7 replies to this topic

[Nev]

I am considering upgrades to my engine atm, so wanted to see what the F23 box is rated to. Apparently it's spec is to only take 170 Lb/Ft on the input shaft ... Argghhh!!! Now clearly, the F23 is commonly fitted to cars that have approx 1800 Kg loaded weight (ie Astra with 4 passengers + luggage), however a VXT with 2 people has a max of approx 1100 Kg loaded. This means that the VX is approx only putting 1800/1000*100 % strain on the box (ie only approx 60% of the stain of an Astra say). Thus presumably, it would be safe to push the VX's box by an extra 40% and still be using it within spec, ie to approx 170 LbFt * 1.4 = 240 Ft/Lb. However, in the real world we all know the actual figure is a lot more than this... QN: What is the max torque an F23 can take in a VXT before you start stripping the cogs, shearing the fixing bolts or buggering the splines and bearings ??? Would anyone care to confirm (or slate) my approx maths ?! I know some of you chaps are in the motor industry, I'd be keen to know what you think. Thankyou, Neville.

Edited by Nev, 16 October 2008 - 07:28 AM.

[SteveA]

If it's any help Stefan Klasen was running a standard F23 box up to 609PS.

[slindborg]

If anyone says 230NM they will get a slap! lol It sort of used to be that the F number was sustained NM/10, but its now just a way of numbering up the gearboxes fo ease of differentiation. eg their F10 and F13 and some F15 gearboxes share IDENTICLE contents (bar the 4 speed varaiants lol) so how the hell does that acocunt for upto 50NM difference? similarly the F16 and F20 are largely the same inside (bar one bearing). blah blah blah. As said Klassen is piling power through his, the Yanks are firing a sh*t load through theirs under harsher conditions as most are S/C'd so the torque is made lower down the rev range where a gearbox tends to commit suicide.

[cheeky_chops]

Now clearly, the F23 is commonly fitted to cars that have approx 1800 Kg loaded weight (ie Astra with 4 passengers + luggage), however a VXT with 2 people has a max of approx 1100 Kg loaded. This means that the VX is approx only putting 1800/1000*100 % strain on the box (ie only approx 60% of the stain of an Astra say). Thus presumably, it would be safe to push the VX's box by an extra 40% and still be using it within spec, ie to approx 170 LbFt * 1.4 = 240 Ft/Lb. However, in the real world we all know the actual figure is a lot more than this...

That doesnt sound right? The fwd astra will weight transfer to rear causing more wheelspin and putting less strain on the GB.

Accelerating off if the VX will transfer the weight over the rear wheels, more grip and less likely to wheelspin = more strain.

Is this why the engine mounts go more often?

[slindborg]

Now clearly, the F23 is commonly fitted to cars that have approx 1800 Kg loaded weight (ie Astra with 4 passengers + luggage), however a VXT with 2 people has a max of approx 1100 Kg loaded. This means that the VX is approx only putting 1800/1000*100 % strain on the box (ie only approx 60% of the stain of an Astra say). Thus presumably, it would be safe to push the VX's box by an extra 40% and still be using it within spec, ie to approx 170 LbFt * 1.4 = 240 Ft/Lb. However, in the real world we all know the actual figure is a lot more than this...

That doesnt sound right? The fwd astra will weight transfer to rear causing more wheelspin and putting less strain on the GB.

Accelerating off if the VX will transfer the weight over the rear wheels, more grip and less likely to wheelspin = more strain.

Is this why the engine mounts go more often?

I'd say the mounts "go" because they were only deisgned to be sat on as lower side mounts for an Omega..... ie they never saw latteral loads, only verticle ones. So they dont do shear very well.

[Nev]

Good point CheekChops. Though, if Stefan Classen is putting 600+ BHP though this F23, I am sure it can handle a paltry 350 BHP in my VXT. Plus also, I never put my foot down in 1st and 2nd gears anyway, which is when you can presumably put the most strain on a gearbox.

Edited by Nev, 16 October 2008 - 12:02 PM.

[Guy182]

Good point CheekChops.

Though, if Stefan Classen is putting 600+ BHP though this F23, I am sure it can handle a paltry 350 BHP in my VXT. Plus also, I never put my foot down in 1st and 2nd gears anyway, which is when you can presumably put the most strain on a gearbox.

hmm.. i dunno

when i was killing clutches mine used to suffer the worst when in 3rd/4th and you boot it at 3kish and all that torque kicks in.

[Nev]

Good point CheekChops. Though, if Stefan Classen is putting 600 BHP though this F23, I am sure it can handle a paltry 370 Lb/Ft in my VXT.