5 speed gearbox
 

Hi,
I have a Blobeye running 375bhp, I want a bit more out of it, will a 5 speed gearbox cope with 400-450bhp
Thanks

Has been known but very, very rarely. Even at your current power you’d be considered as above the ‘safe’ threshold. That’s not to say yours isn’t ok though.

It will cope fine...... until it breaks!

No seriously if mapped with a gentle spool and driven like Miss Daisy then it’ll be fine! It’s the torque that kills them rather than BHP, I’d say if you plan to push the car at all then you need to uprated or switch to a 6 speed.

As I thought, many thanks

In all honesty I think you have done well for a 5 speed gearbox to be in one piece running 375 horses,if you are looking to run 400+you should definitely be thinking about a 6 speed box first.SJ.

I ran 370 on a 2002 Wrx 5 speed including some track work for a few months and it didn't break - I was careful not to launch it though!

It also did some time at 390 on a 2.5 with over 400lb ft torque.

I was waiting for my 6 speed to arrive though!

I was careful not to launch it though!...Thats the trick!...I know that the 5 speed boxes in the newage Subarus are stronger but wheres the fun in babying a gearbox?I also know mates of mine that have run 390+ on a 5 speed,but one hard launch later it all ends in tears....A 6 speed gearbox would run 450+ no sweat with ample room to spare.SJ.

Thanks, yeah got to go to a 6 speed then, I don’t launch it hard but give it some stick though the gears, it’s doing well as it’s done 4K since rebuild, map and rolling road so bhp shouldn’t be far out
Many thanks

In my RA mine lasted over a year at 407bhp and I wasn’t taking it easy, doing 12 dead’s on the quarter side stepping the clutch

Martyn at Engine tuner ran his upto 550bhp plus until it gave up


But then there are plenty that have failed at even 350bhp, so it’s all about luck I guess

It’s one of those questions like James says it’ll be fine unless it isn’t!

You knock the nail on the head:ok:,but Talking for myself i have learnt to be a “prevention is better then cure” type of guy.SJ.

I had a PPG 5 Speed and a low mileage 6 speed from a WR1 at home at the time, Just wanted to know how far I could push it :)

Martyn done well,he mentioned something like that to me when my car was down there,as my wife has broken three 5 speeds already so I picked up a 6 speed for her scooby and the rest as they say is history.SJ.

You done well James with 407bhp driven hard as Jens Subaru only had 350bhp at the time and it seemed she was getting another box every month Lol.SJ.

i'm currently at 350 and it's fine, but 1 thing i have been wondering about, i dont remember the name for it but i have seen people advertise a brace that goes on the outside of a box to make it stronger? do these actually work? i dont remember where i saw the ad though

I've read about these too, they're called blast plates and they're designed to stiffen the gearbox casing as apparently one of the issues is a slight twisting/distortion under heavy load.

http://shop.mooreperformanceparts.co...i-2280992.aspx

Not tried them though, power i'm running doesn't really warrant them. Gearbox needs to be dropped for fitting apparently.

yeh thats the ones, i think the ones i saw where on scoobynet and made by a different person, i spoke to a friend about these cos i didnt see how bolting something to the outside could make the gearbox stronger, he said that under heavy load they can expand and these plates are probably designed to stop that. i dunno lol. when i had my car mapped by duncan at race dynamix he said he has a couple of customers at 500+ with the 5spd and they have no issues. i guess it's abit of a lottery but most people say 350 from what i have seen

Thanks to all for the info really helpful, think after paying to have it forged I will prob go 6 speed but not cheap so fingers crossed the 5 speed holds out for couple more months.
Many thanks