Technical Crankshaft End Float

[jolly500]

Hi all.

Is there an accepted method of taking up end float on the crank. I have about 2mm currently!!

Thanks
Steve

 

[the hobbler]

Is that with the washers, crank sprocket and pulley all in place in place and then the big nut tightened up?

 

[Bleeding Knuckles]

Hi all.

Is there an accepted method of taking up end float on the crank. I have about 2mm currently!!

Thanks
Steve

Hi Steve, the only way of measuring the correct crankshaft end-float is to assemble the crankshaft components completely and use a feeler gauge between the rear shoulder of the crank against the forward internal face of the rear support bearing. Look at thread "Barrels/Pistons Scoring. Salvageable?" post number #45 this will show two pictures giving the procedure. The limits of end float are as follows - .0118 to .0173" or 0.30 to 0.44mm
My engine builder regarded the upper limits to be excessive !!!
If you have some 2.0mm I would council that you replace the main bearings as that is a lot of wear
Ian.

 

[the hobbler]

Following up Ian's comments. The only way to check the end-float of the crankshaft is to bolt the whole unit up with the big nut---washers, sprocket, pulley, oil-spinner, tab washer and then the big hollow nut. You don't need to torque the nut up to the full amount, just fairly tight. When you have done that you will find that you can push the crank TOWARDS the flywheel end--just. I normally build them up with just 10thou end float, so that you are able to slide a 10thou feeler between the rear (t/c end) of the crankshaft and the end surface of the bearing. The bearing with the 2 chain-channels goes to the timing-chain (t/c) end. As Ian mentioned, the factory clearance of between 12 17.3 thou is quite big!

 

[jolly500]

Thank you Tom and Ian.

I believe I do have all the gubbins on the crank and the big nut is tight so tomorrow I shall dismantle enough to take an accurate reading. The movement is definately more than the maximum allowed.

I'll also post some pictures of all the parts in sequence in case I'm missing something, or got the order wrong.

Am I correct in saying that the only way to reduce any excess play is to replace the main bearing? That worries me somewhat as I believe the bearing is a new one.

Regards
Steve

 

[Bleeding Knuckles]

Thank you Tom and Ian.

I believe I do have all the gubbins on the crank and the big nut is tight so tomorrow I shall dismantle enough to take an accurate reading. The movement is definately more than the maximum allowed.

I'll also post some pictures of all the parts in sequence in case I'm missing something, or got the order wrong.

Am I correct in saying that the only way to reduce any excess play is to replace the main bearing? That worries me somewhat as I believe the bearing is a new one.

Regards
Steve

Hi Steve, If you have all the components fitted correctly the only item(s) that can
effect the end float are the two main bearings and the crankshaft itself. !!!!!
Ian.

 

[jolly500]

Hi and thanks for the replies.

I've attached a pic of the replacement main bearing (on left) and one from another early engine I have (on right). The extent to which the bearing protrudes from its casing on the old main bearing compared to the flush fitting on the new, would take up most if not all of my current end float.

I wonder if the 'early' style main bearings are available or how would I fix that?

Regards
Steve

 

[Toshi 975]

I have never seen a rear main bearing that protrudes beyond the face of the bearing case in fact all the engine drawings in the original workshop manual show it flush. I believe that originally you could buy the main bearing white metal inserts to fit the housing so you could have one that has been fitted incorrectly or possibly been made as a repair. Apart from that the crankshaft end float is determined by the components at the timing chain end. The sectional drawings show the crankshaft nut, tab washer, oil flinger, crankshaft pulley, timing chain sprocket, piston ring type seal, spacer with chamfer onto crankshaft & main bearing.

 

[fiat500]

Hi and thanks for the replies.

I've attached a pic of the replacement main bearing (on left) and one from another early engine I have (on right).

Steve, I think some confusion may have set in cause partly by the naming of the parts. On this forum at least, No. 1 cylinder is usually taken to be the one nearest to the back of the car; logically, the front of the engine? So I would call the bearing you have shown, "the rear main-bearing". Although, as Toshi 975 has said your old bearing is wrongly setup, if anything, the protrusion might have taken up existing float in a crankshaft; but the new one looks correct.

It is the front bearing which controls end-float, and it does this, once the pulley-nut is tight, by having the white-metal in a top-hat formation. This provides a thrust surface with lubrication grooves. A new bearing should err on the side of having maybe a little too much metal, which can always be taken away. I confess that I have never measured end-float but never been aware of a problem that could be put down to too much float.
PS. I just realised that we've discussed this before and I am just echoing what I said in response to a similar query. Groundhog Day.[emoji3061]

 

[Bigvtwin996]

Hi and thanks for the replies.
......................
I wonder if the 'early' style main bearings are available or how would I fix that?

Regards
Steve

Early engine...

if 110.000 then forget what dealers tell you..
Early engines may look the same as later ones but most of the parts are different and hard to find....
Most dealers have not seen an N let alone owned one....

Speak to Andrea at Passione 500 if you need early engne parts... if he does not have them nor knows anyone who does you will struggle...

 

[Toshi 975]

Early engine...

if 110.000 then forget what dealers tell you..
Early engines may look the same as later ones but most of the parts are different and hard to find....
Most dealers have not seen an N let alone owned one....

Speak to Andrea at Passione 500 if you need early engne parts... if he does not have them nor knows anyone who does you will struggle...

The factory workshop manual starts with the N engine and the drawing of the engine shows the same crankshaft configuration.

 

[Bigvtwin996]

The factory workshop manual starts with the N engine and the drawing of the engine shows the same crankshaft configuration.

no disrespect...
but simply search this forum for the number of threads where "New"parts have been brought and they simply do not fit....
I do actually remember a thread about crankshaft bearings and a N and the owner eventually spoke to Anrdrea who said they were different and had perhaps 2 or 3 original 110. bearings....

110 parts are stamped with a 110 part number....
Read through Spikes thread at the number of times he has been sold "they will fit they are the same parts" from dealers only for them to be "A country mile apart"....

I don't have time or would go through the factory parts books... you will find they have different part numbers...

 

[fiat500]

I don't have time or would go through the factory parts books... you will find they have different part numbers...

Somebody seems to understand this completely:

http://www.fiatplus.com/FRONT-CRANK-ENDPLAY-SHIM.html