1098 crank end float. etc!!

[Pilkie]

Hi all.

Not being used to the specs on these engines,I just want to pick your collective brains re the 1098's crank endfloat and checking it.
Had a feeling the end float was excessive,so while dropping the sump to remove pistons to check and replace sticky rings,I had a look at the end float on the center main bearing.
Moving the crank front and back,the gap i've measured is 19 thou,ie about 9.5 thou per side.
I cannot find the spec in the manual I have,so what should it be??
Once I know what it should be,I can determine what size thrusts I need to get.
BTW,big ends are excellent,as is the center main bearing,but oil rings on pistons,"which are +030" are all gummed up,so will be renewing all rings.
Bores show no obvious wear,and a very small wear lip at the top,but will give them a light hone anyway.
The head will be treated to the uprated tophat style valve oil seals as the original piddly oil seal ring things were broken,missing and even when new not up to much anyway!
Compression was excellent at 160-170 wet on all 4 pistons,but will clean and give valves a gentle lap in anyway.
I await your comments,questions and suggestions!

Regards Dave

[bmcecosse]

5 thou will be good -and that's NOT 5 thou each side. The thrusts will likely be worn on the face that opposes the clutch operation forces - the other side will probably be 'perfect' .

[Pilkie]

Thanks!!
I will do the maths and then search for some new ones!
Any suggestions as to a good place to buy them,also a set of +030 rings?
Big ends and mains are all good,does anyone see a problem refitting them?

[bmcecosse]

Well - the rule used to be that if disturbed, new shell bearings should be fitted.... But if they truly are 'perfect' then I guess you can take the chance!

[Pilkie]

Well ive spoken to one who knows about thrust washer sizes,and ive worked out that I will be needing a set of +10's.
However it seems the +10's are very hard to get hold of!!
If you know where I can get a set,or a way to solve it without replacing the crank let me know!

[bmcecosse]

You certainly don't need to replace the crank!!! You need more than 10 thou extra thickness.... You probably need to buy a +30 set - only use one pair of them (so +15) and measure carefully again. Should be 4 thou - which is fine !!

[Pilkie]

If I have got my measurements and maths right!
The thrusts in there now are marked +003,and when I measured all 4 of them are within a gnats of being the unworn overall thickness given to me of .095 thou. stds being .092
As the bigs and center main are perfect,or as near as,I have a feeling new bigs and mains + thrusts were put in before it was parked up 25 yrs ago,but they were not big enough!
When I move the crank back and forward,the measured gap is 19thou with 1 side fully open,and the same when I move the crank the other way.
That equates to an even gap either side of 9.5 thou,so given the end float should be about 2.5thou either side give or take a gnats,I need to account for 7 thou either side on top of the +003's in there now,and that means +010's! or .102 overall thickness.
Any ideas where I can buy some!

[philthehill]

Your methodology seems overly complicated.
All you need to do to check the end float is to assemble the crank in the block with all the thrusts in place, push the crank hard backwards and insert a feeler gauges between the rear thrusts and crank web and what ever the sum total of those feeler gauges is your end float. You can double check/repeat the process by pushing the crank hard forward insert a feeler gauges between the front thrusts and the crank web and the sum total should be the same. End float should be 3-4 thou and at max 5 thou.
I do not understand why you are measuring end float with thrusts out (fully open)? Am I missing a trick here or have I misunderstood what you are doing.

[Pilkie]

I think you have misunderstood,as there is no real point measuring end float with them out!
I have measured the gap as you describe with thrusts in!
When I said fully open I mean the gap is as open as it can be with crank forced back or forwards!

[bmcecosse]

[Pilkie]

The information I have is that sizes available are, std,+3,+10 and +30.
However +10 and +30 are hard to find!
If a +30 set can be found,or even 1/2 a set if somebody has done the same,then thats fine,if having the crank everso slightly off center without even size thrusts either side will matter.

Hang on???
If each thrust is +3,+10 or +30 over std size then +30 will be too big to fill the +15 gap!
Each thrust as far as I am aware will not be +15 making the set overall +30 will it?
Think I will have to visit a local engine shop,and see what they say!

[bmcecosse]

[MarkyB]

A circular shim with an ear should do the trick, how thick are drinks cans these days?

[katy]

About 2 1/4"

[Pilkie]

A biscuit tin lid did the trick!
Shim on the front side that doesnt get the thrust pressure!
End float is now 5 thou!

[bmcecosse]

[Pilkie]

CRUMBS! I never thought of that!
I have a mate at an engineering works who has some extra strong glue used for metal on metal,and heat resistant,he will bond them for me.
And as they wont be subject to movement or pressure from crank when operating the clutch,it should work.
I will of course be on the lookout for a set of +10's.

[Rust bucket]

Sorry to jump in on this conversation but i've just finished the bottom end of my engine rebuild fitting a reground crank and standard size thrust washers, crank turns fine but there is no end float on the crank, would this be okay?.

[bmcecosse]

Errr - NO!! There must be some end float usually 3 to 5 thou is recommended. Are you sure there is none ??

[Rust bucket]

One book I have says 3 1/2 thou, at most it would be 1/4 thou.