Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > 998 / 996 / 916 / 748 > Crankshaft Shim size??

[beasty1711]

ive finally made a start on re-building my 2000 748 engine...
and have gotten to the point of needing to order the shim's for either side of the crank.

Now according to Mr Haynes Manual i measure the left hand hight (P1) of the engine case to the inner race, the same on the right(P2), and then the width of the crank shaft (A)

I then use the following formula to calculate the total amount of shim space required.

P1+P2+0.15-A

My figures are
46mm + 45mm + 0.15mm -88mm = 3.15mm


To then figure out how big each shim should be apparantly its

Left hand side =
(P1 + 0.075-A)/2
so 46mm+0.075-(88mm/2) = 2.075

and then the right is the 3.15mm - 2.075 = 1.075

My problem is that the smallest shim i can find in the parts list is 1.9mm... not 1.075mm...

do you lot rekon this is down to my measuring or is there something else i should do/ try ?

[Jools]

Hmmmm...probably a mite technical for 95% of the people on the board, but there's bound to be a guru along in a minute who's actually done this job for themselves.

In the meantime, I'll do my bit by bumping this to the top again.

Welcome to the board by the way...I'll have a nice long cool pint of Guiness

[Chrisiball]

Give Nelly a call at cornerspeed, i watched him measure, and calculate the shim size on a program on the PC, for my engine, he has some shims also.

[nelly]

Can't remember the formula off the top of my head. I use a spreadsheet to calculate the shims. Nothing fancy, just takes the formula and means I just enter the variables.
I have found though that invariably, the formula results in too tight a fit, and I end up reshimming the crank again.
Use the formual to get you in the ball park, but finish the job off by feel......
Also, check all the other shafts in the cases whilst apart. They are usually a bit "sloppy". Getting it all right makes a much smoother bottom end

[beasty1711]

thanks for the replys...

i've re-measured again last night and noticed that one of the bearings need to go in another 1mm...

so that would put my total endlfoat around 5.09mm

using the calcs that haynes suggest that would put me around
3.075mm for the left and 2.015 for the right...

would u suggest 2.55 and the 1.95mm then for the shims if the calcs are a bit on the tight side?

[nelly]

To be honest, it's a tough call to say for definate what will be right. You'll only know when it "feels" right.
The two shim thicknesses look to be a little out. By that I mean they are usually very close to each other. 1mm is a little too far out.
What you are trying to achieve is to center the crank in the cases, using the shims to firstly take up any manufacturing errors and secondly to preload the bearings slightly.
Your shim calcs are basically saying there is a 1mm machining error or that one of the bearings is out. That's a lot IMO.
Double check everything again, and then once more. Make sure the bearings are seated correctly. Take measurements at 4 or 5 places on the bearings to make sure they are seated flat.
If you are going to reduce the shim thickness, they need to be reduced by equal amounts else you'll move the crank off centre.
If you need any more help, call me on 01623 758877. Unfortunately it's not an easy operation with the bits in your hands, it's even tougher to explain in text. Good old Haynes

[beasty1711]

hmm fair enough...

ill have another look later on


out of interest what sort of price to size up shims and supply the correct ones? (approx)

[Edited on 13-9-2005 by beasty1711]

[nelly]

you have a U2U.....