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 Post subject: Coxhead puller seals
PostPosted: Sun May 14, 2023 3:36 pm 
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998cc
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Location: Canberra, ACT
A number of years ago bought a coxhead hydraulic flywheel puller but didn't work.
Finally getting my act together to try and repair.
Yet to pull apart fully but found a pic on another forum of one disassembled (“borrowed” and used here)

The seals look similar to those used in master/brake cylinders.
By chance does anyone know if this is the case and what I could use ?

Thanks

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 Post subject: Re: Coxhead puller seals
PostPosted: Sun May 14, 2023 4:35 pm 
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Joined: Wed Oct 03, 2007 9:04 pm
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Location: Melbourne, VIC
Two suggestions.

1. I have the Lockheed Repair Kits catalogue that shows seals for various applications. If you can describe the seals and precise dimensions this catalogue may give you a part number to use in sourcing such a seal.

Here's an example page.

Attachment:
Lockheed Repair Kits p287.jpg


2. Tony Cripps (user eightfifty on here) researched and then sourced the seals and other bits needed to repair the BMC factory hydrolastic pump. He may be able to advise a way for you to get the correct seals for your puller.

See his paper about the hydrolastic pump on his website here - http://www.leylandaustralia.com.au/articles.htm

There's also an email contact address for him.


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 Post subject: Re: Coxhead puller seals
PostPosted: Sun May 14, 2023 4:41 pm 
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Also see this - https://www.colliermiller.com.au/150024 ... kavent-kit

While perhaps not specifically for your tool the supplier (in Griffith) may be able to tell you the seal dimensions.

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 Post subject: Re: Coxhead puller seals
PostPosted: Sun May 14, 2023 5:28 pm 
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998cc
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Many thanks - will measure up once I've got it all apart.


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 Post subject: Re: Coxhead puller seals
PostPosted: Mon May 22, 2023 2:41 pm 
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998cc
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Location: Canberra, ACT
For information of future searches:

The sykes-pickavant repair kit has:
Screw follower and seal 11.95mm - which are correct for this use. (Follower I took out was 11.85)
However main seal in kit is 22.1mm.
The coxhead puller has a 28.5mm or more correctly 1 1/8” for the main seal.

I visited my local brake specialist and the found in old “spares” box under counter a 1 1/8 Holden brake cylinder seal which they gave me :)

This did not have a thick enough lip to fit snuggly on the main follower (should have inner of 21.2mm, this was a bit larger). So I fitted a small o ring stretched over the follower and then super glued to seal to hold in place while fitting. Ugly but did the job if this does not work long term will look for a better fit seal.

The repair kit comes with grease (petroleum jelly) that you melt to fit. I had an accident in this process - so have used Vaseline. (Doesn’t need much)

Outcome the puller is now functioning in pushing out the ram which it did not before.
It doesn’t seem to want to retract by itself but does with coercion. (Spring in repair kit does not look powerful enough and retained original)

On first attempt on flywheel some grease pushing past the filling plug - so will tighten that further.
Otherwise did tighten up and is applying pressure to the flywheel but is a problem one and not popped yet.


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 Post subject: Re: Coxhead puller seals
PostPosted: Sat May 27, 2023 2:51 pm 
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There could be a problem here. The PBR 1 1/8 seal is not suitable for use in the Coxhead puller if grease or hydraulic oil is used. Only brake fluid should be used with this seal. The picture below shows a PBR seal, 1 1/8, removed from a "refurbished" coxhead puller, alongside a new 1 1/8 seal. Both these seals are nominally 1 1/8" but you can see the PBR one has swelled considerably, and has gone soft. Part of the lip failed under pressure and was forced out past the piston to the spring area. I don't know what grease is supplied with the Sykes kit, and am not sure if vaseline is compatible with this seal, but I suspect not. Brake fluid is an alcohol based fluid while oils and greases are mineral based. I can't recommend a particular kit just now, but am preparing an article which deals with these pullers (presently working on a number of them) for future reference. Regards, Tony


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 Post subject: Re: Coxhead puller seals
PostPosted: Sat May 27, 2023 4:31 pm 
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PBR rubber grease!!

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Cheers Dave.


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 Post subject: Re: Coxhead puller seals
PostPosted: Sat May 27, 2023 6:03 pm 
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998cc
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Location: Canberra, ACT
Thanks for the input.
Will have to see how it goes long term.
Having done once - they are easy to work on.

In the short term - after tightening the filler plug further - it popped the flywheel off on next attempt.
Been trying for a week with normal pullers before that.


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 Post subject: Re: Coxhead puller seals
PostPosted: Sun May 28, 2023 6:55 pm 
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Location: Hobart Tasmania
Can you not simply use rubber grease in these pullers?


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 Post subject: Re: Coxhead puller seals
PostPosted: Tue May 30, 2023 8:48 am 
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998cc
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Joined: Sat Dec 03, 2005 2:23 pm
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Location: Canberra, ACT
The petroleum jelly has a low melting point (40-70C) and can be liquified to fill the cylinder. Thus avoiding air pockets. This is supplied with the repair kit and instructed to fill this way but seals in this kit are also a plastic not rubber.

On being made aware of the interaction with rubber and suggestions of rubber grease looked at this.
The material sheets have no melting point information but much advertising indicates is stable 200-300 degrees C. This would make filling without air pockets difficult.


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