3TJ RR SP Fork Tube Swaps

[Kurlon]

My fork tubes have just enough pitting that my suspension guy is warning me about it. Anyone tried swapping R6 tubes onto 3TJ RR SP lowers/internals, or am I stuck looking for pristine used forks from the UK?

[rockTJ]

You could strip them and get the re chromed. In the UK I would use someone like http://www.pittedforks.co.uk/?

Sureley there must be someone stateside who could do the same?????

Chris

[Kayla850]

My fork tubes have just enough pitting that my suspension guy is warning me about it. Anyone tried swapping R6 tubes onto 3TJ RR SP lowers/internals, or am I stuck looking for pristine used forks from the UK?

I'd thought about this, but haven't had the time to have a go. I'm sure it'd be possible to convert normal RR forks using R6 parts tp have compression in one leg and rebound in the other with both adjuster at the top of the fork, rather than needing a set of forks with adjusters on the slider as well.

If it's any help at all, we have a few pairs of RR forks sat here doing the square root of bugger all.

[Evilchicken0]

SP forks are cartridge and RR are the standard types they (apparently) don't interchange).

I had some SP forks rebuilt with new stanchions - a company in France made them I think. I guess somebody in the US ccan make them but you might need to supply your old ones for a pattern.

Kayla - I "think" you can bulid ThunderAce bottoms onto the RR tops ... it was a while ago but somebody did something like that. You end up with big discs though, and blue spot mounts. Not sure which front wheel they used

Edit 1989-1990 Yamaha FZR1000 are 43mm dia Thunderace are 46mm

[Kurlon]

We've got a couple places that can strip, rebuild up, re-chrome and re-hone tubes, but the cost is prohibitive enough that I'd just start searching for a complete front end swap with a more common to the US mount instead.

Looking for US tube suppliers, there's Forking by Frank which I've heard good and bad about, and TNK who Racetech seems to support. TNK is listing 93 FZR 400 RR units as 43mm x 555mm, the R6 shows 43 x 585, so potentially too long depending on the cartridge setup.

Noodling around TNK's fitment charts... The CBR 400 RR used the same length tube, and also never made it to the states that I know of. More interesting, the Kawi VN1500 Mean Streak used that tube setup, but TNK notes special right and left hand stanchions so something odd is going on there. 88 to 89 GSX-R 750 uses the same tube dimensions, but TNK shows a different part number, might be worth researching as AFAIK those are cartridge forks compared to the RR's damping rod setup...

[Kurlon]

Annnnd, I catch a break. Just spoke with a suspension shop, they're just advising I wipe the forks down with WD40 at the end of a race weekend to prevent the pits from starting to rust again as thats what scraped up my bushings and wrecked the seals in the first place. They'll seal fine once cleaned up.

So, I'll still need to do something to the forks, but as long as I keep up on the oil/WD40 I've got a couple years at least to figure it out.

[Evilchicken0]

A couple of pits you can fill them with superglue and then cut off the excess with a razorblade.

SP forks are hard to find even over here. There were a pair on e-bay that sold for £300 recently so getting them rechromed probably isn't as expensive as you might think.

[rockTJ]

1 old tip I was given was to clean the forks down with an acetyl cleaner then fill any big pits with ladies clear nail varnish worked on an old 350LC I had. If you put too much in take it down gently with 1200 wet and dry.

Pitted forks are one of my pet hates and are a deal breaker in my eyes because of the aggro involved.

Chris

[4StrokePete]

I have fitted early R6 fork tubes to 3TJ SP lowers. I had the complete R6 forks so I used all the internals. A straight swap from what I remember. The fork tubes maybe longer, so I just slipped them through the clamps a bit more.

[Evilchicken0]

I have fitted early R6 fork tubes to 3TJ SP lowers. I had the complete R6 forks so I used all the internals. A straight swap from what I remember. The fork tubes maybe longer, so I just slipped them through the clamps a bit more.

Interesting ... presumably you could do it the other way around and build SP stanchions onto R6 lowers