The Caveman Chronicles

[regcheeseman]

But as detailed before with the fuel setup - the travel was an extra issue. It’s no longer limited to 4K revs like before.

I believe that it was little to do with the travel, but more a case of the advance curve, shutting the port intervals even sooner and you running out of fuel delivery, I think the spill collar travel would show different symtoms, besides, standard spill collar has masses of travel

More pressingly though I’m now starting to seriously look into the gearbox as this is an issue that I don’t want to have me sat at the side of the road like a Tdi or T1/T2 owner.

Does anyone have any practical experience with these boxes? Are the output shafts shared across all gearbox codes? Specifically the gear to the diff? Or is this part of what gives the final drive ratio? I need to get up on boxes and fast.

I've been inside a few boxes in my time.

Pretty sure the output shaft and pinion are one and the same, different final ratio is a result of different diff ring gear and output gear combos. The T4 diff is massive compared to the car one, changing final drive ratio would be the best way to improve these boxes, if someone (fruitbat) could make up a gearset, but there's little room in the o2b for a bigger pinion on the output shaft, maybe a tooth? which would be a decent change cos it's a tiny gear.

But after this you still have the fragile 02B - which was another reason for me buying an 02G

How would you even know what this is? Would it even be measurable just my looking at the lid? The physical travel range yes but surely it’s a mapped range of movement? Isn’t this going to be less for an unmapped van and more for a wildly mapped one? In which case if you have a 200bhp mapped van could you measure it’s movement for me please? Lol

Easy to measure, I'll just measure full range.

I've a JX pump open on the bench, I'll see if I can work out a way to measure that travel as well...

[TommyP]

I believe that it was little to do with the travel, but more a case of the advance curve, shutting the port intervals even sooner and you running out of fuel delivery, I think the spill collar travel would show different symtoms, besides, standard spill collar has masses of travel



I've been inside a few boxes in my time.

Pretty sure the output shaft and pinion are one and the same, different final ratio is a result of different diff ring gear and output gear combos. The T4 diff is massive compared to the car one, changing final drive ratio would be the best way to improve these boxes, if someone (fruitbat) could make up a gearset, but there's little room in the o2b for a bigger pinion on the output shaft, maybe a tooth? which would be a decent change cos it's a tiny gear.

But after this you still have the fragile 02B - which was another reason for me buying an 02G




Easy to measure, I'll just measure full range.

I've a JX pump open on the bench, I'll see if I can work out a way to measure that travel as well...

How else would you explain my need to turn the max fuel down to just above the point it wouldn’t Rev as, I believe, the spill collar wasn’t able to move back far enough to give a good idle? Then in doing so the collar wouldn’t move far enough to deliver fuel up top and limit it to 4krpm?

The advance curve is unknown really. This pump now has the Tdi DA piston, spring, shims and cap. Also it’s got the pressure reg valve from the Tdi. This is always the issue when changing maybe components at once, you’re never sure what the issue was. I haven’t got time to piss up the wall trying them individually though. I’m unsold on the current timing setting (1.05 iirc) as it’s not as good as the old pump (1.54) on cold starts but it clacks well, possibly more than before. Once it’s warmed a bit, the idle raises. If I set the idle based on warm running, I suspect it wouldn’t sustain itself at all when cold. Using the cold start lever makes it run but I’m a firm believer in not using it so it’s playing on my mind more than it should.

Box: so the gear on the end of the shaft in my box (Arf) is specific to the diff and EWB ratios? In which case I can’t nock it out another cleverly and cheaply sourced box of another code? Maybe I should learn more about them before I ask questions so I’m not wasting anyone’s time. We’ll come back to this.

“Easy to measure, I’ll just measure full range” will a 88/102 use full range though? Or would that be in the mapping?


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[TommyP]

Clutch has been shite this week. Not holding the power in 4th and 5th. As soon as the torque spikes (which is low down) it rapidly overwhelms the clutch. I’ve got new master and slave cylinders to fit this weekend but I’m not sure if that would help. Might make the top of the pedal travel feel better.

Also, as mentioned, the box is whining really bad hahahaha. I think the noise has been promoted into now being a howl. I’ve been looking into which way to go about things with the knackered 02b EWB box I picked up last year. I want it for the ratios. Think they’re commonly fitted to the 88bhp vans. I haven’t stripped the box yet but there’s a small hole in the bell housing:

The superseded part no for the output shaft is: 02J 311 205J or 02J 311 205K . Might be a bitch to get hold of but they are out there. I’ll try VW.

As far as I know, the 02a/b/c/j all share the same input side bits and they’re interchangeable. But I need to pull the box to bits to take a better look and see if a repair is viable.


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[S49]

Whats escaped from the hole? Or maybe a clutch cover bolt had made a bid for freedom.

[TommyP]

Whats escaped from the hole? Or maybe a clutch cover bolt had made a bid for freedom.

Not sure what’s escaped but one of the teeth is missing on the output shaft integral gear to diff. The tooth punched the hole so it may have escaped.


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[regcheeseman]

Low down torque breaks gearbox without a torque map to rein in the fuelling at low revs....who'd have thunk it, pity no one mentioned it might be a problem...

[TommyP]

Low down torque breaks gearbox without LIMP HOME MODE to rein in the fuelling at ALL revs...

Which bit breaks? I’ve read of machining the casing to accept a bigger roller bearing on the output shaft.


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[regcheeseman]

Low down torque breaks gearbox without LIMP HOME MODE to rein in the fuelling at ALL revs...

Nope thats not how it works,

The torque map in the ECU limits fuel irrespective of what the drivers wish (throttle peddle) map might want - this is how the all important ECU save the gearbox from the all destroying torque at low revs. Nothing to do with limp mode.

[Fruitbat]

Nope thats not how it works,

The torque map in the ECU limits fuel irrespective of what the drivers wish (throttle peddle) map might want - this is how the all important ECU save the gearbox from the all destroying torque at low revs. Nothing to do with limp mode.

I bet Tom wishes he had an ecu now hahaha

[TommyP]

I bet Tom wishes he had an ecu now hahaha

Nah. Box was always coming out as the ratios are wank when you add more power. Fine when you’ve got the standard 13bhp of the 2.4d but even adding the turbo highlights it as a limiting factor.

If I get any turbo or gearbox issues with the new box in, I’ll just fit a k16/24 hybrid in the hopes that’ll have a bit more lag and leave the torque until later. The GT2052v in it now hoofs a dirty great lump of torque really low down.


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[TommyP]

Nope thats not how it works,

The torque map in the ECU limits fuel irrespective of what the drivers wish (throttle peddle) map might want - this is how the all important ECU save the gearbox from the all destroying torque at low revs. Nothing to do with limp mode.

Why is it just the low down torque? How does it handle torque at higher revs if it can’t do low? And what are we roughly describing as low down the Revs? 1200-1800??


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[regcheeseman]

Why is it just the low down torque? How does it handle torque at higher revs if it can’t do low? And what are we roughly describing as low down the Revs? 1200-1800??


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I believe the shock loads for low rev torque are the problem, the cyclic rate at sub 2000 rpm is what breaks things, it'll crack blocks, twist cranks and smash gearboxes, the vnts are so good at boost low down they had to be reined in by electronics. The lower the revs the less torque the engine can handle.

[TommyP]

I believe the shock loads for low rev torque are the problem, the cyclic rate at sub 2000 rpm is what breaks things, it'll crack blocks, twist cranks and smash gearboxes, the vnts are so good at boost low down they had to be reined in by electronics. The lower the revs the less torque the engine can handle.

I’ll start gathering spare engines and boxes now then. Lol.


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[TommyP]

Gearbox seems to be getting a bit quieter. Random AF. Makes me feel like the pressure of quickly building a box isn’t as urgent now. I will surge ahead and get it sorted though as the clutch is slipping like fuck and the box will just suddenly let go just to take me by surprise whilst I’m enjoying a false sense of security.

Diesel heater is fantastic. For anyone considering it, stop, just stop. Buy and fit one, like me, you’ll wonder what you’ve been doing fucking about and why you didn’t do it ages ago.

Plans for the weekend: fit clutch cylinders, repair plate, wire dash cam to ignition live and hopefully fit the new throttle spindle to get the insane smoke down from previous rudimentary (lazy) setup.


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[TommyP]

So as some of you on WhatsApp saw on my video, the mTdi has eaten 5th hahahahaha! She dead.

The trusty old mtdi just carried on though. If I had one of those shitty new fangled ECU things it would have broken down and died, FACT, and there’s no telling me otherwise LMFAO!

Will post more info later and maybe YouTube the vid lol


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