38mm Marzocchi Questions

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Hi All.

I've attempted to search for some answers but to no luck.

I have 2x Sets of Marzocchi 38mm forks im trying to sort out and have some questions I havnt been able to answer yet.

Question 1 - Set 1 has Brake Lug/Hole spacing for F08 and 300mm disks - but i have been unable to find any bikes that originally came with 300mm Marzocchis and 300mm disks - as far as I know all the Laverdas with 38mm forks had 280mm disks and the same with Ducati? - These forks have 600mm tubes in them. - anyone have any idea what bike these may have come out of?

Question 2 - Springs and spacers - the First set has what I think is the standard set up - a spring that is partly encased in a steel tube and a ~40mm spacer on top. The 2nd set has a much bigger diameter spring and no steel tube, and just a couple of washers as spacers (prob 5-8mm all up) - Is it correct that the original forks had the steel tube? Assuming the larger spring in the 2nd set is aftermarket? - Set 2 has 580mm tubes


I'm likely going to upgrade them with a set of Sports Valve damping units (or Racetech Emulators - havnt decided yet), but just interested to know what ive got before i get to carried away


forks 1.JPGforks 2.JPG
 
Looks like a Moto Guzzi hub in your pic. Both Moto Guzzi and Benelli used 300mm discs. Guzzi fitted their own branded forks, 35mm to begin with, not sure what came later, so I'd bet on the forks originating from a 750 Sei. Can't remember what hubs were used in the Sei, but with the rear being a Grimeca drum, good chance the front would also be the 3-piece Grimeca/Guzzi/Ducati item.

The 38mm Marzocchis used on Lavs had the guide tube and a spacer atop the springs. Check a Benelli parts book for their fitment... I do very vaguely remember washers in the Sei forks, thinking WTF?

This is an excellent source for researching, loads of original factory pics. https://www.motorcyclespecs.co.za/index.htm Descriptions may not always be 100% accurate though.

piet
 
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Cheers, yes it a Guzzi hub and disk. All the Guzzi of this era used in-house Moto Guzzi 35mm forks and 300mm disk's.

Good thought on the Benelli, I didn't even think of them...but from my knowledge they used the same 35mm Guzzi forks as they had a connection with Moto Guzzi at the time. All the photos I can see if Benelli Seis (750 and 900) look to have the Moto Guzzi forks
 
Are these Guzzi forks the ones with built-in sealed dampers like rear shocks? I would be going to Sports Valves if I had my time again. They have clear advantages over Emulators. The Sports Valves have both compression and rebound adjustment, plus the ability to do both adjustments via a tool that doesn't require a bit of fiddling to adjust like emulators. When I did Emulators, Sports Valves had just arrived, and there was no info. BTW, the Gold standard is a full-blown cartridge conversion by Maxtons. I also missed that boat locally; it seems I sat at the wrong end of the table at club nights and heard nothing about the group buy that happened.
 
Guzzi and Benelli worked under the DeTomaso flag at the time of the Sei introduction. Lots of shared components across both model ranges.

The LeMans was the '74 Guzzi flagship, this definitely used the 35mm in-house fork. I could imagine this fork could have been considered too weedy and was substituted by the more substantial 38mm Marzocchi for the Sei. This was also considerably longer than the Lemon fork.

A mate has original early examples of both bikes in his collection, I can check next week for you. The Sei towers over the Lemon!

Vince, only the Guzzi in-house forks had the sealed damper, run-of-the-mill Marzocchis were "conventional". Don't know who actually built the Guzzi forks, Paioli maybe? Guzzi used Paioli rear shocks for a very long time.

piet
 
Vince said:
Are these Guzzi forks the ones with built-in sealed dampers like rear shocks? I would be going to Sports Valves if I had my time again. They have clear advantages over Emulators. The Sports Valves have both compression and rebound adjustment, plus the ability to do both adjustments via a tool that doesn't require a bit of fiddling to adjust like emulators. When I did Emulators, Sports Valves had just arrived, and there was no info. BTW, the Gold standard is a full-blown cartridge conversion by Maxtons. I also missed that boat locally; it seems I sat at the wrong end of the table at club nights and heard nothing about the group buy that happened.
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Yes all the 35mm Guzzi forks had sealed damper units, similar in type (and effectiveness) to a screen door damper......

But these 38s are Marzocchi, and as lavgert suggested they may be period aftermarket as I've not seen any stock bike with 38mm Marzocchi and 300 disk's (without a brake caliper adapter bracket).

Thanks for the thoughts on the sports valve, they look like good bits of kit. I'm not sure my budget will reach to Maxtons
 
sfcpiet said:
Guzzi and Benelli worked under the DeTomaso flag at the time of the Sei introduction. Lots of shared components across both model ranges.

The LeMans was the '74 Guzzi flagship, this definitely used the 35mm in-house fork. I could imagine this fork could have been considered too weedy and was substituted by the more substantial 38mm Marzocchi for the Sei. This was also considerably longer than the Lemon fork.

A mate has original early examples of both bikes in his collection, I can check next week for you. The Sei towers over the Lemon!

Vince, only the Guzzi in-house forks had the sealed damper, run-of-the-mill Marzocchis were "conventional". Don't know who actually built the Guzzi forks, Paioli maybe? Guzzi used Paioli rear shocks for a very long time.

piet
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Yes would be great if you could check what forks and original Sei has. When I look up photos it looks like they all have the Guzzi style 35mm.

And yes, the Guzzi are very low and long. When you take the tank and seat off the top frame rails are barely above your knee
 
From memory, the cost difference between Maxton and Sports valves isn't significant; Maxtons are around $1000 oz, and Sports Valves are around $800oz, Race Tech Enulators $400, give or take, it's been a while. Where it gets complicated is shipping. Maxtons are in the UK, and Sports Valves are in New Zealand. From what I gather, you can buy the bits off either and do the fitting yourself if you're competent. Years back, you had to ship your forks to England and be bikeless for the months it took and if they arrived just before race season, even longer. Another consideration is the lack of bushings in old forks. Race Tech advise getting the lowers Hard Anodised, some real clever types have fitted bushes, but they are few and far between. My Pantah came standard with 35mm Maz forks, replaced early on by a mate with 38mm, the 35s flexed a hell of a lot under brakes.
 
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