19 replies to this topic

[Pickwah]

Hey guys, quick question!

 

 

Really struggling to get my head around the size of the shim required to set the preload on the diff.

 

I've used the method of pushing the diff to the flywheel side as far as it will go, lightly fitting the top casing and fitting the side cover with gasket to the flywheel side (torqued to 18lbs).

 

I then fitted the other side cover without gasket and tightened the bolts until they "bite".

 

Using feelers I measured the gap of the side cover which ended up being 0.004".

 

Ive measured a compressed gasket and it measures to be 0.012".

 

From reading Haynes it is recommended that the preload is set for 0.004" for the bearing I am using (says thrust on the side).

 

Can anyone point me in the right direction as to what size shim is required as I just cant get my head around such simple maths!

 

Many thanks!

[minimans]

.004 + .012 gives a total gap of .016 so a shim of .016 will give zero preload add .004 to give you your preload so shim's of .020 will do it?

[Swift_General]

It's 0.012" using your figures.

[Ethel]

The gap is equal to the required preload so you need a shim of equal thickness to the compressed gasket.

 

 

Minimans,

 

the gap allows the cover to fit closer (preload), the gasket holds it further away so subtract 4thou from 12thou and it's as if you had an 8thou gasket. You'd need a shim to add back the 4 thou preload 8+4 = 12.

 

gap + shim = preload + gasket

[Spider]

Gap with no shim is 0.004" (as measured)

Gasket fitted thickness is 0.012" (as measured)

Pre-load required is 0.004" - Check which bearings you have - if the are the full race bearing they are 0.004", if the '1/2' race type, they only need 0.001".

 

Working to a full race bearing;-

 

Cover fitted with Gasket will leave a 0.008" Gap between the register and the bearing.

 

So, 0.008" + 0.004" (for the preload) =  0.012" shim.

[minimans]

The gap is equal to the required preload so you need a shim of equal thickness to the compressed gasket.

 

 

Minimans,

 

the gap allows the cover to fit closer (preload), the gasket holds it further away so subtract 4thou from 12thou and it's as if you had an 8thou gasket. You'd need a shim to add back the 4 thou preload 8+4 = 12.

 

gap + shim = preload + gasket

Doh!! Need more coffee before replying............................

[Ethel]

I find tea works best if you're working with imperial measurements 

 

It is one of those things where it helps to step back  and think about the basics - You've got 2 "stacks" of stuff, one where the gasket is and the other you want to be 4thou taller.

[johnR]

Interesting post - I followed the pinned engine/diff build and used .004 preload on my diff without realising there were different bearings with different requirements.  Now going back to change it as it transpires I have the 1-2 thou type.  I wonder if the engine building guide which has been so useful could be annotated to flag up the variation?

[Spider]

  I wonder if the engine building guide which has been so useful could be annotated to flag up the variation?

 

Errrummm,,,,,,,, where might I find this thread??

 

Yes, I can hear your laughter all the way from around the other side of the world,,,,,,,,

[johnR]

??

[johnR]

 

  I wonder if the engine building guide which has been so useful could be annotated to flag up the variation?

 

Errrummm,,,,,,,, where might I find this thread??

 

Yes, I can hear your laughter all the way from around the other side of the world,,,,,,,,

 

Please explain?

[Spider]

 

 

  I wonder if the engine building guide which has been so useful could be annotated to flag up the variation?

 

Errrummm,,,,,,,, where might I find this thread??

 

Yes, I can hear your laughter all the way from around the other side of the world,,,,,,,,

 

Please explain?

 

 

John, you've made reference here to "the engine building guide" which I presume is a thread on the forum. Have you a link to that?

[Sprocket]

The late three part bearings were a thrust type and needed the 0.004 pre load. These bearings are no longer available.

The bearings currently available are a catalogue item deep groove bearing much like the bearings used early on in production. These need less pre load. 0.001 to 0.002 from memory

[greenwheels]

The late three part bearings were a thrust type and needed the 0.004 pre load. These bearings are no longer available.

The bearings currently available are a catalogue item deep groove bearing much like the bearings used early on in production. These need less pre load. 0.001 to 0.002 from memory

Perhaps Mini Spares and other suppliers could confirm that for the particular product they are selling on their websites.

[Wiggy]

Minispares do.

http://www.minispare...f bearing .aspx