E29 crank, 3 pins?

[GlenDouglas]

Hi everyone hope you can help.

Rebuilding crank on E29.

It has 3 pins to locate.

Question should these be proud or flush to the bolt hole.

Thanks Glen




[Attachments converted to linked images. 12Dec21 -Doug, Admin]

[Doug]

Glen,

Flush to the face. Should be a tab washer under the bolt head as well.

-Doug

[GlenDouglas]

Yes I have the tab washer.

So this should be flush, therefore pins flush to allow the washer to be dead flat right?

My pins stick up 1mm is. .


Glen

[Doug]

Correct.

[GlenDouglas]

Any ideas on how tight the crank bolts are for torque loading?

[Doug]

Glen,

You never see torque specifications for this old stuff. You were just expected to know the bigger the hex, the bigger the wrench, the harder you can tighten it. Big end assemblies were not something the customer was expected to reassemble, so Douglas' advice was invariably "return to the Works". Even if they had mentioned bolting it back up, they would have said something vague like "dead tight". They did not sell socket sets with meter long breaker-bar handles, so you were limited to normal box and open spanners of the day. It is a highly stressed joint, so it can be safely assumed Douglas used a decent steel and heat treatment on the bolt. I would research torque specifications for a similar size and pitch thread for a modern fastener, in a medium to high grade strength. That is probably the closest you will come to what would be scientifically correct.

-Doug

[GlenDouglas]

Doug, thanks, when tightened was straight through the bearings on the shaft, but were shaft is tapered for fly wheel, it is out. Need to look at getting straightened any suggestions. Or is it get a new shaft pressed and machine.

Many thanks Glen

[Doug]

Glen,

The flywheel taper and the bearing journal are ground in one setup, so it is odd that one is true and the other out. Perhaps it is out at the journal a imperceptible amount. The further out to the end you get, the greater the eccentricity will register. How much is it out?

If you are checking the crank assembly on vee-blocks, then of course the bearing journals are going to run true at the point of contact. The rest of the journal might not be far enough away from the support to register eccentricity but the taper and the timing gear journal are. In that case, it is a matter of the assembly is still not true enough.

The shaft is integral with the throw, so pressing in a new shaft is not an option. To a very minor extent you can re-cut the taper. This will cause the flywheel to seat closer to the crankcase. The problem is due to the shallow taper, a little off the taper moves the flywheel in a lot. You might bottom out the clutch operating mechanism.

-Doug

[Jonathan Hewitt]

Good evening, have been looking at this with a bit of interest and thought that if the crank is assembled without the pins ,is it then possible to get it true ? 
If the pins are flush will this not stop the crank half from pulling down flush and tightening fully ?
As previously noted any small amount of inaccuracy at the big end end will amplify  to the crank end.
Has this been assembled and run previously with the pins proud causing damage to the  big end pin shoulder ?
presumably the two mating parts do rest on a shoulder and if any damage has occurred to the shoulder / mating face this would cause the misalignment ?
How much is the runout ?
Jonathan
My thoughts make sense to me but I can't translate to print very well

[GlenDouglas]

The main bearing surfaces run out is .003" the taper end shaft for fly wheel is .035"

So bearing side as said was machined in one, looks like the fly wheel has been hit and put out.

[GlenDouglas]

See pic with notes




[Attachments converted to linked images. 12Dec21 -Doug, Admin]

[GlenDouglas]

We think this was also caused maybe by the fly wheel being loose. The key way is chewed out.


I am thinking can the taper be sprayed with metal and then machined?


Anyone used Thermal metal spraying?

[Bert]

Hi Glen,
Is the outer end of the timing side out at all. If it is, is it on the same side as the .035 of the drive side? This would mean the crank assembly may be out of true axially and could be trued more by squeezing the opposite end of the crank pin gently in a vice.
I came across an article which explains truing of cranks very well. Google “Oz Vincent Review”, it is an online magazine and the latest volume #46 has the article written by “Slide rule”. My father in law tells me this was the Nom de Plume of one Mr. Philip Irving which explained why it was so accurate and simple to follow.

[eddie]

Hi Glen,
             You show the drive side main journal as being 'good' but with .035" runout on the taper. Could I suggest that you make up a couple of crude, narrow 'V' blocks from 2mm sheet steel with a flange at the bottom so that they can be clamped down. You will then be able to support the crank close to the shoulder on the main shafts and check for runout at the other end of the journals, as well as the end of the taper. This will then determine whether the whole drive side shaft is running out or is bent close to the end of the taper. Having had a good look at the photo, it seems as if it is just the drive side shaft that is not true to the rest of the crank ( the gap between the webs looks narrower at the crankpin - in which case, a gentle squeeze in the vice, on the open end, may bring it back in line). If it is just an optical illusion, and the open end is actually narrower, wedging the webs apart with a screwdriver may have the desired effect!
  I know this sounds crude, but it is surprising how much 'give' there is in a newly assembled crank.

  Good luck!,
                   Regards,
                                 Eddie.

[GlenDouglas]

Split the crank and locked aligned in chuck. Pindle end bent.

Any good grinders and spray metal companies for cranks anybody can recommend UK ?