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Turbo Shaft Play...

Samon

By Samon,
in Engines & Forced Induction

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Samon Proficient

Samon

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Hello all,

My first post (I think... maybe not) over in the 'dark-side' of the forums...

I'm about to do the big RB25DE => RB25DE+T conversion, and I'm pretty sure I've got everything I need... only worry I have is with the turbo itself. It's a stock R33 RB25DET one, but there's a little bit of shaft-play. I've heard that it's okay to have a little bit of up/down movement, but no back/forwards (I guess you'd call it 'end-play' or something)... is this right? It moves about 3mm back and forwards... is it worth getting it re-built? What kinda prices am I looking at for that? I've done plenty of searching, but can only really find threads related to 'items for sale' adverting 'no-shaft-play' or 'minimum shaft-play' so far!

Cheers,

Sam.

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https://www.sau.com.au/forums/topic/221097-turbo-shaft-play/
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Samon Proficient

Samon

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so your facing the wheel and you can pull it up and down or your facing the wheel and can move it side to side with 3mm of play?

if second one then yes its rooted.

If I look directly into where the dump-pipe bolts on, i can slide it... in-and-out about 3mm

R31Nismoid Grand Master

R31Nismoid

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Better than moving side to side? wtf?

Side to side is perfectly OK, every single turbo will have S-2-S movement even for a ball bearing turbo. Bush bearings move substantially more.

When the car is on, running with oil pressure this movement is taken up by the oil in the cartridge.

Front to back (or in and out) is the BAD movement of the lot.

Samon Proficient

Samon

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Better than moving side to side? wtf?

Side to side is perfectly OK, every single turbo will have S-2-S movement even for a ball bearing turbo. Bush bearings move substantially more.

When the car is on, running with oil pressure this movement is taken up by the oil in the cartridge.

Front to back (or in and out) is the BAD movement of the lot.

That's the impression I was under. I'll have to have a look at it tonight when I get home, but how much movement (in and out) is okay?

Kinks Grand Master

Kinks

Posted
Posted
Better than moving side to side? wtf?

Side to side is perfectly OK, every single turbo will have S-2-S movement even for a ball bearing turbo. Bush bearings move substantially more.

When the car is on, running with oil pressure this movement is taken up by the oil in the cartridge.

Front to back (or in and out) is the BAD movement of the lot.

From what I have picked up over the years, in a bush bearing turbo any axial (front to back, in and out) movement is bad because it means the thrust washer has worn out. Some radial movement is OK. In a ball bearing turbo, a very small amount of axial movement is OK. Radial movement is a bad sign.

That said, a friend's brand new ball bearing HKS turbo had about 3x more radial play than the stock item we took off. I was quite surprised but I guess they run wider clearances as part of the design.

Plenty of disclaimer on the above though, I have done 2 turbo swaps myself but never one due to imminent failure :down:

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

The new turbo = no oil in it.

Turbo taken off car = some oil to pickup the slack.

Turbo off a car, same model etc probably should have less play (except if its worn and so on)

I've had my turbo's off, bush bearing, had a bit of play, same with my GT30

So one of each type, and both had side-t-side, the GT30 had less... but then we are talking MM here so its minimal overall

Samon Proficient

Samon

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  • Author
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The new turbo = no oil in it.

Turbo taken off car = some oil to pickup the slack.

Turbo off a car, same model etc probably should have less play (except if its worn and so on)

I've had my turbo's off, bush bearing, had a bit of play, same with my GT30

So one of each type, and both had side-t-side, the GT30 had less... but then we are talking MM here so its minimal overall

Just had another look, much closer this time, and in reality we're talking about less than 1mm in/out play. This should be fine, right?

nizmonut Community Regular

nizmonut

Posted
Posted (edited)

i was reading manufacturers manual the other day and browsed past this particular subject, factory manual says ideal maximum forward to back movement or thrust should be .8 of a millimeter.

Edited by nizmonut

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