96(?) bomber z3s seized up

[jkmelbs]

Hi all
I got an old 80s (I think) bike recently with a set of locked up bomber z3s on it. The date stamp on the inside of the fork is 96

ive read online (and this forum seems to have the most knowledge about these forks) that it was kind of common for these to lock up after sitting unused

Is there a quick and dirty way to unstick them without doing a full service?


are the oil seals just a generic 30mmx40mmx7mm seal that are a few dollaroos from auto parts shops?

I’ll probably redo the oil and seals if I can get them unstuck and they seem ok and the seals are a standard kind


im a bike noob - But ok at diy

this is my first bike in about 15 years and the one I had before was a basic cheapie rigid fork so I’ve never had suspension forks. Might need simple words and crayon drawing to help me understand

I’ll post some pics of when I get home

 

[sam_white]

'96 date stamp means they're a 1997 fork, in this case a Z3 as you've identified. I've a set, bought in good cosmetic condition but the internals were a mess. The have a spring/elastomer stack and a friction damper, no coil/oil bath in them. The elastomers had turned to a cake like consistency and gummed everything up.

Plenty of plusgas or WD40 around the bolts and seals and down inside the stanchions and they may move. A full strip is probably needed, but you'll need to see what state the elastomers are in first.
To do anything useful with them, you'll probably need new internals. A set of oil dampers and a spring set will convert them to coil/oil although you may also need seals. Unless you're particularly keen on them, a non-leaking set of Z5s may well be cheaper and much less hassle.

 

[jkmelbs]

thanks for the info

They were stuck to the dust covers
Once I pried those up they moved freely

a little too freely. There’s almost no resistance and they drop straight down under their own weight.

Guess I’ll bin them

 

[FluffyChicken]

97 Z3's first of them

They're also the fork Marzocchi and any repair guide leave in the bin.

I can't remember with these if the lower seals* would leak, but dump oil in them and create a bath.
Check they don't leak out the bottom.
Might be fun modifying the none valving to be a bit like the SSV of later forks.
Scrap the elastomers that will not be doing anything by now.
Get any other bomber fork...

*The foot nuts, the main oils seals are the same, not really sure why they are even fitted.

Use them as spares.

 

[jkmelbs]

I have some leftover atf I could donate to this experiment

I tried undoing the 25mm nut on top of the stanchions but it just stops after about 10 turns

Is there anything else holding it

 

[sam_white]

The spring preload adjusters should unscrew fairly easily from the tops of the stanchions. I've always found they unscrew by hand once the initial slackening has been done.

 

[jkmelbs]

Heh yep

turns out i had to remove them completely from the crown - the ring clip was keeping them in. Once in locked I could finger unscrew. So much shredded foam in there, like the padding on crutches

argh I’m struggling getting the stanchions off now

according to the manual there should be a nut (17mm) on the underside that's holding the stanchion tubes in place

http://my-sport.spb.ru/manual_1/1997%20z3.pdf

part no 22

but mine dont have that

I have the Allen key damping adjustment and beneath that is something no socket wrench I own can undo

 

[jkmelbs]

I can't remember with these if the lower seals* would leak, but dump oil in them and create a bath.
Check they don't leak out the bottom.
Might be fun modifying the none valving to be a bit like the SSV of later forks.

all the bikes ive had have always had rigid forks (and thats my plan for this bike - ithink its an 80s scott). i got my last bike in the 90s and sold it when moving about 10 years ago - so i'm totally in the dark when it comes to suspension forks, the different types and how they work

i dumped some oil into the stanchions and they're air/oil tight. putting all my weight on it to bottom them out. no oil escapes whether the forks are the right way up or upside down.

but the stanchions themselves are sealed - should the oil be in the sliders?
wait no they're not. the oil level goes down when i pull them up

how are these meant to work? is the spring meant to engage first then the hydraulics? - my springs are too short after i shook out all the shredded elastomer. they're 85mm but the "depth" of the stanchion when it's fulled pulled up/out is 180mm

 

[FluffyChicken]

Those forks had a part spring/part elastomer compression 'spring', so without the elastomer they'll not work.
So you need to find a full length spring.

The damping (rebound) is by some elastomer ring inside the lower of the stanchion.

Your oil sits in all the forks(note these forks never used oil in this way, they are classed as dry forks).
So the oil is now lubrication everything like all other Bombers, and if there are any holes in the lower rods then it'll act as a damper as oils moves from inside the stanchion and into the lowers and vice versa.

Manual and blow out diagrams are in the Archive.

 

[jkmelbs]

unfortunately all the manuals i've found in the archives here and elsewhere dont 100% match mine - especially the foot nut - mine don't have one

i cut a few mm off one of the springs and put them both in 1 fork as as test and filled both stanchions with oil

it... works, a bit too firm though. i think i need to get the stanchions out to drill some extra holes to allow the oil to move more freely..