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Collection, Preservation and Display of Old Lawn Mowers

Out of drive but cylinder knifes continue to rotate

I have now managed to get my Suffolk Colt running, I am so pleased with all the work that has gone into saving this dead lawnmower but the cylinder knifes continue to spin while not in drive that includes little to no throttle, is there a setting I have missed to keep the cylinder stationary before engaging into drive and increasing the throttle?

Any step by step guide would be appreciated to resolve the cylinder knifes issue as described.   



John.Sutherland Sat, 19/06/2021

I am starting to think it is a clutch issue, would I be right in that I will have to slide the engine off to access the clutch and once there, what would I need to identify the cause if indeed this is the cause to the Cylinder knifes rotating when stationary   

wristpin Sat, 19/06/2021

Any one of these. Engine misaligned with drum in either or both x or y axis,  centrifugal clutch shoes stuck on their pivots, spigot bearing dry or, if riveted linings, loose rivets.

DJD Sat, 19/06/2021

If the cylinder isn't in contact slightly with the bottom blade, engine will sometimes be able to turn cylinder, especially if your tickover is on the high side.

Occasionally a spring will break holding the clutch arms in, it will then fly out and engage drum with very little engine speed. At other times a very worn shoe or rivet will come away and have same effect.

A very loose chain in the chaincase will not help.

My first port of call would be the clutch area too.

John.Sutherland Mon, 21/06/2021

Do you have any pictures of what a healthy clutch looks like for me to compare mine with please.

I looked at the first photograph I took of my Colt before I did any work and noticed there is a space between the engine and the C - Clutch  which I failed to make a note of when fitting the donor engine and you can clearly see in the pictures I did not leave a gap which brings me to this question, What is the correct measurement of how much of the shaft should be visible and can I access the clutch from the chain panel side rather than disconnecting the the engine? I am not looking for short cuts, merely looking at the best option

And Thank you  





John.Sutherland Mon, 21/06/2021

Thanks for the extra info, I will need to fit all these inspections during a week of dry weather and a few days off work, not that it will take a week.

I was over the moon when the old girl started for the first time but its like having a second wife, I keep having to get my wallet out.

DJD Mon, 21/06/2021

The space is created when you disengage the drive by grabbing the clutch outer and forcing it over away from the engine, it moves about 3/4 inch.

villiers98 Wed, 23/06/2021

Slide the engine along the mounting bars and post a photo close up of clutch which may help . As mentioned you need a slow idle, some contact between the cylinder and bottom blade, and don't push the engine right into the clutch drum as the drag will turn the cylinder.

John.Sutherland Fri, 25/06/2021

Looks to be a wet weekend and my hopes to resolve the issue might be dashed, in which case I may have to delay until the following  weekend.

I plan to first pull the engine back to create the 3/4 gap between the engine and the centrifugal clutch and close the gap a little more between the cylinder and the bottom blade, if there is no change, I will I disconnect the clutch and take a picture for your opinion.


John.Sutherland Fri, 25/06/2021

Many thanks, I will amend the current bad positioning, weather permitting of course. 


DJD Sat, 26/06/2021

Don't move the engine back so far that end of rotating shaft from chain and sprockets is unsupported or in by only a small amount, you will have problems then, there's a ball bearing embedded into the shaft if I remember correctly, which helps engage/disengage the drive. That should be your rough  guide, not having the machine in front of me is most frustrating! Good luck with it, it isn't overly complicated.

John.Sutherland Sat, 26/06/2021

I only just read your message about not pulling the engine back all the way, Opp's too late. I gently tapped the clutch to create 3/4 gap from the engine, took these pictures, followed by spraying Clutch cleaner to remove any dirt and shoe deposit dust and put it back together followed by adjusting the Cylinder knifes. I do not know what a healthy clutch looks like but I hope these pictures will be enough for you to tell me if its good or bad news. 

I did start the Colt and the Cylinder knifes remained motionless in idle and once engaged the drive and increased throttle,  off it went and as you can see from the last picture I got a reasonble cut, throttle off and the cylinders stopped spinning. I feel it is far from perfect though. 

wristpin Sat, 26/06/2021

It’s difficult to tell from your images but it does look as though there is dried grease etc on the shaft and also on the rim of the top hat spigot bush . If the clutch is pushed too far onto the drum that face of the spigot bush will be pushed up against the inside of the drum and transmitting some drive to that drum even though the speed is low enough for the shoes to remain disengaged. Your clutch shoes are the early pattern each with a tiny grub screw that bears on an equally tiny compression spring allowing some adjustment of the shoes reaction to the centrifugal force needed to engage them.

Have you removed the shoes from their pivots to check that they are not binding? When doing that, take care not to loose the afore mentioned tiny springs.

John.Sutherland Sun, 27/06/2021

I have not made any adjustments to the clutch shoes because of a lack of confidence and knowledge, I merely used a spray cleaner suited for this particular area.  I would be best off getting my hands on a spare used part to practice on and getting an understanding on how it comes apart and reassembly before I tackle mine.

It is a shame we don't a Haynes style How to / trouble shooting videos on popular Lawnmowers, I think it would be a benefit.

I appreciate the help and from everyone who has added tips to help resolve my issue.   

wristpin Sun, 27/06/2021

I appreciate your reluctance to get out of your perceived depth but there really is very little risk of doing anything irrevocable . By far the best way to learn is to have a go. As far as YouTube vids etc go there are lots that are far wide of the mark and one or two that are plain dangerously wrong.

Way back, the Readers Digest published a slim volume of lawnmower repairing and I believe that Haynes also did one but they tend to be more of an enlarged owners manual as opposed to a mechanic’s  “ starter manual”.

As far as your clutch shoes go there are no hidden nasties , just squeeze the spring steel retainers to release them , then gently wiggle the shoes off their pins; just watch out for the tiny springs under the grub screws. In passing, one of your images suggests that at least one friction lining is worn down to its rivet at one end - may just be the camera angle. 

John.Sutherland Sun, 27/06/2021

I have seen You Tube videos by those working on the Suffolk Colt but they tend to skip past the all important areas of interest to me . One particular video the fellow bought new old stock clutch shoes with brass rivets but he did not include stripping and assembly in his tutorial, its videos like this that annoy me because I come away learning nothing after sitting through 40 minutes of Radio one style garbage talk. If any thing, I would like to source as he did new old stock but then it must be a rare find.

The early version of the Centrifugal clutch on my Colt is stamped "Pony" internally on the cup, I read somewhere that apart from the engine Colt and Pony have compatible parts as they are near identical lawnmowers, one last thing - what is the right method/tool to squeeze the spring retainers to release them?