Ok if you watch a torque curve you will see that torque tends to build up in lower revs and fade out towords higher revs. Right? So if you change gear at HIGH revs as you would accelerate in a race then torque values at new rpm points are lower then if you would shift from lower rpms.
For example:
1st scenario: needle is at 4500rpms and you change gear, push the clutch pedal, select higher gear, neddle drops to around 3000rpm, lift off the clutch, reapply 100% throttle. When you reapply throttle at 100% (assuming you don't lift off more than 20%) the torque delivered by the engine has a particular value X.
2nd secnario needle is at 2000-2500rpm, you drive more relaxed, and shift to a higher gear, and after the shift rpm drops to 1000+rpms and you apply after that almost the same throttle as in scenario 1. Now the engine delivers a higher torque Y value than in scenario 1. Y>X
So considering this will often happen the stress will not be the same on the clutch.

 

100% correct. However, most people at most times use their cars in the lower half/two thirds of the rpm band. So it's likely that an engine with a very peaky torque curve (M5? ) will actually put less stress over time on the gearbox than an engine with very high torque at low revs (335i?)

 

Or better yet the 535d/335d because the rev range is wider and peak torque sits lower+the higher diesel torque values. That was what i was trying to say.

 

Ah, yes. But have you seen the 335i's torque curve? It's totally - and I mean totally - flat from about 2000 rpm to 5000. And I was trying to avoid to turn this into yet another "Diesel v. Petrol" comparison!

Actually, an old Volvo 480 turbo would have been as good an example as the 335i.

 

Yes yes, flat torque curve has an advantage...when i first saw it i remembered the wankel RX-8 engine, but of course not it's value (half as much)
I don't think we were getting into a diesel vs petrol dbate. No petrols have been discussed and the topic is about the manual 535d. So we were on track
Sorry i don't know that volvo or i know very little. What was the production year of that car?

 

Sorry for that mistake, i dunno what i was thinking.

 

I suppose that dates both of us... Launched in 1986, withdrawn 1996.

Not that it was a great car, but the torque curve was completely flat.

 

To avoid transmission vibrations that will wear the transmission quickly

 

You would be right IF there would be any vibrations from engine. BMW inline six don't have vibrations! Only vibration comes when tyres struggle to get grip!

Funny thing is that "big T" does not accelerate car, but it break things. Like volts drives things and amps melt things.

Skaffa

 

Well, bear in mind that torque at the wheel is probably relatively constant for a given maximum engine power, as a Diesel (or V8) gearing will be taller than for a smaller/petrol engine, so acceleration will not necessarily be that different. But input torque to the gear box WILL be different depending on engine characteristics.