This was brought up in the "PPG vs. RA" thread going on right now.

I'm trying to combine old, recent, and brand new data on our trannys and find another tranny solution.

I noticed that some people have complained that the PPG 1-2 combo ratio doesn't match the WRX 3-5 perfectly. Also, the strength of the 3-5 may still be at question.

Since Dave at Rallispec enlightened us on the differences on the JDM STI RA and non-RA gears to WRX gears, there's definitely some proof those gears are stronger. Granted, it's not as big a difference from the WRX gears in 3-5, they are definitely stronger.

I've felt for a long time that tranny options for WRX 5mt guys have a gap. $1500 for RA gears, $3500 for PPG's and 6mt's. Unabomber did a great job of coming with the PPG 1-2 combo that costs people around $2500. I want to take that idea to another level.

In doing research, I noticed two PPG gearsets that have similar ratios to JDM STI gearsets. The PPG Helical Dogbox has IDENTICAL gears to the STI RA 1-2 gears, and the PPG Helical Synchro set is very similar to the STI non-RA set.

Since all of these sets can utilize the existing 5th gear, I'm hoping people can get the JDM STI gears for around $500-$600 for 3-4. With the extra shotpeening, cryotreating, etc. with the stronger JDM STI design matched with PPG 1-2's, we have $2500 sets that are stronger than PPG 1-2 and WRX OEM 3-5, better matched ratios, and stronger overall sets.

I find people who are near 300-400whp numbers are those who will utilize this the most. Since we have several 2.5l hybrid guys including new WRX owners hitting these numbers, I thought this is something that should be looked into.

I hope some vendors chime in. I've logged several users using ONLY RA or non-RA sti gears on setups of this much power. All the people I've asked who have broken RA's were all done in 1st or 2nd.

I plan on eventually going 1-2PPG and rest my RAs. I posted in Andrews thread to see if I can get a 1/2 set that is the Sti 3.16 1st and the RA 2.062 second which I feel would be a wicked setup :devil:

Would do straight cut for the fun sound :D

I will fill in here if I get a price and if it is doable.

RA ratios:

First Gear 3.083
Second Gear 2.062
Third Gear 1.545
Fourth Gear 1.151
Fifth Gear 0.825

V6 Sti ratios:

First Gear 3.166
Second Gear 1.882
Third Gear 1.296
Fourth Gear 0.972
Fifth Gear 0.738

You can't mix dogbox gears with synchro gears, so that option is a no-go. PPG/RA set is an option, but it will be costlier than you'd imagine as from what I remember you have to buy the RA shaft and use it as well + machine the PPG gears to fit on the bigger RA shaft.

Aside from that, I differ in my opinion that the RA gears are stronger than the WRX gears. Tooth gear size is NOT an indicator of strength. Only FEA or other testing can prove which gears are better in the RA vs WRX "battle". I've seen/heard plenty of broken OEM 1/2 and RA 1/2 gear stories, but OEM 3/4/5 or RA 3/4/5 broken gear stories are damn rare. With the limited facts I've seen, they RAs and OEM (04+ RA width, mind you) are identical in terms of strength. This is MY assumption based on what's been reported in this forum and is not fact, just like others' opinions that the RA gears' increased tooth width due to their different gearing means they are stronger. I'm not saying other people or myself are right or wrong, I'm just saying that without testing, there is no right answer.

Hmmm. I've heard of Dogbox/synchro hybrids. Does that mean those gears were made that way?

Dave from Rallispec just did a huge write up on the difference between JDM 5mt sti gears (ra and non ra) vs. WRX gears, and noted that the RA's and sti's were stronger. The strength diff was minimal from 3-5, but should still be stronger.

Snapped 2nd on OEM box...it lasted forever tho
Got Kaaz close ratio for a yr....brilliant box but got sick of short gearing
Fitting now full ppg..1/2nd straight cut..3/4th helical,5th OEM ,all with syncro.

Sold Kaaz gearset to a guy who snap 2nd on his rally RA.

ps.was not able to keep 1/2nd kaaz & fit ppg 3nd/4th with 5th OEM

To combo or not to combo!

I have a similar issue - should I use all 5 RA gear's or 1-4 RA and stock WRX 5th for highway cruising. Any opinions?

^^^

Just a matter of opinion. I think the WRX 5th gear is worthless unless cruising at 85mph or higher. I drive on the freeway in 4th all the time. A 4.44 FD seems to fit my preference.

Hmmm. I've heard of Dogbox/synchro hybrids. Does that mean those gears were made that way?

Dave from Rallispec just did a huge write up on the difference between JDM 5mt sti gears (ra and non ra) vs. WRX gears, and noted that the RA's and sti's were stronger. The strength diff was minimal from 3-5, but should still be stronger.

I just know you can't mix/match dog/synchro on a PPG set. I can't speak for other manufacturers though.

Yeah, I saw Dave's post and didn't want to correct him in his post as it has a lot of good info. That being said, Dave is 1000000% wrong on a lot of stuff. RA vs WRX gear strength has never been proven and never will be. His OPINION is that they are stronger. Since he has no data to back this up, he should come off it and admit it. While I have no axe to grind with him, me thinks his entire post is all about RA gear sales. 04+ OEM gears and PPG gears are becoming more and more popular and his post seemed to fuel the sales fires to me. Though his post has a lot of good info, he is also unaware of the benefits of final drive changes with regard to gear strength, what causes gears to fail, and his assessment of shot peening is very short sighted.

Ron, there are quite a few guys that don't get that what you do with the final drive will effect the trans gear loads. Glad that you understand it and I'm sure that Andrew and Dave Clark would understand.

As far as the RAs being stronger, Rallispec's points in theorey should be correct in the tooth root size making the RAs stronger and also the taller first gear.

Until someone tests it somehow, we won't ever know for sure :alien:

+1 for understanding basic concepts of force

gdhjty

Ron, there are quite a few guys that don't get that what you do with the final drive will effect the trans gear loads. Glad that you understand it and I'm sure that Andrew and Dave Clark would understand.
:


Didn't mean to resurrect a dead thread, but explain this to us....

Final drive effects shock load how? Does the shorter final drive help with strength on shock load, or hurt?

The Transmission FAQ details it better. The essence is that a 3.90 final drive can be looked at as first gear on a 10 speed meaning you have to physically work harder and the first gear isn't supplying that much of a mechanical advantage. A 4.444 final drive would be 10th gear, whereas much of the work is being done by the gears vs your legs. So first gear/3.90 puts more stress on your legs/shock load and tenth gear/4.444 takes stress away from your legs/shock load. All things being equal, a 4.444 equipped car's gears will last longer than a 3.90 equipped car's gears.

^^^

Thanks. You know, I've read that FAQ at least 5 times! I should print the FAQ's are read them. I think I scroll too fast.

$2500 for PPG 1-2 installed??? Where did you get those numbers. I walked out of Andrewtech with 1-2 PPG straight cut for $3400 when all said and done. Thats labor and install. the gears alone cost $1.8-$2k. I did have some problems since I drove on a broken second, but those extra parts ended up being ~$400