alternative fork oil seals

250 2c- the Wee-WeeVees

alternative fork oil seals

Postby morini250 » 19 Jun 2018 19:30

Hello, I already posted in parts wanted for the originals, but would it be possible to use fork seals of another bike where parts are easier to come by? I'd be very grateful for any hints!
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Re: alternative fork oil seals

Postby Ming » 20 Jun 2018 06:59

Any seal will do. Measure the inner diameter (fork diameter) and the outer diameter (where it sits in the stanchion) and search for that size oil seal. When you come to fit them, use a suitable drift to push them in, such as a similar sized socket or the old seal, then lubricate the lips before inserting the fork legs.
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Re: alternative fork oil seals

Postby Ming » 20 Jun 2018 07:09

Try 32mm oil seal in ebay, there are plenty there.
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Re: alternative fork oil seals

Postby davel182 » 20 Jun 2018 17:26

I believe the 'official' size for the Paioli forks is 31.7x42x7/9 and these are/were available from Ariete / Athena, and NLM have/had part number A31.742X7/9 (not listed in the parts.pdf) for the 250 models. I think the Italian Subito site advertises part number 42.05.17 as size 32-42-7 but I'm guessing the 32 is just a rounded up number.
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Re: alternative fork oil seals

Postby mbmm350s » 02 Jul 2018 11:54

I replaced the fork seals on a 250 2C using the parts from NLM last weekend, no problem. The parts are 31.7 x42x7/9 as mentioned previously. 31.7 mm surely that's 1 1/4 inches! Fork capacity is 160cc I am using 10W (castrol) from Halfords.
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Re: alternative fork oil seals

Postby jacks the lad » 08 Aug 2018 12:28

Having only just acquired a 2c and sorted the foot rests I took it for it's first decent ride over the weekend. Only to find upon my return the front fork seals were weeping (there was nothing in the paperwork that came with the bike to indicate that they had ever been changed, so they could well be 38 years old by now), therefore the above posts were of some interest.
Perhaps someone here can tell me, do I need any special tools in order to replace them? Other than a large allen key (12mm?) to take out the top fork nuts.
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Re: alternative fork oil seals

Postby mbmm350s » 08 Aug 2018 13:45

Hi,
No special tools needed, though do take care when prising out the old seals as the slider walls are quite thin.
The seals, two per side, are held in by a snap ring which might be rather corroded.
I use a length of wooden dowel down the tube to hold the damper assembly whilst undoing the bolt in the bottom of the slider.
Seals available from NLM and I am using 10W fork oil 160cc per leg

Years ago I ground a half inch radiator tail key to be a snug fit, but you could probably buy a 12mm Allen Key for less....

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Re: alternative fork oil seals

Postby jacks the lad » 24 Jul 2020 10:49

It has taken some time but I have got round to fitting new fork seals. "The seals, two per side", " held in by a snap ring" but. not in mine. The old seals marked 32-42-7 were simply pressed in, no clip. There is a reassess machined in the stanchion presumably for a spring clip, but as there is only a little over 10 mm beneath the reassess two 7 mm seals are not going to go in. Probably why who ever put the seals in last time left the clip out. I either need to try and find seals that are only 5 mm thick (and then find the right clips) or do what the last person did and just leave the clip out. The old seals were firmly in the stanchion and had not moved so maybe I am worrying unnecessarily
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Re: alternative fork oil seals

Postby jacks the lad » 24 Jul 2020 14:02

Up date on the above, I have since removed the other fork leg and found that it did have a spring clip holding in the oil seal, I say seal, not seals as there was only one!
Might explain why there was so little oil in the leg.
Update, got the other seal out, it's marked 31.74.42-7/9. I had wondered what the 7/9 meant but I think I now know, measuring the seal once it was out I found that the seal is 7mm thick but the lip extends a further 2mm, ie 9mmm overall. Still can't two of them in though.
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Re: alternative fork oil seals

Postby EVguru » 28 Jul 2020 17:30

The Paioli forks as used on Morini 125/250 are 1.25" diameter (31.75mm), not 32mm.

Having been sent a picture of one of the sliders, the seal recess doesn't look as deep as any of the Morini examples I've seen. I just took a couple off the shelf to check.

The original seals were just standard rotary shaft seals, whilst the Ariete seals (ARI.078 - readily available) are a modern double lipped style actually designed for forks.

With the Ariete seals, you only need one per side, which will also reduce stiction and may improve the fork action. Use a spacer under the seal.
Last edited by EVguru on 28 Jul 2020 20:30, edited 1 time in total.
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Re: alternative fork oil seals

Postby JonD » 28 Jul 2020 20:27

I may have read the Arieta catalogue wrong, I think the code for the 31.75mm seal is ARI.078. Best to check before ordering. The complete seal catalogue is on line giving dimensions and seal type.
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Re: alternative fork oil seals

Postby jacks the lad » 03 Aug 2020 10:05

Problem solved, after a internet search I found an Athena fork seal set ATH-FORKSEAL-019. Ordered, arrived the next day, fitted. The missing retaining clip took a little while longer to find, in the end I found one for a slightly larger fork, but it responded to a little bit of trimming.
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