Alternative forks.

[Mark]

Hi all.
Looking at the latest 350 project in the lock up the other day.
I need new or rechromed forks, and unless someone can otherwise suggest what to do with very rusty discs, a new pair of front discs too.
Are grimeca discs still available?
Are there other options?

Cheers, Mark.
Ps - are the 500 forks the same?

[MickeyMoto]

Hi Mark,

I believe the forks are different lengths. Discovolante sell new ones. I have some 609mm from a Estrada if interested.

Mike.

[Daddy Dom]

New fork legs are also available from Tarrozzi.
DD

[hombre]

I don't think the 500 and 3 1/2 forks are different. You can also use the discs that were fitted to Excaliburs, only the offset changes a bit...

[MickeyMoto]

Hi DD.

The discovolante forks are from tsrozzi, and are very nice.

Mike

[vtwinguy]

I had some fork tubes replated and reground last year by Philpotts in Luton. Took about 6 weeks but the quality seems OK.

[George 350]

Hi Mark,
Further to the earlier replies, if you go for new tubes, just be aware that there was a design change sometime between 1978 and 1981 in the bottom of the stanchion where the damper piston runs. The internal counter-bore was made about 30mm deeper. Therefore if you have the earlier type tubes (I did), you need to shorten the spacer tubes at the top of the springs, add spacers to the bottom of the damper rods where they bolt to the sliders and between the damper block and circlip. All spacers need to be about 30mm long (can't remember the length exactly). If you don't want to make up the spacers, you may need new damper rods and blocks.
Finally, the fork top nuts changed thread pitch - they went from (I think)1.5mm pitch to 1mm pitch, meaning I had to get some new top nuts as well. If I had known about this when I ordered the Tarozzi Ducati Pantah fork stanchions (allegedly the same, well part number is..) I think I would have gone the replating route.

Another source for fork stanchions I found out about later (they list them anyway) is Allbike Engineering in SE London.
They also do 1000's of different brake discs too. I think that Pantah 260mm Brembo discs may be a straight swap.
Dom should be able to confirm this as I recall he fitted these.

Regards,
George.

[EVguru]

The discs work just fine with no Chrome, you just don't want patchy Chrome. New Discs are available from NLM (they had Grimeca make a batch).

A semi-floating disc modified from a Ducati rear application was being offered a while back, but a change in master-cylinder bore gives a much cheaper improvement in feel.

The earlier damper rod design (which has a ball valve on top) needs the deeper couterbore in the stanchion. I've not seen it on bikes circa 1976 onward, but that's not to say some weren't so equipped or haven't had forks swapped.

The Paoli/Tarozzi stanchions are a Chrome Molybdenum alloy and less likely to take a permanent set following an impact (pothole rather than crash). The original Marzocchi stanchions are a pretty low grade steel.

Allbike Engineering are very expensive unless you're ordering a batch.

I've had variable results from Philpots. One pair of stanchions came back two different undersizes.

[Mark]

Thanks a lot for all the info guys.
I wouldn't have considered the forks changed over the years.
It's interesting to hear the discs work ok if stripped of old chrome too.
I'll have to scratch my head a bit and decide how to go forward!
Thanks again,
Mark.