Protecting my 5MT (blast plates, uprated mounts, etc.)
 

I've got a V1 WRX with, as far as I know, a TY752VB3AA 'box. Is there any way of pre-emptively protecting it?

The car is currently just running a Z4 ECU with 3" exhaust and, even though I planned to get it mapped (on a different ECU, obviously), I'd be more than happy with 'just' 310-320bhp. I am, however, fairly partial to launching it from a standstill, and am planning a track day or two in the near future.

As I understand it, flex under torque breaks the box by creating insufficient gear engagement, so my plan is to fit:

- Uprated engine + gearbox mounts (to limited the flex in the driveline)
- Kein blast plates
- change the oil from Motul 300 to Redline Shock Proof

Is this a sound plan or am I wasting my time (and cash)?

Thanks in advance!

The "blast plates" are a waste of cash

How so? Not disputing it - I can't find any evidence that proves either way!

the launching will kill it quicker than all the trackdays you can manage harry-the imprezas forte is grip and lots of it-at 340 i killed a gearbox a year on average with the early ty52 boxes(when there was lots of 2nd hand units about) - the later newage ty54 5 speeds are reportedly stronger and of course much newer.
in the day 20 years ago plenty of 5 speeds shat there guts with standard powered cars--better mounts and clutches unfortunately puts even more strain into the box-

Wrecked 3 x 5-speeds with 340+ lbs.ft (it’s the torque not the bhp).
I still have the blast plates I tried fitting to the last one somewhere.

I was was just wasting my time and money.

Running a 6-speed now.

What is it that actually fails on the 5 speed box? And why?

The weaknesses are the internal parts, not the case. Certainly bolting some bits of metal to the outside of the case won't address any internal issues.

Either drive with more mechanical sympathy
Fitted an uprated 5-speed gear set
Fit a 6-speed box.

Thanks all - I was fairly sure the blast plates would be useless but hoped otherwise. Hadn't considered that stiffer mounts would actually put more strain on the gearbox, so thanks for that too!