just sat here thinking about this. my old car had 30 psi t4 boost spike at about 4k and came in very hard and would regularly trash 2nd or 3rd gear. my current car has less torque low down but more top end bhp and no gearbox trouble whatsoever so is it the big punch of torque power low down that kills a t5 ?

 

as the age old saying goes......

"Torque moves cars..........BHP sells cars"

 

thats why f1 cars are all hp and no torque then

 

When was the last time you bought an F1 car

 

Congratulations on the worst answer this week!

Take a bow Tiff

 

It wasnt an answer..........it was a statment that people use....................

Why did he ask the question if he all ready knew the answer

 

A gearbox is just a torque multiplier..........there's the answer.

 

It's actually Torque wins races, hp sells cars"

Henry Ford said it I think

 

and the relevance of that is ?

 

Torque kills gearboxes.

 

Carol Shelby is the one that I normally see people quoting as saying it!

Rod said Colin Chapman and now we have Henry Ford!


Its a GHEY load of crap anyway F1 cars have less Torque than a lawnmower and seen to do ok!

 

Or more specifically, low down torque kills gearboxes .

This is why T34 equipped cars with big mid-range spikes kill MT75s as soon as look at them, but T4 equipped cars with the same peak torque (albeit higher up the rev range) give them an "easier" time and they last "longer".

 

Abuse kills gearboxes you bunch of arguing fairys


Luciano

 

If you call pressing the accelerator down flat to the floor as "abuse", then I have to agree .

 

I am no gearbox expert, in fact i hate the things, but i doubt that the engine speed it is generated at matters greatly to the box.

I would guess that the T34 cars kill boxes fast as they generate that torque FAR FAR more of the time because its easily accessible in daily driving, where as T4 power is not.

 

I thought it was all due to the tractive effort that is put through the gearboxes at lower speeds. The greater the torque low down, the more tractive effort is transferred through the gearbox, but at higher rpm (and therefore road speed) the tractive effort has tailed off and is putting less load on the gearbox.

 

i tried to break my gearbox on the cossie for over 5 years and the fucker just kept taking abuse

forget abourt a quick gearchange tho

 

my lawn mower is a v twin 20 bhp i doubt it has 250lb/ft of torque it is also red but it isn't a Ferrari

 

You could be right, i admit i dont know, just seems to me that a T34 would be hammering it with torque at every throttle squeeze, and a T4 wont. Makes sense...

 

I would think it is because the boost and therefore torque increase will come on a lot more suddenly than on a t4 engine, therefore more of a shock to the box.

The same would apply if you are cruising in 3rd and then put your foot to the floor as well I think.

 

i was constantly breaking boxes on my T34 55lb setup,

the last one broke in 5th gear at 35mph 1500rpm after cruising off the motorway ....dabbed the throttle and BANG....stuck in fifth, gear lever lurched forward.

the t34 as stu said uses all its power all the time, and very early, it does come in with a bang to


oh, front diffs dont like it up em either

 

You could have resolved this by remapping the boost curve to climb with revs. This is what the APT boys did on Churcy's car. 370bhp / 350lbft standard box, still going well. No midrange spike .

 

i liked my midrange spike. i could destroy almost anything i came across in the mid range

it made 370bhp, 420lb/ft on DDrollers @36psi. was a .48

 

Good comparison, as similar set up (Churchy's is on 0.63 a.r) and his figures are also from DD rollers. He hasn't broken a gearbox or front diff though .

 

lucky bugger

 

mine seemed to make full boost just over idle

 

Luck has nothing to do with it - lack of mid-range spike has .

 

ahh, hes a wimp then

 

See how long my T5 box lasts

 

is he gay aswell then mike

 

Mr Shelby actually said it, I was incorrect & went to check it some time back.
Hes spot bollix of course unless you have 19k revs to wind up, which didnt happen when that quote was made. .

 

shelby is talking out of his arse lol

my torque wrench has 300 lbs/foot of torque and it wouldnt win any races lol lol

people get so confussed about the ralationship with torque and power!

torque is a force acting at a length, BHP is "work done"

 

Surely if peak torque is made at higher revs then it is spread over a greater amount of gear teeth in a given time meaning less torque per tooth and a longer lasting gearbox ?

Mark

 

might sound like a stupid question but would the weight of the car make any difference atall

 

"less tourque per teeth" this isnt true, a tooth might see the torque for a shorter period of time, but the unit of torque id the same!

 

yes,absolutely.more weight means more strain on the system.

 

why do people say this?

 

Don't upgrade your gearbox, simply reduce the mass of your car (or the grip available). Its much cheaper.

 

or being a 2wd just use it in the damp etc

 

1/4 MILE breaks selector forks

track days break gears....

If you a top speed or point and squirt person the box is very strong

On track its very weak.

5 standard boxes and 5 bernie rebuilds on a quaife later.....it seems to work LOL...