After discovering a crack in the brake arch I need new lowers on my 2008 Rev forks. The uppers are in top nick and you can't buy them in 100-130mm U-Turn anymore.
I happen to have a set of Reba SL 2009 lying around, as you do, so I wondered if I could drop the lowers off the Rebas and pop them on the Rev uppers. From initial measurements they appear to be the same length from the dust seals to the middle of the axle centre anyway. So, am I likely to die horribly in flames?
Depends.
If your rebas are capable of 130mm travel they *should* be fine (they're 32mm forks from memory, the only Rockshox fork that uses a different size is the Dart and new Boxxers). If not then it'll cause problems.
Lowers can only take a certain amount of travel, which is determined by what bushes are fitted into them. If you ask them to accept too much travel, the bushes won't offer enough support and fail.
I suppose you could still use them if they won't take 130, just set the U-turn to whatever the Rebas are and don't use it beyond that. However you might as well just ditch the Revs and use the Rebas then.
might it also be the case that the position of the bushings in the lower relative to the axle/crown length could effect how they work if there's a difference between the two forks?
Lowers can only take a certain amount of travel, which is determined by what bushes are fitted into them. If you ask them to accept too much travel, the bushes won't offer enough support and fail.
How do what bushings are fitted have an effect on the travel a fork can take? I thought Reba and Revs used the same bushings
might it also be the case that the position of the bushings in the lower relative to the axle/crown length could effect how they work if there's a difference between the two forks?
True. I'm going to take the lowers off both and have a look at the relative position of the bushings. TBH the Reba lowers look a bit more substantial, certainly around the brake arch.
didnt later lowers have "power bulges" around the bushing position to increase stiffness?
Yep, that's what the 2009 Reba lowers have.
why not set the rebas to 120mm travel and not bother with all the faff of swapping them round? Esp if the rebas are the newer style.
How do what bushings are fitted have an effect on the travel a fork can take? I thought Reba and Revs used the same bushings
Different travel forks (even of the same size) will use different length lower bushes generally (i.e. longer travel forks will have longer lower bushes, which is why you can't use 7" Boxxer lowers on 8" Boxxers even though they are otherwise exactly the same). They use the same width, but will probably be different lengths (especially on the lower ones)
If the travel is identical then the lowers will defo work I reckon, but if the Rebas have shorter travel then you will only be able to use the maximum travel the lowers were designed for (as the Bushes will not be able to deal with it)
Bushings seem to be the same height. Top bushings are the same place on both lowers but the lower bushings sit 5mm higher on the Revs than on the Reba lowers.
Upon further measuring whilst the Rev and Rebas are the same height from the dust seals to the axle centre, the Rebas are 5mm shorter between the dust seal and bottom of the tube section.
I don't think it's going to work so back to the drawing board. Thanks for the help....got to try these things 
If you can't find a solution, can I be cheeky and have the internals from the spring-side leg (pushrod, spring, etc.) please? I've been trying to change from air to coil for ages but not found anything suitable.
I'll bear that in mind CaptainBudget but I haven't figured out what to do with the uppers yet...might find some second-hand lowers.
I sent my 130mm Revs to RockShox for a service and they came back as 115mm Revs 
no 100-130mm left in stock
150mm wouldn't fit + I didn't want it.
so I have 115mm Revs at home hanging on my bedroom wall.
Kev
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