How to rebuild your front fork anti-dive unit

Step-by-step tutorials on how to maintain and fix your GL1500
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How to rebuild your front fork anti-dive unit

Post by wingdings »

Hi - folks - just on the last leg of rebuilding my front forks on my Honda Goldwing GL 1989 k - model. As part of that rebuild I am servicing the anti-dive units and renewing parts as required . The units I have found are getting harder to get parts for however I did manage to get suitable replacement seals from my local seals and bearing company just take your old rubber seals with you - they should be able to fix you up with replacement ones .

This how to assumes that you have already stripped your forks down and separated them from the springs - Using the very good how to rebuild your forks by wing admin view topic - viewtopic.php?t=16118 - if you have not got the forks stripped down yet Please refer to this and then click back on this how to -So you can then proceed with this how too.

Ok how to rebuild your -front fork anti-dive units .

You will need the following :-

Tools -

5mm long reach hex key ( for more leverage some blots are rusted in !!!. )T

Small pick tool ( To hook rubber seal over the piston if you cannot remove the grub screw on top of the unit. ) .

Can of -W- D 40 - Anti seize oil .

Parts list :-

M6 (6mmØ) A2 Stainless Steel Cap Screws, Hexagon Socket Head Allen Key Bolts 20mm ( cut down to 17mm to fit. ) ( Optional ) . x 10-off 8-needed 2 spares

Blue thread lock ( to lock in the stainless steel cap screws - Again - optional but advisable too . ) - 1tube off .

R- 31mm O-Rings x2 off .

Dust cap seals x 2off .

Piston sealing rubbers x 2off .

Method :-

Begin by finding a nice clean flat work surface to work on lay some news paper down ( just in case any fork oil is still around in the tubes ) .
lay the fork down flat as you can with the anti-dive unit facing upright (see pic below ) .
20170324_190756.jpg anti-dive pic 1.jpg
Next - Take a 5mm long reach hex key also take a good hold of the fork leg too and loosen off the four hex cap screws they will be very stiff indeed !! ( mine had rusted in ) . Once the screws are loosened off take out the two opposing screws diagonally ( see pic above ) This is because their is a spring under the top that works the plunger be careful of this when removing the last two cap screws again do this in a diagonal fashion when removing the last screw press down hard and hold the top cover down and slow gentle release the top of the unit ( see pic below )
20170324_181356.jpg anti-dive pic 2.jpg

Next - With the top of the unit now separated place the top of the unit on its side - you will see there is a rubber O- ring that seals the unit this will need to be replaced with a R-31 new O- ring . ( see pic below )
20170324_184336.jpg anti-dive pic 3.jpg
Next - with the R-31 O- ring now removed place the unit flat down with top facing towards you - ( there is a very small grub screw that holds the bush into the ball housing spray this with WD- 40 penetrating oil and leave for a while to soak in !! - then find a hex key to fit this grub screw ( on mine both these grub screws where messed up -where someone had tried in the past to remove them ) if you cannot get these grub screws out - you will have to do what I did and leave them in and first pull off the dust rubber dust cap over top of the bush housing to remove it ( see pic below of dust cap )
20170324_181741.jpg anti-dive pic 4.jpg
Next - With the dust cap now removed take the unit in your hands and with your thumb push down on the bushing this should make the plunger come down and you should be able to see the rubber sealing washer which is underneath the plunger -turn the unit back to the underside then - Take a pick tool and very carefully lever this over and off the plunger ( you will need to take this and the dust cap to your local seals and bearing shop to get replacements as I have not seen anywhere these are now sold as kits !! ?? .) ( see pic below of parts removed and needed )
20170324_192121.jpg anti-dive pic 5.jpg
Next - With all the parts removed give them a wipe with a clean rag and inspect them - replace both the plunger sealing washer and the R-31 O-ring as a matter of course !! - it just not worth the risk of putting these parts back on again only to fail later and having to strip the bike again !! .. penny's now - pounds later and time lost riding too !! .

Next - inspect the dust cap cover - if any cracks holes found replace ( see pic below ) on mine it was cracked with a hole you could nearly put your finger though ( see pic below )
20170324_180614.jpg anti- dive pic 6.jpg

Next - With the top of the unit now striped down - replace any worn parts and reassemble in reverse order to diss-assembly !! .

Next - With the top half of the unit now rebuilt its time to take a good look at the fork leg part of the unit - Inspect the rubber insert where the spring sits - you are looking for cracks - wear - etc . on mine this was ok so there was no need to proceed any further . (see pic below )
20170324_180806.jpg anti-dive pic 7.jpg

Next - With all the inspection work now done its time to put the unit back together - Having had the old cap screws rusted in on me I opted for using M6 (6mmØ) A2 Stainless Steel Cap Screws, Hexagon Socket Head Allen Key Bolts 20mm ( cut down to 17mm to fit. ) and thread locking these in with blue lock-tite248 compound to stop any chance of them being vibrated loose . If you choose to do this you will need 8 cap screws I ordered 10 - 2 spare just in case !! . Cost me £1.60p and saves a world of pain next time !!.
20170324_181320.jpg anti-dive pic 8.jpg
Next - Place the spring back in the hole and carefully place the top of the unit back on again - being mind full and making sure the rubber R-31 O-ring does not fall out while you are setting the cap screws back in again - ( A good tip here is if your using new cut down cap screws - put back in two old ones first in a diagonal fashion then tighten these two down first - Then set your new cap screws into the 2 adjacent holes once these are wound down tight !! - Remove old ones and replace with two more new ones and tighten down the same too !! job done !! )

If you have not managed knock the -R-31 O-ring out of its seat and have tighten down the cap screws - job done - you have just rebuilt your ant-dive units ..

All pics of this project are available to view via this link -!AghZXu-GTTGro18Lt5KoEn48dEMD

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Re: How to rebuild your front fork anti-dive unit

Post by Corkster52 »

That is an awesome O-ring kit. Is it easy to get one?
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