Why are some cars torque limited at lower gears?

Makhaira

Makhaira

Makhaira

Soldato
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As per title really - I understand the potential effects of torque steer etc, but I don't understand why some cars have torque limiters in place on their engine setups for lower gears?
 
Because some cars produce a lot of torque and if you boot it in 1st a lot its going to cause a lot of wear and tear on parts like driveshafts, cv joints etc. By limiting the torque these components dont need to be built like a tank.
 
As already said, to protect the transmission.
Same thing with trucks - Scania's 16litre V8 engines only produce maximum torque in 11'th & 12'th gear for this very reason.
 
My Mr2 turbo has lower boost in first and second from the factory, 0.7 bar with 0.9 for third and above. As said to protect the drive train and possibly the driver.

Thankfully I've removed the limit and could get to 1 bar if I wanted.
 
sovietspybob said:
Mostly to conserve the life of things like the clutch, gearbox, driveshafts and differentials.
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The clutch doesn't get more punishment in lower gears, quite the opposite in fact. It's the torque multiplication of low gears that presents the problem, so the vulnerable parts are anything from the gearbox up to the hubs.
 
Dogbreath said:
The clutch doesn't get more punishment in lower gears, quite the opposite in fact. It's the torque multiplication of low gears that presents the problem, so the vulnerable parts are anything from the gearbox up to the hubs.
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Yeah i did think this after i wrote it! Hence clutch slip occurs in highest gears when the clutch is worn!
 
The Running Man said:
My Mr2 turbo has lower boost in first and second from the factory, 0.7 bar with 0.9 for third and above. As said to protect the drive train and possibly the driver.

Thankfully I've removed the limit and could get to 1 bar if I wanted.
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In an mr2 turbo It will still be limited in 1st gear as the gases can't get through the engine quick enough to build sufficient boost before you hit the limiter :p

I bet it's a bit of an animal in 2nd now though!

At lower gears more torque is being transferred to the wheels per wheel revolution. At higher gears (and higher speed) less torque would be required to complete a wheel revolution.

Think of it like bicycle gears. So in say 1st gear you are pedalling like mad, putting a lot of turning force through the pedals for each wheel revolution. Once you are up to speed and in a higher gear this higher turning force (torque) is more useful in creating acceleration. The same amount of torque is going through the chain but it is not turning at such a high speed, this is more efficient and reduces the wear on the chain, pedals, gears etc.

Therefore there is more strain on the running gear of a car at lower gears; as they spin very fast with lots of energy running through them, creating lots of friction and wear. But this torque is useful for performance in higher gears.

Manufacturers can either beef up the running gear to deal with the increased wear or reduce the torque in lower gears. Of course they go with the cheaper option.
 
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lol, main reason i can see isnt for wear and tear on parts but wear and tear on driver, less chance of booting it in lower gear and ending up in a hedge with less torque
 
I have to manually limit with mine. If I did full boost in 1st or 2nd the box would grenade :( Something to do with a gearbox originally designed for 60bhp having 185bhp through it :p
 
Matt82 said:
with the MR2 i think it was a policy to try and extend the life expectancy of the owners
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I rarely if ever use full boost in second, not to the top of second anyway!. That's some scary stuff. I don't think ice ever used boost I'm first or second above say 0.2 bar taking a corner it would be madness!
 
The 1.7 puma has a limiter in 1st, a simple snip of a wire and rejoin with a switch on the dashboard makes for a very good, almost free mod.
It takes off in a far more 'spirited' fasion!

I belive it was to protect the cheap (probably from a 1.3 60bhp fiesta) drive shafts in this particular case.
I never had any issues, but I guess thats why you fit a switch, so it's only on when you fancy it, and not always causing stress when your in 1st.
 
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The Running Man said:
I rarely if ever use full boost in second, not to the top of second anyway!. That's some scary stuff. I don't think ice ever used boost I'm first or second above say 0.2 bar taking a corner it would be madness!
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the most awesome thing about driving an MR2 was adapting your right foot to work as a boost control rather than a throttle control. youd have to feather the pressure onto the throttle as you were exiting a corner, as the pressure increased you heard the note changing of the rushing air. really fine delicate (life dependant) inputs

ace cars and i dont know why theyre not more highly rated
 
mattyfez said:
The 1.7 puma has a limiter in 1st, a simple snip of a wire and rejoin with a switch on the dashboard makes for a very good, almost free mod.
It takes off in a far more 'spirited' fasion!

I belive it was to protect the cheap (probably from a 1.3 60bhp fiesta) drive shafts in this particular case.
I never had any issues, but I guess thats why you fit a switch, so it's only on when you fancy it, and not always causing stress when your in 1st.
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I really should do this on mine when I get some spare time... :p
 
The mr2 turbo gearbox is an absolute beast and can easily cope with 500+bhp launches all day. I have seen some pics of the differential etc laid out and compared to some other transaxle and it totally dwarfed it.
 
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