StrikerChris
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| posted on 20/5/11 at 09:17 AM |
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Turbo bearings info?
Having removed my turbo to get at another job I noticed a large amount of play in the shaft,both axial and radial,fortunately not quite enough to ruin
the fins.Brg kit £50ish,then £50 to get it balanced which is about £200 cheaper than most companies charge to overhaul so I stripped it.
Question is,there seems as much play between the bush and the housing,as there is between the bush and the shaft.There is no visible sign of wear on
either the shaft or housing,so,is the bush designed to spin in the housing aswell as on the shaft due to the high speed of the turbine,and worn on its
bore and circumfrance,or is it likely the housing is goosed too?
I haven't bought new bearings yet,and dont want to fork out incase the housing is worn,if thats the case I'll throw it back together and
pay the extortionate price to have it done right and atleast get a guarantee!
Info seems hard to come by because most companies just want to do the whole job,which frankly is about the simlest component on the car, so any help
from LCB would be appreciated!
Chris
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lotusmadandy
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| posted on 20/5/11 at 09:37 AM |
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I have rebuilt a few turbos now and use a compamy in
blackpool called turbo rebuild.do a search on ebay,they have a shop on
there and are very helpfull.
Andy
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theconrodkid
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| posted on 20/5/11 at 10:11 AM |
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i splashed out the afore mentioned £50 ish for a rebuild kit,doing it is a doddle really,just remember to mark the 2 fans in relation to themselves
and job done
who cares who wins
pass the pork pies
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StrikerChris
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| posted on 20/5/11 at 10:47 AM |
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Did you notice slack between the bearing and housing when rebuilding yours?
Chris
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MikeRJ
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| posted on 20/5/11 at 11:04 AM |
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When I rebuilt the T28 turbo in my Fiat Coupe I was a bit surprised that the bushes weren't a press fit in the housing, neither the old ones nor
the new ones. They pretty much fell into place but I wouldn't say there was much clearance, you could move the bushes around a small amount.
It's done nearly 40k miles on the turbo now and still doesn't use any oil or smoke.
I did remove quite a lot of carbon from the back of the turbine, this area was partially milled away for balancing, but with the carbon you
couldn't tell - the surface was level. I suspected this could cause imbalance and shorten the life of the bearings so I used a hard plastic
scraper and finished with brake cleaner and a toothbrush - don't use anything that could scratch the turbine as you certainly don't want
any surface stress raisers here.
Had to do a lot of digging to get the torque for the compressor nut as well - one time that I definitely didn't want to guesstimate what it
should be!
[Edited on 20/5/11 by MikeRJ]
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speedstar
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| posted on 20/5/11 at 11:41 AM |
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I disassemble and assemble turbochargers almost everyday in my job and can say that BOTH cases are acceptable, as long as the turbo was designed that
way.
You need to find out if the bearings are fully floating or not. Its very very rare (I've never come across it) to have press fit bearings in
turbochargers due to the miniscule tolerances involved. the shafts spin upwards of 100 krpm, combined with 1000 degC exhaust temps, your thermal
expansion is just to great to allow press fit bearings/bushes.
Contact the turbo supplier and get the tolerance spec sheet from them. Then get out your micrometer or vernier and give it a go
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sebastiaan
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| posted on 20/5/11 at 06:07 PM |
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the bearings are floating. This means you effectively have two 50.000RPM bearings which keeps the shear forces in the oil within spec.
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theconrodkid
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| posted on 20/5/11 at 07:04 PM |
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as others have said,the whole affair is pretty slack,there was some play in the old bearings.
today,s top tip,i used oven cleaner on the housing
who cares who wins
pass the pork pies
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