JoshFSM

Wassup yall.....Since I have 4 w58's, and a couple broken ones, Ive dissected a few to see whats going on. My head tech's family has a 30 year old transmission business, and its just in his blood. I take his word on just about anything, and after inspection, we determined the two to be identical. Ive seen people posting about synchro differences, gear ratio's, and other differences. But, after busting them open, all the gears, syncros, shafts, case, etc...seem to be identical.

Oddly enough, the supra w58's seem to break 3rd gear, while two of my SC w58s broke input gears, leaving me with 4th gear to limp home. Im wondering if there is a differnce in the SC 3rd gear, and the supra input gears? Well, after a little R&D, im going to do a little hybrid trans, using the supra input shaft, and SC300 3-4 gear sets. As far as my ability to do the testing, well the car makes decent power, enough to chew up a trans easily. One of mine broke on a hard 1-2 shift, with significant traction. The othe broke during a hard 5th gear pull(which is stupid anyway).

I did have an issue converting a supra W58 to work in my 92SC. The shifter mechanism needs to be switched...Easy, just split the case, swap parts, etc....Welp, the trans did not go into 1,3, or 5 when i put it in the car. WTF!? SO i took it back out, and apparently the shift rod itself has an extremely minor difference, which can make for a big problem. The bolt hole for the mechanism are in slightly different locations, and make the rod hit the case when trying to go into 1,3,5. Below is a pic of the supra rod and the SC rod, so no one else runs into this issure when swapping in a trans.

We may in the future, become a sponsor, and offer a W58 rebuild service as well as some cryo treating for longevity. Maybe we can turn this into a little informative W58 thread, if you guys have found anything else that may be informative, post it up! In all, the W58 is a simple trans to work with, they just have 1/2in gears, which is going to be the weak link.

Josh


The two shift rods, the SC being the further one, these need to be changed out for a 92-94

Another shot of the two shafts and shifter mechanisms

My most common breakage, the input gears on the SC W58

Todd1225

Great post! I wish someone could "build up" the W58 so that we would not have to resort to the R154 or V160 from the Supra. What horsepower level do you feel is the breaking point for the w58?

JoshFSM

It all depends on how you put the power down Todd....WIth less traction, my transmissions have held near 600wheel. But as soon as they hook, things start stressing. All day long, Id say the 58 can hold 450wheel. Alot is driving style, tires, etc....If our cars were 4-500lbs lighter, I think they would last a hell of alot longer. The best thing Ive found, is to be gentle. When making that kind of power, there is no reason to pound gears. Im going to try one more time, before I throw the Getrag in.


Damn, 70 views and 1 reply? Guess there arent too many people making enough power to break a W-58

Epik

iTrader: (7)

I'm looking to do a manual tranny swap in my 93 GS300 that is set up to drift and has a custom twin turbo 2jzgte. Despite the capabilities of the power plant, I'm wanting to keep the power at about 350-400whp.. in your opinion, after seeing the w58 up close.. would it handle it?

There's your informative/inquisitive post.

SCoupe

Thanks for posting your insight into the W58. Do you know if the w58's from other Toyota applications are compatible with the SC, (the tranny was in Celica and other vehicles, right?)

dejacky

iTrader: (2)

JoshFSM,
any updates? I'm starting to read of more persons rebuilding their w58's with cryo treated internals among other things and are running 400+rwhp successfully so far.

JoshFSM

Jacky- unfortunately no updates as My car is just simply making too much power for any 5spd at this point. We are trying to put 800 to the tires, and I got a smoking deal on a 6spd. I do have plenty of 5spd cores laying around with various things broken. I can rebuild these transmissions, but havent gone as far as cryoing them since the arrival of the getrag.

Shellhouse

iTrader: (2)

Great info. But are you sure the differences wouldn't be attributed to different year revisions vs. different models?

Referring to the previous poster's comment about other (previous) W58 applications, the earlier units are reportedly not as strong. There was a fairly significant update a some point (for the Soarer/MKIV):
http://forums.toymods.org.au/index.p...3ab7949d4d793b

vipsoarer

the main problem with the w58 is that it was built as a truck transmission. It can handle low end torque perfectly but the issue relies in high end power where josh said he was experiencing, the input gears. Third gear is also a weak gear for some reason. while cryo-treating the gears may help surface strength of the metal the sprog faces arent the problem its the splines that are weak and with cryoing can make them brittle if they are not perfectly done to match the material. I have done a lot of research after i fit the mk3 r154 in and the fact of the matter is the application of the w58 is mismatched to our goals of high power. Only by changing the gears to a set of dog gears (straight cut with no syncros) will the w58 be able to handle high power with abusive shifts.... as of now dog gears would cost an arm and a leg to get, around the price of a v160 and possibly more depending on the materials used for the gears.

JoshFSM

I just freshened up my getrag, and whew, no wonder it holds the power. The gears are 1in thick, and the input shaft is massive. If I break that, lol, its just not meant to be. The original w58 in my sc was the strongest of the three i had in there, and took a serious beating before letting go.

Doing 500+ whp pulls with a w58 IS a roll of the dice. I cringed everytime, but stayed in it at all times. The question isnt will it break, its when will it break?

chidoks

my fingers are crossed that mine will hold...

Sintari

Josh, did you ever finish the hybrid transmission and get it to work?