How much torque can a TY754 handle.
 

I am fitting a TY754 VN box this sunday - as a stop gap - whilst I save for my 6 speed conversion. (From grade A - 55k - miles tested before delivery)

The low simtek map which I run is 302bhp 342lbs torque. So will stick with this low map for safety and will take it a touch easy. The car is a UK car with a standard rear diff.

A friend on here ran 360lbs through a TY754 for a few years with no problem.

Am I on borrowed time with 340lbs or not!

What do you lot recon. Have many of you run that torque through a TY754 VN box with out problems or not?

Thanks

450bhp/380ft lbs torque on a P1 5 speed box only changed it for a 6 speed dccd - but I don't do drag strips/ or traffic light GPs

The UK VN box is not as strong as the sti 5/6/P1 box, you are on borrowed time with that torque imho.

Banny

343ft lbs on a standard MY99 box, for best part of a year now. (Fingers crossed)

I do drive with mechanical sympathy though and don't do drag starts.

Ns04

Reasuring thanks :thumb:
Just want it to last 3-6 months max really - Again I will be carefull with it and rev match on downshifts

Driven sensibly you would be very unlucky if you had a problem. They are tougher than all TY 752 boxes with much more rigid caaing and these boxes are far stronger than many people think.

Thanks Harvey

Ok final train of thought on this.....

As a stop gap stop gap

would dropping my UK TY754 VN and matching rear diff out at somepoint soon and then putting in a STi V5/6 TY754 VN with a match diff in improve things greatly - before I go to six speed.

1. Is the Sti V5/V6 TY754 VN 'that' much stronger than other TY754s. Or is the difference marginal (In the case of the V5/V6 box...the casing I assume is the same - but the gears are stronger). Would this just be a waste of effort or not?

2. If I did the above realisticaly what ballpark price could I sell my Uk rear diff and UK spec TY754 box for. I can can get the Sti V5/V6 box and rear diff for about 950ish

Your thoughts please fellas.

A reasonable amount of added durabilty for a few hundred .....or a waste of time?

Thanks :)

sorry to jump in but what turbo was that running mate? and i assume you have a forged block? how long were you on the std box for

Im running about 400lbs through my 754, Ive just replaced the bearings in the transfer box because they started to become noisey, well see how long a fresh set last, the box has covered 36k mls.

I was told the UK 754 box is the same as an STI 754, bar different gearing, the STI has shorter ratios IIRC.

I was running 350 lbft on a classic with a 2.5 & a UK 754 with no problems. I wasn't driving it hard, ie dumping the clutch.

It's one of RCM's hybrid GT 35 VF ball bearing ones with a P20 ported shroud - forgotten exactly which one to be honest and they don't seem to sell the same ones any more - this one is 4 year's old now. It's good for 480bhp at 2 bar.
Yep, very forged engine built by RCM, not much standard left to be honest, but it was built to be over engineered at 450bhp so that it "could charge around Donington all day...". With a rotated turbo and uprated head studs it'd be a 550bhp engine

The standard box took about 9,000 miles at that power and was fine - just had an opportunity for a 6 speed dccd

I have been running a 2.5 hybrid for past 6 months with 400lbs torque/390 bhp on a TY54 and no problems so far. Again I do not launch the car but do use it on trackdays.

Steve : The strength of the TY754 VB as fitted to the STi 5/6 will be no different than that of the TY754 VN fitted to your UK car so I think that changing it before it breaks or more likely, becomes noisey, is a waste of time.
The VN box has longer legs so I guess it can be subject to greater strain but I have no reason to believe it will not last as long.
In the past I have found, just as indicated above, that it is the centre viscuous that is likely to become noisey or give trouble first.
I actually tore the centre out of an AP Racing Organic Uprated at Bruntingthorpe (STi 6 Wagon) and this happened a second time on the road but the box itself was OK but in time I replaced the centre diff twice and eventually the box was overhauled as it was noisey and slipping out of 5th.
My STi 6 Wagon now runs the latest Forrester 6 speed with improved ratios.
The STi 3 Wagon, 409 bhp and 360 ft/lbs runs an STi 5/6 with one of my own adjustable, quickshifts, (£75) TY754VBAAA with viscuous diff. 4.44 diffs.
The 95 WRX Wagon, 422 bhp and 355 ft/lbs, my own adjustable quickshift, TY754VBAAA but with DCCD and 4.11 diffs for greater top speed runs. The diff has a mappable Gems ECU and that is fun!!!

My 754 didn't hold up long with a TD05-16g and less than 340ft/lbs of torque. It did do a few drag runs though.

As above, Forrester 6 speed is the one to go for.

Lots of people use the TY754 box to good effect with far more power than a TDo5 16G can ever develop. I think in part it has to do with driving style and mechanical sympathy. The TY754 from my STi 6Wagon did numerous drag runs including winning Scooby Shootout and then went into my 95 WRX Wagon with no refurbishment where it did further thousands of miles of road work and many drag runs and top speed runs before the centre diff was replaced for a DCCD. Still the original gears. That gearbox has only just been refurbished for the first time after several years of hard service. The TY754VBAA would not have been chosen for my STi 3 Wagon, running over 400 bhp and 360 ftlbs if it was not up to the job and the Forrester six speed is now in the STi 6 only because that will be one of the most powerful two litre daily drivers, ever.

Thanks Harvey :)
Spot on answer :thumb:

I ran a TY754 box all last season in my RA with a 16G mapped to the limit.
It was certainly not used sympathetically :norty: I competed in around 16sprint and hillclimb events with multiple unsympathetic launches in each event. I have just removed the box and it was still working fine when it was removed. Would it handle much more torque when used this way mmm I have my doubts.
As far as I was aware the 754 new age boxes, the one I used was from an 04plate blobeye, were the same, with the exception of the ratios, to the earlier 754's.

The later 754's as fitted to the 2.5Lt WRX's are different again and are supposed to be stronger than the earlier 754's but I will put this to the test in about 6 weeks :D