by David Gentleman » Mon Jul 24, 2006 3:03 pm
Give it a go, tis worth it if it is knackered. but still be prepared to maybe get it reconned properly..
The difference between rebuilding a turbo yourself, and having a company do it, is they can check all the tollerances on the wheels to housings, shaft thickness and wear and rebalance the thing..
If the shaft is scored or worn (or scorched) then it will wear the bearings or seal again, and it could smoke or fail again. If the compressor or turbine wheel have excess tollerance through wear to their housings, then the turbo has to work double time to maintain the original boost level, and thus wears out quicker. This then coupled with a turbo that hasnt been rebalanced means that it dies even quicker..
Turbo rebuilding companies first strip the whole turbo down, then bead blast every component. This will also clear any debris from the oil ways to prevent contamination when later fitted back on the car. Then all the parts are checked for tollerance, if they are too far gone, they are replaced for new. Most of the time only the housings are used, most of the 'spinny' bits are always replaced.
As for the old 270 degree bearing against the 360 degree unit, no one has ever answered what is better. 360 degree thrust bearing is meant to be better as it is 360 degress round, but saying that, no modified turbos have ever lasted 100k miles, yet the original units can, even with increased boost.
You have to consider why Garrett used a 270 degree in the first place. There must be method in their madness!