Turbo rebuild...need manufacturers clearances

[RampantWolf]

Howdy!

I rebuilt my stock turbo with a kit from Majestic Turbo in Waco, TX. I assembled the turbo and there is still some amount of shaft play.

I was hoping someone would know the tolerances needed for the brass bushings? I currently have 0.005". I'm guessing I need 1-2 thousands???

If there is interest I can follow up with a stock turbo rebuild write up with pictures. If there is already one please post the link.

Thanks in advance.

Markus

 

[Damian]

Re: Turbo rebuild...need manufacturers clearances

There is always going to be some shaft play. The journal bearings float on oil when pressurized. As long as the shaft itself was fine, no wear marks and you didn't machine the shaft, then you have nothing to worry about.

 

[RampantWolf]

Re: Turbo rebuild...need manufacturers clearances

I have Garrett turbo for comparison and it is real tight. Definitely less play.

I can machine another set of brass bushings with less tolerance if I only knew what is appropriate?

 

[Damian]

Re: Turbo rebuild...need manufacturers clearances

You can try calling Mitsubishi and asking them. I can't imagine a brand new rebuild kit being too loose unless it's a cheap a$$ kit.

 

[RampantWolf]

Re: Turbo rebuild...need manufacturers clearances

It could be the kit but it could also be wear on the mating surface to the bushings. I think there is a press-in brass sleeve. The two new bushings were within 0.0005" of each other and the inner diameter of the press-in sleeve where the bushings go are the same diameter to 0.0001". The difference between the outer diameter of the bushing and that of the push-in sleeve is 0.005". I can easily make new inner bushings with a larger out diameter to minimize the 0.005" clearance if I only knew what that tolerance should be.

 

[RampantWolf]

Re: Turbo rebuild...need manufacturers clearances

FYI, I got word from Majestic Turbochargers that they allow for 0.002-0.003" clearance between the bushings. The bushing sleeve should be honed to smooth bore of sleeve.

 

[RampantWolf]

Re: Turbo rebuild...need manufacturers clearances

I found in the Chilton online guide that the turbo on my 2006 Dodge Ram 5.9L Cummins diesel one can use feeler gauges to measure the amount of play between the turbo housing and turbine blades. For that particular turbo 0.015" to 0.020" is allowable.

If you know what the above tolerance on your stock Syclone turbo is please post up some numbers?

 

[Damian]

Re: Turbo rebuild...need manufacturers clearances

I'd just try and get new journal bearings from Mitsubishi and be worry free. As far as the Holset turbo, that's a completely different brand and should only be compared as a reference only and not actual tolerances.

 

[RampantWolf]

Re: Turbo rebuild...need manufacturers clearances

The stock turbo appears to have one journal bearing. Talking with Majestic Turbo the stock turbo does not have a journal bearing. Perhaps the turbo has been rebuilt once already.

A hone of the journal needs to be done then cut a new bearing with a OD 0.002" tolerance.

I'll update the clearance between the impeller and the housing when I'm done.

Thanks for all the input guys!