Rebuilding Marzocchi Strada Shocks

  • Thread starter Thread starter Grant
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M6NTL said:
Here's the foot valve in pieces;




And the tophat part chamfered to hopefully slide back home better;




Fingers crossed..!!..
Click to expand...

let us know how it works out.

as mentioned previously, I do not have a lathe, or for that matter any lathe skills worth mentioning.

looking at the "top hat" I suspect I can run a bolt through its center with a washer/nut on both sides, then chuck it into a drill and go at it with a file to make a crude chamfer, and I think I am going to give that a go.

I am going to start a thread here in the technical thread asking for advice on what to look for in buying a used lathe and a used milling machine for a beginner to learn on.....

Paul LeClair
 
Paul LeClair said:
I am going to start a thread here in the technical thread asking for advice on what to look for in buying a used lathe and a used milling machine for a beginner to learn on.....
Click to expand...

I would enrol on a basic Lathe/Turning course at a local technical college first.
The college might have some bright ideas.

Me? Can't go wrong with a Colchester Lathe.
 
I am after a set of heavier springs for my Maz Symbols,seems they are not so common.Oddball size to miss the remote reservoir.Icon springs wont work and the bloke who rebuilt them has nothing suitable in his 20 year collection.Seems I need to have some custom made.The suspension bloke said $60 oz to have a set made.
 
I actually think a machine tool thread would be a good idea, there are people here with years of experience who could offer great advice on cutting speeds and methods. Yes its available elsewhere but why not have it here as well ?
I would be happy to advise on buying equip as I'm sure would many others here  with first hand experience. first question i suppose on any machine tool would be imperial or metric ?
 
Paddy said:
first question i suppose on any machine tool would be imperial or metric ?
Click to expand...

Ha ha! That old chestnut.
Some lathes have a sliding collar that converts units from metric to imperial, I find this most useful as I generally work in imperial. Depends what the drawing says, if it's in metric then it is awkward to calculate back to imperial.
 
SimonR501 said:
Ha ha! That old chestnut.
Some lathes have a sliding collar that converts units from metric to imperial, I find this most useful as I generally work in imperial. Depends what the drawing says, if it's in metric then it is awkward to calculate back to imperial.
Click to expand...

Metric all the way for me!
Can't stand imperial - thousandths of an inch, can't see that in my head. But, tenths of a millimetre I can visualise easily!
My lathe is an early '60s Smart and Brown Model A Toolroom lathe, and it's METRIC!!!
My milling machine, a much earlier Hayes Diemaster is 'orrible Imperial, 125 thou per rotation of the handles. Can't get on with it, the maths to move say 1724 thou, is a royal pain in the ass! So, it now sports a rather trick 3 axis DRO I bought and fitted. Does all that oblique milling, PCD etc etc now, and is METRIC!!!
 
M6NTL said:
Here's the foot valve in pieces;




And the tophat part chamfered to hopefully slide back home better;




Fingers crossed..!!..
Click to expand...

Didn't work dammit. Still gets stuck open. But, I can see why. The shim outside diameter is 20mm, the inside diameter of the tube it goes inside is 24mm. This allows the shim to move sideways when the valve is open, and the tophat part catches on the shim and can't go back down.
What it needs is a shim with an I/D of 12mm, and an O/D of 24mm...
Where the hell I'll find that I know not!
 
SimonR501 said:
Ha ha! That old chestnut.
Some lathes have a sliding collar that converts units from metric to imperial, I find this most useful as I generally work in imperial. Depends what the drawing says, if it's in metric then it is awkward to calculate back to imperial.
Click to expand...
Yes i was meaning the lead screw gears as well. I have a Colchester student with duel verniers but it has a metric lead screw in effect. The Bantam i use has an imperial wheel set which is ok if you can get a metric wheel set for it ie it will take a 127 tooth wheel With there being 25.4 mm to one inch that is 254/2 = 127.
anyway its a topic that could work well here IMHO.
 
M6NTL said:
Metric all the way for me!
Can't stand imperial - thousandths of an inch, can't see that in my head. But, tenths of a millimetre I can visualise easily!
My lathe is an early '60s Smart and Brown Model A Toolroom lathe, and it's METRIC!!!
My milling machine, a much earlier Hayes Diemaster is 'orrible Imperial, 125 thou per rotation of the handles. Can't get on with it, the maths to move say 1724 thou, is a royal pain in the ass! So, it now sports a rather trick 3 axis DRO I bought and fitted. Does all that oblique milling, PCD etc etc now, and is METRIC!!!
Click to expand...

Its what you learn really, i was bought up on imperial, right up to when i gave up engineering 2 years ago we were still paying a surcharge for metric stock. Metric screws are pretty poor compared to imperial, i could never see why metric didn't do a small round head instead of that bloody great pan head they seem to use as std. We did eventually go metric but it meant re designing a lot of our machines we manufactured simply because of the poor range of screw sizes. As i say its what you know really, i cant picture microns but i know they are a about 25 to a thou, i used to grind to within 1 micron on an old war time grinder :) Now i do spares i have to work out box volumes for postage... I cant see 260mm in my head but i can see about 10" :)
 
Incidentally, does anyone know which way up the bump stop rubbers are supposed to go. They have a snug fitting 12mm hole at one end, and a bigger hole at the other.
Like a fool, I didn't pay proper attention when I took mine apart!!!
Cheers...
 
M6NTL said:
Didn't work dammit. Still gets stuck open. But, I can see why. The shim outside diameter is 20mm, the inside diameter of the tube it goes inside is 24mm. This allows the shim to move sideways when the valve is open, and the tophat part catches on the shim and can't go back down.
What it needs is a shim with an I/D of 12mm, and an O/D of 24mm...
Where the hell I'll find that I know not!
Click to expand...

speaking from total ignorance, can't the shim size required be made on a lathe?

also, Hi Pete, thanks so much for the link!

Paul LeClair
 
Paul LeClair said:
speaking from total ignorance, can't the shim size required be made on a lathe?
Click to expand...

If it's really thin then it will probably be punched out of a sheet and perhaps surface ground! Making something very thin is very difficult on a lathe (it is for me anyway).
 
M6NTL said:
Incidentally, does anyone know which way up the bump stop rubbers are supposed to go. They have a snug fitting 12mm hole at one end, and a bigger hole at the other.
Like a fool, I didn't pay proper attention when I took mine apart!!!
Cheers...
Click to expand...

At a guess I'd say the snug-fitting end goes to the top mount, the larger hole allowing more deformation of the rubber for a "softer" bump.


Paul LeClair said:
speaking from total ignorance, can't the shim size required be made on a lathe?

also, Hi Pete, thanks so much for the link!

Paul LeClair
Click to expand...
Paul,

Although real wonders can be accomplished with a lathe and a bit of imagination, there are limits...

piet
 
sfcpiet said:
At a guess I'd say the snug-fitting end goes to the top mount, the larger hole allowing more deformation of the rubber for a "softer" bump.

Paul,

Although real wonders can be accomplished with a lathe and a bit of imagination, there are limits...

piet
Click to expand...

Good point in the bump stop, thanks!
Might have a go on the lathe - I parted off a 1mm thick ring once, ally though, not steel. Worth a try though...
 
M6NTL said:
Good point in the bump stop, thanks!
Might have a go on the lathe - I parted off a 1mm thick ring once, ally though, not steel. Worth a try though...
Click to expand...

Thinnest washer I've made on the lathe was 0.3mm, made from brass. I forget what it was for now but it was about the size you're talking about (cut from 25mm OD bar). Turned the OD to size and drilled the centre hole fist, then made the initial parting off cut at about 1mm thickness to within about 1mm of the centre hole. Took the final cut all the way through at the required thickness. Moved the tool in slowly and carefully and it worked OK. Rub it on some emery to take off any burrs and bob's your uncle.

My local nut and bolt shop has shim washers in various thicknesses and diameters. I'm sure they have them for 1/2" shaft but I duno what range of ODs they have. I can check if you like.

 
[quote
Didn't work dammit. Still gets stuck open. But, I can see why. The shim outside diameter is 20mm, the inside diameter of the tube it goes inside is 24mm. This allows the shim to move sideways when the valve is open, and the tophat part catches on the shim and can't go back down.
What it needs is a shim with an I/D of 12mm, and an O/D of 24mm...
Where the hell I'll find that I know not!
[/quote]
Most - in fact pretty well ALL japanese gearchange shafts are 12mm OD. Again, most have a shim washer somewhere along their length for location etc. Usually at least 24mm OD...and around .5mm thick. How thick do you require ?
 
Dellortoman said:
Thinnest washer I've made on the lathe was 0.3mm, made from brass. I forget what it was for now but it was about the size you're talking about (cut from 25mm OD bar). Turned the OD to size and drilled the centre hole fist, then made the initial parting off cut at about 1mm thickness to within about 1mm of the centre hole. Took the final cut all the way through at the required thickness. Moved the tool in slowly and carefully and it worked OK. Rub it on some emery to take off any burrs and bob's your uncle.

My local nut and bolt shop has shim washers in various thicknesses and diameters. I'm sure they have them for 1/2" shaft but I duno what range of ODs they have. I can check if you like.
Click to expand...

That would be appreciated, thank you. I need 0.3mm thick.
They are spring steel, and I'm guessing that is for a reason, and as such I won't be 'having a go' on my lathe with mild steel...
Thanks you!
 
M6NTL said:
That would be appreciated, thank you. I need 0.3mm thick.
They are spring steel, and I'm guessing that is for a reason, and as such I won't be 'having a go' on my lathe with mild steel...
Thanks you!
Click to expand...

I might have found some shims - chap at www.racesuspension.co.uk reckons he can help!
I shall keep you posted, and thanks!
 
Just sorting through a load of 500 stuff and found these Marzo units - don't know if any use to anyone here - would need
refurbishment - 330mm C/C and 10mm bushing - ?25 plus delivery - Regards - Phil

 
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