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Remove stanchions from crown?

8628 Views 16 Replies 4 Participants Last post by Clinojim, Jun 23, 2009

Clinojim

Discussion Starter · Jun 16, 2009

I have an early 90's (1992, 1993) Bontrager race frame that came with a Rock Shox Mag 21. I broke a dropout on the fork and I'm trying to get it back up and running. The bike has a 1" threaded steerer, I'm not opposed to going to threadless, but the 1" steerer limits my options. I'm searching craigslist for a replacement fork, but no luck so far.

I have an old Rock Shox Indy fork that has a 1 1/8" threaded steerer, is there a way I can remove the stanchions from that fork and put them on the mag 21 crown? The Mag 21 has sinch bolts that hold the stanchions in so they would come out no problem, but on the Indy there are no bolts, I presume it's glued/epoxied in there. Any way to remove them from the crown without destroying them? If not, are there other forks out there with unboltable stanchions that might fit my application?

1 - 17 of 17 Posts

mtnbiker72

· #2 · Jun 16, 2009

You could try and Frankenfork it. The stanchions are press-fit in the Indy...it might be possible to press them out. I assume the stanchion spacing is the same on the Indy as the old Mag but I don't know for sure.

I've heard of people actually cutting the stanchions at the crown, then putting larger top-out bumpers in the fork and bolting the stanchions up to the old crown. I would by no way endorse this but there are rumors...

Clinojim

Discussion Starter · #3 · Jun 16, 2009

mtnbiker72 said:
I assume the stanchion spacing is the same on the Indy as the old Mag but I don't know for sure.

I didn't think about that, I'll have to measure that when i get home. I might put a little heat to the crown with a torch to help pull them.

Dougal

· #4 · Jun 16, 2009

Yes stanchion spacing is the same, but I doubt you'll get a good result press fitting an indy crown onto mag stanchions.
Some of the old quadra 10/20/21R's had bolt on crowns, maybe trawl ebay or put up a wanted add for some.

Clinojim

Discussion Starter · #5 · Jun 16, 2009

Dougal said:
Yes stanchion spacing is the same, but I doubt you'll get a good result press fitting an indy crown onto mag stanchions.
Some of the old quadra 10/20/21R's had bolt on crowns, maybe trawl ebay or put up a wanted add for some.

I need to do the reverse, put the indy stanchions onto the mag crown, I need a 1" steerer, the indy crown has a 1 1/8".

Dougal

· #6 · Jun 16, 2009

Clinojim said:
I need to do the reverse, put the indy stanchions onto the mag crown, I need a 1" steerer, the indy crown has a 1 1/8".

Oh right, sorry.
Yes you can carefully saw the indy crown off and use the mag crown.

Clinojim

Discussion Starter · #7 · Jun 22, 2009

2

This weekend I swapped the crowns on the two forks. My first thought was to use a 4.5" angle grinder to cut the crown off the indy, but that was a disaster waiting to happen so I just used a dremel and a small cut off wheel. Originally I wanted to make only one cut on either side of the crown so it could be repaired if I needed it again, but one cut wasn't enough to get the crown to let go of the stanchions. It took about three cuts per side (would have been less if I had though ahead of time on the cut placement) plus one big cut with a sawsall to get either side move independently.

I got it all bolted up the way I need it so I opened up the stanchions to see what I was dealing with and I find only one elastomer bumper. Hmm, that's no good. Look around on the net for replacements I found this http://shop.vendio.com/benscycle/item/948193846/?s=1245655562 but those springs don't look like anything in this fork. Would they be used in addition to the elastomer bumpers? If I can't find replacement bumpers, I wonder if I can use springs from another fork perhaps? Maybe Tora springs?

If anyone has some Tora springs laying around can you measure their outside diameter?

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mtnbiker72

· #8 · Jun 22, 2009

The Indy S only used an elastomer on one side unlike the C/XC/SL

Nice job on the Frankenforking BTW :thumbsup:

Clinojim

Discussion Starter · #9 · Jun 22, 2009

mtnbiker72 said:
The Indy S only used an elastomer on one side unlike the C/XC/SL

Nice job on the Frankenforking BTW :thumbsup:

Thanks.

Elastomer on one side and that was it? It has preload adjustment knobs on both sides which made me think something was missing.

mtnbiker72

· #10 · Jun 22, 2009

Yep...I remember when they came out and the S was single sided...which is the norm now but back then almost everything was spring/elastomer on both sides.

Anyway, here is a nice set of "upgrade" springs if your so inclined
http://cgi.ebay.com/Coil-Springs-Ro...ItemQQimsxZ20090620?IMSfp=TL090620142004r2703

or these if your heavier

Zoke2

· #11 · Jun 22, 2009

check http://www.suspensionforkparts.net they might have replacements for that fork

Dougal

· #12 · Jun 22, 2009

Clinojim said:
Thanks.

Elastomer on one side and that was it? It has preload adjustment knobs on both sides which made me think something was missing.

I remember the travel on those was really short too. Something like 30mm.

mtnbiker72

· #13 · Jun 22, 2009

48mm travel...it was the replacement for the Quad 5

Which is actually perfect for the old Bonty its going on

Dougal

· #14 · Jun 22, 2009

mtnbiker72 said:
48mm travel...it was the replacement for the Quad 5

Which is actually perfect for the old Bonty its going on

Measure it, it's a lot less than that.

The old Q5/Q10 only got it's claimed travel if you wound the preload all the way up to compress the topout springs.

mtnbiker72

· #15 · Jun 22, 2009

Of course, none of the elastomer forks ever got full travel...it was "advertised" as 48mm

Clinojim

Discussion Starter · #16 · Jun 22, 2009

Thanks for that link Zoke2, not only does it have replacement elastomers for sale, but it's got manuals for this old fork too. It confirms what mtnbiker72 said, only one elastomer. It even says that the preload adjustment on the right side does nothing, so why include it then? :crazy: This fork sure seems oddball, but I'm glad it will work.

Clinojim

Discussion Starter · #17 · Jun 23, 2009

1.1 to 1.8 inches, not much but it's something to hang the front wheel from. If nothing else, I'm hoping that this new old fork (it is newer than the one it is replacing

) will give the bike character.

1 - 17 of 17 Posts

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