How much shaft play is acceptable?
 

How much shaft play is acceptable on a t78. I took my filter off to feel for shaft play and it moves very very very slightly from side to side. It cant be more then a mm or 2, and it is fairly hard to move the wheel that small amount.

Im trying to see if I am having any turbo problems being that I feel I am making a lot less power then I should.

I only trapped 109 mph at around 14-15 psi on my t78 with a 1.9 60 ft time. I did on the other hand burn my clutch out the next run directly after this, so im sure It had some to do with the clutch slipping, but im not sure. I feel at 14-15 psi, I should be trapping somewhere around high teens.

Adam

wow, nobody?

someone posted some numbers in a previous thread

i don't recall who posted but did record the numbers and since you haven't received any responses thought i would offer them...

radial play .004
axial play .0015

i assume that's for a journal bearing turbo as ball bearing turbos would have next to nothing as clearance.

my guess is my turbos have more play than the numbers above. keep in mind that you have a floater bearing which has 2 areas containing oil and when you are wiggling the compressor there is no oil pressure so the wiggle, it would seem to me, should be the total of the two clearances on each side of zero. i would think you would have two approx 3 thousands on each side of zero so you could have total play of .012

i admit i am speculating and invite any informed opinions.

howard coleman

There should be absulutely no front to back shaft play.. The shaft play should be minimal and none if its BB. In other words, if the blades touch the housing, then its no good.

Thanks for the response, thats the exact kind of info im looking for. The turbo has absolutely no back and forth play, and the up and down play is very very small, and absolutely does not touch the sides.

The more i sit and think about it, the more i think my problem is clutch related. For the past month I have noticed that the car would get a little choppy around 5000 rpms, and i always thought it was either water injection related or ignition related. The more i think of it, the more i realize it was my clutch slipping. I also noticed that my boost fluctuated quite a bit during wide out throttle, and could never figure out why I was getting such fluctuation, even after ajusting the boost control to a ton of different settings. I have been thinking that a slipping clutch could cause to the boost to fluctuate, do to the fluctuation of the load due to the slipping. Does this make any sence to anyone? Has anyone else had boost fluctuation while their clutch was on its way out?

The new clutch is going in on thursday, so I am praying this solves my problem. If it doesnt I am back a square one, which is exactly where I dont want to be.

Adam

hey adam,

the turbo play sounds within spec, I wouldnt worry about the T78. So when are we going to race ;)?

lol, its not looking good for this season. Maybe after this winter, I can make my way down that way for some kind of meet or bbq. Or maybe Rotary revolution 2006, if you go. Either way, im looking forward to it.

Adam

wjat if they almost touch the housing?

as long a it doesnt touch the side, youre fine. if you arent sure whenther it touches the side, just look at it, it will get real shiny right before it starts to actually rub, and then you will start to see scratch marks. if it gets shiny, thats time to rebuild it, if it scratches more than a tiny bit, then you have to get a new compressor wheel when you rebuild.

pat

Well, At least I know why my quarter mile time was soo shitty. We got everything apart and apparently i destroyed everything that has to do with the clutch. Not broken but completely worn out. My flywheel, pressure plate, clutch disk, and throw out bearing are completely shot. After spending another 740 dollars on parts, i should be back together by next weekend.
Man i really am starting to hate this car!!!!! I keep telling myself "If one more thing goes wrong with this car, I am done with it!" Somehow it just never works the way I plan. I always seem to dig deeper into my pocket (or in this case my credit, lol)to get it fixed. ugh. I guess I can say it again, but i just have that feeling I wont follow through. :)

I let you guys know how much faster the car feels after i get the clutch and shit done.

Adam

well if you decide youre done with it, and you want to give it free to a good home, give me a call, i'll come get it :D