How complicating is it to build a tranny?

[httrdd]

I have access to a 07 Wrx 5 speed tranny with some bad gears that I want to build and swap into my car. I want tougher gears anyways to handle some boost so how hard is a tear down and rebuild. Is it easier than a engine tear down? What do you think I will be paying for the right cut gears? What options do you recomend?

[grayguy]

Maybe it's just me, but I'd say rebuilding. Tranny is at least 10 times harder than rebuilding an engine, possibly more than that. It's pretty much the last frontier of the automotive world that's is still completely mind boggling to me.

[Garrison]

I would say quite the opposite. I saw the tranny you're talking about, I believe. On that same forum, there is a set of 5 wrx gears in the f/s, so you could theoretically just swap them out.

[httrdd]

Yea but would this tranny handle over 400 hp?

[Garrison]

Yea but would this tranny handle over 400 hp?
Are you trying to drag launch it? If not, then it would hold for a while, but I would say as a general rule >400hp is sti 6-speed territory.

Edit:
http://www.youtube.com/watch?v=kKvqvi3KsdI

See? You can do a 5k launch on a stock sti 6-speed. I would never think of trying that in a subie 5-speed (they're all relatively similar in terms of gear strength).

[anothernord]

What do you mean, "handle"? Do you mean that it can handle a redline clutch dump? It's the shock load from dumping the clutch with the extra torque load of 2 extra wheels to spin that breaks the 5MT's.

[httrdd]

Yea no clutch dump but definately some hard autox and drag strip. Not really a launching kind of driver.

[httrdd]

Yea but trying to find a 6 speed for good money is nearly impossible.

[Garrison]

http://sacramento.craigslist.org/pts/2607554787.html

Dunno what your budget is

[redlegacygt]

i'd say that trans is stronger than some of the previous subaru trans ( 02-03 wrx "glass" trannys) that everyone complained about. If you got it for a good price its worth a shot to rebuild or just swap in new gears. I think alot of it has to do with just how much beating on it your going to do. I've seen stock 5spds last through dozens of autox's and high powered builds, but also brokens on just normal DD's...

[httrdd]

Wow that is actually a great price! I am just getting together ideas untill I make some side work money. The 5 speed swap is going to happen right after christmas (or sooner).

You are right red it is all in how you drive it. I am pretty hard on my 4eat, but never wind the tranny out or neutral drop. It may last a little while longer. Lol.

[rougeben83]

i'd say that trans is stronger than some of the previous subaru trans ( 02-03 wrx "glass" trannys) that everyone complained about. If you got it for a good price its worth a shot to rebuild or just swap in new gears. I think alot of it has to do with just how much beating on it your going to do. I've seen stock 5spds last through dozens of autox's and high powered builds, but also brokens on just normal DD's...

It's actually quite the opposite. Just go to any 06-07 specific forum and you'll find a few people complaining of their broken transmissions. 2.5l torque + 3.7 FD (taller than previous gens, 3.9 at the trans) = more gear strain = kaboom. I doubt you'll have any better luck with an H6 attached to one.

For my money, I still say a 4.11 FD N/A trans (yeah you heard me), or a 4.44 FD outback trans, both with forester XT gears, or simply a forester xt gearbox would be my choices if I have to stick to the 5 speed family.

To get back on point, swapping gears seems easy, but looking at the FSM, you have to deal with gear lash and other subtle things with the rebuild, so yeah it's possible, but don't go in thinking you can hamfist your way through the process.

[httrdd]

Thanks for the info. I might just pick one up tear it apart and rebuild. I like a challenge! If I am going to spend 2,000 on a tranny it might as well have better performance mechanical parts in it. Picking up a 08 Dodge Ram Mega Cab as a daily so I will have more tear down time. :smt002

[2000gtb]

if you are going to do it for t he first time.. just snap some pics before you take each part apart

[httrdd]

Yea and well document the tear down. I did the same thing with my first car wiring job and engine swap.

[Garrison]

Bump for this. I was reading through Unibomber's manifesto over on NASIOC and I found this: definitely worth considering

"Best Gears for 300WHP or below and non hard core drag racers: 2004+ OEM WRX gears that have been shot peened. 2003+ OEM WRX 1st, 2nd, & 3rd gears (AKA the ones that break the most) were increased to STi RA width, though no one knows the cut-off date in 2003, so the best bet is to go with 04+ gears. Shot peening increases their strength quantitatively by 20%. Some may also be interested in additional cryo treatment. A complete OEM gearset can be had for ~$850, shot peening is ~$150, & cryo treatment is ~$150. Any of these options are cheaper, stronger, and more readily availble than RA gearsets available through Vendors."

[chuckthefuk]

That quote is misleading.

1) The Internet + RA gear sets spawned evil myths that make people believe RA gear set are stronger then any regular gear set and can handle ubber power.
2) A complete OEM gear set can not be sourced for under $1000 new.. Why buy used gears with wear/tear?
3) 6MT swaps can be done for $1800 if you just want the 6MT / Clutch / Flywheel. NO axles/hubs/r180/dccd/brembos
4) NO 5MT can handle Redline standstill launches.. Each launch will wear/tear/grind your gears down to nothing.
5) NO AWD transmission will survive constant launching! Shock Loading kills all gears unless fortified or straight cut.
6) NO 5MT will survive aggressive use.. Subaru never designed them for that.. that's why they designed the 6MT to handle 300BHP with room to expand.

Honestly the RA gear sets are more of JDM bling item then purpose / function.. Same goes with the 4.44 JDM trans.. sure it accels quickly but pointless if you use the highway and no stronger then my outback transmission :-D

[httrdd]

Yes so for now I think my 06 wrx tranny will hold till I give it a lot more power. I dont plan on doing any really hard launches as of now. Lol.

[chuckthefuk]

But why not just save for a 6MT. You will be happier in the end :-D

[httrdd]

I already have a 06 5mt that i got for 50 bucks.

[chuckthefuk]

Sense this makes.. :p

[Grafton]

I've replaced a bearing on my 5sp, it was an interesting process to say the least, but if your going as far as rebuilding because of broken gears might as well get a limited slip diff for the front, since you'll be in there. you will need a press to move gears on and off the shaft, a way to hold everything while putting some serious torque on it when re-assembling ~150 ft/lbs + and tools to measure clearances so it doesn't wear it self out prematurely.
also look into upgrading the center diff to one with a faster lockup* ( the correct terminology escapes me atm ... ) for more awd goodness

[httrdd]

Ok thanks. I am sure I will have more questions once I start the rebuild.

[d1giPhux]

Hope you like swimming in trans fluid! :P

A friend of mine just rebuilt the trans on his truck.. guy was literally swimming in that crap for weeks. Not to mention it got everywhere. He said.. never again! :lol:

[httrdd]

I was in the Navy I am a great swimmer!

[tylerkroh]

I got lost throughout this thread but for one of the original questions, it is extremely easy to rebuild a manual trans ive done 4 or 5 in my trans class, on the other hand auto transmissions are terrible ive done 1 or 2 of those and you really have to be observant and take a lot of pics to help you.