Main bearings - could this be part of it?

Neil_E. · Mar 2, 2008

Just wondering if the spreading of a crank contributes to the main bearing issues. This can't be good for the bearings. I think the extra spacing of the main bearings due to the width of the balancer must allow some crank flexing and spreading.

How many of you engine repair guys actually dial indicate their crank during a rebuild? I think this should be standard fare for a dealership, but do they do it?

BOSS · Mar 2, 2008

Neil_E.

When you say dial crank during rebuild are you referring to a dial indicator?

If one does not have the cases when rebuilding a crank for them then there are
some issues that may happen even if the crank is perfectly true!

One must make sure that the crank has enough end float (side to side) or the mains
may not live! Anyone who rebuilds cranks for people or themselves does use a dial
indicator, you see that is standard issue.

Neil_E. · Mar 2, 2008

Yes, I left out "indicate". I edited the sentence so it makes sense. I understand the need for end float, there must be allowance for tolerances and temperature expansion. I am wondering if an engine is down for a repair not related to the crank or mains would you check crank runout just to know it is within spec?

How often do you guys find that a crank has spread?

Enginehardware · Mar 3, 2008

Neil_E. said:
Yes, I left out "indicate". I edited the sentence so it makes sense. I understand the need for end float, there must be allowance for tolerances and temperature expansion. I am wondering if an engine is down for a repair not related to the crank or mains would you check crank runout just to know it is within spec?

How often do you guys find that a crank has spread?

When we assemble the engine we always messure the crank, but since we weld it it never twist.
But sure is that its flexing.

The tread regarding this subject is so large, but have some info about this.
//Thomas

Taffy · Mar 24, 2008

Neil_E. said:
Just wondering if the spreading of a crank contributes to the main bearing issues. This can't be good for the bearings. I think the extra spacing of the main bearings due to the width of the balancer must allow some crank flexing and spreading.

How many of you engine repair guys actually dial indicate their crank during a rebuild? I think this should be standard fare for a dealership, but do they do it?

so what is the run out figure for a crank then neil?

and what do you deem the right amount of end float?

regards

Taffy

Neil_E. · Mar 24, 2008

RE: Re: Main bearings - could this be part of it?

The 2007 repair manual page D7 shows a picture of a crank mounted between centers with an indicator over the shaft. The text reads: lateral runout maximum = 0.12mm (.0047")
I doubt the term lateral is used correctly here. I believe they mean to state TIR (total indicator runout). I certainly would not want more runout than their maximum specification.

When I first measured my crank between centers (lathe) I got a maximum of .008 (large runout). This was totally from crank spreading not twist. Some brass mallet work brought it down to .003 (lathe). Thomas suggested that a lathe is not the best method so I constructed a roller stand. I got a measurement of .002 using the stand.

More mallet work got it down to .0015, but it opened up from the TIG welding. The flywheel end is now at .0015 and the primary end is at .0025 TIR. This is based on the stand bearings running right beside the flywheel cheeks.

On the ignition side, the indicator tip is placed at the end of the flywheel taper. On the primary side, the indicator tip is placed at the end of the 30mm diameter (just inboard of the primary gear location). There will be more runout near the very end, but this is only at the oil seal.

I believe that once a crank spreads a significant amount, there is more chance of it moving during welding. A new crank that hasn't spread will likely stay put.

The factory spec for the 550 of .45-.55mm crank end play (.0177-.0216") sounds right to me. I do not see the Husaberg crank as being what I would call "stout". I believe it needs this much end play to allow for flexing (more so than temperature expansion). I feel that roller bearings should be acceptable in this motor, but keep in mind I'm only a casual rider. Racing conditions are much more severe.

Taffy · Mar 24, 2008

RE: Re: Main bearings - could this be part of it?

i knew you had a story to tell!

i'll set 'em up - you tell 'em!

regards

Taffy

AUSBERG · Mar 24, 2008

Re: RE: Re: Main bearings - could this be part of it?

Neil_E. said:
The 2007 repair manual page D7 shows a picture of a crank mounted between centers with an indicator over the shaft. The text reads: lateral runout maximum = 0.12mm (.0047")
I doubt the term lateral is used correctly here. I believe they mean to state TIR (total indicator runout). I certainly would not want more runout than their maximum specification.

When I first measured my crank between centers (lathe) I got a maximum of .008 (large runout). This was totally from crank spreading not twist. Some brass mallet work brought it down to .003 (lathe). Thomas suggested that a lathe is not the best method so I constructed a roller stand. I got a measurement of .002 using the stand.

More mallet work got it down to .0015, but it opened up from the TIG welding. The flywheel end is now at .0015 and the primary end is at .0025 TIR. This is based on the stand bearings running right beside the flywheel cheeks.

On the ignition side, the indicator tip is placed at the end of the flywheel taper. On the primary side, the indicator tip is placed at the end of the 30mm diameter (just inboard of the primary gear location). There will be more runout near the very end, but this is only at the oil seal.

I believe that once a crank spreads a significant amount, there is more chance of it moving during welding. A new crank that hasn't spread will likely stay put.

The factory spec for the 550 of .45-.55mm crank end play (.0177-.0216") sounds right to me. I do not see the Husaberg crank as being what I would call "stout". I believe it needs this much end play to allow for flexing (more so than temperature expansion). I feel that roller bearings should be acceptable in this motor, but keep in mind I'm only a casual rider. Racing conditions are much more severe.

Its always interesting to hear how truing cranks between centres is not really acceptable, but yet there are plenty of this style fixture out there and even a lot of OEM manuals show this style in use...........

I cant really see the harm in using a lathe as long as you turn a piece of round to the appropriate angle and dont remove it from the chuck after the angle has been turned.

I think most of the paranoia about truing between centres comes from the potential damage cranks incur at their centre drillings due to some styles of flywheel pullers without buffer pieces and people who belt on these.Any crank that has damage on either end is definetly best set up with the roller type truing stands-

What style rollers did you use on your stand Neil?- did you turn up some knife edge rollers or just used a flanged bearing or similar??

Neil_E. · Mar 25, 2008

RE: Re: RE: Re: Main bearings - could this be part of it?

Ausberg,
You are correct on the method. I turned a hard piece of bronze as a headstock center. It stayed in place during all my lathe based measuring. That is why the lathe method almost matched the stand method for accuracy. My only concern about "between centers" is that a light touch must be used to engage the centers so no undue force is placed on the crank. And yes the condition of the crank ends is critical.

http://www.husaberg.org/index.php?set_a ... _photo.php

As you can see by the photos I used small ball bearings (.375 x .875 x .281") on the stand. The stand was based on what was handy (scavenged from the short ends rack). The bearings were the smallest I had, never thought about a knife edge style. I'm doing this as a hobby because the ground has been frozen solid for the last 3 months (and covered with a few feet of snow). The annoying part is that I only get to sneak in the shop after hours and it's been so busy here, not many "after hours" have been available.

chilledspode · Mar 25, 2008

Neil

Dang nice work on the crank stand!

Mark

nsman · Mar 25, 2008

A quick and dirty check for crank run out is to remove the LH side cover and the spark plug and slowly rotate the crank shaft.If you can feel even the slightest binding between the primary drive gear and the clutch basket gear you can be pretty sure your crank needs to be trued.
Assuming you have a good set of crank bearings of course.

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Main bearings - could this be part of it?

Neil_E.

BOSS

Neil_E.

Enginehardware

Taffy

Neil_E.

Taffy

AUSBERG

Neil_E.

chilledspode

nsman

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