big end caps question

[steveo3002]

i have an old polo engine that im fitting new piston rings and bearing shells to 

 

everything looks in order , i fitted the first piston and rod and noticed the rod will wiggle end to end a couple of mm , i wasnt expecting this is it right ?   note thats end to end - same direction as the crank sits , not play or slop in the bearing 

 

out of intrest i fitted the 2nd rod with the old orig servicble looking bearings and thats just the same , so guessing its totaly normal ?

[garbaldy]

If you mean the Conrod slides side to side on the crank journal then yes normal,

This movement should be minimal though

[spartacus]

You mean from side to side? There'll be a specific tolerance for this, it should be in the HBOL, (other manuals are available). Measure it with feeler gauges.

[steveo3002]

yeah moves from the cambelt pullety to the clutch ....i just wasnt expecting this 

 

whats the haynes term for it ...is that end float?

[andy18s]

O you mean the whole crank moves along its length? Thats end float

There may well be a set of thrust bearings to go in which control it

Slightly side to side movement of the big end on the crank is normal as long as it's not excessive.

[steveo3002]

no just the ends moving on the crank....what should i look for in the haynes to check it 

[Junkman]

Connecting rod side play. But I don't think there is a specific measurement/tolerance for it.

At least I have never seen anything to that accord.

[garbaldy]

It doesn't give a measurement in the Haynes,

[steveo3002]

alright then thanks ...its just i wasnt expecting it at all so felt a bit gutted 

 

if the old parts do it then i'll assume its all golden 

[Station]

Oil will provide the extra padding if movement is very minimal.

[steveo3002]

just curious ....so what stops the rod clattering against the sides then , or wearing the edge of the bearing 

[spartacus]

Sorry, I'm surprised there isn't a measurement. If you can't find what you need on the internoodle then maybe call a local engineering shop, they should be able to give you some idea of what's acceptable. I think you need to try and measure it though, so you know exactly what you're dealing with.

[steveo3002]

crank shaft still....big end /rod moves side to side a bit  , i was expecting it to be no slack 

[garbaldy]

They has to be some slack to allow for expansion

[RayMK]

As others have said, crankshaft end float is tightly specified and controlled/altered using thrust washers to achieve spec.  The observation by the poster i.e. big end axial float, is not often specified and there is no real reason why it should be.  The piston in the bore will control the position of the big end on its bearing, subject to some slight variation if the small end also has some axial float.  There are no significant axial loads during engine operation which will force the big end/conrod to grind against the crank, so don't worry.  It is normal.  The crankshaft has to be controlled more tightly because the clutch and probably some internal shafts will apply end loads.  These are properly resisted by thrust washers.

[Junkman]

just curious ....so what stops the rod clattering against the sides then , or wearing the edge of the bearing 

 

The conrod will centre itself at the right position on the crankshaft lobe based on a combination of the direction of the load input it receives during the power cycle offset by the centrifugal force it receives when the crankshaft is rotating.