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Question How Much Shaft Play Is too much?(K27)

Update:

YouTube video:

http://www.youtube.com/watch?v=V4x9AiWVfS4


Hello Everyone!

I am Noob, I am trying to collect parts before I can turbo charge...

Anyway, I bought a "eBay special rebuilt" turbo... Thought it would be a good turbo...

Its a k27-7006 with a k27-7002 cold side. Is this a very poor choice to begin with? Should I try to return and run?

I am planning to rebuild my 3.0 with turbo rods machined to work with my 3.0 crank and stock 3.3 P&C. Which will make it something like a 3.16L

To make the matters worse, there seems to be a lot of shaft play on the cold side... When I wiggle the shaft lateral the gap between the fan blades & housing grows from .008 to .025 thou. ( As far as I can measure with my normal feeler gauges.)

What size of gap tips of the blades supposed to have normally before I wiggle the shaft?

Is the shaft supposed to have free play in it at all? Or how much is ok for a "rebuilt" turbo???


Thank you very much gents!
Gene


P.S. Would a YouTube video help?


Last edited by KoenigsTiger; 05-20-2013 at 05:14 PM.. Reason: YouTube Vido Added
Old 05-16-2013, 09:07 PM
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According to what I have to reference, I have .35mm for end play and .65mm for radial play.
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Old 05-17-2013, 03:28 AM
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can a turbo be a source of an air leak?
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Old 05-17-2013, 05:01 AM
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Thank you for a quick reply sundevil64!

".35mm for end play and .65mm for radial play" this is for a max allowable play before a rebuilt is required? or is this for a new unit?

Thank you very much sundevil64!
Old 05-17-2013, 05:02 AM
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Quote:
Originally Posted by T77911S View Post
can a turbo be a source of an air leak?
I am sure an expert will answer this for us.
You're asking if the gap around the compressor wheel can be cause an air leak? It sucks the air in, but the more gap the less efficient it is. Of course hose connections can leak...
Old 05-17-2013, 05:09 AM
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I'm not a turbo expert, but here's a post I left recently...information I scabbed from someone who has more experience than I rebuilding turbos:

Some turbo measurment guidelines:

Can a .010” feeler be inserted between the tips of the small dia portion of the compressor and turbine and their related housings? Generally all these small auto turbos seem to have similar tolerances when new. Roughly .010 to .015” measured radially at the nut or at the extension of the turbine.

On new turbos the end play seems to be well under .005” and often hard to detect with your hands. If it’s exceeding .005” the ring seals will take a beating and are more likely to pass oil.

When the radial play is around .025” but more importantly if the feeler gauge measurement between the wheels and the housings gets down to .005” it’s time to have the unit overhauled prior to having the wheels rub which will ruin the balance and potentially damage the wheels.
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Old 05-17-2013, 05:54 AM
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Quote:
Originally Posted by KoenigsTiger View Post
P.S. Would a YouTube video help?
Yes for some of us still cutting teeth!
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Old 05-17-2013, 07:26 AM
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yes, air leaking past the shaft.

mark, was that article on pelican?
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Old 05-17-2013, 10:24 AM
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This is a question that comes up often. Proper measurement is nearly impossible with the proper equipment and the best of circumstances.
I advised my customers that visible rubbing at the tip of the compressor blade is indication of bearing wear sufficient for rebuild.
If you don't have it use it as is.
Same with shaft end play, no rub when lightly pushing the shaft toward the compressor, turbo is good to go.
Old 05-17-2013, 03:37 PM
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yes, air leaking past the shaft.

mark, was that article on pelican?
No, it was from PM's between me and another member when I looked into rebuilding my turbo. This is a highly debated topic, DIY turbo rebuilding. The rebuilding part is easy, the balancing part is impossible DIY, although a person can get by pretty well by marking the shaft and turbin wheel(s) before disassembly to assure they are re-installed exactly where they were before taking it all apart. Personally, I think this is all shrouded in mystery but again, not difficult at all to rebuild, but to get the longevity a person should have it professionally balanced.
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Old 05-17-2013, 06:53 PM
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Feeler gauge on a curved surface isn't ideal. A pin gauge IMO is far more accurate.
Old 05-18-2013, 07:07 PM
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Originally Posted by Tippy View Post
Feeler gauge on a curved surface isn't ideal. A pin gauge IMO is far more accurate.
Good point. Would make a difference of several thou fer sure. But if it's that close, then it's out of tolerance anyway and time for a rebuild.
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Old 05-18-2013, 07:24 PM
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Quote:
Originally Posted by KoenigsTiger View Post
Hello Everyone!

I am Noob, I am trying to collect parts before I can turbo charge...

Anyway, I bought a "eBay special rebuilt" turbo... Thought it would be a good turbo...

Its a k27-7006 with a k27-7002 cold side. Is this a very poor choice to begin with? Should I try to return and run?

I am planning to rebuild my 3.0 with turbo rods machined to work with my 3.0 crank and stock 3.3 P&C. Which will make it something like a 3.16L

To make the matters worse, there seems to be a lot of shaft play on the cold side... When I wiggle the shaft lateral the gap between the fan blades & housing grows from .008 to .025 thou. ( As far as I can measure with my normal feeler gauges.)

What size of gap tips of the blades supposed to have normally before I wiggle the shaft?

Is the shaft supposed to have free play in it at all? Or how much is ok for a "rebuilt" turbo???


Thank you very much gents!
Gene


P.S. Would a YouTube video help?


If there is no oil inside you will have more play... ''A specialist" told me if the propeller doesn't touch all is fine (when no oil inside)
Old 05-19-2013, 04:04 PM
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Yep,

Pin gauges are probably best, I'll have to borrow from work.

Yeah, I don't think there is oil. But there is sound that there maybe some oil, at least I hope so. For the first start up... kinda like when rebuilding an engine...

The impeller dosn't seem to touch, so

Anyway finally got a video uploaded


K27 Turbo Shaft Play - YouTube


Thank you Gents!!!
Old 05-20-2013, 05:18 PM
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Normal, use it as is.

Last edited by copbait73; 05-20-2013 at 07:08 PM..
Old 05-20-2013, 06:09 PM
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Yep,

I just heard all the guys always say "tight shaft," so when I wiggled this one, I felt let down...

Thank you Gents for all the support
Old 05-20-2013, 06:15 PM
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Quote:
Originally Posted by KoenigsTiger View Post
Yep,

I just heard all the guys always say "tight shaft," so when I wiggled this one, I felt let down...

Thank you Gents for all the support
In some circumstances, a "tight shaft" fit is very desireable and to find the fit too loose would indeed be a let down (at least for one's ego)!
Old 05-20-2013, 06:36 PM
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Old 05-20-2013, 06:38 PM
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Quote:
Originally Posted by klefroid View Post
If there is no oil inside you will have more play... ''A specialist" told me if the propeller doesn't touch all is fine (when no oil inside)
Yep, these turbos use bushings that're purposely bored relatively loose...but when pressurized with a bed of oil, it allows the shaft to center itself and 'float' as it were, enabling them to spin up to those high rpms quickly. Even a brand new bone dry turbo will show some play, and that's by design. All measurements provided earlier have that in mind as to what is normal vs. excessive wear. As long as the turbine blades don't touch the sides of the housing, then presumably you're ok to run but may lose some efficiency due to excessive wobble. Sooner or later, it will wear enough to rub.

As to tight shafts....well now, it's been a long while. Not sure about the turbo WG dump pipe as being a suitable 'port in the storm' by any means, irrespective of the 930's wide hips.
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Last edited by mark houghton; 05-20-2013 at 07:24 PM..
Old 05-20-2013, 07:20 PM
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Ha - too funny, Mark! Regarding the WG dump pipe, mine has both, different sized holes, side by side, in between the hips - wonder what that means?!

Old 05-20-2013, 08:08 PM
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