ak13

iTrader: (1)

Hi,

Planning on rebuilding a TDO4L for my wrx.

Question I have atm: What torque do I apply when re-fitting the nut on the compressor wheel side of the shaft?

Searched Google but can't find an answer

Forester sti

Wow,
That is specific!
Am I right in saying that you want to put the nut onto the turbo shaft??
I would defo say leave it to the professionals!
Seriously, you'd have to secure turbine side, and then twist the comp side!
There is a really big chance of bending the shaft!
Maybe get on to one of the turbo building companys for some advice,
Dan

Splitpin

Forester, you're right urging caution, as this ultimately is a job best done by the people with the kit to do it right, but there's a little hyperbole in your post nevertheless.

There's no chance at all of bending the shaft (or turbine/comp fins) provided everything is held and reassembled correctly, and it's easy to hold the turbine nut with a 12 point socket.

AK, as far as I'm aware the correct torque should be 8.75Nm. However, if you're not already aware of this issue you should be: If you want it to work remotely correctly after you put it back together you must ascertain the relative alignment of the turbine/shaft, compressor wheel and nut before taking them apart, and reassemble them in exactly the same manner, or the balance will be out. If the rebuild kit comes with a new nut, don't use it - put the one that came off back on, especially if it has some tip balancing on it, and, for that matter, make sure you use good quality sockets on both ends so the heads don't get chewed up.

If you concentrate on reassembling everything exactly as it was, by definition you'll get the torque pretty darn close as the nut will be back in exactly the same position it was in before it came off. Also don't forget that the nut has a left-hand thread, so clockwise to remove.

If you're doing this both to learn about turbos, and also ultimately to get a good replacement on your car, it might be worth doing the rebuild yourself, and then getting the CHRA balanced professionally before you complete the reassembly. At least that way you can be confident you're going to get a good unit out of the experience. Even if you manage to reassemble it exactly as it was, which is itself quite difficult, there remains the possibility that the balance might have shifted slightly since the turbo was originally built. Getting it dynamically balanced properly after you've put it together would be the better option.

masterx81

iTrader: (4)

AFAIK MHI turbos aren't balanced at the factory after the assembly. I've never seen an MHI turbo's with the nut grinded out, as you notice ALWAYS on a garrett or other turbos. Actaully, i've not see a garrett turbo without balancing marks on the nut...
Seem that this turbos are only component balanced, then assembled. For sure it's not the best thing to do, and a dynamic balance will do a better job.
In any case, it's always a good precaution to mark the relative position of the wheel and the nut...

ak13

iTrader: (1)

They are balanced. There is marks on the compressor nut.

Still looking for the torque value guys, I would ideally like to see a webpage with it on as I have read on other forums what people are guessing it to be! I appreciate the help but I can't afford to make the mistake of over tightening the bolt and sheering it off. Or I don't want to not tighten it enough and it coming off!

Splitpin

Masterx: As has already been said, MHI turbos most certainly are tip balanced.

Reality check: You've asked the question and I've given you a full response, including both a tightening torque that comes from a very reliable source, and also the specific comment about ensuring the exact alignment of shaft, nut and compressor, and making sure you return it to the correct state on reassembly - which will replicate whatever tightening torque is on it at the moment.

There is next to no risk of the assembly loosening off once in the car as the shaft is left-hand threaded. In use it will therefore tend to tighten up under load, rather than the reverse.

If you want a definitive answer to the torque, phone a turbo rebuilding house and ask them what they use on a TD04 assembly. And then phone another one, and see if the answer is the same, just for peace of mind. Presumably if the number you were seeking was available "on a website", your original search would have uncovered it and you wouldn't be here asking.

ak13

iTrader: (1)

So far I have got a torque value of 17nm /18 nm / 15nm and yours been 8.75. Maybe for every different version on the TDO4L has a different torque?

Yes I appreciate the rest of the advice you have given me and I have already learned it a while back whilst rebuilding some other Toyota ct turbos.

I might try phoning some rebuilding companies or I might actually email MHI themselve (<now there is a better idea!)

Thanks for the help mate

masterx81

iTrader: (4)

Search on google this words:
+mhi "component balanced"
My td04 from a v4 subby desn't have any balancing marks, maybe it's something that they have added over the time.
And if you see grinding marks only on the turbine 'nut' doesn't mean that it's dynamically balanced. But if you find grinding marks on the nut on the compressor side it's for sure not only component balanced. The compressor wheel due to it's bigger diameter is where there will be more imbalance at high rpm, so where if there isn't a component balancing before the assembly, you will find grinding marks on it's nut (and because on the garrett's that are dynamically balanced you will find always some grinding marks).
For the torque, i've searched all over the net without success....
I would say that looking for torquing of similar small turbines the 8.75nm value suggested by Splitpin would quite right. Please note that the torque depends also on the type of lubricant used ...
Else, you must find someone that rebuild turbines and maybe write here the value