Rebuilding Marzocchi Strada Shocks

  • Thread starter Thread starter Grant
  • Start date Start date
If anyone is interested I can rebuild their Stradas for them. Already have a couple to do for folk.
Price dependent on how much needs doing.
I ise a lighter weight oil so action feels ligher.
PM me if interested.
 
Haggis said:
I'm running with PLeC here. Surely we can work out what is too 'hard' on these dear old Marzo's and fix it? Maybe I'm sad, but I do like to disctinctly 70's look about them and would like to use them, for the 'completness' of the bike. However, every Lav I have ridden with Marzo Stradas had shocks that were completely knackered, so cannot accurately comment. What is it, learned guys? Spring rate, compression damping, rebound damping, internal friction, some or all of the above?

Paul H

Most of what you mentioned, Paul.  On top, mediocre production quality control.  Some work quite OK for a rather long time, some start leaking after only a few months of use.  This cannot be an issue of the seals alone, methinks the fit/guidance of the rod and damper elements may be a bit inconsistant, giving the rod the chance to wear the seals quickly and would also explain the extreme differences in damping I have often come across.  My overall experience with them is the same as yours, all more or less knackered, but for one exception.  A mate of mine has a pair on his 1200, at least 80000km on them and still working perfectly, like they were taken from the box yesterday!

piet
 
Haggis said:
Surely we can work out what is too 'hard' on these dear old Marzo's and fix it? <snip> What is it, learned guys? Spring rate, compression damping, rebound damping, internal friction, some or all of the above?

For me, Paul, the problem starts with resolving what people mean when they say their shocks are 'too hard'.

I?m kinda guessing here, but I suspect it's when they get a boot up the backside whenever they hit a bump.  Dunno ...  But if it is, that points to springs with too strong a rate, possibly/probably coupled with a shock giving too much compression damping.

But it might also suggest that the rider may - note: I said ?may:D - be ?sat in the seat? too much.  If you tend to ride ?deep in the saddle? rather than supporting your weight on the pegs, you?re going to feel those bumps.  It?s one reason why Cruisers have such soft suspension, of course.

As to the longevity of these things, well, I suspect Piet?s got it right (as normal) - poor quality control especially with reference to the rods.  We?re talking relatively small dimensional tolerances in something which I imagine was always built down to a price ?

Btw, I get the impression that the Marzocchi AG range is much less 'rubbished' than the Stradas, even tho', as standard equipment on off-roaders like KTMs, Fantics and SWMs, you'd think they get/got a much harder life.  Which raises the suspicion that Stradas were, in fact, a down-grade.  Perhaps the clue is in the name ...  :D

No knowledge - just idle speculation ...
 
No1. They look real good,
No2. They look real period,
No3. You change the springs easy enough,
No4. You can also change the damping easy enough (just think the difference between "too hard" and "fucked" and you see where I am coming from)
N05. You can make anything work with a little thought.
No6. Even a Laverda  :LOL: :LOL: :LOL:

I hate seeing nice classic bikes with modern bits on so love the look of the Strada and A2Gs

Julian
 
Agreed.
You can change the oil viscosity.
You can even play with pressure in the air sac (if that actually does anything)
You can change spring rate
You can change the number of shims in the piston stack
You also have a preload adjuster

I think the Stradas suit to look of the silver framed Jotas very well. Period and correct.
Plus I rode harder, faster and for longer on these back in the day than I ever will in the future with my Wilbers/Maxton or my YSS/Maxton shod bikes. The shocks on the back were never a reason for me to slow down.
 
Another thing you can do is modify the top cap to take a bearing bush, a proper wiper seal, and a proper 'U' rod seal.  Then you can restore the correct running clearance and use proper axial seals instead of what seem to be pretty much rotating shaft oil seals.  And buy replacements dirt cheap at any cylinder seal supplier should you ever need to.
 
Thats what I think Sean at SOS suspension's is doing to the Symbols off my Pantah,couldn't get seals.Hope he looks at the reason why they go rock hard at haft there range of travel. Will pass on any info.
 
Should have known better,my quick rebuild before the holidays ended up taking 5 and a haft weeks.He did a nice job.Put them on and did a lap on my bumpy test track and found them just as harsh as before the rebuild,I am thinking I should have put the money towards a better quality of shocks.I then looked at the job notes.I had asked to get the springs measured,and found something interesting.I had set the sag at 30mm,thats 1/3 of the 90mm full travel.That was 2 clicks from full soft on the preload adjuster.It seems my shocks have progressive springs and after adding this preload most of the lower spring rate travel was used up.Backed it off the full soft and its now acceptable.Firm but with enough bump absorption to work OK.I hadn't noticed the progressive spring,Pantah shocks are 40mm shorter than Laverda shocks with less travel so this has a bigger effect.So maybe check if your spring is the same.
 
Hi new to the group here and have found this thread very useful so far.

I have a set of Stradas here that I want to get the shafts re hard chromed on. Has anyone done this before? If so how do you get the (cast on?) on Rod ends off so that you can get the shafts re-hard chromed?
 
You don't.
They grind and rechrome with the top mounts intact.
I use A M Philpot and they have just done 4 pairs of damping rods and several fork stanchions.
They are in the UK.
 
Whoops, I tried to heat unscrew the end fitting but unfortunately as I have leaned from Grant after the attempt (many thanks Grant) these end it things are cast on.
My plan was to make a new shaft ....it's cheap to buy 12 mm hard chromed rod, and I have a lathe available.

All I did was success in loosening the shaft on the casting.

Anyway I have learned from Grant that what I should have done was just get the shaft reheard chromed with the end fitting still attached.

Has anyone got a spare one that I can purchase, don't mind if the shaft needs re chroming as I was going to have to get this done anyway.
 
G'day Wobbly

If you have a lathe, then all is not lost. Now that you've succeeded in loosening the end fitting, you may as well remove it entirely, machine up a new rod and reattach the end fitting to the new rod.

If your enthusiastic attempts to remove it have damaged the bore in the end fitting, you nmay have to over-bore it and make an insert.

Cam

 
Dellortoman said:
G'day Wobbly

If you have a lathe, then all is not lost. Now that you've succeeded in loosening the end fitting, you may as well remove it entirely, machine up a new rod and reattach the end fitting to the new rod.

If your enthusiastic attempts to remove it have damaged the bore in the end fitting, you nmay have to over-bore it and make an insert.

Cam

I like your thinking! I bought some 12 mm hard chromed rod today and will make up some new shafts. I think removing the shaft from the end fittings will destroy the end fittings. So once I have made up the shafts with a thread on one end and a stepped key on the other end, I will get the foundary down the road to cast some new end fittings on them. The entire cost should be about the same cost as re chroming the original shafts and give a better end result.

I will post back here how it goes and if anyone wants some just let me know because I have extra rod and it's easy to cast more ends.
 
  Would it not be easier to put a 12mm female rose joint on rod - leave rubber in bush at lower end to take any shocks? - just a suggestion - regards - Phil
 
phil37 said:
  Would it not be easier to put a 12mm female rose joint on rod - leave rubber in bush at lower end to take any shocks? - just a suggestion - regards - Phil

That is WAY easier - and gives you a ride height adjustment too...
 
Good idea Phil. It may require a custom spacer made to seat the spring collet.

Greg, interesting idea, but it won't work. Adjusting the position of the rose joint on the rod will only move the damper rod up or down inside the shock body. The only way to get effective height adjustment would be to have a separate nut below the rose joint for the spring collet to seat against, so the rose joint could be adjusted independently of the spring. You'd need a long threaded section to do accommodate locking nuts for everything, so the whole thing might end up too long to start with.

Cam
 
Dellortoman said:
Good idea Phil. It may require a custom spacer made to seat the spring collet.

Greg, interesting idea, but it won't work. Adjusting the position of the rose joint on the rod will only move the damper rod up or down inside the shock body. The only way to get effective height adjustment would be to have a separate nut below the rose joint for the spring collet to seat against, so the rose joint could be adjusted independently of the spring. You'd need a long threaded section to do accommodate locking nuts for everything, so the whole thing might end up too long to start with.

Cam

Would be easy to make a spacer to go under the spring seat to achieve this, it could also double as the jam nut. But because I think you want the rod to be threaded in at least 14mm into the rose joint for safety and you need a jam nut you aren't going to be able to achieve much adjustment anyway without quite a bit more re engineering.

Besides I want to keep things original for this project and a rose joint definitely wouldn't look original. Interestingly casting on the end fitting costs just as much as a good quality female rose joint and you don't need to machine up a seat for the spring seat to sit on.

See photo of one of the new shafts below shown along side the original assembly. I have done six of these so I will have two spare pairs for anyone who wants some. I will get the foundry to cast the ends on all six of them next week. We are going to cast them in a higher grade alloy because it adds such a minimal cost to do this for such a amall production run. I have made the other four a bit longer so I can machine them down to whatever length anyone wants,
 

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Dellortoman said:
Good idea Phil. It may require a custom spacer made to seat the spring collet.

Greg, interesting idea, but it won't work. Adjusting the position of the rose joint on the rod will only move the damper rod up or down inside the shock body. The only way to get effective height adjustment would be to have a separate nut below the rose joint for the spring collet to seat against, so the rose joint could be adjusted independently of the spring. You'd need a long threaded section to do accommodate locking nuts for everything, so the whole thing might end up too long to start with.

Cam

It does work - i've made up replacement shafts for several sets of shocks now. Female threaded piece with shoulder for spring retaining collet - held onto the shaft with a jam nut of course. Male threaded heim joint above this with another jam nut. Loosen jam nut on heim and wind in/out as required. Most of those I've done have needed to be longer than stock for post classic race bikes so the extra length is no problemo....If you want OE length or shorter, it's just a matter of correctly locating the shoulder for the spring collet and working out length with the shaft and heim butting together.
 
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