was discussing this with a buddy and would like to hear some of your opinions on shaft play. He said some is acceptable and im not quite sure i believe that. Would slight movement from side to side be acceptable?

 

Typically, .018-.022 is acceptable, which feels like a lot. Turbos need a lot of bearing clearance cuz they are what's called a floating bushing type of bearing. Which means the shaft spins in the bushing and the bushing spins in the housing so it splits the rpm between the two to handle the high rpm they run.

 

now that amount of play you spoke of is that removed when adding oil? i know that comes across poorly said but understand what im saying

with that given amount of play you described, would that allow of a slight touching of the fins against housing when you spin it?

 

Oil pressure and centrifugal force will tend to hold it centered, but it shouldn't touch the housing. I have seen some turbos with a lot of ware that will just barely touch then you push them all the way to one side, but when ran they never touch.

 

so your saying all turbos even new ones have some play? main reason for this topic was i was playing with mine today and wanted to see if it had play and it did have some. my PT88 is brand new. I just dont want to be screwed and figured i would ask.

 

The measurement you quote seems a like a radius measurment (centerline to max deflection), for a typical journal type bearing, no? So, if thats what it is then total side to side or up to down would be double that, right? I think thats right... which would make it seem like journal bearing can appear sloppy. But as long as they measure out good and the blades are not contacting then its all good. Been a awhile since I've tried to measure bearing play...

Bill

 

if this matters you actually have to apply some force to move my shaft. just touching it and etc no movement but when applying any force it then moves

{yes i know that sounds in a manner i wasnt trying to type lol}

 

Yep, even brand new. It's necessary. Visualize a match book covers thickness that's about what a new turbo will have side to side and it take a fair amount if pressure to move it, especially in a new turbo because its has slide the bushing between the side of the housing and the retaining snap rings for the oil clearance between the bushing and the housing and it is assembled with assembly lube which it thick and stiff. Make since?