Thread: Low Stall Torque Converter

Sounds like you're low on fluid. I'd stop driving immediately.
And on the low stall torque converter, it will still lock up at the same speed, just lower rpm. Which should be 82, not 62...

Thanks disco muppet... I always found tc lockup to be around 62kmh into 3rd and 80 odd into top
Just picked car up from transmission specialist ... I would think the levels should be ok as they do one of these a week...so i'm told

Can someone explain the reasoning behind(and what they do) using a low stall TC?

You mean like how Wardy had his gearbox rebuilt by two different specialists a total of 4 times before it was right?
The very first symptom of low fluid level is failure to lock up in top gear.
Regardless, at the very least you should take it back to them, because that's not how the gearbox should be operating.
Pedro
The larger torque converter for the Td5 is the one from the 4.0 V8. Having a lower stall point reduces the revs for the same work as compared to the smaller one, which means you're using the low down torque of the motor rather than just revving past it as the TC slips. The other benefits are cooler operating temps due to less slip and lower lock up, as well as a much stronger lock up clutch

so why call it a low stall? I know about the three different TC/s, so when the gearbox and engine lockup its considered stalling the engine?

It's in reference to when the torque converter effectively provides enough drag to stop the engine from going to a higher rpm. It's not in lock up, it's still fluid transfer, but the drag back on the engine stops it from getting any faster. It's related to condition of gearbox and engine (i.e. stalling out at 3300 might be a bad gearbox or a tuned engine, and so on).
The TD5 standard converter stalls out about 2800rpm, the heavy duty one is 2200 ish, I would guess that the super heavy duty one is still 2200 ish. The other change is that the lock up plates are bigger and/or better. The standard TD5 one is apparently borderline for mild tune, but will slip (not enough pressure/face) with higher tune, the heavy duty will take more power through it and then the super heavy duty will obviously take even more (I think the last is definitely down to the surface area).

When I did the gearbox I got the heavy duty one and even with a tune in it, the stall speed is 2300 (at the moment, that is probably going to rise...). I'm not convinced that without a tune and a few extra things that the HD one is better for general driving. The drag kicks in correspondingly lower (i.e. free reving stops at 1500, it used to be about the 2300) which the turbo is only just coming on boost for, makes the bottom end a big sluggish. Compared with a nearly identical td5 with std converter he suffers less turbo lag because he spins up to 2300 with virtually no drag and so is getting a bit better boost.
Drag racing off the line with him he pulls away for the first 20ft and then the HD reels him in as it sits at 2300 at best torque while he's at about 3000.

I'm considering whether to go performance intercooler (economy, egt, bit more power) vs VGT from TD5 Inside (more bottom end boost, less lag) next. Intercooler is winning at the moment, but I'm a bit concerned it might increase lag...

Having had one for a year or two I don't know if I'd recommend the HD version, we just bought a camper trailer, so that may turn around my feelings as it is apparently much better for towing.

Unfortunatley we see this quiet a few times when people do mods, things go pear shape. Always been a believer leave things alone and don't try and reinvent the wheel. The techoloogy on these vehicles is old now .

It's hardly reinventing the wheel, it's basic modification principles. Some modifications are going to require other work to maximise the gains provided. There's no point having 5" of lift if you stick to stock tyre sizes. Just like there's limited point having an HD torque converter designed to be used in vehicles running a higher than average state of tune, if you're not running that tune.
Steve. Go the VNT. VNT plus HDTC is widely regarded as a phenomenal improvement to a Td5 auto, meant to go together. You're not going to see a performance improvement from the IC, if anything a bit less due to increased volume of the IC, more than likely increasing boost drop. Don't forget the Td5 is sensitive to high EGTs when mapped, so make sure you do eventually get that big shiny fridge up front