Fork service with Landsdowne damper question

As I need to remove the forks to replace my damaged headlight mounts (1973 Commando 850) and as I have no previous service history on my bike I have ordered the front fork rebuild kit from Old Britts on the assumption that I may as well refresh everything while I have them off. Kit consists of leak proof seals, new filter washers, new bushings etc…

My question is this. My bike has had the Landsdowne fork damper kit installed by the previous owner. Will that in any way affect the steps I take to service the forks or any of the parts I need to replace?

Also I am planning on using Maxima 57901 20WT Standard Hydraulic Fork Oil. Is that right?

Thank you,

Mike

I seem to recall that the late Lohn Robert Bould recommended 15 wt oil, but apart from that all the seals, bushes etc are standard. You will find an allen screw in the bottom of the sliders retaining the damper tube and that and the damping adjustment screws are metric as are the nuts under the top nut.

HMNYC said:

My question is this. My bike has had the Landsdowne fork damper kit installed by the previous owner. Will that in any way affect the steps I take to service the forks or any of the parts I need to replace?

Click to expand...

It shouldn't, as the Lansdowne dampers replace the original damper assemblies with no other modifications, just don't mix up the left and right-hand Lansdowne damper parts (fork caps and valve needles).

HMNYC said:

Also I am planning on using Maxima 57901 20WT Standard Hydraulic Fork Oil. Is that right?

Click to expand...

SAE 20 fork oil would be correct for the original forks/dampers but John Bould (the Lansdowne inventor and original manufacturer) recommended (180cc/ml) of 10 grade or ATF for the Lansdowne dampers (although my preference is for 15 grade).

L.A.B. said:

HMNYC said:

My question is this. My bike has had the Landsdowne fork damper kit installed by the previous owner. Will that in any way affect the steps I take to service the forks or any of the parts I need to replace?

Click to expand...

It shouldn't, as the Lansdowne dampers replace the original damper assemblies with no other modifications, just don't mix up the left and right-hand Lansdowne damper parts (fork caps and valve needles).

HMNYC said:

Also I am planning on using Maxima 57901 20WT Standard Hydraulic Fork Oil. Is that right?

Click to expand...

SAE 20 fork oil would be correct for the original forks/dampers but John Bould (the Lansdowne inventor and original manufacturer) recommended (180cc/ml) of 10 grade or ATF for the Lansdowne dampers (although my preference is for 15 grade).

Click to expand...

I have 10 weight in mine. Perfect!

Leak proof oil seals increases stiction.
Mike B

Hey Les, my installation notes say 10 Wt oil at 160 cc's for Commandos, 140 cc's for Manx /Dommie/Seely's
Regards Mike

Brooking 850 said:

Hey Les, my installation notes say 10 Wt oil at 160 cc's for Commandos, 140 cc's for Manx /Dommie/Seely's

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John must have revised the quantity, as I believe his original recommendation to me, at least, according to my first post in the thread link below after buying one of the early Lansdowne kits was 180cc.

lansdowne-fork-damper-kit-t4683.html?hilit=sae10#p41780

180cc/ml of SAE10 fork oil (as recommended by John)

Click to expand...

Edit: I found one of John's posts where he does mention 180cc.
equilibrium-fork-breathing-t6464.html#p64523

My instructions say: Fill with 150 ml of S.A.E 10 grade fork fluid in each leg.

Thanks all for the recommendations. Good thing I asked!

Mike