How do I fit this washer? correctly

Possibly an obvious question, but it’s costing me a small fortune!

I had my front master brake reservoir chromed a short while ago on my Evo so I had to strip it bare for the chroming operation. When reinstalling (as per the Harley manual) I purchased a new master cylinder repair kit (45006-96). However, when fitting the final washer/seal (the largest washer in the picture below & the bit that holds the thing together & makes it air tight) under operation - fluid leaks out.

I assumed that this was my error as when I fitted the seal I used a screwdriver to push it back in so could have damaged the seal slightly, so I purchased another repair kit (just for the washer). When I fitted it again I used a lolly stick, but had trouble bedding the washer down as it’s a tight fit. However, after struggling to seat it correctly & looking kinda right – although not 100%, but still leaks!

I’m now on my 3rd repair kit which arrived today (cheaper aftermarket version this time as even through Guernsey HD they still cost £27 as you can’t buy the washer separately). I’ve check the bore and it appears to look good & undamaged so it must be the way I’m installing this very expensive washer - before I commence on this one …. has anyone any ideas?

I’ve also got lots of spare parts from the previous repair kits so if you need any pieces please ask!

[Mr B]

Have you inspected the seals for damage when you remove them after they leak. It seems that the sealing lip is getting nipped as you install it. I hope you are lubricating the seals and the cylinder first, before you try and fit them. Use either brake fluid or the proper rubber grease to make them slip in. The seal needs to be inserted evenly, so instead of useing a stick, use a piece of plastic tube just smaller than the seal and push it in evenly. Also check for even the slightest sharp edge that can mark the seal.
I work on industrial hydraulics and fit hundreds of different seals every week, they are the same principle. The first kit should have been enough. Has anything got damaged during the chroming process. If the tolerences are right and the seals are correct for the job...there shouldn't be a problem. Also are you fitting it the right way round. If it's a vee shaped seal, the vee needs to face the pressure side.

Brian.

Thanks for your help Brian. After I remove the seals I normally have to destroy them to remove them so they are pretty cut up so I can't check for damage & I lubricate them with brake fluid as per the instructions.

The actual hardware doesn't appear to be damaged & the seal is being fitted the correct way round (as I made a note when I removed the original). I'll find some plastic tube & see if I can get the thing in evenly this time round!

I'll let you know!

[S.T.Chapman]

I think the advice about lubrication is sound, what I would say is that from the description you have inserted the seal not in an even manner.
it may help to use an appropiately sizes socket to insert the seal squarely and avoid the chance of it not sealing right.

I’ve check the bore and it appears to look good & undamaged

Would the chrome plating make the bore smaller in turn causing the washer to distort?

[Mr B]

Originally Posted by harleyhog

Would the chrome plating make the bore smaller in turn causing the washer to distort?

The chrome plating is not likely to have gone in the bore, but it can leave some nasty little edges. The cleaning chemicals can make the bore rough as well.
I have chroming plating done on Industrial hydraulic rams, and the platers never finish the job...they expect you to clean up the edges. It's normal practise, they're platers...not engineers.

Brian.

[Phil]

What stands out to me is that you just had it chromed.
Did you thoroughly clean the bore & lightly hone it?

Originally Posted by Brian

The chrome plating is not likely to have gone in the bore

Haven't had one apart yet, Phill's mention of a light hone sounds logical.
Now instead of saving money by chroming instead of just buying chrome ones, 3 re-build kits later and the prospect of buying a TINY hone...

Live an learn, feel for you, something soo tiny and stupid
costing so much.

[Mr B]

Originally Posted by harleyhog

Now instead of saving money by chroming instead of just buying chrome ones, 3 re-build kits later and the prospect of buying a TINY hone...

Live an learn, feel for you, something soo tiny and stupid
costing so much.

My thoughts exactly.

Brian.

[panster]

Hi, this might just be an assembly issue.
When the plunger and other parts are in the cylinder
there isn't enough room to fit that washer/seal.
Try pushing the plunger in then fitting it.
If the lever's not on it will just push out again.
I re-fitted the lever and just held it pulled in slightly while
fitting seal.
The thing is, when the lever is fitted there is no spring pressure on that washer, the lever is in constant contact with the plunger when assembled,
and is all that stops the whole mess falling out !!
I think it may be that that's stopping it seating correctly.
Hope this helps.
(I could do with a spare spring).