Repairing A 1999 Marzocchi Bomber Fork

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Repairing A 1999 Marzocchi Bomber Fork
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Posted: Aug 3, 2020 at 19:42 Quote
I have a 1999 Marzocchi Bomber V2 BAM fork that has a cracked crown, where the left stanchion clamp bolts are, causing the fork to leak oil.

I was wondering if it would even be worth it to have this small crack welded and then heat treated and put back into use on some gnar.

I have read about how you can't weld aluminum frames without heat treating them because of how welding weakens aluminum. However, seeing as how the crown completely separates from the stanchions a steerer tube via Allen clamp bolts, could this repair be done?

Thanks, and I hope to hear some responses/ideas on how to solve this problem, besides just straight up buying another fork.

Posted: Aug 4, 2020 at 11:00 Quote
Post some pics? You might be able to find a replacement crown off of a cheaper z3 or z4 and transfer that over. Welding could work but I'm not sure if trust it long term

Posted: Aug 4, 2020 at 21:25 Quote
Lowers are usually magnesium, which I think is a very uncommon material to weld. I think swapping the lowers out would be a better idea.

I could be wrong. Some lowers are aluminum but again, most are cast mag.

Posted: Aug 5, 2020 at 6:57 Quote
"Lowers are usually magnesium, which I think is a very uncommon material to weld. I think swapping the lowers out would be a better idea.

I could be wrong. Some lowers are aluminum but again, most are cast mag"

You may find reading the OPs post again and again and again to better understand
that your response doesn't quit fit : )

Its possible, but depends on where the crack is, how big the crack is, how much
material is there to support a weld etc, the CSU uppers are usually Aluminium,
perhaps even cold forged to shape, though I can't be certain, only going by
the Bomber 04 marathons I have.

The crown takes a beating from riding, so if someone does undertake welding it,
be sure you understand the risks your taking. I have had a weld repair on a cracked down
tube, the proffesional welder who undertook the job said, it can be welded but could
not guarantee how long it would hold up.

its been welded but no heat treat after, Ive tried to mitigate further stress and
potential risk by foam injection to the main tubes, but its all on me and I'm happy to take
that chance, I'm more curiuous to how it holds up over time.

You are better getting advise from folk who are knowledgeable on this, round here we
are all experts and questionable at best, me included.

Costs, you may find another of correct size Marzocchi Bomber Fork in used spares repairs is a more
viable option, as a doner fork, keep a look out on Ebay and the like.

I had often wondered if a Pace RC35 box crown would work on the Marz fork stanchions and
lowers, as they share the 28mm stanchion, and pace crown has complete removable stanchion
clamps, and removable steerer.

Posted: Aug 12, 2020 at 19:38 Quote
If you are really attached to your fork a machine shop could fabricate a new crown pretty easily. To me though it sounds like you’ve gotten your money’s worth out of the thing and it’s time for something new.

Posted: Aug 12, 2020 at 20:00 Quote
So you've got a cracked z2 that's leaking oil. Crowns don't leak oil. Lowers don't leak oil by crowns.

Do you mean a cracked stanchion tube? The gold-ish colored portion of the fork that slides into the lowers?

Z2's are great forks, either a cracked crown or stanchion would be easily replaced with the proper part. I've seen a few on eBay. I'll have a spare stanchion from a z3. If you want to disassemble we can compare measurements. If it fits I'll send it to you if you cover shipping.

Otherwise eBay might have what you need.

(Pace crowns won't work, marz z2's are 30mm stanchions)

Posted: Aug 14, 2020 at 5:35 Quote
(Pace crowns won't work, marz z2's are 30mm stanchions)

Some Pace crowns will accomadate 30mm stanchions.

Though the early Pace forks were 28mm stanchions, the
Pace MXCD forks that came on a Proflex I had,
have a hollow box crown for 1.25" steerer and the
stanchions have a lipped sleeve at the crown clamping point,
when you remove the stanchions your left with two nice 30mm diameter
clamping holes on the crown that will happily accommodate Marzocchi 30mm
stanchions, whense my thinking, what not so sure is the spacing
of the lowers matching up.

My 98 Pace RC36's are 28mm stanchions and no such luck with the crown fitting
a 30mm Marzocchi in there.

Posted: Aug 15, 2020 at 1:07 Quote
Replace your crown or like one dude mentioned pay a machinist out of billet
I wouldny be welding on cast magnesium!!!
Or a heat treated crown!!!
You can weld 7005 aluminum up as it is non heat treatable series , food for thought when shopping for a DH rig!!!
We are MM performance cycle in calgary
If you have any alloy related questions pls contact us ,

Posted: Sep 16, 2020 at 12:31 Quote
Update: I took the fork apart to service it myself and to figure out better how the fork works, as well as the extent of the damage. Turns out, the top cap was justr loose underneath the crown. The only thing that was cracked (and actually came right off) was the piece of the crown where the bolts to clamp on the stanchion tube go in.

I figured I would risk trying to weld the crown because the way I see it, the crown will either be put aside and probably never used again, being replaced with a newer crown, or, I try getting it welded and see how long it holds up.

So, I got the piece welded back onto the crown, fork oil replaced as well as dusts and oil seals, put it back together and hit the trails! It seems to be holding up well after a couple days of light XC trails.

Doubt I will push the bike much farther than XC trails, as the Z2's are on an XC bike anyways. It's a 1999 Gary Fisher Joshua F2.

Thank you to everyone for the advice! I'll make sure to post some pictures of the fork and bike when I get a chance!

Posted: Sep 16, 2020 at 12:34 Quote
muddytreker wrote:
"Lowers are usually magnesium, which I think is a very uncommon material to weld. I think swapping the lowers out would be a better idea.

I could be wrong. Some lowers are aluminum but again, most are cast mag"

You may find reading the OPs post again and again and again to better understand
that your response doesn't quit fit : )

Its possible, but depends on where the crack is, how big the crack is, how much
material is there to support a weld etc, the CSU uppers are usually Aluminium,
perhaps even cold forged to shape, though I can't be certain, only going by
the Bomber 04 marathons I have.

The crown takes a beating from riding, so if someone does undertake welding it,
be sure you understand the risks your taking. I have had a weld repair on a cracked down
tube, the proffesional welder who undertook the job said, it can be welded but could
not guarantee how long it would hold up.

its been welded but no heat treat after, Ive tried to mitigate further stress and
potential risk by foam injection to the main tubes, but its all on me and I'm happy to take
that chance, I'm more curiuous to how it holds up over time.

You are better getting advise from folk who are knowledgeable on this, round here we
are all experts and questionable at best, me included.

Costs, you may find another of correct size Marzocchi Bomber Fork in used spares repairs is a more
viable option, as a doner fork, keep a look out on Ebay and the like.

I had often wondered if a Pace RC35 box crown would work on the Marz fork stanchions and
lowers, as they share the 28mm stanchion, and pace crown has complete removable stanchion
clamps, and removable steerer.

I was thinking of trying to find a different crown and steer that might fit my Z2's. They have 30mm stanchions though. Talked to a guy "Marzocchi Mark" who carries old Marzocchi fork parts and was quoted $120 USD for a crown and steer... We will see how the weld holds up for now...

Posted: Sep 16, 2020 at 12:37 Quote
eshew wrote:
So you've got a cracked z2 that's leaking oil. Crowns don't leak oil. Lowers don't leak oil by crowns.

Do you mean a cracked stanchion tube? The gold-ish colored portion of the fork that slides into the lowers?

Z2's are great forks, either a cracked crown or stanchion would be easily replaced with the proper part. I've seen a few on eBay. I'll have a spare stanchion from a z3. If you want to disassemble we can compare measurements. If it fits I'll send it to you if you cover shipping.

Otherwise eBay might have what you need.

(Pace crowns won't work, marz z2's are 30mm stanchions)

Turns out the top cap on the stanchion was just loose. I have noticed a design flaw where, if you turn the preload adjustment knob too far to the left, it can loosen the cap on either stanchion even when the cap is properly torqued. Stanchions were in flawless conditions though! Thanks for offering to sell me one.

Posted: Sep 16, 2020 at 12:41 Quote
Carbondogleg wrote:
Replace your crown or like one dude mentioned pay a machinist out of billet
I wouldny be welding on cast magnesium!!!
Or a heat treated crown!!!
You can weld 7005 aluminum up as it is non heat treatable series , food for thought when shopping for a DH rig!!!
We are MM performance cycle in calgary
If you have any alloy related questions pls contact us ,

In the service manual I found online from 1998, the crown material is "forged and fast aluminum" although it does not say what series aluminum it is.

Got the small clamp piece where the stanchion clamp bolts go in welded, seems to be holding up ok for now, although I do acknowledge the safety risk I am taking.

The bike is a '99 Joshua F2 so I don't think I will be doing more than just XC trails on it... Hopefully it will hold up... Thanks for your input though!

Posted: Sep 16, 2020 at 14:17 Quote
Nice work!

Glad you got it figured out, fixed & back on the trail. Great forks.

Posted: Sep 16, 2020 at 23:00 Quote
Carbondogleg wrote:
Replace your crown or like one dude mentioned pay a machinist out of billet
I wouldny be welding on cast magnesium!!!
Or a heat treated crown!!!
You can weld 7005 aluminum up as it is non heat treatable series , food for thought when shopping for a DH rig!!!
We are MM performance cycle in calgary
If you have any alloy related questions pls contact us ,

I WOULD weld on cast Mag. It's not rocket appliances. Hence the red seal in the trade.

Alloy type, preheat, interpass temps, filler material, and postheat. Any dude with a ticket worth their salt can run a TIG pass, blindfolded, while having a dart and drinking a beer.....as long as attention is payed to specifics, there's little to be concerned about.

Same as any other process involving due care and basic metallurgy. And that's why bike shops don't employ specialists. We cost too much, because.....well....stuff.

As for the Al, it's not much different. Engi's will tell ya it's a matter of manipulation of the basics.

People acting like heat treat, peening, welding, or any other process - as though normalization or other manipulation of mechanical strength is something that's solely up to the good folks in Valhalla......not so. Most of it is easily repeatable. Relax, you'll be fine.

Posted: Sep 17, 2020 at 8:08 Quote
https://lh3.googleusercontent.com/XOQWR4W9fMWeQAm9jhvlTxiXXpAw4-EjqiH5Ct0iEEK0z2uETCPnkH19LGaTXJIOpY5uW_nPcoajWdbeNDSsF-JW5R8objkYzNrjIDBeoEeliInGLl7z7wUjuFkNkr6hTTqkm9-TW-1bu1coqCbonOJQZUkJXj5aoGmYZ8fakgN46tO8NwCmcgVfiBxkZz7bgHoq3eVkrMnBDrgOjN4s0OykQKsnQp_Gz_5fYCvweGU3xOFSepXWpw4q9mW7itfwH9WeT1Od_ThWwS3qV8UTvcas9gXRfv0D6Ot1Sr73noZ3aBG5_4MqMxlMpVCwC0hFSmTuXPo0GjCSAMe-jGR67KNpDSaO1hKuF-qn2TVdFfEU0UY9iPAlS-CeTHamgBd39IV_f7H3tviJPZPpRm-YR6upx0gid87GR98iHe4KPYJI2CG_bbhKzmqkaJlEFSY1T4kuF0EmptDWFWrorJGMemkCK_KJJ60Qg8X7k_WJqVP2U85wrZnrJV90bAvQh0CNwbz1rLl78hkfpQ_Qs7o5fObz6fVIEd9EHXCHqDORIDtls6x0TjYRJyLukq7F_BqE8zJpzUf8x38WaABkjRPOe8w3fml4hPf4hFFfsC2s7JaACYkuHxrVEDqgPx7wF_t8TvmNUeva-fNoSW2gECVtlrQJTqcT7oLmSjzv3Gc-T_Wx13_rG-QlIUbPtCi4=w1108-h608-no?authuser=0

Here is a photo of the forks completely disassembled when I serviced them.

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