Increase the torsional stiffness of the gearbox

Can the load capacity of a gearbox be increased by changing the longer gear ratio within the transmission (which would effectively lengthen all gears)?
More specifically:
A standard transmission is designed for a torque of 300 Nm, but the engine produces 350 Nm. This force must be withstood by all components of the transmission. If the transmission has a weak point, let's say it's the fourth gear (I don't know, based on some experiences with this type of transmission).
Can the force on the gears be reduced as described above?
Best regards, Hoin.

Hi,

Will the load on the bicycle chain be reduced if you install a smaller sprocket at the rear (thus increasing the gear ratio)? Of course, this is only true as long as you apply the same amount of force (i.e., with an unchanged motor torque).

So, it's nonsense unless the rear-wheel drive is the weak point (which I don't believe).

Best regards,

Jan.

Hello Jan,
I think your comparison is a bit off; based on what you've said, I would compare the bicycle chain to the input shaft of the gearbox. What happens to the downstream components?
I'm now thinking about the gearboxes in off-road vehicles that can be significantly reduced.
I'm not sure how the gearboxes are geared down; I suspect it might be done with a pre-reduction gearbox. There are frequent reports of gearbox failures, especially in the lower gears.
Best regards, Hoin.

Hi,

Okay... the large wheel at the front is the input shaft, the chain connects to everything downstream, and the sprocket at the rear is the axle drive, which you want to extend.

If you want to change the load, you need to start at the front... that is, by making the front sprocket larger. This will reduce the load (with the same pedaling force) - the chain runs at a higher speed, but with less stress.

To get back to the car: You would need to make changes on the input side of the transmission, not the output side (the pre-transmission... as you yourself wrote). However, you won't be able to achieve this with a reasonable amount of effort.

Best regards,

Jan.

Generell tust Du Deinem Getriebe mittels zusätzlichem / größerem Getriebe-Ölkühler was Gutes...! Beim Bus werden zBsp. Ölleitbleche aus dem Süd-Afrika-Modell für die 4./5. Gänge vbuilt.

Sure, here is the translation of the text from German to English:

"cu" translates to "see you" or "goodbye" in Spanish. It can also be used as a greeting, similar to "hi" or "hello."
January.

hiho

Okay, but how do you attach it? Or how does the oil get pumped through there?

Hey buddy,

What kind of car/transmission are you looking for a suitable part for?
Jan.

Hello Jan/Jan,
A T3 transmission will be modified.
"@Jan/TDI, I have a 4-speed gearbox with a 4.57 axle ratio and 0.77 gears on the 4th gear. I've installed oil deflectors from South Africa."
In front of the transmission is an engine with 130 horsepower (TDI). I'm concerned that the transmission might not last long under these conditions.
"@Jan, the plan is to extend the 4.57 axle ratio, which is located directly at the gearbox input (pinion and ring gear)."
I think the axle ratio (4.57) is equivalent to the large sprocket on a bicycle.
If your/my considerations are correct, the downstream area should be relieved of its burden.
Best regards, Hoin.

Hello Hoin,

If you're interested, I can reduce the maximum torque in the engine control unit.
The torque curve peaks at 310 Nm. What do you think about a flat, horizontal line representing constant torque at 240 Nm between 1900 rpm and 4000 rpm?
The power output would be 136 horsepower at 4000 rpm, and with other modifications to the chip, the diesel fuel consumption could even be further reduced.

Details via private message.

Best regards, Rainer.

I'm looking for a transmission for a Polo with the engine code 085.

'These cars have had problems with the bearings since the Polo 2, but it gets really bad with the G40 and 6N models producing over 75-100 horsepower. In my opinion, about 8 out of 10 GTIs need a new transmission around 60-80,000 km because the shaft for the fifth gear breaks or the bearings wear out. I believe this is due to insufficient lubrication of the fifth gear at high RPM and overheating of the oil.'

My idea was to screw a hose onto the drain plug, then connect it to a small pump (where can I find one? The ones from ISA Racing are really expensive), followed by a small oil cooler, and finally back into the engine through the oil filler cap. But even with that, I still wouldn't get oil in the fifth gear.

Hi,

Quote:

"@Jan, the plan is to extend the 4.57 axle ratio, which is located directly at the gearbox input (pinion and ring gear)." I think the axle ratio (4.57) is equivalent to the large sprocket on a bicycle. If your/my considerations are correct, the downstream area should be relieved of its burden.

If that component is actually located at the INPUT of the gearbox, meaning it's directly driven by the engine, then I agree with you (provided you use gears that can handle the stress).

Best regards,

Jan.

Hello there,
Thanks for your thoughts so far.
Hi Stummel,
I wouldn't actually have any concerns about the oil temperature.
Due to its design, a T3 doesn't go very fast; the top speed is around 140-145 km/h.
at least for me.
However, I am not aware of what happens in the event of damage.
Is something breaking or are the tooth flanks rubbing against each other?
Hello Jan,
"I would rule out damage to the sprocket and chainring."
With a longer translation using a worm gear and bevel gear combination, I expect to achieve a reduction in stress on the entire downstream set of gears and shafts.
Are there any other experts here who can provide input on this?
Best regards, Hoin.

The pinion gear and ring gear are already part of the axle drive system, so what's next?

Extending the drive shaft puts more stress on the T3 transmission because the engine is likely to be operated in a higher torque range.

Oil deflectors probably won't help either, just like an oil cooler, because the problem isn't temperature, as it is with high-revving gasoline engines in South Africa, but rather torque.

It can only be helped by either a torque limiter in the accelerator pedal or an adjustment to the software of the vehicle's engine management system (EMS).

Greetings,
Sure, here is the translation of the text from German to English:

"Dieter"

Nochmal zur Öltemperatur und zum schlecht geschmierten 5. Go back...

What do you think about simply overfilling the gearbox? Of course, only enough so that it spills out when the oil is warm, and nothing leaks out. VW even retrofitted some G3 models with AAZ engines with this modification. More oil means more oil reaching the outside of the gearbox casing, which can dissipate more heat.

I also slightly overfilled the automatic transmission in my 3B after changing the ATF following my major modification (to a VNT17).

Nebelwerfer_TDI wrote:

More oil also means more oil reaching the outer surface of the wellbore, and therefore, it can release more heat.

Yep, but a higher oil level also means, in my opinion, that the gears are deeper in the oil and it mixes more strongly -> increased friction losses -> more waste heat = potentially lower transmission efficiency .

A higher oil level, in my opinion, also means that the gears are submerged deeper in the oil and that it circulates more vigorously .

...and that metal-on-metal contact occurs less frequently due to the increased availability of oil between the friction surfaces. This results in lower losses and reduced wear.

When starting up, the oil rises much faster because the gears don't have to 'draw' it up from so far below... resulting in less loss.

The topic could be debated endlessly now, but I think that an oil level that is slightly too high causes fewer problems than, for example, incorrect tire pressure, or spoilers & ant killer. Besides, a too-high oil level in the transmission technically at least has some purpose, which cannot be said of many questionable modifications .