2004 Factory Ohlins Fork Stanchion - please help!!

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   Hi everyone, here's my tale of woe. Hoping some will know what's happened here and perhaps guide me on a way forward.

’m desperately In need of help. Bought a 04 and love it to bits. Had an 06 before so I went back for more, thought it had 25,000 miles but looking at the MoT tests it’s done more like 45,000 after a couple of clock resets that I didn't pick up on. Restoring the bike has been a real labour of love but I might be in too deep now.

Both forks started to leak too much and lost their damping, so I rebuilt them. I used. GSXR seals. The stanchions were visibly worn. The oil was rancid, black and the consistency of water.

Examining the forks, the stanchions had visible wear but I threw them back together on a wing and prayer in the hope it would improve. It didn’t. 

Above and below, justification for stripping the forks.

Below, the wear can be seen on both stanchions around where the seal spends most time. There are vertical scores marks. The gold plating is only done half way up the stanchion.

I ordered a pair of replacement stanchions from TNK in Italy.

There are two possible parts for an RSV Factory, I was surprised to learn, so care is needed to get the model year correct.
https://www.tnkforktubes.it/forcelle-100-0050607.html
https://www.tnkforktubes.it/forcelle-100-0730080.html

The 0730080 seems to be the part for an 04 Factory. The "filetto esterno" spec seems to be critical. 43mm and what seems to be the thread pitch.
The TNK part listed is 0730080 - 1.0mm pitch
0050607 is 1.25mm pitch.

Below shows the replacement parts are different lengths and there's a recess for the top bush. Top bush on my existing forks is on the inside of the outer tube.

Arrangement at the fork stanchion bottom is different (below)

New forks have 1.0mm thread pitch.

Old forks have 1.25mm fork pitch.

Lugs are clearly stamped as FG8902

So the TNK stanchion for an 04 Factory is different. I’m trying to sort with the supplier just what has happened here. So I’m not looking for recommendations to go back to them. The design seems to be very different than for the expected
FG8902. My old stanchion is longer. There is no recess for the top bush on the old stanchion and the thread pitch for the lug is different. If nothing else this thread will probably be vital for others trying to rebuild their forks in the future.

Can anyone help with why my OEM stanchion is so different to what the supplier is listing as a replacement? Has this happened to anyone else? Is mine some sort of early FG8902 that doesn’t comply with the expected design?

Lastly, what the hell can I do if TNK don’t have a solution? Obviously I can seek a refund but it may but not exactly be their fault if Aprilia haven’t documented this variant? (update: TNK will take them back)

Am I faced with having to replace these forks altogether with later model parts? Maybe get hold of Fork outer tubes and have TNK supply the 1.25 thread pitch variant?

Are these forks actually end-of-line Gen 1 making the bike I have a very early gen 2?

Any constructive help would be greatly appreciated!!

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mcsellski Members Profile Send Private Message Find Members Posts Add to Buddy List L Plates Joined: 15 Aug 2025 Location: Dorset Status: Offline Points: 5	Post Options Post Reply Quote mcsellski Report Post Thanks(0) Quote Reply Topic: 2004 Factory Ohlins Fork Stanchion - please help!! Posted: 15 Aug 2025 at 09:58
	Hi everyone, here's my tale of woe. Hoping some will know what's happened here and perhaps guide me on a way forward. ’m desperately In need of help. Bought a 04 and love it to bits. Had an 06 before so I went back for more, thought it had 25,000 miles but looking at the MoT tests it’s done more like 45,000 after a couple of clock resets that I didn't pick up on. Restoring the bike has been a real labour of love but I might be in too deep now. Both forks started to leak too much and lost their damping, so I rebuilt them. I used. GSXR seals. The stanchions were visibly worn. The oil was rancid, black and the consistency of water. Examining the forks, the stanchions had visible wear but I threw them back together on a wing and prayer in the hope it would improve. It didn’t. Above and below, justification for stripping the forks. Below, the wear can be seen on both stanchions around where the seal spends most time. There are vertical scores marks. The gold plating is only done half way up the stanchion. I ordered a pair of replacement stanchions from TNK in Italy. There are two possible parts for an RSV Factory, I was surprised to learn, so care is needed to get the model year correct. https://www.tnkforktubes.it/forcelle-100-0050607.html https://www.tnkforktubes.it/forcelle-100-0730080.html The 0730080 seems to be the part for an 04 Factory. The "filetto esterno" spec seems to be critical. 43mm and what seems to be the thread pitch. The TNK part listed is 0730080 - 1.0mm pitch 0050607 is 1.25mm pitch. Below shows the replacement parts are different lengths and there's a recess for the top bush. Top bush on my existing forks is on the inside of the outer tube. Arrangement at the fork stanchion bottom is different (below) New forks have 1.0mm thread pitch. Old forks have 1.25mm fork pitch. Lugs are clearly stamped as FG8902 So the TNK stanchion for an 04 Factory is different. I’m trying to sort with the supplier just what has happened here. So I’m not looking for recommendations to go back to them. The design seems to be very different than for the expected FG8902. My old stanchion is longer. There is no recess for the top bush on the old stanchion and the thread pitch for the lug is different. If nothing else this thread will probably be vital for others trying to rebuild their forks in the future. Can anyone help with why my OEM stanchion is so different to what the supplier is listing as a replacement? Has this happened to anyone else? Is mine some sort of early FG8902 that doesn’t comply with the expected design? Lastly, what the hell can I do if TNK don’t have a solution? Obviously I can seek a refund but it may but not exactly be their fault if Aprilia haven’t documented this variant? (update: TNK will take them back) Am I faced with having to replace these forks altogether with later model parts? Maybe get hold of Fork outer tubes and have TNK supply the 1.25 thread pitch variant? Are these forks actually end-of-line Gen 1 making the bike I have a very early gen 2? Any constructive help would be greatly appreciated!!

426hemi Members Profile Send Private Message Find Members Posts Add to Buddy List Premium Member owner of the big bore! Joined: 30 Mar 2012 Location: cannock Status: Offline Points: 5795	Post Options Post Reply Quote 426hemi Report Post Thanks(0) Quote Reply Posted: 15 Aug 2025 at 10:19
	It would be worth talking to kais suspension about getting your original tubes re tin coated, when they rebuilt and modified my gsxr1100 forks I had them tin coat them.

mcsellski Members Profile Send Private Message Find Members Posts Add to Buddy List L Plates Joined: 15 Aug 2025 Location: Dorset Status: Offline Points: 5	Post Options Post Reply Quote mcsellski Report Post Thanks(0) Quote Reply Posted: 15 Aug 2025 at 10:53
	Cheers for that! Just called them and Kais will do the recoating for a similar price to the TNK jobbers and 6 week lead time. Non-gold which I’m not bothered about now as all I need is it back on the road. Lessons learned. 1. all on the forum first before taking on jobs like this 2. strip the parts down before ordering anything!

Spoonz Members Profile Send Private Message Find Members Posts Add to Buddy List Admins Group Joined: 11 Feb 2008 Location: North Devon Status: Offline Points: 10957	Post Options Post Reply Quote Spoonz Report Post Thanks(0) Quote Reply Posted: 15 Aug 2025 at 11:10
	Brooks suspension are a Uk TNK dealer. I would ask them re the fork tubes you have from Italy. They may be able to swap them for the right ones and they also do re Chroming/nitride/DLC etc.

mcsellski Members Profile Send Private Message Find Members Posts Add to Buddy List L Plates Joined: 15 Aug 2025 Location: Dorset Status: Offline Points: 5	Post Options Post Reply Quote mcsellski Report Post Thanks(0) Quote Reply Posted: 15 Aug 2025 at 13:34
	Brook are very supportive. I source a lot from them on projects that I have neither the skill or tools to take on.

mcsellski Members Profile Send Private Message Find Members Posts Add to Buddy List L Plates Joined: 15 Aug 2025 Location: Dorset Status: Offline Points: 5	Post Options Post Reply Quote mcsellski Report Post Thanks(0) Quote Reply Posted: 25 Aug 2025 at 09:54
	For anyone reading this post, this info could be useful. Based on taking measurements of the stanchions I took off the bike; 43mm tube, 1.25mm thread pitch, 529mm tube length, no top bush recess. These forks are from an RSV4 donor. I have also discovered that the radial caliper mount bikes, ie 2004 on, all have the same external dimensions, Hence, RSV4 Ohlins slot straight in to RSVR's. Obviously anyone wanting to do this will need to confirm absolutely that it's the case, but there appears a least to be some overlap in the 43mm Ohlins fitted to Aprilias from Gen2 RSV through to early RSV4 models. I am not 100% certain that the lower triple clamp on mine is not also RSV4; I'm going to say it's OEM RSVR Factory. The curve-ball is the Ohlins part number stamped on the lug (fork bottom if you like). FG8902 2004-01-07 FG8902 makes it an RSVR Ohlins part, but 1.25mm makes it NOT a Factory. Looking into TNKs compatibility information, The 2004 Factory has 1.0mm thread pitch, but it's the RSV1000R Dream has 1.25mm thread pitch! Allegedly, the RSV4 lugs would have fit the RSVR Factory axle, so it's possible that the previous owner sourced RSV4 Ohlins but needed to change the lugs for cosmetic reasons perhaps. Apparently the RSV4 damping internals are better than the RSVR. Kais have quoted £280 and 6 weeks, although I am not sure if that's each or for the pair. I've ended up ordering a pair of tubes from China via eBay for £138. These will get me back on the road for what remains of this year. If they work out, then great. If not, I have the originals that I can send to Kais. This has been an ordeal, but I can't help but feeling that if I'd just sent the forks off it would have cost me much more £££ due to these being some sort of Frankenstein hybrid.