A50 Fork seals

Tigerfeet · 12 December, 2023, 18:03:16

Has anyone got an idiots guide on replacing the fork seals on a 1968 A50 Royal Star. My original workshop manual references binding twine ... I'm guessing modern alternatives are superior.

JulianS · 12 December, 2023, 18:13:12

Instead of twine use a length of PTFE tape and twist it into a cord.

Allan G · 12 December, 2023, 18:17:06

+1

Use gas tape, and twist it. It's thicker and less likely to tear. Ptfe the threads also. It will also aid threading and removal as well as forming a seal on the thread.

Dibble · 13 December, 2023, 08:28:25

Ptfe is the way to go. I was able to buy some in cord form. Its a Loctite 55 item available from plumbers merchants and no doubt ebay! Very convenient to use and aven comes with its own cutter! Staying with plumbingi was able to locate a square section o ring which is part of the 40mm waste pipe connections used in kitchen sink applications. It fits perfectly in the recess at the bottom of the threaded section. The holder tightened down onto a smear of liquid gasket gives peace of mind! Hope this helps.
Dave.

cdsdorset · 13 December, 2023, 08:35:35

You can also buy paint on liquid PTFE.

Allan G · 13 December, 2023, 08:58:32

Quote from: Dibble on 13 December, 2023, 08:28:25
Ptfe is the way to go. I was able to buy some in cord form. Its a Loctite 55 item available from plumbers merchants and no doubt ebay! Very convenient to use and aven comes with its own cutter! Staying with plumbingi was able to locate a square section o ring which is part of the 40mm waste pipe connections used in kitchen sink applications. It fits perfectly in the recess at the bottom of the threaded section. The holder tightened down onto a smear of liquid gasket gives peace of mind! Hope this helps.
Dave.

Good tip about the sq section o'ring. Are you referring to the section where the original rope would go?

Dibble · 13 December, 2023, 20:50:20

Hi Allan sorry for the late reply but yes it slides nicely over the threaded section and sits neatly on the flared top section of the fork leg and tucks into slight recess where the threads end. It just looks like it was made for the purpose. You can pick the fittings in question up for pence at boot sales and the like!
Regards Dave.

Tigerfeet · 14 December, 2023, 09:54:53

So - taking on board all the advice already gained - for the rest of the job I just follow the Workshop Manual? And I need to drop each leg out of the yokes?

Is there no way of dropping the sliders off the stanchions, leaving them on the bike?

I've owned and ridden the bike for twenty five years - but never had reason to take the forks apart. So it is new territory for me.

Mike Farmer · 14 December, 2023, 11:27:35

You could probably do that but I think it would cause a lot of grief. especilly replacing the circlips (unless 've missed something here) I certainly wouldn't try it.

Mike

Allan G · 15 December, 2023, 12:45:51

Not as easy to take the sliders off and leave the stanchions in place on pre 69 forks. You could use a strap wrench to take them off, but you would ruin the oil seal holder and would have to replace them when rebuilding... Meaning you'd have to take the whole stanchion out anyway.

Tigerfeet · 17 December, 2023, 09:09:20

Thanks for that. So I'll need the seal removal tool (which I think I already have from a Triumph Daytona 500) and I'll need a tool to pull the forks back up into the yoke. https://www.classicbikeshop.co.uk/bsa-fork-stanchion-puller-tool.html

Will I need a tool to drive the stanchions out of the yoke?

Are there any other seals or similar that I will definitely need to replace - other than the fork seal and drain plug seal?

Gup holland · 17 December, 2023, 10:06:44

While back i renewed the oilseal holder seals, left the stancion on. Made a home made tool for the holder, it workt for me. A65 1970.

Tigerfeet · 17 December, 2023, 11:00:05

Hi Gup
I suspect you have the newer fork type. Seems they changed some time in 1968 - which is the year of my bike. My guess is, given that I have the single leading shoe brake, I have the older fork type and that the new forks came in with the twin leading shoe brake.

JulianS · 17 December, 2023, 11:46:02

The new shuttle valve forks with a different seal assembly were introduced for the 1969 model season when the TLS brake was fitted to all the twins.

The 1968 forks all used the same seal assembly which was basically the same from 1946, the 1968 SLS braked forks used a screw in wheel spindle and was fitted to the A50 and the A65 Thunderbolt, the 1968 TLS braked forks used on the Lightning and Spitfire a spindle retained by bolt up caps.