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Code Burr
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Discussion Starter · #1 · (Edited)
Maybe a question for Dougal, but i'll throw this out for all. I've been on a Manitou Machete 110 for a while and did the ABS damper upgrade a few years back. It was a nice upgrade but I have never been able to get the LSC just right. So I pulled the damper out and then removed the needle valve from the shaft. I was expecting the typical conical needle valve shape but instead see a shouldered or slight tapered cylindrical shaft instead. I dont think this ever completely opens the low speed ports. Or if it does, it keeps the recessed end in the way to severely limit the oil flow. If you look through the ports on the shaft it appears to be closed when its fully open. I feel like at the top of its adjustment range(fully ccw/out) it barely lets any oil through. I think this is consistent with how the fork performs. It stays very high in the travel and I cant ever feel any brake dive. But maybe as a consequence the low speed compression feels harsh. So i'm wondering how to improve this needle valve if possible. Maybe an idea to chuck it in the lathe and turn the end down to a taper or maybe just remove a few thou from the end of the shaft to let more oil flow through. Do you know if the original damper has a more conventional needle valve that I could introduce into this damper? I liked the Manitou simplicity and shimmed damper, but also considering a move to a Marzocchi Z2
 

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Have you got a photo? A low speed adjuster only needs a tiny flow area, so even if it looks tight it probably isn’t restricting flow as much as you think. If you look at other forks with a larger bleed orifice, they are actually so wide that the shims don’t open until very high shaft speeds.

And trying to modify a low speed needle is not a good idea - even a few thou would drastically reduce the compression damping.
 

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What's the rider weight? Average rate negative coil spring + heavy rider = no bueno
 

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Maybe a question for Dougal, but i'll throw this out for all. I've been on a Manitou Machete 110 for a while and did the ABS damper upgrade a few years back. It was a nice upgrade but I have never been able to get the LSC just right. So I pulled the damper out and then removed the needle valve from the shaft. I was expecting the typical conical needle valve shape but instead see a shouldered or slight tapered cylindrical shaft instead. I dont think this ever completely opens the low speed ports. Or if it does, it keeps the recessed end in the way to severely limit the oil flow. If you look through the ports on the shaft it appears to be closed when its fully open. I feel like at the top of its adjustment range(fully ccw/out) it barely lets any oil through. I think this is consistent with how the fork performs. It stays very high in the travel and I cant ever feel any brake dive. But maybe as a consequence the low speed compression feels harsh. So i'm wondering how to improve this needle valve if possible. Maybe an idea to chuck it in the lathe and turn the end down to a taper or maybe just remove a few thou from the end of the shaft to let more oil flow through. Do you know if the original damper has a more conventional needle valve that I could introduce into this damper? I liked the Manitou simplicity and shimmed damper, but also considering a move to a Marzocchi Z2
LSC circuits are only supposed to control a few percent of the oil flow for fine-tuning. If they flow more than this you get a horrible transition into the actual damping provided by your shim-stacks. So do not bore or machine anything out. You will ruin the damper.

You're feeling harshness because your shim stack is too firm or too heavily preloaded. The ABS+ damper piston allows for preloading for an anti-bob platform for XC racers but can also be setup with no preload for trail riding.
Basically if you can't ride with the LSC dial closed then your shim stack is too firm.

Manitou ABS+ dampers are better than anything Marzocchi/Foxzocchi has put in a fork.
 

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Discussion Starter · #5 ·
Have you got a photo? A low speed adjuster only needs a tiny flow area, so even if it looks tight it probably isn't restricting flow as much as you think. If you look at other forks with a larger bleed orifice, they are actually so wide that the shims don't open until very high shaft speeds.

And trying to modify a low speed needle is not a good idea - even a few thou would drastically reduce the compression damping.
But I want to drastically reduce the compression damping, thats why i'm asking. The LSC is absolutely wooden on this fork. It would be very easy to bump up the shim stack to cover up if I went to far, which I wouldnt. No I didnt take any pics but I'm basically done with the fork. If I dont mod it, or swap out the needle, i'll probably order a Z2 and put this on the for sale boards. BTW I weight 230lbs. I think I run anywhere from 70-100 psi air.
 

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Discussion Starter · #6 ·
LSC circuits are only supposed to control a few percent of the oil flow for fine-tuning. If they flow more than this you get a horrible transition into the actual damping provided by your shim-stacks. So do not bore or machine anything out. You will ruin the damper.

You're feeling harshness because your shim stack is too firm or too heavily preloaded. The ABS+ damper piston allows for preloading for an anti-bob platform for XC racers but can also be setup with no preload for trail riding.
Basically if you can't ride with the LSC dial closed then your shim stack is too firm.

Manitou ABS+ dampers are better than anything Marzocchi/Foxzocchi has put in a fork.
How do you preload the shim stack? Its on top of the piston and buts up against the piston rod. The only adjustment i've seen besides the LSC is the nut that holds the check valve cup/spring in place.
 

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How do you preload the shim stack? Its on top of the piston and buts up against the piston rod. The only adjustment i've seen besides the LSC is the nut that holds the check valve cup/spring in place.
ABS+ has two shim stacks:
The "velocity stack" which is flat against the compression piston ports. No preload.
Then the "platform stack" which is bigger and seals against the raised outer lip of the piston. This one can be preloaded depending on the height of the velocity stack.

For trail riding you want no platform stack, concentrate on getting the velocity stack right.
Shim kit: ABS+ Tuning Mini Kit (Manitou) | Shockcraft
Tuning guide: https://www.shockcraft.co.nz/media/wysiwyg/Manitou ABS+Tuning Guide.pdf

Don't modifiy the LSC needle. A fork with lots of LSC flow really really sucks.
 

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Discussion Starter · #8 ·
ABS+ has two shim stacks:
The "velocity stack" which is flat against the compression piston ports. No preload.
Then the "platform stack" which is bigger and seals against the raised outer lip of the piston. This one can be preloaded depending on the height of the velocity stack.

For trail riding you want no platform stack, concentrate on getting the velocity stack right.
Shim kit: ABS+ Tuning Mini Kit (Manitou) | Shockcraft
Tuning guide: https://www.shockcraft.co.nz/media/wysiwyg/Manitou ABS+Tuning Guide.pdf

Don't modifiy the LSC needle. A fork with lots of LSC flow really really sucks.
Dougal, I removed the "platform stack", which I think was two very thick shims that went over the piston ports, or sat on the lip like you said, years ago and it was a vast improvement. I did not like the stock setup of ABS+. I've been running what you call the "velocity stack" only. The stack that fits inside the piston lip against the ports. Thank you for the advice and the tuning guides. Its a great reference for us Manitou owners.

I'm curious why you think modifying the needle would create too much low speed flow? If I increased the taper of the LSC needle(just a little) and stayed off the shoulder, the ports would still close when the needle is fully in. The increased taper should only flow more when the needle is backed out, right? All i'm proposing is increasing the taper which should increase the flow out of the low speed ports. Lets say I ruin the damper and introduce too much LSC i'll put the old damper back in or order another needle.

Thanks for the tech talks
Toby
 

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Dougal, I removed the "platform stack", which I think was two very thick shims that went over the piston ports, or sat on the lip like you said, years ago and it was a vast improvement. I did not like the stock setup of ABS+. I've been running what you call the "velocity stack" only. The stack that fits inside the piston lip against the ports. Thank you for the advice and the tuning guides. Its a great reference for us Manitou owners.

I'm curious why you think modifying the needle would create too much low speed flow? If I increased the taper of the LSC needle(just a little) and stayed off the shoulder, the ports would still close when the needle is fully in. The increased taper should only flow more when the needle is backed out, right? All i'm proposing is increasing the taper which should increase the flow out of the low speed ports. Lets say I ruin the damper and introduce too much LSC i'll put the old damper back in or order another needle.

Thanks for the tech talks
Toby
Anything you do to the LSC needle will make it flow more or lose resolution. There is no gain to either. The LSC is only there to control the transition into the shim stack. If you think LSC is too tight it's always the shim stack that is too tight.
 

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But I want to drastically reduce the compression damping, thats why i'm asking. The LSC is absolutely wooden on this fork. It would be very easy to bump up the shim stack to cover up if I went to far, which I wouldnt. No I didnt take any pics but I'm basically done with the fork. If I dont mod it, or swap out the needle, i'll probably order a Z2 and put this on the for sale boards. BTW I weight 230lbs. I think I run anywhere from 70-100 psi air.
If you look at the plots on Manitou's ABS+ tuning guide you can see in the fully open (mx-7) position the damping curve has close to zero slope already well past 250mm/s which is the traditional threshold for low speed compression. Increasing the bleed size (or removing the needle entirely!) will make no difference at all in this region as it can't physcially get any less. It would just remove damping from the very high speeds which you don't spend a lot of time in anyway.

This is the standard "trail" stack which it sounds like you have changed from already so your forces in the firmer positions or higher speeds will be much lower, but the low speed damping is roughly similar in the open position. If you want to alter the damping in any way, stick to changing shims

From the sounds of things I'm guessing your problem is friction related or in the spring design. Possibly tight bushings? I'm not familiar enough with the air spring you have to know if it might be an issue or not. But usually a "wooden" feel is how I would describe a fork with too much friction rather than a damping thing
1942190
 

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If you look at the plots on Manitou's ABS+ tuning guide you can see in the fully open (mx-7) position the damping curve has close to zero slope already well past 250mm/s which is the traditional threshold for low speed compression. Increasing the bleed size (or removing the needle entirely!) will make no difference at all in this region as it can't physcially get any less. It would just remove damping from the very high speeds which you don't spend a lot of time in anyway.
This is completely incorrect. In the plot shown the HSC shims set the damping curve and the LSC needle position just sets the rate of quadratic rise up to that.

There is no point where it has zero slope and no change past 250mm/s.
 

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It stays very high in the travel and I cant ever feel any brake dive. But maybe as a consequence the low speed compression feels harsh. So i'm wondering how to improve this needle valve if possible.
What's the rider weight? Average rate negative coil spring + heavy rider = no bueno
But I want to drastically reduce the compression damping, thats why i'm asking. The LSC is absolutely wooden on this fork. It would be very easy to bump up the shim stack to cover up if I went to far, which I wouldnt. No I didnt take any pics but I'm basically done with the fork. If I dont mod it, or swap out the needle, i'll probably order a Z2 and put this on the for sale boards. BTW I weight 230lbs. I think I run anywhere from 70-100 psi air.
What are your current LSC setting and exact shim stack? The needle shape seems giving descent resolution and range for LSC as the graph shows.

As kiwibaconator said, your negative coil spring may be not doing anything at your weight.
 

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Everyone stand back! Insufferable expert on everything at work. OP, you're dead wrong about everything. So is almost everyone else.
 

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Everyone stand back! Insufferable expert on everything at work. OP, you're dead wrong about everything. So is almost everyone else.
Are you here to provide anything useful? It appears you're just here to post incorrect info and then snark about people with knowledge and experience correcting you.
 

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What oil are you using?

I had Tower and it felt bit harsh even with preload shims removed. Actually it seemed to get harser during the ride. I started to use the Silokolene RSF 2.5 and it felt much better.
 

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Discussion Starter · #17 ·
Well I thought i'd post a follow up for posterity, .. over the weekend I pulled the low speed needle adjuster out of the damper, (.hold the shaft wrench flats with a 10mm and then unscrew the top cap 24mm and the needle will pop right out of the shaft, you dont have to monkey with the shim end. I marked the end of the adjuster with marking fluid and lightly sanded a nice little taper on the very end of the needle with the belt sander. I then lapped it with some 800 sandpaper and threw it back together and i'm happy to report it feels better now. I went and rode it on the trail and it really has a bit more plush feeling to it at low speeds over roots. I did not notice any additional brake dive and I did not blow through the travel.

I know this is simple empirical data observed by the seat of my pants and completely subjective so take it for what its worth but I never saw a down side to this change. In my humble opinion I think the stock needle adjuster and shim stack is built to give a platform type ride and that just does not suit me. The low speed needle that is now "ruined" as some predicted is probably a $10 part and can be bypassed by simply turning the adjuster knob in full until the shoulder of the needle closes the ports. I doubt Manitou sells the adjuster but you can by a new ABS damper pretty easily if needed. Its basically a 8" aluminum rod thats threaded on one end and tapered on the other.

Arnea, im using Maxima 5 fork oil. I dont think my local shops carry 2 wt but i'll keep an eye out for it.

Dougal, thanks for the response. I'm glad your still active after almost 20 years in here.
 
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