Hayter 21 gearbox

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jameshockey
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Hayter 21 gearbox

Hi everyone, having restored my Hayter 21 she is now in regular service mowing the normally very long grass around the lakes of a fishing club I help run. So to keep it in full working order I thought i would get keen and service the gearbox, it has no paint left on so im unsure as to which one is fitted but it looks to me like its the serviceable one. So my question is any idea on what oil to refill it with?? EP90 would be my first guess but the old oil does not have that lovely and unmissable EP90 smell ha ha ha. Im also thinking EP90 might be a bit thick when its cold, I did wonder if something like AQF auto transmistion fluid might be better? any ideas guys???

Cheers James

jameshockey
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Having just read though a few

Having just read though a few posts here i found a link for the 21 / osprey manual.... Gearbox oil should be SAE90

wristpin
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There has been quite a lot

There has been quite a lot written about the detrimental effects of EP additives on "bronze" worm wheels in all sorts of applications but it does appear that the box would have to be running fairly hot for any harm to be done. Sae 90 is probably as good as anything but most oil blenders do specific worm drive oils so cope better with the sliding and shearing situation between the worm and the worm gear.

The reference material to which you refer may be the dropbox file that I posted some months ago but in case no,t here it is again . Note the last page regarding the "sealed for life" boxes.

https://www.dropbox.com/s/5sjvlcenhz6ghfe/Hayter%2021%20%26%20Osprey%20G...

jameshockey
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Yes thank you for posting the

Yes thank you for posting the manual, ive spent ages looking for a copy. Maybe you can help me as im now not sure if mine has the sealed box or not? The serial number is 21337, ive found a tiny trace of green paint on the box but it might have been repainted! I cant see a breather on it though?  so many things now seem to be sealed and non serviceable... call me old fashioned but oils still oil and it still wears out! So i would still like to change the oil, after 30+ years it cant hurt! I feel i may be over thinking the gearbox service a little (as normal) it is after all a fairly slow running gearbox and i cant imagine the stresses on the gears are going to be too high. My biggest thought with EP90 was as its so thick how much of a drag it will create, obviously the gearbox and final drive are taking some of my massive 5hp already and for the work i ask it to do it is slightly underpowered anyway... sorry overthinking it again ha ha.

wristpin
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Even back in the day there

Even back in the day there seemed to be a bit of confusion but what sort a level plug has your box got?

if has a male square it was definitely designed to be checked and topped up. If it Is recessed it may have started life as " sealed for life" but as you observe, times have moved on. I will have a look through some of my old Hayter stuff and see if there is anything more of interest. 

Meanwhile  how about a straight 90 with a squirt of something like this ?

http://www.molyslip.co.uk/products.php?cat=50

jameshockey
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To me the plug although not

Thank you for that, you are a star.

To me the plug although not square does look like it is designed to taken out and checked? Thats a good idea about an additive though, i think im probably just over thinking this! Ive found a sae 70w90 gearbox oil which im sure will be fine and will be a little thinner when cold... athough knowing my luck it will just leak being thinner ha ha 

wristpin
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I think that falls into the

I think that falls into the flat or socket head plug mentioned in the last bulletin in my Dropbox post.

hortimech
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Do not use EP90, this is an

Do not use EP90, this is an hypoid oil and may attack the gears inside the box, just use an SAE90 oil.

The later sealed boxes were filled with a red oil, no idea what it was, Hayter wouldn't tell us.

jameshockey
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That would explain the lack

That would explain the lack of awful EP90 smell!!! the old oil looks to be quite thin too, mines now black but if it used to be red then im wondering again if its something like aqf automatic transmission fluid? 

wristpin
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I doubt that it was akin to

I doubt that it was akin to ATF , possibly some long life synthetic but as the guts of the box will be the same as the one using 90 I would go with that plus an additive if the mood takes you.

The spec of the 21 may appear underpowered but they are so low geared that 5 hp is adequate. Hayter even offered a trailer seat.

jameshockey
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Thats my thinking, will grab

Thats my thinking, will grab some SAE90 tomorrow. I think maybe i might be asking too much of the old girl sometimes although it always plodds though even the longest stuff haha, I have changed the engine pulley already to the lower the gearing slightly and reduce the forward speed from the normal fast walking speed to more of a steady stroll which is much more forgiving on the rest of the machine.