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She is not sounding healthy

Immortality

Can't live without smoky bacon!
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The converter shares the fluid with the rest of the trans.
 

Skylarking

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I know how to read transmission fluid.

And I can tell you 100% the stuff that came out was thinner than the stuff that went in and the synthetic trans fluid is fairly thin to start with.

Trans fluid isn't your traditional oil and seems it doesn't behave like it either.
I wasn't implying you don't know how to read trans fluid, but i thought it's useful to put up such info for some others who may also be reading this thread. Oddly, I did think you may have found the blotter test interesting, wrt viscosity :)

I also have not doubt you're simply passing on your experiances with your sons trans flush so I wasn't doubting your statement.

In any case, I'm sure you know, trans fluid volume changes with tempertaure, that is, it's volume increases as it gets hotter. And IIUC, the viscosity of trans fluid also reduces as it gets hotter, that is it gets thinner. So the volume increases while the viscosity decreases. The complex bit, again AIUI, is that the viscosity increases as the fluid oxidises.

Ultimately, the viscosity of what comes out of a transmission is a jumble of properties and very much depends on the temperature of the fluid and what level of oxidation is has suffered. How this relatres to what was in your boys trans i have no idea. I think he has a BMW but no idea what fluid goes in it... probably some exy BMW certified fluid...

In any case, I do know that transmission fluids are rather difference to engine oils which are also different to LSD oils. For a starter trans fluids have a lower viscosity, they have to deal with different issues and their viscosity has been getting lower over the years. We now have LV and ULV trans fluids ;)

Unfortunately none of this answers why Daniels trans almost porked itself.
 

chrisp

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It is just a awful coincidence to have the trans issue just after i worked on the car. It undermines the self confidence for a while until the issue was found.

Unfortunate coincidences do sometimes happen when repairing things! You’re doing a fantastic job with the rockers so hang in there and don’t let it rattle you. We’re all looking forward to the next chapter!
 

Skylarking

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Do you think the fluid inside the converter is cooked or it is actually physically broken.

The slipping behaviour of the converter doesn't seems to have changed from before the noise started.
If the mechanic only dumped what was in transmission pan, he's only changed around 1/2 to 1/3 of the trans fluid. The converter, passages within the transmission, even the pipes to the radiator/trans cooler all contain old fluid. a pan change wont change this old fluid. Probably why he's getting you back in do do another pan drop change... but that process is still OK...

Personally I prefer a full flush with pan drop and filter change but not all mechanics do that as it does cost more and requires specialised equipment.

Interestingly there have been posts about a known defect with the trans oil pump or neck or the torque converter cracking in low millage vehicles. Just can't rememebr the details clearly and whether it was in VE's, early VF's or VF II's. Supposedly this defect causes shuddering within the driveline which isn't what you've been experiancing.

I'd check out the left side rockers and then do the next trans fluid change and see how you got after that :D

PS: never tried to remove TC bolts from flex plate and pushing the TC back towards the trans. I guess it's similar in theory to pushing a clutch down to test/check if some gearbox bearing noise goes away... Just not sure what's to stop the TC moving forward towards the flex plate while things are turning... any comments on this @hjtrbo ?
 

hjtrbo

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PS: never tried to remove TC bolts from flex plate and pushing the TC back towards the trans. I guess it's similar in theory to pushing a clutch down to test/check if some gearbox bearing noise goes away... Just not sure what's to stop the TC moving forward towards the flex plate while things are turning... any comments on this @hjtrbo ?

It moves about 5mm back. It's enough for a quick test. Just mark it so it goes back to the same bolt holes. The starter is a pain to remove. In my case it involved taking the header completely off the engine and removing the trans cooler lines.
 

hjtrbo

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The 6L90 converter is a worthy choice if you have to replace yours down the track. Slightly higher stall speed at around 2200rpm. They'll handle 550rwkw all day long. Small mods required to convert your flex plate from 3 bolt to a 6 bolt pattern. I bought one last year from Holden for $950. Torque converter tune is required.
 

dassaur

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The 6L90 converter is a worthy choice if you have to replace yours down the track. Slightly higher stall speed at around 2200rpm. They'll handle 550rwkw all day long. Small mods required to convert your flex plate from 3 bolt to a 6 bolt pattern. I bought one last year from Holden for $950. Torque converter tune is required.
That's the same as the ZL1 in the US, right?
 

hjtrbo

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Correct. Also the same as HSV LSA and Cadillac CTS-V LSA
 

hjtrbo

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Just an FYI another mod you can do is get the OEM 6L90 restalled up to 2800rpm. That would make a very nice best of both worlds converter. Smooth factory lock up (frictions designed to work with progressive slip lockup) and a stall speed perfect for any mild street cam to instantly light up the rear tyres. This mod isn't done over here yet. I asked TCE about it and they had no idea.

Anyway, it's a good package for the taking if anyone wants to market it.
- OEM 6L90 converter re-stalled to 2800rpm
- 6L80 flex plate converted to 6L90 bolt pattern
 
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