1996 Bomber Z2 Refurb

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1996 Bomber Z2 Refurb
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Posted: Jun 13, 2021 at 13:47 Quote
(Originally posted this elsewhere but think this might be a better place for it) Just finished a tear down/rebuild of my 1996 Bomber Z2. This is the original fork I got when I built up my Cove Stiffee back in the day and now fork and frame are enjoying a more sedate life as my daily driver to and from work. A couple of weeks ago the seals gave out and when I stripped it down it was clear it was well overdue for an overhaul. I drained the scudgey oil out, pulled the springs etc and cleaned everything up. I was surprised how good the internals looked - Marzocchi's truly deserve the description, "Bomber".

Anyway, the challenge was the seals. I ended up going with these (https://www.enduroforkseals.com/products/front-suspension/enduro-classic-fork-seals/FSKMZ30B-UPGR.html) from RWC. When I got them I was stoked but this quickly turned to despair when I could not get the old seals out. In fact these were so old and hard that I thought the part that remained in was part of the fork lower. I tried to get it out and was thinking I had the wrong new seals as I originally tried to seat them on the old seal. Chris at RWC put me right and, after soaking the lowers in hot water for 15 minutes, the remaining part of the old seals softened and popped out. New seals went in with little fanfare and I got new oil on board and got it all torqued up. Just went for a test run and it all works great.

I relied on a Marzocchi manual I found on-line to guide me through the process. Use a proper seal press tool. I expect you could make one but given these things seat in very snug you want to make sure you have have the right tool for this. I watched some videos that accomplish this using a stanchion bulked up with electrical tape but not sure your want to be whaling on your stanchion try to get the seal and wiper seated. Use the right tool.

Anyway, a good rainy weekend project and great way to keep the old Bombers rolling.

Posted: Jun 15, 2021 at 15:35 Quote
Nicely done, the 1st time is always the worst. I've been in the same situation trying to remove old seals. If you ever plan on doing it again a Pedro's DH Tire lever is the perfect tool. RWC is the go to for these old 30mm Marzocchi's. Great company.

Love me some Marzocchi rebuilds! Although that oil sure reeks! My garage will smell like that for a week after.

Posted: Oct 2, 2021 at 20:33 Quote
OvernightSensation wrote:
I relied on a Marzocchi manual I found on-line to guide me through the process.

OvernightSensation,

Would you do us the service of sharing your Marzocchi manual with a link of some sort? I'm sure others in the future, myself included, would profit from your experience - especially since there is little online on the topic as it's a dated fork.

Thanks!

Jack

Posted: Oct 3, 2021 at 11:52 Quote
http://marzocchiworkshop.blogspot.com/p/oil-quantitys-and-levels_858.html?m=1

https://www.enduroforkseals.com/resources/oe-fork-manuals/pdfs/mz/98z2manual.pdf

The 98 manual can be used to fit just about any early z series Marzocchi, everything is similar or identical assuming it's a coil fork, oil levels are in the link above. Golden Spectro 125/150 is stock Marzocchi oil, liberally applying slick honey, sram butter or slickoleum to the seals is recommended but it's a little messy for the first half dozen rides, sometimes longer. But this eliminates the chance of sticky seals.

Posted: Oct 3, 2021 at 12:30 Quote
eshew wrote:
http://marzocchiworkshop.blogspot.com/p/oil-quantitys-and-levels_858.html?m=1

https://www.enduroforkseals.com/resources/oe-fork-manuals/pdfs/mz/98z2manual.pdf

The 98 manual can be used to fit just about any early z series Marzocchi, everything is similar or identical assuming it's a coil fork, oil levels are in the link above. Golden Spectro 125/150 is stock Marzocchi oil, liberally applying slick honey, sram butter or slickoleum to the seals is recommended but it's a little messy for the first half dozen rides, sometimes longer. But this eliminates the chance of sticky seals.

You're a [insert Shimano's best downhill groupset]

Posted: Oct 3, 2021 at 13:01 Quote
As an afterthought, a couple things:

My 1996 Bomber Z2 seems to be bottoming out. I know lower weight oil should help increase rebound, but the

..... http://marzocchiworkshop.blogspot.com/p/oil-quantitys-and-levels_858.html?m=1 ...

link shared by @eshew doesn't seem to specify 7.5W or 20W specifically. Will it matter? I see Golden Spectro 125/150 is linking me to a 7.5W variety. If this doesn't improve bottom-out sensation, is there a way to swap in (or is there an aftermarket company that would have) a coil with a higher spring rate?

Thanks in advance!

Posted: Oct 3, 2021 at 13:59 Quote
Chances are if you're bottoming out you need to increase the oil height. Slightly higher oil volume will reduce the air gap increasing air pressure build up and ramp up at end of stroke. It's possible to add to much oil as well limiting full travel for the same reason.

20w will probably be way to thick, 7.5w is stock. Some 7.5 & 10w can be "thicker" if you look at this oil weight chart stock golden spectro has a cst of 26.4. higher cst will act as a thicker oil. I've jumped up to a 35cst 7.5 weight oil before on a 888 rc3, felt a tad stiffer on compression but the rebound was too slow at full open. Ended up draining about 2/3 of it and refilling with stock.

The long list of oils is towards the bottom of the page https://www.peterverdone.com/wiki/index.php?title=Suspension_Fluid

Playing around with oil height is pretty easy, add a few mm at a time, if overfilled and travel is reduced use a straw to dip into the oil, finger over the top to capture and remove.

There are different springs, higher and lower weight but there are very difficult to find, if you do some searching you can find the part numbers/colors for different weight springs and save the search in ebay. https://www.retrobike.co.uk/threads/marzocchi-z2-spring-ratings-and-part-numbers.397640/

Vintage Marzocchi spring information
Marzocchi vintage spring info

Posted: Oct 15, 2021 at 16:22 Quote
eshew wrote:
...
There are different springs, higher and lower weight but there are very difficult to find, if you do some searching you can find the part numbers/colors for different weight springs and save the search in ebay. https://www.retrobike.co.uk/threads/marzocchi-z2-spring-ratings-and-part-numbers.397640/

Vintage Marzocchi spring information
Marzocchi vintage spring info

Try to seach @ Eb##. There is a guy in Poland, who bought off 1t Marzocchi from the Netherlands (?). He as a lot of springs online, some are 65 or 80mm, like the Z2 has. If you don't find it, drop me a note, I will find it.

Anyone knows, why searching in Europe does not results in nice finding in USA or elsewhere international?May be Google did this??

If you search for 30mm Bomber seals you should have found a note to my website. I'm doing seals reproductions for years for the older Marzocchis and finished the 30 and 32mm seals also this year ==> https://dr-marzocchi.projectweb.de/produkt-kategorie/marzocchi-bomber-seals-30mm/

Regarding manuals : As far as http://my-sport.spb.ru/manual_1/index-16.htm is somehow dead by disc failure for the most *.pdf manuals I set up an archive for Bomber Manuals here : https://dr-marzocchi.projectweb.de/MANUALS/Marzocchi/ - if possible please support!

All the best!
M.
https://dr-marzocchi.projectweb.de/

Posted: Oct 26, 2021 at 21:50 Quote
@eschew, fork feels great post-rebuild. Or at least much better than before, which I would liken to feeling like riding on a flat tire, zero damping, full bottom-out on the most modest of curbs.

For those interested, I went with the PJ-1 10wt, which has a viscosity of 33.90 cSt @ 40˚C (~100˚F). Recommended was the Maxima 125/150 7wt, which has a viscisity of 26.70 cSt @ 40˚C (~100˚F). Without paying much attention to what was displayed on the bottle (7wt, 10wt, so on) I focused on the cSt @ 40˚C reading. 33.90 versus the standard 26.70 cSt provided a more bottomless feel for heavier than recommended riding, which is just what I was going for.

For anyone interested, I used the following link (spreadsheet at bottom) to compare different available fork oils:
https://www.peterverdone.com/wiki/index.php?title=Suspension_Fluid

In the 80mm travel Z2, I used a base 75cc in the left fork leg and 85cc right fork leg. With a high post (dropper to come) I was pretty forward biased over the front end of the bike. Even for a 6' rider, 180lb, I only maxed out suspension on some particularly steep and high impact segments in Durango, CO. For good measure, I added roughly 5-6cc of PJ-1 upon return to both legs (perhaps should have filled one more than the other on account of the left fork leg housing the damper and the right being an empty shaft, but don't know the anatomy beyond the recommended 75cc/85cc L/R fill levels) and can report a huge difference.

As for my mentioning you, @eschew, I'm wondering if you know of a way to modify the damper or purchase an aftermarket mod to provide more variable damping. You've been an expert advisor so far, so I figured you may know (or know someone).

While the fork feels great and is now bottom-out-proof (let's hope), I can't help but hope (and perhaps I'm being unreasonably hopeful for a first-gen suspension fork) for a softer top end with more progressive damping to stave off the unwanted bottom-out. A more progressive damper (or perhaps a higher rated spring) would allow me to run a lower viscosity oil to soak up the smaller bumps and less sluggishly. Just a first-or-second-time suspension rebuild and I'm fixated on optimizing what I've got here.

Thanks!

Posted: Oct 27, 2021 at 8:23 Quote
Nice work! Sounds like it's as dialed as it's going to get. I'd assume you'd benefit from a firmer set of springs.

Trouble is finding a set, they do come up every day often on the Ebay, but given that they are rather old, used sets can just be stock springs in firm packaging. Try to verify color code, which is just a small dab of paint on the first few coils.

If you're not bottoming out hard you've got the oil levels right. I run them at equal height, both sides but it's not really critical.

Posted: Oct 29, 2021 at 19:37 Quote
Apologies - I did not see any of these updates and so did not respond to thread that I started. Most of the answers I have seen are better than any I could have given, so perhaps that is a good thing!

In terms of oil, I went to a motorcycle dealer and got Maxima 7wt fork oil. It was as close as I could get and local bikes stores just did not have what I needed. I followed the '98 manual guidelines as best I could in terms of levels. I have been riding the Bomber daily since I refurbed it in June and it has been flawless.

Just stripped my XT v-brakes and was amazed at the crud accumulated in there. Took them completely apart (thank you, youtube) and they are now like new again. Strapped on a pair of Schwalbe Billy Bonkers for my commute through wet autumn leaves and some muck (if I am lucky and have enough light to scoot up the short muddy trail near home). Am going to need to replace the BB next.

The Cove Stiffee repurposed for my commute is consistently the best way to start and end the work day. It reminds me of my trail namesake here that it rolled many times back in the day before dualies ruled the earth.

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