Maxton GP20

[bentebent]

I'm doing some research on sticking Maxton's GP20 cartridge kit (http://www.maxtonsuspension.co.uk/files/gp20.htm) on my bike. Had some correspondence with them and this is the information I have gathered so far.
 

We throw everything inside the forks away and start again with our own Maxton Cartridge damping system. The cartridge damping system is designed like any modern fork internal; it has separate rebound and compression damping pistons, with shim stacks valved to suit the MT-07 and what you use the bike for. This damping system gives a very progressive action that supports the bike under braking with the springs, without making the ride too harsh. The cartridge is adjustable for damping to. We also fit a spring to the cartridge; the spring is chosen to suit your rider weight. The Maxton cartridge conversion costs £380.00 + V.A.T. To install the cartridges and service the forks costs £120.00 + V.A.T plus fork seals at £25.00 + V.A.T a pair.

Seems like a good price for what seems to be a decent piece of kit. 
This is what was said about mounting it.

We can supply the GP20 cartridges as a kit, they come with basic fitting instructions. We expect people fitting the cartridges to have had experience of working on front forks in the past.  
It is a very simple job if you are used to working on forks. The biggest engineering task is removing the original damping valve from the bottom of the chrome tube. This is pressed into the end of the chrome tube, so you have to grind off the end and knock out the damper valve from each leg. Afterwards you must also clean up the end of the chrome tube so there are no sharp edges.

So here comes my question, as someone who is not very mechanically inclined but has still been able to do some work on his other bike's forks, what does this really mean? It doesn't seem very daunting, I just need not to fuck up. Do I need a lathe like with the Andreani kit? Is there a chance someone could point out on the exploded front fork view what he's talking about?
 

[Guest Ralph]

Not ridden a 07 with Maxton stuff on it but have ridden tow identical Suzuki's back
to back one with one without and the difference is amazing, been down to their place
once or twice and had a look round their works only a small place but they know what
they are about.

[wickedtwister]

Parts 10,29 are held in place by the bolt 13,32. Not sure what guy is talking about grinding. I did not need to do any of that with my matris kit. Maybe @pattonme can chime in on this one.

[JanM]

According to the description from Maxton you need to do exactly the same irreversible modification to the checkvalve at the bottom of the stanchions as you need to do for the Andreani and Traxxiuon cartridge kits. It is not possible to show what you need to remove or modify on the fiche picture, but search for the stanchion modification necessary for the Andreani and Traxxion cartridgekits and you just need to do the same for the Maxton kit. It is easy to remove the folded over part of the stanchion using a lathe and then remove the checkvalve, but sometimes it is also possible to break and remove the parts of the checkvalve that interferes with the new cartridge kit and then be able to fit it. Both ways are irreversible modifications, so you can not just remove the Maxton (and Andreani and Traxxion) cartridge kits and refit the stock damperrod. As said, the modification is irreversible.

[bentebent]

Not ridden a 07 with Maxton stuff on it but have ridden tow identical Suzuki's back to back one with one without and the difference is amazing, been down to their place
once or twice and had a look round their works only a small place but they know what
they are about.

Yeah, looks like a really high quality product, especially since they seem popular in BSB and IoM-TT.
 

According to the description from Maxton you need to do exactly the same irreversible modification to the checkvalve at the bottom of the stanchions as you need to do for the Andreani and Traxxiuon cartridge kits. It is not possible to show what you need to remove or modify on the fiche picture, but search for the stanchion modification necessary for the Andreani and Traxxion cartridgekits and you just need to do the same for the Maxton kit. It is easy to remove the folded over part of the stanchion using a lathe and then remove the checkvalve, but sometimes it is also possible to break and remove the parts of the checkvalve that interferes with the new cartridge kit and then be able to fit it. Both ways are irreversible modifications, so you can not just remove the Maxton (and Andreani and Traxxion) cartridge kits and refit the stock damperrod. As said, the modification is irreversible.

Alright, thanks! Sounds like something your average machine shop should be able to help out with. Not too worried about not being reversible, don't know why I would want that to be honest. It only took 500km to realize the suspension is quite horrifying at times.
 
Edit: In the case of a lathe not being readily available, would an angle grinder suffice?

[markstertt]

Part 11.30 is inserted into the end of the stanchion and sits on a machined lip, then the end of the stanchion is pressed over to hold 11.30 in place. You can carefully take this off with the use of a stationary disc sander and if you do a good job of it you will just break thru the rolled over lip and leave 11.30 and the stanchion intact. Despite what others have said, this is totally and easily reversed if desired, by inserting 11.30 back into the stanchion on its locating register, and with a tig welder, tack it back in place in either 3 or 4 spots.
 
when working on the disc sander, wrap a pc. of cereal box or similar around the stanchion so as not to scratch it up on the sanders table and have a bucket of water to periodically dip the stanchion in as you go along, it gets hot and there's no need to alter the heat treat of the tube.
 
Hope this helps, I just did this while installing a set of GP suspension 25mm cartridges without instructions and I've never done fork work before, it's not rocket science but you need to be mechanically inclined and have tools such as the upper fork bushing and seal driver, a way to measure oil level etc.

[twotone]

The NIX 22 requires no machining, so the Maxton may cost similar by the time you mess around with modifying it.

[JanM]

Part 11.30 is inserted into the end of the stanchion and sits on a machined lip, then the end of the stanchion is pressed over to hold 11.30 in place. You can carefully take this off with the use of a stationary disc sander and if you do a good job of it you will just break thru the rolled over lip and leave 11.30 and the stanchion intact. Despite what others have said, this is totally and easily reversed if desired, by inserting 11.30 back into the stanchion on its locating register, and with a tig welder, tack it back in place in either 3 or 4 spots. 
when working on the disc sander, wrap a pc. of cereal box or similar around the stanchion so as not to scratch it up on the sanders table and have a bucket of water to periodically dip the stanchion in as you go along, it gets hot and there's no need to alter the heat treat of the tube.
 
Hope this helps, I just did this while installing a set of GP suspension 25mm cartridges without instructions and I've never done fork work before, it's not rocket science but you need to be mechanically inclined and have tools such as the upper fork bushing and seal driver, a way to measure oil level etc.
 
 
Nice clarification, thanks.

 

[bentebent]

Part 11.30 is inserted into the end of the stanchion and sits on a machined lip, then the end of the stanchion is pressed over to hold 11.30 in place. You can carefully take this off with the use of a stationary disc sander and if you do a good job of it you will just break thru the rolled over lip and leave 11.30 and the stanchion intact. Despite what others have said, this is totally and easily reversed if desired, by inserting 11.30 back into the stanchion on its locating register, and with a tig welder, tack it back in place in either 3 or 4 spots. 
when working on the disc sander, wrap a pc. of cereal box or similar around the stanchion so as not to scratch it up on the sanders table and have a bucket of water to periodically dip the stanchion in as you go along, it gets hot and there's no need to alter the heat treat of the tube.
 
Hope this helps, I just did this while installing a set of GP suspension 25mm cartridges without instructions and I've never done fork work before, it's not rocket science but you need to be mechanically inclined and have tools such as the upper fork bushing and seal driver, a way to measure oil level etc.

Great clarification, thank you!
 

The NIX 22 requires no machining, so the Maxton may cost similar by the time you mess around with modifying it.

Is the NIX 22 actually out or still vaporware?

[markstertt]

Thanks but I goofed and need to clarify my mistake, 11.30 is what I believe is called the oil flow stopper and should be the white plastic pc. and not what I was assuming. I don't think Yamaha shows or calls out the pc. that we are removing since it's integral with the stanchion and not a normally replaced item.
 
When looking at the bottom end of the stanchion, the part to be removed will be obvious, all else remains as I previously said. I wouldn't recommend using a hand held grinder but yes, you could if your very careful. Removing the damper rod allen bolt was fairly easy using a 3/8" pneumatic butterfly ratchet, I held the damper rod from the other end by jamming a slightly tapered 3/4" pc. of bar stock down it's throat, by pushing hard, it gave just enough traction for the ratchet to loosen the bolt.
 
 

[twotone]

The NIX22 is showing up on eBay for €639
From Milan. Check it out and see if they actually hold stock

[norwest]

Removing check valve assembly for insertion of cartridge in damper rod fork.
 

 

[bentebent]

Removing check valve assembly for insertion of cartridge in damper rod fork. 

Looks like a dremel would work just fine?

[bmwpowere36m3]

With certain cartridge kits, just the white plastic piece (believe oil lock) needs to be knocked out with a chisel and hammer.

[bentebent]

Well, Brexit just happened so depending on how the GBP develops this kit just became a lot more interesting. I got these options yesterday:
 
There are two different choices of GP20 cartridge for the MT07 not four :
 
1. Adjustable rebound damping only = £456.00 including V.A.T per pair
 
2. Adjustable rebound damping and preload adjustment only = £624.00 including V.A.T per pair
 
Regards the rear shock we have not supplied an MT07 shock with Hydraulic preload adjustment. We two different types of rear shock either :
 
1. NR4 rear shock = £522.00 including V.A.T
 
2. RT10 rear shock = £726.00 including V.A.T

[twotone]

Is there no option for compression?
 
I'd say wait for the ohlins

[bentebent]

Is there no option for compression? 
I'd say wait for the ohlins

You're right, don't know how I missed that. I'll mail back and ask about it.

[pattonme]

Not to side-track too much but compression damping adjustment really isn't all that useful. You want slow/moderate shaft rates to have little damping (needle orifice wide open), it's only when you hit a pretty serious bump that you want it to interfere (shims stack) and keep the suspension from blowing thru the stroke. Said in another way, on big bumps you want the hydraulics to "increase" the spring rate.

[bentebent]

Not to side-track too much but compression damping adjustment really isn't all that useful. You want slow/moderate shaft rates to have little damping (needle orifice wide open), it's only when you hit a pretty serious bump that you want it to interfere (shims stack) and keep the suspension from blowing thru the stroke. Said in another way, on big bumps you want the hydraulics to "increase" the spring rate.

Not sidetracking at all, I'm by no means claim to know anything about suspension, this is the first time I go fully adjustable and I see it as an opportunity to learn. So you would say not having external compression adjustment is fine?
 
I know you're the resident suspension guru, any input on having separate rebound/compression per fork leg or having both compression and rebound in each leg?

[pattonme]

If they did the shim stack well then yes, external compression adjust isn't needed. Sadly many/most OEMs do a downright crappy job of shim stack building so the needle helps stiffen the slow-rate behavior. For example, a 1.5mm orifice is a bit too restrictive, a 2mm is reasonable and a 2.5 flows a bit much. The 01-03 GSXR600 has a 2.5 orifice and a disturbingly weak shim stack so cranking in the needle was needed.
 
It's all a balancing act, really. Some pistons use a 3mm hole (x3), or a 2.5mm hole x4, some use a wedge that's equivalent to 3.8mm.
 
Just because I have opinions doesn't make me a "guru". I much prefer a 4-piston setup which is traditional vs separating out Comp in one leg and Reb in the other which generally means only 2 pistons are involved. For rebound it's not a problem. For compression there simply isn't enough valve area to accommodate the flow rates needed. And if you design the piston and shim stack for said flow, you pretty much end up negating the needle (it does very little).
 
Matris in their F15K (FZ07, etc) has all 4 pistons even if 3 of them are working in compression and just one in rebound. A bit of an odd duck. In their F12 systems (on some bikes at least) they have a 3-piston setup with 1 rebound piston and 2 comp: which you can think of as for 'slow' vs 'fast' but even that I'm painting with a bit of a broad brush.
 

[bentebent]

Thanks for your input pattonme, it is much appreciated. Maxton strikes me as a company that would get it right but that is of course impossible to know before actually trying it. I might go as the guinea pig on this one.
 
Edit: Got an answer from Maxton on adjustable compression.
 

We could supply a cartridge with adjustable compression damping but its very complicated to fit. For this reason we do not supply this type of cartridge as a kit.

 
 

[robsoup]

Hey did you end up getting the Maxton suspension? What did you think of it. I'm currently weighing up K-Tech and Maxton...

[bentebent]

Hey did you end up getting the Maxton suspension? What did you think of it. I'm currently weighing up K-Tech and Maxton...

 
Not yet sadly, I'm kinda iffy about the lack of adjustable compression damping to be honest. Still weighing my options, no rush since the riding season is about to end here in Sweden anyway.

[rick]

Hey did you end up getting the Maxton suspension? What did you think of it. I'm currently weighing up K-Tech and Maxton...

Not yet sadly, I'm kinda iffy about the lack of adjustable compression damping to be honest. Still weighing my options, no rush since the riding season is about to end here in Sweden anyway.

Been riding an Aprilia with a rebound adj. only Showa suspension and have never missed not being able to adjust compression. If Maxton does it right, and it sounds like they understand the pitfalls of having just one small valve for both, the suspension will be sooo much better than OE, you'll never miss not beuing able to adjust the C side either. 

[rick]

I have the Andreani cartridges in my FZ. Turns out that the way that system was built, the bottom end caps are designed to take a base compression valve. Andreani could have made those cartridges to be a 4 valve cartridge just like the Showas in my Futura. Yeah, there'd be no compression adjustability, but as it is with just 2 valves, 1 each, ( or 3, see below) fluid flow is so limited that the compression adjuster winds up full open and that's with fairly light fluid.
 
So, with Pattonme's expertise and help, my Andreani cartridge is now a 3 valve set-up. Using my weight and my desire for more compliance, he prepped a new compression valve ( the big holes are now regulating instead of Andreani's where the small holes have the shim stack) that's adjustable and a base compression valve that's now in the bottom of the rebound cartridge.
 
I'm still running 10cSt fluid ion the compression side and the more normal 16cxSt on the "rebound"/base compression side. I have the left fork's "compression" adjuster still full out and the rebound 3 of 4 turns out. The front is now still fairly firm, but big bump compression is far better than it was straight from Andreani and that was far, far better than OE.
 
Only have about 75 miles on this set-up and will try to get more miles in this weekend. I'll move my impression of this modded cartridge back to the Andreani thread