Handling & Suspension 2004-2008

Just thought I'd try a thread about this era: the 2004-2008 MX and enduro machines.

Just want to break down the handling, balance and suspension of these years and how we make them handle better!

I'll start the ball rolling by saying that I've tried to work out what the factory thought was the best handling/sussie set-up on their bikes.

looks like a set of WP race forks and rear shock as the standard stuff wasn't up to much right? handling wise the factory appear to have gone to 17mm triple clamp/yokes and my recent tests show more weight going onto the front. the trouble is that to keep weight on the front by lowering the forks or jacking the rear: means that the rear shock is hard.

that in turn means that there's no transfer of weight to find grip on the rear and the other loss is that the bike doesn't point around the corner with a stiff spring but always outwards off the course!

looking at old tests and previous info here shows that the factory did two or three things for the rear.
they appear to have raised the engine at the front with new plates making the bottom line of the engine parallel to the bottom frame rails.

they have also raised the swingarm pivot point by 3mm by machining the frame and welding stepped collars in (perhaps) and putting 3mm 'above-centre' crankcase holes in so that the coutershaft sprocket is up say 3mm but that the swing-arm pivot has gone up another 3mm so that the sprocket to S/A pivot is the same but that the swing arm must surely point down now more steeply.

the pivot to shock point is 21cm and the distance to the wheel spindle we'll say is 60cm so the rear wheel has been forced down by 6mm or so.

In order to get the back to sit on acceleration leaving the corner I trust a softer spring would allow this and the droop at the back end is accounted for in some way by the 6mm? this should give good or better hook up and the better the hook up the more it would sink.

in the meantime over rollers etc the extended rear wheel well below the S/A point will force the wheel down for great drive? I suppose another way was to have a completely new top shock mount about 5-10mm lower and allow for the soft rear shock yet keep the same rear ride height.

what I cannot for the life of me understand is why the Husaberg riders wanted the headstock out 15mm and 25mm respectively? I have found the more weight on the front the better! I don't think that they used that extra material to steepen the head angle again as they did in 2004? the photos I have of TMenduro's 496 special and of the welding done clearly show the head stock was merely extended and that the rake didn't change.

I'm hoping all these years later that I can persuade him to show a full side on photo. I don't believe the one about the tyre touching the headers.

anyway, your thoughts?

regards

Taffy

moving the wheel forwards puts the centre of mass closer to the geometrical centre of the bike more like an 09

with less weight transfer to deal with in rocking chassis movements where the nett chassis pitch should be zero ie over whoops, beaking bumps etc where you don't want the front to dive you can use softer springs because its easier to hold the front up from further out.

with softer springs you then have no trouble making the chassis pitch when you want it to so the front can come down for the corner if you are able to get forward ie ditch the stock tank or cave it in.

also consider extending the frame at the steering head along the same angle lowers the front of the bike. 50mm head extension = about 18mm lower COG so extending the head without changing the angle actually steepens the forks which was the wrong way to go for me, i need more trail not less.

if you shorten the shock or move the top shock mount up to lower the back end the swingarm angle is flattened.

this has a detrimental effect on chain pull moment which is "at the centre of the motorcle handling universe" according to GMD. my guess is they shortened the shock to increase front wheel trail and then to to get the nice swingarm angle back they raised the Sarm pivot.

depends what sort or riding you do.. I think the stock 08 frame would be better for sumo and for casual trail riding, flat track and smooth hardpack..... anywhere where rocking chassis movements don't happen often. lower is always better for handling though unless you hit the frame on rocks and logs all the time.

I like my modded frame better than the stock one.

MK 2 frame starts today! finally got all the cromoly delivered.. aussies are so lazy .... will be about 6 kgs lighter, 60mm lower and have more front wheel trail, very similar to 2010 RMZ450 geometry but with better boingers the big 700 engine and carbon fuel tanks / airbox.

like the one about the headstock extension. very good. explains the thinking leading into the LDCs.

I didn't say they shortened the shock? perhaps you know what I don't?

the test of that particular bike has been done before, and at the moment the gallery isn't working (I think) so I can't put it back up but the bike was as stiff as a plank so not necessarily what the customer wants. however the front of the engine is clearly raised.

a 25mm increase in headstock length, 6mm drop at the front with an increase in trail - hadn't thought of that! got to be nearly 1 degree.

6mm drop at the front, 3mm lift of the SA pivot....finite stuff and all too hard to keep up. no wonder codemonkey and fry couldn't get anything out of dave larsson! bigger secret than the V1 rocket this here LDC!

regards

Taffy

Taffy said:

.

however the front of the engine is clearly raised.

regards

Taffy

Click to expand...

if they raised the Sarm pivot the chain would rub on the top of the sarm more. raising the engine at the front brings the angles back up so they could run a piddly 14T front.

it also move the COM back away from the front wheel ala 2010 yamaha but I think its more likely they were thinking about the chain guide there..

finite stuff for sure Taffy and ALL of it more significant handling wise than shim shuffling.

I reckon that if i hadn't read that the Tarkala bike was as stiff as a plank: that in fact the rear was effectively jacked up with the S/arm mod but that the shock spring could then be softened to allow more transfer to the rear under acceleration.

there is a way of pressing the shock downwards from the top mount and it's not too difficult. the top mount has a huge 30mm Heim and the bottom a 25mm one. by organising an off-centre bush you can place a bottom Heim in the top and gain another 1,2 or 3mm easily. jack the rear, soften the spring, better weight transfer for acceleration, better steering mid corner onto the throttle and with a droopy swing-arm it picks up drive better over the whoops!

...so I'm bound to have got it all wrong then!

regards

Taffy

great idea!

I have a removable insert in the bottom of my TTX so I can change the length of the shock without altering the travel.

didn't really plan it like that, just a bonus

I like the seat/handlebar realtionship when the backs up with a long shock but it reduces front wheel trail = a very sad Bushie

correct trail and a raised rear shock mount at the same time would be nice but its raising the engine and the COG. most bikes have the output shaft located well up high on the cases to achieve just that, its 40 - 60mm lower down on our engines... GRRRRR good ground clearence but but but.......

given these bikes are so top heavy Ive found the the benefits of a lower COG outweigh those of "correct" swingarm geometry. a pic of weeds bike side on would be good if he wants to put one up.

nothings right or wrong with this handling stuff... far to many people spend too much time trying to do what everyone else has allready done rather than working out what works for them, the rider is an important part of the geometry so if you're going to change the chassis the bike needs to be customised for the rider..

I'm not sure which way is quicker ...... will find out I guess

well my engineer (lovely to say that here again!) is knocking up several parts:

1) two engine plates with the front holes up 6mm. this will make the belly of the engine parallel with the bottom rails.
2) I'm having off-centre bushes made for the back of the engine. 3mm off-centre.
3) an off-centre bush for the lower rear shock mount as well as 3B) the shoulders to suit. this will make the shock 5mm longer.

I haven't decided about raising the S/arm pivot actually in the frame....thought I'd try this other stuff and if necessary I might lower the back of the engine rather than raise the pivot point.

lots to do and unfortunately a stag and a wedding for two weekends now.....

regards

Taffy

I'm thinking about getting me some adjustable triple clamps from KTM 525sx 2006.
The offset on them can be adjusted from 20 to18mm.

My question is how little offset is it possible to run on the 2004 berg with out the front wheel hitting the frame or exhaust.

My front wheel did hit the headers when new until i got some update headers to fix that.

Regards Hilmar

depends on the tyre? I'd remove the springs and air bleeder screws then colapse the forks and measure it up

anyone know what the actual rake spec is for the 2 different frames?

I see its 1.5 degrees steeper on the new one

did the wheelbase stay the same with the change or get shorter?

the RMZ is interesting. over the years its rakes gone from 25 degrees to 29.5 and as a result now has the most trail of all the current MXers

Bushie

In the 2004 owners manual it states Steering head angel 63° weird how they measure that but i think that translates to 27° rake
Wheelbase 1490mm +-10mm

2003 owners manual states caster 28,5° wheel base 1490mm

Regards
Hilmar

thanks Hilmar

my first frame mod of the 08 frame had the rake at 28.5 deg with the relocated shock upper mount then when I moved the steering head out 50mm it went back to 27.5 deg and wheelbase 1520 so stock wheelbase should have been around 1470 -1480 maybe they measured it wheels off the ground

the front still feels heavy so im going for wheelbase 1560 and rake 29.5 to 30 deg with the centre of mass 50mm behind the midpoint between the wheels. if it wont turn i'll extend the swingarm to bring some weight back to the front.

the idea is to increase trail by 20-30mm get some weight off the front to help in sand whoops and lower the COG to help in turns

engine is dropped 60mm at the front compared to stock while the swingarm pivot height is retained at 450mm

almost the opposite of Taffy

1 degree change in rake is roughly 11mm change in trail with the berg 20mm offset tripples and 34mm offset large diam axle fork clamps

it gets hard to make everything fit with 30 deg rake and under 1560mm wheelbase

zero offset tripples could be good in the sand could probably get 14 out of these ones.

I had 14mm triples in my old frame no problem and I had trouble with the standard front droop nose mudguard from the off with this 2004 frame. I simply melted the mudguard away from the frame and the tyre just kisses the lower back (leading) edge.

For me more weight on the front is important. I've never been able to drop the Husaberg into the corners with what i perceive to be the correct sags.

the new 18mm offsets have changed that. I've had them on the shelf two years but wanted to just do the suspension first to within distance. now the bike drop right onto the berm no problem.

so this weekend I changed the gearing from 14/51 to 14/50 and could have gone further. the bike still drop in nicely but comes out just above the 'bite' of the rear tyre I think. I'm carrying 2-3mph extra speed as i make the bike howl in parts but without changing gear so I know 49T is coming.

this weekend I tested the pre-load on the rear back down one turn and the bike steered out of the bends a lot better as the back end sunk a little - no steering required just open the throttle and the next apex comes into view not the billboards on the outside of the track.

I also tried the forks through the triples by 5mm and lost nothing and finally I tried them 5mm proud which was a 10mm change and again the grip was extraordinary compared to what i had. firstly with them even. however the practice was abandoned when I crashed. I got so much grip I nailed it off a corner and shot over a jump and was clearing into the flats beyond when a gust of wind just took both wheels clean away from me and I got quite shook up.

i asked the photographer stood nearby not to rub them but to count them! :lol: :lol: :lol: :lol: :lol:

so for me, yes I have loaded the front, the gearing BTW sent the rear wheel back 8mm making it even more front loaded. a 49T will do the same again. it's all a circle....I have a weighted front but have 48 springs to hold it up.

the next test will be to jack the rear end up and down with my off-centre heim bush. I can also raise and lower the engine at the front with new plates as well as at the rear I can raise or lower the gearbox sprocket by using off centre swing arm bushes in the engine.

my views on the suspension I'll place elsewhere.

regards

taffy

I'm Going to try this gizmo

E Axle from rekluse http://www.rekluse.com/E-axles.html

A lot easier to fit and meddle with than triples the ktm one can go -3 to +2 and if i like it i might buy different offset claps to get more adjustment.
This axle would go well with the ktm adjustable 20 to 18mm triples you would then get adjustment from 15 to 22mm.

regards Hilmar

anyone remember the WRM 450? adjustable rake

adjustability is nice the offset adjustment you're getting from 15-22 would be a great timesaver I would think Hillmar

well its got me beat taffy, you like it the exact opposite to what i like.
different conditions & different riding styles...maybe :?:
as far as i'm concerned,there are 2 things that have a major negative impact in loose dirt or sand,
and that is to have a bike that is front end heavy & for double trouble just add a sharp fork rake.
on hard packed grippy surfaces it is less of a concern having the above.
have you every riden a drz400 or husky 450/510 in loose sand.
mate the only way you can stop the front from closing, is to be at full throttle & to have 6ft long arms like inspector gadget(so you can get beyond the back wheel).
love my berg the way it is thanks.
..weed..

Aah great! a pissing contest!

I do whatever I feel I need next. they say that the contact point of the tyre moves forwards in sand infront of under the axle stub. I've forgotten what that means so do remind me? LOL!!!

also, the factory Husaberg's had the headstock extended by 15 and 25mm respectively taking weight towards the rear BUT keeping the same rake and trail. all that changed i guess was the balance ratio - less on the front....

regards

Taffy

the thing I'm trying to do is to separate the ride height so i get the steering angle right: from the suspension function on the rear. if the two are mutual then that's fine.

regards

Taffy

what steering head angle are you aiming for Taffy?

not really sure Bushie. I've never had this much grip on the front. the 18mm TCs are a major boost, I have the extra free bleeds as well and the rear wheel back 8mm so as you can tell I've been whacking weight on the front and now my forks are bottoming out on a MX track and the ride height and dip on cornering is excellent. I still have a standard seat even though you'll have seen that very tall one in the doc. I'm stuck pretty much at the bottom of the standard seat whereas the tall seat lead you to moving around. you just sat so high though...

I've been speaking to Per quite a bit lately and he has far greater skills than me and rides other bikes etc. The Husey is considered front end heavy thus the extension to the very last frames. we'll see.....

just got my nitrogen gauge and all the parts today for playing with the engine position.

regards

Taffy