Namxi

I was checking the turboshaft play on my stock primary the other day and made a video:


Is this too much? I read in here that a little bit is normal due to the fact there has to be some space for the oil pressure, but I didn't find what a bit means. Other than that its pretty impossible to meassure correctly down there.

I think it doesn't make contakt, its not scraping if i turn it pushed down or up. I see no marks either. I'm not sure if the play is only radial (up/down) or also axial (in/out), but I would say axial is nearly zero.

How easily should the wheel spin? If I spin it, it slows down rather quickly. When I start the car, it spins.

alexdimen

iTrader: (13)

Looks like it's on the high side, but you are correct: oil pressure and shear between the moving parts keeps these bearings floating as they were intended to by design.

If you have a decent gap between the housing and compressor and it's not leaking oil, then I might be tempted to leave it alone.

One option is to swap in a CHRA from the secondary turbo of a spare set. These usually have far less wear due to not being used as much. Or just buy a less abused set of twins.

The tricky part is clocking the new CHRA correctly as far as the angle, but if you put alignment marks on everything before taking apart and transfer to the new CHRA you will be good.

IRPerformance

iTrader: (41)

Looks like a lot of play. Does the wheel rub the housing when turned?

Namxi

No, it doesn't rub.

I'm not sure if I dare to mess with the inner parts of such a delicate thing as a turbo. Used twins are around 300-400 dollars in my region, so I'm not sure if its worth it either. But I will consider it of course.

alexdimen

iTrader: (13)

If you replaced a CHRA, you would just be unbolting and replacing the cartridge that contains the delicate parts like seals and bearings. The hardest part would be the snap ring on the compressor housing, which Knipex makes a great tool for.

If you source a used set you should take a boroscope or remove the hot side turbine housing to inspect for blown motor apex seal damage before installing. You cannot tell if they are damaged or not without looking at the entire turbine wheel.

Namxi

Thanks for the tip, its much appreciated since I found a set for 300$ shipped. Seller will measure the play, if its good I'll probably by them.

Primary and secondary are not interchangeable, right?

Smokey The Talon

iTrader: (33)

After going thru many sets of turbos on my track car I found that if it doesn't touch the housing (spin it while moving and you'll hear it), doesn't smoke, nor blow oil in the intakes....then leave it alone and don't worry about the play. The bigger play may mean that it's closer to the end of its life but I wouldn't go thru the trouble of replacing if you're not experiencing other issues worth solving for. Used sets are a gamble too. I've had some great looking sets that smoked.

Namxi

Hm, would you say that this kind of play could be the reason for not producing any boost at all? I have that problem, no boost from primary up to 4500 rpm and very little boost afterwards, here to find: https://www.rx7club.com/3rd-generati...ndary-1096222/

Other than that, nobody wrote how easiely the wheel should turn. Is it normal, that it stops when spinned after only some turns?

Oh, and I'm not to sure whether it blows oil into the intakes. There are some drips of oil in the couplers, but its not much though.

Smokey The Talon

iTrader: (33)

If you have the stock PCV valve hooked up that'll also contribute to oil in the intercooler pipes. If it's not excessive don't worry.

As far as the turbo spinning, are you saying after a couple of turns you can no longer turn it with your fingers and it's stuck? Or that you spin and let go and it turns a couple of times and then loses momentum and stops? If it's the 2nd, then I doubt that's your issue. If it's the first then I think it could be.

Namxi

It's the second, I spin it with my fingers, let go, and after 2-3 turns it stops.

CarbonR1

iTrader: (2)

It looks like the bearing is near the end of it's life. Keep in mind that it might be self clearancing because the wear likely has been gradual.

alexdimen

iTrader: (13)

The CHRA's including turbine and comressor wheels are identical. I've heard several ill informed people say they are different size turbos but they are both Hitachi HT-12's IIRC.

Namxi

Here is a video of the unit I could buy for around 300$:


The seller would also sell the exhaust manifold for around 30$, but one stud is ripped off. Is that repairable? (Of course, this is only necessary if I rip off more than one stud when removing the turbos or if mine is badly cracked)

Namxi

I just meassured the play on both twin-sets (I bought the one above) on the cold side.

I put a dial indicator right on the shaft, pressed the shaft down, zeroed the indicator and pushed the shaft up as far as possible. Here are the meassured values:

My old twins:
primary 0.60mm
secondary 0.50mm
The used twins I bought:
primary 0.42mm
secondary 0.47mm

So the second one looks JUST a tiny bit better, BUT: If I press down (or up or whatever) the shaft and spin it on one side (Can't remember exactly if it was primary or secondary, but I think it was primary), it is hard to turn the compressor wheel at first. On my old twins this problem doesn't exist on either side. I'm pretty sure the compressor wheel doesn't scratch the housing, so it has to be in the bearing. Is that normal?

Since my old exhaust housing looks much better crack wise (The "new" one has a very long crack right into the sealing area) I'm not sure now whether to just use my old twins or to change the exhaust housings and use the new twins.

Namxi

I forgot to mention something: My old primary has some axial play, unfortunately I didn't meassure it. The "new" one has none.

Namxi

No opinions?

Smokey The Talon

iTrader: (33)

I'd go with the newer twins that have less play. Don't throw away the old ones till you're sure the new ones are better. As mentioned, oil leaks aren't always tied to shaft play so there's still a risk to the new ones smoking.

You can absolutely swap the exhaust housings but want to make sure they're lines up the same way (clocked) so that it doesn't cause issues when fitting to the motor.