Looks great. I like it keep up the good work.

 

thanks mate, i also forgot to mention a alftermarket ride height ajuster would benifit this setup to fine tune the ride height

 

Awesome thanks for sharing, I want to do this but that last in depth thread scared me. Sounded like a lot of work.

 

Hi,

Is the 996 pivot link the same as the 748 one do you know?

Cheers Kit

 

A quick look at the exploded view parts catalogs for each of these bikes shows that at least the '00 996 Mono, the '01 996R and the '02 748R all use the same rocker assembly... P/N # "372.2.004.1A".

 

to clear up any confusion my parts list was

a 848 swingarm
a 848 shock
a 848 ride height bar

a 996 pivot lynk


and the pivot lynk is the same for the 916,748,996,998 all makes and years

im going to be tearing back down to powdercoat my frame so i will take more pics asap

 

i also have a spare 848 swingarm and ridehight bar if anyone needs one pm me

 

... i was looking at other threads!!

... i have a 996 and wanted to fit an 848 swingarm and wheels the other threads whent in depth at looking at the geometry with cad drawings and macking parts,all well and good if you have access to that sort of thing but nothing works as well as bolting it all together and looking at a problem!!

I agree that those tools are not required to solve the problem... but they definitely help. I am assuming that you are referring to the job that mpaschetto did fitting the 848 swingarm on his 748. If so, you did see that he had to manufacture a custom rocker correct? I think you can get around the ride height issue by flipping the rocker around, but part of the problem that I hope you are not overlooking is one of link alignment, e.g., the angle between the rocker/link/swingarm, shown in the 4th picture above.

In the standard configuration that link is perpendicular to both components. Keep in mind that as that angle increases, so do the forces on those components... ideally you want a solution where the force vector from the linkage is inline with the damper. There are other issues with reconfiguring in this manner that I can think of, but they all have to do with the geometry of the damper/linkage and the free length vs spring stiffness of the spring itself.

There is a free piece of software that will help you enormously if you have access to an iPhone/iPad or Android device, Autodesk Force Effect, and/or Force Effect Motion. App Store - Autodesk ForceEffect

 

yes i could see that the rideheight rod is on the sque, but so is my swing arm its not as bad as the picture shows it to be, the ride height rod also has a ball joint at each end and once my engine is in and the swing arm is sitting true the sideways force will be elliminated further, i really dont think it will make much difference if any, the shock sits nice and true so once the engine is in and running setting up the suspention is a given.

there is also the fact im not rossi, and will never ride anywhere neer the limit on my newly yet to be finished pride and joy

 

Understood, but just be aware that due to the geometry change there will be an increase in reaction forces on the linkage itself, as well as it's mounts on the rocker and swingarm. Unless I am mistaken, by rotating the rocker, the damper is still mounted to the "long side" (approx 75mm) of the rocker and the linkage is still mounted to the short side, correct? Keep in mind that unless the distance from the upper linkage pivot to the rocker pivot (approx 50mm) and swingarm pivot to lower linkage pivot (approx 120mm) is proportionally maintained, you are going to see more or less "included angle" or angular distance in degrees of travel on the rocker for the same amount of travel on the swingarm. This distance, as I pointed out, is around 120mm on the 748 swingarm, I have no idea what it is on the 848. If it is more than 120mm this could be a problem.

I am mentioning this because the ball end joints have a maximum angular offset from center and if this is exceeded, which is a distinct possibility, they will max out and the linkage will bind and then the bulk of the compressive forces which are normally transferred to the damper, will end up applied to the end of the rocker, linkage and swingarm linkage mount. This would be bad, and the weakest link, which I believe would be the end of the rocker pivot as it is forged (?) AL, will take the hit.

 

this is how it looks with the swing arm pivot in so the swing arm isnt twisted ive just spent 5 mins jumping up and down on it feels ok lol i will give it a measure up later thanks for the input

 

As much as having the linkage on the angle (when viewed from behind) is not ideal , it will not 'max out' as the angle will not change throughout the stroke of the suspension as the swingarm and the top pivot are prevented from moving sideways. As such, if it isnt binding once eveerything is bolted up properly, it shouldn't bind through any part of the stroke.

Having said that, i agree that the suspension ratio will be different to the 1098/848 rocker if the distances from the pivot point on the 996 rocker are not proportionally the same. I haven't measured the two different rockers, but if the 996 is 50mm(link side) and 120mm(shock side) thats 2.4.

Anyone have a 848 linkage around to compare this to ...?

 

let me know how it works out! i wanted to do this swap myself but the other threads made it seem too complicated...

 

more pics, i have put the stock 848 piviot lynk on to try and show the amount of travel before it bottoms out its less than the 996 item due to it being deeper or thicker set,

also some pics of the 848 and 996 piviot lynk together side by side

 

about the pivit lynk

so ive now compaired the 996 and 848 pivot lynk!! to see what i have

first off, the shock and ride height bar are pulled in 5mm at the top
from the 848 set up when useing the 996 pivot lynk not perfect but not to bad!!

the 848 shock distances from center to center of the bolts
falcrum being the center balance point

shock to falcrum: 65mm
rideheight bar to falcrum: 70mm
toatal distance bettween shock and rideheight: 140mm
the falcrum is offset by: 12mm

the 996 shock distances from center to center of the bolts
falcrum being the center balance point

shock to falcrum: 75mm
rideheight bar to falcrum: 55mm
toatal distance bettween shock and rideheight: 140mm
the falcrum is offset by: 10mm

so by useing the old 996 shock i have gained 10mm on the shock to fulcrum and lost 15mm on the rideheight to falcrum

the longer section pressing down on the shock it will act faster and the ride will be harder the same will be true the other way and the shock would have to be set so it can react faster when the wheel travels down eg when the load is removed.

i do not know the position of the 848 point on the frame where the falcrum sits and unless you know that i dont think you could ever truly get this to be the same.

bear in mind if you have a part made, up if you change anything, you change load,angle,force applyed or removed what ever you do you must maintain the 140mm distance and the move the falcrum in relation to the offset

for the moment this solution of useing the 996 pivot lynk serves me and my needs very well, and if when im done i cant get the suspention to work i will find another way, appart from the loss of rideheight when using the 848 pivot lynk the reason you cant use it is it fouls the frame when at its extream point of travle this is caused by the fact the cross section is 40mm where it fouls the frame, as opposed to 31mm on the 996 one, this was not shown on the cad drawings and unless you was looking at the two items bolted in place you would not see what the problem was! :think:

my hope is that ether i or another following this will get to the point where we can road test and armed with the right knolage can get this to work then i will have my work cut out re-posting this thead so someone that wants to do it can have the information first and the debait alfter

 

good info. thanks.

 

i really wanted to avoid over-complicating this thread so i will have to edit or re-post at a later date, im glad people want to question what im doing keeping me and others safe (very important) but i wanted to avoid to many numbers or terms of phrase that might stop someone trying this mod, im not 100% how the exaust will fit:think: or if i will encounter any more problems but that will be for a later date until then:abduct:

 

As you will see i have done the 1198 swing arm on a 748 frame conversion.

What i think you are missing here is

All the bits should not only fit, but fit in a correct position, the tie rod just looks wrong on your build.

but more importantly, when the bits are all fitted correctly, the ratio of movement of the swing arm to the shock absorber should be the correct ratio to what you intend its use for.........

I havnt seen you mention once what the ratio of your fit has worked out to, and this is the most critical of numbers.....we sometimes forget just how much research and work is done by a manufacturer prior to homologating a bike. Its not just a case of throwing some bits together......

 

but more importantly, when the bits are all fitted correctly, the ratio of movement of the swing arm to the shock absorber should be the correct ratio to what you intend its use for

all in good time, ratio is on the list and i will get to testing ratios of movment
but that will ony take you so far you might put somthing that moves perfect but acts in an unexpected way

we all need to start somewhere!!

 

i wont be able to go into this in to much detail unless i can get to see a 848 for me to measure and playwith! im sure ducati work very hard on there bikes to get them ready for the road until some kind sole tells me where in space the falcrum point is on an 848 this is the pice of information i am missing!!

the fact is that the 848 swing arm is different technology it works in a different way to my 996 the threads that i looked at, the information was good! but not tactile or clear and unless you had masters in maths hard to understand and it scared a lot of people into not doing the mod, so what i would like to do is just put it toghether and fix the problems alfter, i might end up having a part made or modding the frame and will talk about the forces and effects as i need to, i am under no preconceptions that what i have cobbled toghether is not the ideal solution but it is tactile i can measure it and i can move it!
mabey if i remove the spring from the shock put it back together and start to measure movement and force cause and affect.

 

this has been bugging me!!!!

ive been experimenting!!

my shock with no load is 300mm center to center! fact

it will compress 40mm max! fact

so when compressed fully its 260mm center to center! fact

as its a 848 shock i dont know if it gets longer than 300mm i assume not but i could be wrong!!!

i made a mock up of my shock at 300mm and 260mm using some alli' bolted toghether at the distance required representing the two extreams of shock. then applyed the two different pivot lynks hears what i found.

848 PIVOT LYNK.

full extention 300mm applied (no load) no fouling of the frame

full compression 260 mm applied (full load) i could not apply this due to the swingarm fouling the frame where the rearsets bolt on (see pics) also i think the wheel would foul the exausts!!

996 PIVOT LYNK

full extention appied (no load) no fouling of the frame

full compression 260mm (full load) no fouling of the frame and no rear wheel fouling the exausts!!

you could use the 848 pivot lynk and a longer ride height bar, but with extra length the bar would become less strong and may fail evrything lines up well with this lynk
with the 996 pivot lynk not everything would line up true although its only 5mm the ride would be harder

when looking at an 848 set up it looks as though the rideheight bar, shock and pivot lynk forms a triangle i think the 140mm must be maitained on the pivot lynk if you flattern out the pivot lynk maintaining 140mm the only point that can move is the falcrum and that would have to be moved to the place where the ride height bar and shock most closely resemble the 848 set up under natural load (eg) when the bike is upright and not moveing with the wheels on the ground with the weight of the bike on the wheels.

i think the thread i read before i miss understood where and what gets fouled against eachother its not the pivot lynk as i thought its the swing arm, and there is no cad drawing that would have showed me this! as stated the ride will be harder with the 996 set up by how much i dont know yet!! but i know this because the force of the shock acting on a longer arm transfers more of its force acting onto a shorter arm!!!

the best example i can give :think: its like the differance bettween using a hammer to remove a 6" nail or a crowbar/nailbar the shock (your arm) is the same but the falcrum has moved and the energy transferred has changed the 996 pivot lynk is the crowbar/nailbar and the swingarm is the nail :think:

this is my starting point not the final solution!!!

 

ratio

ratio!, in this case it revolves around 140mm and the fulcrum, the rideheight bar is what it is and so is the shock!! one moves and one dose not!! im very drunk and this debate is annoying me to the point i want to (fall asleep)zzzzzzzzzzzzzx

 

ok i can see you are from Downham market........:abduct:

take the spring off of the shock, fit it all together on the frame.

now measure the movement of the swing arm arc in say 5mm sections from its lowest point up to its highest point

if you also measure how much the shock compresses each time you move the swing arm you can then work out the rocker ratio ie swing arm movement to shock absorber movement.

from these numbers you can now see if the ratio increases decreases or stays the same........

 

As a bit of a clue i recon most will have around 120mm of swing arm arc and around 60mm of shock stroke give or take what kit youre using and for what purpose

so you can see its around 2 to 1 ratio.....

the corse track stuff will stay consistant around 2.2/2.3 to 1....ie a flat rate or linear...

 

i wont be removing the spring from the shock, but i will mock up a shock tool from alli for your ammusement!! 60mm of travel the numbers wont lie lol

then i will be able to mock up a solution ie a new piovot lynk.

i live near to downham in norfolk, im not from norfolk lol

 

dont forget each make model of shock may be different in stroke so youll need to know what stroke the shock is you have..

Also you need to be really accurate with the numbers........if a jobs worth doing........for example i read that you said your shock was 300mm...........you sure its not 298........

 

http://img.ducati.ms/forums/images/ducatims/editor/attach.

ok this is my mockup of a shock!

i will be able to measure the shock distance lockit in with the nut and bolt and add it to the swing arm and measure how far the ride height bar has moved to find out what the ratio is!!!

but that is for another day im going to bed!!

 

the pivot lynk!!!

ok so i have been doing some measuring up, and have found although the 996 pivot lynk is not perfect it dose work and the ratio is not that far off stock but......i say..... FUCK ALL THAT!!

I have a mate that is going to make me one up, hes a machinest by trade and all round lunatik. so hes going to make one the same as the 848 stock item, just flat! elliminating the rideheight issues and ratio problem all in one go!! so the suspention will work as the stock 848 dose no hassle for me no hassle for you just pm me if you want one!!

anyways it will be a while before i get my greasy mits on one but i cant wiat lol

I belive now that it will just be the exaust that causes issue now, so i have brought a 1098 titanium exaust and that is what i will use to cure the issue!
as i understand it the stock item would rub on the swingarm so it will be a chop and weld job but until i get my engine in the frame, that will have to wait!!

all im wondering now is how much longer i have to wait for my pivot lynk cos im an impatent git!!:abduct:

 

I have a mate that is going to make me one up, hes a machinest by trade and all round lunatik. so hes going to make one the same as the 848 stock item, just flat! elliminating the rideheight issues and ratio problem all in one go!!

Awesome... I don't have access to either the swingarm or the rocker from an 848, so I am not sure if this is an issue or not, but make sure he takes into account any side to side dimensional difference for the linkage pivot between the 916/848 rockers as well. This will let you get rid of any potential angular offset on the linkage/ride height adjuster, like you had in one of your first mock ups.

If you going to go this route, go all the way and do it right!