1st & 2nd helical PPG gears

[ReaperSS]

Looks like i will keep the WRX now and intsead of paying $1500+ for a 2nd hand box that may just fail not long after anyway, ive decides to buy PPG gears set for around $2400 and get my uncle to to the labour.


Anyone had these?

Are they as strong as they say?

Are the helicals noisy?

[bodybodyrock]

helical cut gears arnt noisey. its straight cut gears that are noisey, are u only using ppg gears for 1st and 2nd? or complete gearset?

[joey89]

Helical's are alittle more noisy than stock but noway near as noisy as straight cuts.

They say straight cuts are stronger than helicals but helicals are more than enough plently strong.

For $2400 im guessing just 1-2nd as 1-4th is 5k+

[Boza]

put a my99/00 box in it (can be found 2nd hand for 1k) and sell your case to someone to fund the labour swapping it out

put some NEW tyres on it as ones now are ridiculously bald & get a non cracked rim on it

lastly license the bloody thing !!

ppg set not needed as it is near std

my 2c

[Nemi]

like the 2 boxes unnamed liberty driver has broken ?
putting in a nice strong 1st and 2nd is much wiser as numberous wrx owners with stock cars have managed to pop boxes the broken original box is a shining example of this.

[ReaperSS]

put a my99/00 box in it (can be found 2nd hand for 1k) and sell your case to someone to fund the labour swapping it out

put some NEW tyres on it as ones now are ridiculously bald & get a non cracked rim on it

lastly license the bloody thing !!

ppg set not needed as it is near std

my 2c

I was only days from getting it licenced when the box let go. Got new tyres on it. Have all 4 good rims. No cracks.

If i go back to stock box i can guarentee i will blow it strait away :(
I will be hanging onto the car now for a while and it might be cheaper and less hassle in the long run.
If i decide to upgrade to new wrx or hatch i will swap box back to std and keep my ppg's :)

[ben351]

farking dog box it bullay

[bodybodyrock]

do it ninja, go the ppg gears, alot less hasels in the future

[Nemi]

plus if you decide to sell the box off for any reason you will be able to get a reasonable amount of money back.

[ReaperSS]

Cool! Will go the straitcuts now FTW.

Just hope that the dudes at pits dont have a barnie

[Boza]

like the 2 boxes unnamed liberty driver has broken

yep 220 or 240hp atw is standard....?

read my post, i said a std one will last ok....plenty of examples i could name, but im sure will fall on deaf ears...

go the ppgs then marc...i was sure your car was still same and nothin had changed, plus was jsut tryin to get you out of it cheaply as you were gobsmacked when i told you a 2nd hand box was round 1k, hence your for sale thread, but go for it, im sure it would prob be a wiser move if you do plan on hangin onto it etc...

[ReaperSS]

go the ppgs then marc...i was sure your car was still same and nothin had changed, plus was jsut tryin to get you out of it cheaply as you were gobsmacked when i told you a 2nd hand box was round 1k, hence your for sale thread, but go for it, im sure it would prob be a wiser move if you do plan on hangin onto it etc...

Yeah, i think i will hang onto it for a fair while. I was only thinkin of selling it due to money issues and now they are sorted and im cashed up to do the job good.

Hey has Seans Wrx (GTR ETA) got straitcuts or heli? If straitcuts then thats good. Its not that noisy when i heard it last time i was down ASG.
Lee is tryin to talk me outa strait cuts but i dont mind the noise. They are stronger and also same price

[Boza]

fair enough..

yeah ppg straight cut synchro 1-4th in his...

[LarryDavid]

Could someone please enlighten me how straight cut gears are stronger than helical gears.

[Joe]

Ok from years of gearbox discussions on a WRX forum (surprise, surprise), this is what I've learned:

Straight cut gears ARENT stronger than helical gears!

The main advantage is a reduction in friction and therefore less power lost through the drivetrain. Straight cuts create less friction than a helical cut gear, because less teeth are in contact. A helical gear can have 2 or even 3 teeth touching each other at a given time (depending on the pitch of the gear cut), where as a straight cut will generally have only 1 or 2 teeth on each gear at any given time touching the teeth of another gear.

In reality, this means that more load is placed on each tooth with a straight cut box (less teeth to spread the load over), but the strength is made up in the metallurgy, and the load is more directional, rather than the sideways thrust loading evident in a helical gear.

Also, straight cut gears sound sicker than helical cut gears.

[doriae86]

haha
no way u need a modded box
i used ot hammer my 98 wagon, ran 12.5 on stock box. never once had a problem

[LarryDavid]

Yes correct, straight cut gears aren’t stronger than helical gears.

But I don’t agree that straight cut gears operate with a reduction in friction. Yes its true that less of the teeth are in contact at any given point in time for spur gears, but it is the engagement motion of helical gears which create less friction, hence making them more efficient.

Helical gear teeth have a gradual (rolling) engagement, rather than the sliding contact that straight cuts have. The rolling motion also allows the lubricant to remain as a film on the tooth surface again reducing friction.

i’d like to see PPG’s evidence to support their statement that their straight cuts provide more strength than their helicals.

The only reason I can think of why straight cuts are recommended for high powered cars are due to the thrust loading which helical gears create. This loading must be absorbed by the bearings which are not designed to withstand high axial loads. spur gears are also cheaper to manufacture for custom applications. Other than that, yes they sound sick.

[TJ]

Dont compare me in this argument, we all know I'm a little violent on my cars.

[Philbot]

understatement

[Joe]

Yes correct, straight cut gears aren’t stronger than helical gears.

But I don’t agree that straight cut gears operate with a reduction in friction. Yes its true that less of the teeth are in contact at any given point in time for spur gears, but it is the engagement motion of helical gears which create less friction, hence making them more efficient.

Helical gear teeth have a gradual (rolling) engagement, rather than the sliding contact that straight cuts have. The rolling motion also allows the lubricant to remain as a film on the tooth surface again reducing friction.

i’d like to see PPG’s evidence to support their statement that their straight cuts provide more strength than their helicals.

The only reason I can think of why straight cuts are recommended for high powered cars are due to the thrust loading which helical gears create. This loading must be absorbed by the bearings which are not designed to withstand high axial loads. spur gears are also cheaper to manufacture for custom applications. Other than that, yes they sound sick.

Again, this also comes down to the manufacturer. You can get a poorly designed straight cut box that creates more friction than a helical box.

Also comes down to the design of the tooth. If you wanna get technical, check this page out http://www.cs.cmu.edu/People/rapidproto/mechanisms/chpt7.html#HDR106

This is the diagram for a correct mesh.

http://www.cs.cmu.edu/People/rapidproto/mechanisms/figures/gear.mesh.gif

Correct meshing also comes down to the involute curve.

http://www.cs.cmu.edu/People/rapidproto/mechanisms/figures/gears.involute.gif

The convolute curve is the path traced by a point on a line as the line rolls without slipping on the circumference of a circle.

A little bit hard to digest, but theres a lot more to it than "helical vs straight cut". It comes down to the design of the teeth, the gears, the metallurgy, the bearings, and all sorts of other variables.

Straight cut gears are cheaper to manufacture than helical also, which is a big advantage for many, plus they sound awesome...AND they are stronger than the stock gearbox in most cases, so there really isnt an argument to be had for many people.

[doriae86]

google for the fucking win!

[DCIEVE]

Larry David covered it pretty well Joe, you muddyed it up haha

[Joe]

google for the fucking win!

Fuck yer...I googled this topic about 2 yrs ago, and saved that link...didnt think I'd be using it again :D

[POTTER]

Ok from years of gearbox discussions on a WRX forum (surprise, surprise), this is what I've learned:

Straight cut gears ARENT stronger than helical gears!

The main advantage is a reduction in friction and therefore less power lost through the drivetrain. Straight cuts create less friction than a helical cut gear, because less teeth are in contact. A helical gear can have 2 or even 3 teeth touching each other at a given time (depending on the pitch of the gear cut), where as a straight cut will generally have only 1 or 2 teeth on each gear at any given time touching the teeth of another gear.

In reality, this means that more load is placed on each tooth with a straight cut box (less teeth to spread the load over), but the strength is made up in the metallurgy, and the load is more directional, rather than the sideways thrust loading evident in a helical gear.

Also, straight cut gears sound sicker than helical cut gears.

here here

buy a 6 speed box they are strong trust me!

i broke a mates straight cut box 3 times
6 speed never broke

or u could just buy an evo

[ReaperSS]

Dropped the box out today thanks to Nemi! :)

He survived the trip to Locko lol!

We drained all the oil out the box and guess what??? No lollys??????????

Even on the magnetic plug...No chunks??????????????????

WTF??????????

[bodybodyrock]

there probly jammed up somwhere, or maybe it was a missdiagnosis??