Hi all.. i have what are hopefully some basic questions about gearboxes.. this is all a little new to me and i have been confusing myself a bit with all the terminology in other posts..

I have a 96sti.. gearbox seems fine at present. I have various bits and pieces (fmic, apexi ecu etc..) to put on my car and i understand that with 440cc injectors on there i would be able to get at most 320-330bhp

1. is this likely to make my gearbox go bang/how much power can they handle?

2. presumably the later version sti gearboxes can handle a bit more power? can anyone tell me how much i.e. v3 - v6?

3. if i was to install a later gearbox would i also need the corresponding diff?

4. at what sort of power would a 6 speed box be required?

5. i was advised that for example to reach 400bhp i would be looking at 3k for a gearbox rebuild!! what would be changed in it to handle that much more power??

6. what is a ppg box?

I thought i would just get all the q's in from the start, if anyone can comment on any of the above that would be great!

 

I've broke a late and an early one with approx 300bhp, its just luck imho if one lasts.

 

cheers 172, comments noted.

Can anyone else comment also?

 

do a search fella, loads of advice about

 

Your 96 car has a TY752 gearbox and these can break quite easily especially when power gets above 350 bhp. Late 98 onward 5 speed boxes are TY754 and these are stronger with many examples running over 400 bhp and several at 500 bhp. At that power level I guess the gearbox, even the 754 should be regarded as an expendible item.
A lot depends on how the gearbox is treated and the clutch in use. A harsh paddle clutch will kill either gearbox quite quickly.
The main difference between the 752 and the 754 is that the 754 has a much more rigid casing.
Your TY752 will have either a 4.44 or 4.11 diff ratio and so you must replace this with a gearbox with the same diff ratio which can be determined from your complete transmission number. Obviously the diff ratio has to remain the same.
The 6 speed gearbox is a stronger item all together, 400 bhp is not an issue and plenty of these run well over 500 bhp.

 

thanks harvey.. exactly what i was after.

 

Thought I would give my input as im currently researching into stronger gears/boxes.

My cars almost standard uk turbo classic, probably about 220bhp. The standard box on the car hadn't been right for a while crunching into 4th, the box gave up on me when I launched the car and I couldn't get it into second gear, box code TY754vn1aa. Two weeks ago replaced the box with the TY754vn4aa which is from the newer shape wrx, run it all in and felt fine, launched the car and it popped out of first. It now crunches into second, wont always stay in first and high revs it wont go into 4th. Looks like its coming back out joys of motoring, but I guess these guys running big power have just been lucky.

Keep me infomed of any info you find, cheers.

 

I stripped second gear on a TY754 in my UK classic, at the time it hadn't been remapped so would have been running close to standard. It did have a twin plate carbon clutch on it though which gripped very well, so it would appear shock loading killed mine. I then had the PPG gearset fitted along with other parts and a re-map. Car was making 300bhp and 315ft/lbs of torque. I then broke the rear diff, this looks like it was caused by an oil leak that had gone unnoticed. After that I broke the drop gears and centre diff, so had Type R drivetrain fitted and the PPG gears swapped into the new setup. So far not broken anything, but should have gone 6 speed from the start.

 

Mister Melon have you checked out the PPG website? Australian company which makes very strong boxes, both striaght and helical cuts..

also just found this link which may come in handy if you are changing boxes/diffs/gearsets:

http://www.northursalia.com/techdocs...rannychart.pdf

 

Yea, i've looked into that but then i've read things on here of people even stripping those, its alot of money to spend for fear of stripping them my cars pretty much standard and i've done two boxes from lauching the car and that wasn't even flat out. Id be nervous of building a ppg box and the thing breaking

 

I do think you would struggle to break the PPG with the power your running ryan

 

What about a scoobyclinic gear set?