates both have groove marks on them where the bearing might have touched them but I can't see how this could have occured. Can you tell me the diameter of the cutting cylinder from new ? This one measures 5.005" .Does that sound good ?  



sparkymike Sun, 12/05/2024

I am checking the land rolls clutch and very slight side play (wobble) on the chain wheel edge around 1/16". Is this normal ? (I don't mean end float just to avoid confusion.)  I have now made up a clutch tool and it worked a treat. I used two 7/16" UNF bolts, and turned down on the threaded end to 1/4" diameter and the same length. I then drilled and tapped two holes in a 3/8" thick length of steel, same distance apart as the holes in the clutch centre boss. Now a question. What are the two hooks for on the rear of the frame, near the handle support triangles ? 


sparkymike Mon, 13/05/2024

Or possibly a means of hanging up the rear kick stand, if fitted ? I am sure Wristpin will have a clue. I worked in RS&J's lawn mower works in the 60's, but still learning !!


wristpin Mon, 13/05/2024

Not quite to support the transport wheels but to anchor the over centre springs that position the jacking stand that holds the rear roller off the ground while fitting or removing the transport wheels  - or even turning the roller drums to give access to the oiler holes.

wristpin Mon, 13/05/2024

Removing the cylinder drive dog. My 3/4” whit ring spanner fits ok but makes no attempt to engage with it ! However a 4mm parallel punch inserted into one of the gaps sorts it out!

sparkymike Mon, 13/05/2024

Hi Wristpin, that was a good move with the spanner. If my spanner had not been ok I was going to slip some 5 thou shim round it, but was not needed.  Now one more question and all will then be stripped down so I can then re-paint the complete frame/chassis.. On the Mk. 8 auto Certes, what is the correct method of taking the land rolls assembly to bits ? By the way, on my machine, the nut that holds on the sprocket was not LH thread, but RH. ?  I thought they were LH ?                                        All input so far appreciated greatly. Thanks.


wristpin Tue, 14/05/2024

I’m assuming that your Auto Certes , being a Mk8, is an 18” machine. I don’t have a parts book, and it also appears that the OLC library does not have one either.

When you have dropped the rear roller assembly out of the chassis and removed the sprocket  - pull off , not screwed as on a Marquis there are certain differences regarding bearings etc. If the AC follows the construction of a similar sized Marquis of that era , it will help to know what you’ve got. I only have the shaft assembly from a 20” but both nuts are the same, RH thread, on a 7/8” shaft. 1.5/8” across the flats (33.4mm). So when you get to that stage, an image or two may be useful.

sparkymike Wed, 15/05/2024

Hi Wristpin, my shaft looks to be same design as your lower photo. Now had a bit of a calamity. I have removed one land roll, but when pulling off  the bearing housing,the circlip was inside the housing next to the bearing ??? and not where I had assumed it would be.(behind the housing) The result of my actions pulled out the very thin centre casting of the housing. Now I can get over this by mounting the housing in the lathe and facing the inner side off and then I can make an 1/8" plate and fix that on with three or four small 2BA screws. and then boring the centre hole for the shaft. Should be fairly easy to do. However, I don't want to repeat my actions on the other side, which is still in one piece. If that circlip is in same place, then the only way I can think of removing the housing is to push the housing inwards and off the bearing, then remove bearing to get to the circlip.  if there is enough free shaft to do that.                    Ransomes had a weird way of doing things, unless some previous fitter had put circlips the wrong side of the housings. What do you reckon ? I had not noticed the circlips in the parts book before I started to do the work, but that does look like they are inside the housings, after having second look, although parts books are not always accurate.


sparkymike Wed, 15/05/2024

Some photos and one of the frame and under the second coat of paint I found this original sticker. Supplied By Ben Burgess of Norwich. The original paint finish underneath the label was perfect and a very good quality job , more like you would see on a car. I will have to strive to get the same finish if possible. Wife bought me a new spray gun for my birthday. (My suggestion !!)

sparkymike Wed, 15/05/2024

I now have the right hand roll off the shaft. I had to tap the bearing housing inwards first. I could then get to the large nut (1 3/8" AF) and undid that. That ,like other end of shaft ,was also normal right hand thread. I then removed the ball race bearing with an extractor and then the circlip.  It seems a strange way of designing things. When you are fitting the parts and tightening the nut on shaft ends, final tightening will be pushing on the circlip which in turn is pressing on inside rear of the bearing housing  which is only around 1/8" thick and cast iron.. Possibly in the factory, the split collar was slid back against the bearing housing and clamp bolt tightened up , end nut tightened, then clamp finally replaced against the land roll.  I will add photo later.


wristpin Wed, 15/05/2024

Oh dear! But at least you have the knowledge and wherewithal to dig yourself out of trouble. With that setup I usually clean up the visible wall in the bearing carrier, give it a good squirt of lube and gently tap the carrier inwards until it clears the bearing and falls inwards exposing the bearing and circlip. Then easier to get a legged puller onto the bearing. When you’ve done that at both ends it’s easy to slide the roller drums off . Usually no need to remove the ratchet assembly from the shaft , just degrease it and make sure that all the pawls are free  swinging.

I remember from an earlier post that one of the roller drum lubricators is missing . As far as I know they were pressed in but while you have access to both sides I  would replace them with current pattern screw in snap fitting . I have a modified long tap that enables a thread to be cut via the access holes in the roller drum. When you have the new nipples fitted give them a good pump of OIL to clear any congealed grease from the roller oil ways. In case you are not aware, Ransomes have always recommended that all lubrication points are Oiled, not greased. Particularly in the rear roller drums, lubrication is more often or not ignored or is greased, not oiled. In either case it usually results in one or both seized roller drums.


sparkymike Thu, 16/05/2024

Photo showing bearing housing pushed back to allow access to the large nut, which is normally recessed in the bearing housing and then only way to remove it would be along series socket of correct size , or one of those old type double ended tube spanners, which thinking on, I will need to refit it later, once rolls are cleaned up. Surprising how much rubbish had collected inside, a mixture of grass cuttings, dirt and oil from over enthusiastic lubrication of the rolls.which is better than no oil.  The paint removal is progressing fine and at this point I should have invested in a sand blast cabinet, but frame would not fit in one anyway. My good old orbital DA sander is working fine and leaves a good key for the primer.



sparkymike Sun, 19/05/2024

Some progress photos. The main frame is stripped down to bare metal and not rust found which indeed was good news. I just have the chain case edges to prep. I may well leave the internal side of the chain case ,as is, because it is in very good order and only paint to do is the area under the clutch parts where is has been scuffed due to clutch adjustment in the past.  The land roll bearing housing is now back in one piece. I found a 3/16" thick piece of steel, and cut it into a rough circle with a disc cutter in angle grinder. I then turned the outer edge in the lathe to match the housing and also turned a spigot to fit in the enlarged rear hole, where I had to turn it out to remove the damage seen in previous photo. I drilled and tapped three equally spaced holes to take 4BA steel screws. I was going to use 2BA, but the wall thickness of the casting, in my opinion, prevented that.        With the plate in position, there is clearance depth for the circlip behind the bearing. Needless to say, I breathed a sigh of relief when I had completed the job as another housing would have been hard to find as it had a different part number to the Marquis that I have a parts list for. Maybe later Marquis ones are the same.? One note : I drilled the rear plate in different positions to the original bolt holes, to avoid any casting weakness.


sparkymike Tue, 21/05/2024

I have made a start on the build up of the land rolls. I now have the first one fitted and not sure what sort of end float should be made, so I slid a 0.003" feeler gauge between the roll and the slotted clamp and then tightened up the clamp bolt. I now need to know the correct way of fitting the engine cowl and fuel tank, as one of the tank bolts is awkward to get to. I also need to know the correct route for the fuel line/spark plug HT lead and the cutout toggle switch wire. There are cable/pipe clips on both sides of the cowl. Photos would be handy. Thankyou for any input.


wristpin Fri, 24/05/2024

I’ll see what I have to take some relevant images but for a start the top bolt on the fuel tank is easier to fit without the flywheel fitted.  Alternatively fit a short length of studding , loctited into the block and sticking up behind the flywheel, drop the tank over it and just run on a spring washer and nut . Second alternative is to use a longer bolt with a nut run up under its head so that its original head  is visible behind the flywheel.