750 GT forks ‘topping out’

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Ianhood
Cucciolo - the Lil Pup
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750 GT forks ‘topping out’

Post by Ianhood »

I’ve recently acquired a ‘74 GT with centre axle Marzocchi forks and when going over a bump the forks are topping out as if there is no rebound damping, and it sounds almost like metal on metal. I had assumed the oil level was low and so I pulled them off, fitted new seals and refilled each with 210ml of 10w fork oil. Unfortunately they are still much the same.

I didn’t pull the forks apart completely so wondering if the previous owner assembled them incorrectly. Has anyone seen something similar?


Ian
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Re: 750 GT forks ‘topping out’

Post by BevHevSteve »

HI Ian, when you reassembled, were the springs (or a preload spacer) sticking up out the tube before you put the top nuts back on?

Sounds to me like there is no preload on the springs and/or the long tubes that were over the outside of some/most of these springs was left out. The tube was used because the original springs OD was smaller than they should have been so they would clank around.

Consider installing a new dual rate fork spring kit - 2 springs, adjustable crossover, the correct OD for these forks. They work very well.

https://store.bevelheaven.com/Chassis-S ... Dual-Rate/

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Ianhood
Cucciolo - the Lil Pup
Posts: 11
Joined: Mon Jul 15, 2024 2:48 am

Re: 750 GT forks ‘topping out’

Post by Ianhood »

Thanks for the reply Steve but yes, the spacer was sticking out of the top so there is definitely some pre-load on them.

Ian
Ianhood
Cucciolo - the Lil Pup
Posts: 11
Joined: Mon Jul 15, 2024 2:48 am

Re: 750 GT forks ‘topping out’

Post by Ianhood »

Steve,

This saga continues and it looks like I already have that Works fork kit (or similar) installed. My question is, from the picture below, is the assembly order correct? In particular, should that spacer be inside the top spring? The problem I'm having is that the forks are topping out rather than bottoming out which would suggest too much preload, rather than too little.

Regards

Ian

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Ianhood
Cucciolo - the Lil Pup
Posts: 11
Joined: Mon Jul 15, 2024 2:48 am

Re: 750 GT forks ‘topping out’

Post by Ianhood »

Sorry, image of the disassembled forks is here - https://photos.app.goo.gl/YCdkNLF7pyTw5GP29

Can't seem to add the photo in the usual way
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