Rear shock spring mods

I contacted renowned suspension experts "Maxton Engineering" in Cheshire regarding upgrading my Scrambler's suspension.. this was their response.

REAR
The standard rear unit is a very cheap unit, probably one of the cheapest you will find on a
modern bike. The unit is not adjustable for damping and is sealed, so it cannot be serviced or
revalved.
The standard unit has very little rebound damping so feels very ‘bouncy’, but it has too much
low speed compression damping which makes the ride feel harsh over bumps. The spring
fitted is a progressive spring, the first rate of the spring is OK for the average rider weight, but
the second rate is too hard and can also make the ride feel hard over big bumps.

We can fit a Linear spring to the standard shock but it will not stop the back of the bike
feeling like a “pogostick”. To dyno and respring the standard unit costs £95.00 + V.A.T. We
recommend a replacement Maxton unit.

The replacement Maxton NR4 unit is a fully adjustable, alloy bodied, high pressure gas unit
that adjusts via shim stack system. The unit has a spring to suit your rider weight and to suit
what type of riding you do. The unit is suited to high temperatures because it adjusts via a
shim stack not via a needle valve system. The NR4 unit costs £435.00 plus V.A.T it is adjustable
for rebound damping, compression damping and preload. Each adjuster is separately and
independently adjustable even though the shock does not have a remote reservoir.
The NR4 shock is NOT an emulsion shock absorber even though there is no remote reservoir.
The NR4 has a floating piston inside to separate the oil and Nitrogen. This is very unique, all
other shocks without remote reservoirs are emulsion shocks which suffer from damping fade
when hot.
Unfortunately due to the length of the shock being very short we can not fit a ride height
adjuster to the NR4 shock. But as we build this shock to order we can make it longer to raise
the ride height, this makes the bike turn quicker. There is no extra charge to do this.



FORKS
The front forks on the Ducati Scrambler look nice but are actually cheap and very crude.
The forks are upside down forks with a spring in both legs but damping only in the right
leg. The standard forks feel very harsh over small bumps this is because the forks have got
too much low speed compression damping. Over high speeds the forks feel like ‘pogosticks’
which means they dive very quickly and spring back at you very quickly. We would describe
the front forks as digressive.

The damping system fitted to the right leg is very crude and it's not possible for us to revalve
the leg successfully. To cure the problems with the front of the Scrambler we supply a new
GP20 cartridge to the right leg. Unfortunately due to the design of the left leg it is not
possible to fit a GP20 damping cartridge without major modification. The GP20 cartridge we
fit to the right leg has more damping than normal to compensate for the left leg having no
damping. This is a little unusual but actually works very well on the Scrambler. The GP20
cartridge makes the ride a lot more compliant and gives much more feel mid corner and
control to the front end. We fit a spring to the GP20 cartridge so when used with the left leg
suits your rider weight and what you use the bike for.

We can also make the right leg adjustable for damping by drilling and tapping a hole in the
fork top, you then fit a small allen screw with a Dowty washer to seal the tapped hole. To
adjust the damping you remove the allen screw and put a 3mm allen key down the hole, the
allen key then adjusts the rebound damping.

The GP20 cartridge costs £190.00 + V.A.T and to service and fit the cartridge with a new fork
seal costs £75.00 + V.A.T. If you wanted us to drill and tap the original fork top so you access
the rebound damping adjuster there would be no extra charge for this.

As mentioned we can fit damping cartridges to both legs but it would be very expensive for a
Ducati Scrambler. We fit our GP30 cartridges which have rebound damping in the right leg,
compression damping in the left leg and springs in both. To get the GP30 cartridges to fit we
have to remove and refit the bottom brackets from the chrome stanchions and weld a
platform into the bottom of the leg, we can then bolt a cartridge against the new platform.
The GP30 cartridges cost £895.00 + V.A.T and to modify the sliders to accept and GP30
cartridges and service and install the cartridges costs £245.00 + V.A.T. So the total is £1140.00
+ V.A.T.

OK, here we go with our brand new 476 in/lb Racetech spring:



Notice that cut off hex wrench, that's what you'll need to access that lower shock bolt, unless you'd rather remove the passenger peg bracket. We used Smifff's trick and put the Toyota's scissor jack between the rear wheel and fender, made it super easy to pull the bolts and lift the shock out. You can get to the nut at the top with an open end wrench, just go straight up from the footpeg and finagle a bit. We went the homemade route and used 3 hefty hose clamps as a spring compressor. Cheap enough for sure and did the trick, but these springs are so short we were running out of bite on our clamps by the time we got them cranked enough to compress. If any of you decide to go this route be sure to get clamps that bite nearly their entire length. We got around the problem by using blocks of wood to add some bulk:

The real hitch came with Racetech's sizing collars. They were perfect for the bottom of the shock, but too big and sloppy at the top. Racetech had very little to go on, so this whole project was a guess. We got some aluminum from a machine shop buddy and as wak did earlier, Doug set in making a collar to fit. You can see the Racetech collar compared to Doug's:


Racetech collar:



Collar Doug made:



I'm hoping Racetech can supply a collar with a better fit for the rest of you, as I said they had very little to go on as this was their first go round with a Scrambler. Here's Doug's collar along with the specs he noted:



(Thank you, thank you, Doug!)

Here it is put together:



And on the bike:



Now how about the ride? A definite, definite improvement. I can actually feel the bike soaking up the bumps rather than the bumps skittering my butt on the seat. Actually sort of an odd sensation after being jarred and jostled for so long. I could have used a lighter spring for sure; I weigh 136lb geared to ride, and I have just under an inch sag at the lightest preload setting. Doug, at 175lbs, feels it's perfect for him and is impressed with the improvement. I may talk to Racetech about a swap, or maybe not; we plan to ride the bikes out West for vacation next week, and I don't want to be putting the bike back together right before we leave. Hand's down, I can tell you it's an improvement over the factory shock just as is.

Sarah

Hi Sarah,

Thanks for the information and for blazing this path. I'm guessing the suspension was not calibrated for lighter people (I'm about 150 lbs. w/ gear) riding rough secondary roads, plus the components are budget quality. To me, the hash suspension is the Scrambler's biggest flaw and probably contributes much to the complaints about the seat and abrupt low speed throttle response. It's unfortunate that the left fork sounds difficult to disassemble. On most other machines that I've owned, a swap of fork springs would alleviate at least some of the suspension problems. On our Scramblers, this replacement doesn't appear to be a simple task. I live in a rural area, so looking for solutions that can be done at home (with my basic skills and tools) or by sending the forks to a suspension specialist for cartridge or spring replacement, which while expensive, may be worthwhile. Neat machine, but the suspension is bad for me.

Sarah

You and your "mechanic" have done a great job at finding low cost solutions to the suspension

Would it be too much to ask to have you call Racetech and share your experience to get their feedback? The question I would have is whether they think a shorter spring vs lower spring rate would be better.

I'm fairly light as well 150 dry, perhaps 165 with gear and carry maybe another 50 lbs when loaded. If you think your spring would work for me, I could buy it from you and you could buy a better one for yourself.

Ideally I can make a plan and upgrade before a road trip in early September.

Have fun and thanks for sharing your experience

Phil