[rays748]

I am currently building a 916 engine and have some questions about the crank shims.
I have done a couple calculations and one number has come up different on my measurement on one half of the cases.

Formula “S”= P1 + P2 - I + 0.15
Calc #1-
44.7 + 44.5 - 87.7 + 0.15 = 1.65
P1= 1.025
P2= 0.625

Calc #2-
44.7 + 44.3 - 87.7 + 0.15 = 1.45
P1= 0.925
P2= 0.525

I ended up putting in the following shims
P1= 1.00
P2= 0.5

How critical or precise do I need to be?
Any input would be appreciated.

Side note: I’m not a mechanic and this is a bucket list project I’m working on.

 

[bradblack]

you're better off physically measuring the end float and calculating shims from there. you want to be within 0.05mm.

 

[rays748]

I’ll try the end float way and see what numbers I get. The thrust washers only come in
0.2
0.3
0.5
0.15

Thanks

 

[bradblack]

you just stack them up as required.

 

[Turbomart]

Brad , please correct if I'm wrong but I would think you would be better off slightly loose rather than too tight. That is within the specs still though.
I believe the ones that failed where due to being to tight.

 

[bradblack]

late spec is 0.30mm, i wouldn't go any higher than 0.2mm. but no less than 0.15.

when i've reshimmed the thick shim engines (which always seemed tight ex factory) i know i've taken 0.3mm out and still had 0.15 - 0.20 preload.

 

[rays748]

Ok, I was able to set up a dial gauge to test the end float. I still have the 1 mm and .5 mm shims on the crank case. For the end float the dial gauge reads .36 mm. Do I now add all these up and divide by two?

 

[Turbomart]

You need enough shims to = 0.56mm in total. Then divide them as equally as possible so half the shim stack goes in each side. I usually measure shim stacks with a micrometre to get accurate readings particularly when reusing 2nd hand shims. 0.36 will remove existing free-play bringing you to 0 free-play. Then you add the disired amount of preload 0.2

 

[rays748]

So, if I understand correctly, I currently have a total free play of 1.87mm then add my preload of 0.15 giving me 2.02mm. If I divide this by 2 I basically put one 1.0mm shim on each side.