750 GT forks ‘topping out’

[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

[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/

[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]

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

[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

[Inoule]

Hi
I am interested if you found a reason why your forks were topping out and how you fixed the problem.
Thank you.

[BevHevSteve]

ian - shoot me an email & I'll email you the worx installation instructions. the small tubes in the short springs are crossover spacers meaning the. stop the soft (short) spring from compressing which forces the stiff (long) spring to come into play. shorter crossover tube give you more fork travel before stiff spring is used. the kit came with 3 pairs of crossover tubes each pair different length. when you got the bike did you get spares? if so look for 2 pairs of steel tubes similar to what you have there probably each pair shorter..

[BevHevSteve]

These are the insides of the Marzocchi forks on the Greenframe I am restoring. You might be missing some parts based on your photo...