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Collection, Preservation and Display of Old Lawn Mowers

hayter twenty one

hi all and thanks in advance for any help. Ive just recently been given a hayter twenty one with the 5hp block. Im wanting to restor it and make use of it for work for the first cuts of the season. Im giving the engine to my local mower repair man to service and doing the rest myself. I need to know the 2 belt sizes and maybe a link or size of the 2 cables i should buy.
Many thanks


wristpin Mon, 11/11/2013

Transmission , single peed Pt No 2349, M24/Z24

                          Two speed pt No 4013

Cutters Pt No 2348, A46

transmission adjusted by moving the engine then lock the engine adjustment and adjust the cutter belt by moving the whole front assembly.

No measurement for the clutch cable but they should be  still available . If not OLC member John Cruse at the Mower Centre in Hailsham, East Sussex  will make you one.

At some point in production the original "normal duty" cable was replaced with a much heavier duty item but they were interchangeable.

Throttle cable  - proprietary "piano wire" push/pull cable.

Clutch adjustment is critical. Early machines the left hand rear wheel was secured with only a split pin and correct adjustment was a bit of a pig. Later machines had a castleated nut locked with a split pin and it was easier but it was amazing how many people never understood it. 

On both types it is essential that all left to right end float of the axle id eliminated before adjustment is attempted and also that the handle bar clutch lever is not worn. If the locking latch on the lever is worn allowing a little "re-engagement" of the clutch before the latch bites all efforts to obtain correct adjustment of the clutch will be in vain! There is a fix for worn levers but it's best described with illustrations and at present I don't have a lever handy to photograph.

Clutch adjustment Service Bulletin for the later machines.

Same principles apply to earlier machines but without the advantage of the "adjustability factor" of the castleated nut a bit of tial and error is involved. 

The spelling checker doesn't like my spelling of "castleated" and offers castrated as an alternative!


hortimech Mon, 11/11/2013

That was the day when Hayter actually wrote service bulletins, though to be fair they did cover most things on the service courses. Just two comments though, forget item one on the list and the bulletin never mentions the clutch/chain cover, so how you are meant to adjust the clutch without removing it, I do not Know.

Yes, I do remember the early models, they were a pig, spacing the splitpin out with washers and then when you couldn't find a slightly thinner washer, having to grind the back of the splitpin instead, oh yes those were the days  smiley

One last comment, you may find that the clutch disk linings are glazed with grass etc, we just used to give them a vigorous wire brushing, but if you do this, please wear a mask.

wristpin Mon, 11/11/2013

In reply to by hortimech

Good points and I'll add a couple more. If the machine has been sitting about for ages in a damp atmosphere you may find the clutch lining has either bonded itself to the pressure pate and won't disengage or has "blown" off its backing plate. You can glue it back on  - my favourite adhesive for the job was Loctite Multibond but I expect there are others just as good.

Finally,( for now !) The right angle drive gear boxes that transferred the drive from the engine to the axle could be painted yellow, green or blue. If blue, it will have no breather and a flush internal hex level plug. These were described as sealed for life and were not to be topped up or, in the event of failure,  opened for repair but returned to the factory for exchange.