Amortisseurs White Power!

[THIERRY]

Thank you for your help Cyclone. Interesting. On my side i'am looking for the right lower springs. As you can see on tne picture the one i have are not the right one. It looks like the sens of the spirals was inversed. They are not turning in the right direction. Dont know if my explanations are clear...

[Cyclone82]

In terms of repair options for the WP twinshocks, particularly the 1977 - 1983 versions with 12.43mm shafts and 31.75mm body tube ID, these are the main solutions.

With the 31.75mm small body type, virtually everything besides maybe a few o-rings and gas valve are available from WP/KTM today. If you have the floating piston type (usually only on the last version made in 1983) and not the bladder then the piston, piston ring and piston o-ring maybe are still available from KTM since they continued to use this piston up until the 2000's. Apart from these few parts nothing will be available from KTM/WP now.

With the smaller body WP's most of the design and parts are imperial and not metric. Wim Peters was using many parts from a UK car shock manufacturer at that time so they are imperial/english dimensions. However some o-rings are metric and some are imperial size! I know all the correct o-ring sizes used in WP shocks 1977 and newer. Many of the threads are imperial too. Don’t assume that because they were made in Holland that they are all metric sized parts.

Although these early shocks used 12.43mm shafts, they used some odd dimensions for the seals/bushings. The wiper seal is actually 12.7mm ID and uses a small o-ring to compress the lip in tighter. This wiper/dust seal is still available from 'Eriks seals' https://shop.eriks.nl/en/seals/. Eriks was the seal supplier to WP. If you are careful removing the dust seal you can read Eriks on it and the size. Very early pre 1980 WP used a plain o-ring for the main oil seal. I dont recall the size at this time though. Later ones use the same type of seal as Ohlins. WP called it seal 'd.12.4' but i have compared it to Ohlins seal for 12mm shaft and it measures the same so i think this 12mm seal is stretched over the 12.43mm shaft. Originally these WP’s did not use a DU Teflon bush. It ran straight in a steel bush, maybe it was a softer metal with lead in it? I don’t know but it was not a sintered bronze bush and it wore out quick and damaged the chrome. By the mid to late 80’s on the 36mm ID body shocks WP started fitting a DU bush and this was 12.5mm inner diameter and the fitment of it possibly compressed in a little smaller for 12.43mm shaft. This bush is similar size to KYB/Showa bush which use 12.5mm shafts so this is a possible source and the older plain still bush can be machined to accept it. Other option is to make custom sintered bronze bush to perfectly match the 12.43mm shaft.

So the options are for 31.75mm small body shocks

1 – stay with 12.43mm shafts, find/make the correct bush/seals to suit with the original multi piece sandwiched seal head or make a new easier to install 1 piece aluminium seal head

2 – convert to 12mm shafts and make new seal heads to suit and easiler to obtain 12mm seals and bush. Its also possible to machine down Ohlins seal heads and use those. This is a fairly popular conversion.

3 – convert to 12.5mm shafts and then use KYB/Showa 12.5mm parts. Either make your own seal heads or machine down 12.5 x 36mm KYB seal heads so they are 12.5 x 31.75mm


Opions for 36mm body 3612 shocks 1983 and newer

Mostly the same options but the seal heads thread in so press in Ohlins or KYB seal heads are not easily used. Since most of these shocks now have hollow shafts with rebound adjustment its not recommended to convert to smaller 12mm shafts as they will bend easier. I would recommend 12.5mm or go to 14mm. WP actually did make these 3612 twinshocks with 14mm shafts too and the parts are much the same as the 4681 monoshocks. WP made these shocks with 14mm shafts up to mid 2000’s but the problem is the newer style dust seal is NLA and was special so if you using original style seal head/body cap you are stuck with using the pre 1991 style 3612/4681 14mm dust seal or making modification and adapting your own. If it wasn’t for this problem, we could use the later KTM 50/65 WP seal heads and parts and this was a great update until they discontinued the dust seal.

Due to neglect the early pre 84 shocks are prone to having damage inside. Broken rebound springs and broken shims and pistons. These shims are mostly special designs with little slots/holes/flaps. Unfortunately nothing else uses these type of shims today that I know of and no other brands use 31.75mm body/piston size. Closest I know is Showa 33mm body/piston. It may take 2 or more pairs of shocks to make one good pair. I strongly recommend to remove the top out springs and change to a rubber based top out because I have seen a lot of these springs broken and when pieces of metal float around inside the shock it causes lots of damage.

You may notice on the old shocks the stickers say ‘GP Replica R-M System’. R-M stands for Reverse Membrane. Membrane is another name for bladder. Its reversed because the open side of the bladder faces/is filled with oil and expands when the shock compresses. Early 1980’s Reigers also use the same design. The most normal way for bladder mounting is to have the open side facing the gas and when the shock compresses the bladder compresses. These bladdrs are not available anymore. The best option is to convert to piston but the reservoirs need attention. The bladder reservoirs are often rough machined and they need to be polished smoother for the floating piston can move easily. Another option you can do is use a Showa bladder and make a new reservoir & gas cap the right dimensions and have a bladder on the gas side like most shocks have these days.

So to summarize this, no shops/dealers sell a ‘rebuild kit’ for the old WP twinshocks now. It all got discontinued just around covid 19 time. To restore these old WP’s it takes some time to make conversions and updates.

A little more info i posted a few yrs ago here - https://www.srcf.fr/forum/viewtopic.php?t=6418

[Cyclone82]

These WP are not actually very, rare except for in countries outside europe when you know where to find them LOTS were made and i have many of them. In terms of the 1977 to 1983 style twinshocks, they are ok/good but are let down by the smaller 31.75mm ID body tube so they contain less oil compared to Hulco/Ohlins/Corte & Cosso/Reiger and other brands that used 36mm ID at the time. The reservoirs are fairly short so increasing the length can gain a little more oil capacity. They also use a horrible seal head set up that is extremely hard to disassemble, they dont use a low friction DU bush and instead of a rubber internal top out like Ohlins, they use a metal spring and these are prone to breaking. They also use an odd size shaft that is 12.43mm.
By 1983 WP improved the design of these shocks a little, better piston, rubber top out, a floating piston to replace the bladder and a spherical bearing in the lower mount. This design was called 3281 'Pro Stereo'

PRO STEREO.jpg (270.38 Kio) Vu 130 fois

and they were only made for 1 -2 years before a totally new design came in late 1983 with a bigger 36mm body, better internals and external rebound adjustment which were called '3612', By late 84/85 they further expanded the design with external compression adjuster. At the same time there were remote reservoir designs with and without external adjusters too.

Here is the remote reservoir WP 3612. This version was also available with adjustable compression on the reservoir

remote res 3612.jpg (118.18 Kio) Vu 128 fois

Here is the WP 3612 from 1983 onwards with just the rebound adjuster. Although it looks similar to the 3281 Pro Stereo shock virtually nothing is interchangeable besides the reservoir.

3612 piggy.jpg (208.32 Kio) Vu 127 fois

Unfortunately i only have one of the 3281 Pro Stereo versions and i am attempting to find or make the parts needed to make a second shock.
I know a lot about the 70's to 80's WP shocks. Any questions are welcome.

[ESPADA]

A l'époque WP était une marque Hollandaise qui offraient une alternative aux équipements hydrauliques des motos de compétition client TT .
L'offre s'étendait aux ressorts de fourches et d'amortisseurs et aux combinés hydrauliques (brevet DeCarbon) bi-amortisseurs dans un premier temps puis l'offre s'étoffa avec l'introduction de la génération des amortisseurs monoshock puis à la commercialisation d'une fourche inversée révolutionnaire (permettant une rigidité accrue) la fameuse WP 4054..
A l'instar de Ohlins (le concurrent) ces amortisseurs utilisaient des ressorts en acier de qualité supérieure qui produisaient un gain substantiel et qualitatif indéniable .
Les tops pilotes Européens ont très vite plébiscité les produits et le succès commercial a rapidement suivi.
L'offre WP était aux débuts des années 80, la plus qualitative, car adaptée au style de pilotage et au poids du pilote.
Elle était également complétée par un suivi client qui s'occupait de la maintenance et du SAV des produits à l'instar des divers équipementiers pneumatique qui garantissaient un suivi tout au long des différentes épreuves internationales.
Mais le produit n'a pas reçu le même enthousiasme aux Etats Unis car le nom "White power" était synonyme de ségrégation raciale ... Louper le marché américain était dramatique pour une entreprise à vocation commerciale internationale !
L'entreprise fut vendue à KTM qui délocalisa l'usine hors de Hollande et s'empara des produits pour son usage personnel.

a112732_1.jpg (123.45 Kio) Vu 438 fois

Combiné WP à double bonbonne : une référence selon Graham Noyce.
https://www.leguidevert.com/viewtopic.p ... 97#p113897

[THIERRY]

Mon ami Paolo Rovini, vient de me refaire une paire d'amortisseurs White Power d'époque. Comme les FOX, voire plus ils sont très rares. Qui connait ou a roulé avec?

Quelle est leur histoire?

WhatsApp Image 2025-07-25 at 12.04.11.jpeg (167.02 Kio) Vu 495 fois