Verifying a w58 gearbox

[dave368]

Hi guys,

I don't know if anyone else has seen this sort of thing before, but since there are so many people out there claiming that their gearbox is a w58, I thought I would put this together so you can verify a w58 gearbox so you don't get ripped

Before I get into it, this is a document of what I have done to confirm my own w58 gearbox. I have reasonable mechanical skills so if you don't know why you have to tighten bolts to a specific torque setting, then this is NOT for you.
I also make no warranty, guarantee or any such claim. If you are not confident and you can't take responsbility for your own actions, DO NOT DO THIS PROCEDURE. Most wreckers will NOT provide warranty/guarantee if you perform this procedure, so either get them to do it or ask for an independant qualified mechanic to do it for you. It should only take about 30-45 minutes, so it is a good investment.

There are plenty of sites that have the gearbox ratios for the w5x series, the w57 and w58 have the same first 4 gears as the same ratio, but fifth is different (w57 = 0.86 and w58 - 0.783)* This is how we are going to verify a w58.

Now since these ratios are very close to each, it is quite difficult to get accurate by marking the input and output shafts and rotating the input shaft 1 turn and seeing how far the output shaft goes. This may work for you, but if you want to be really sure, you have to count the teeth of 5th gear.

Luckily enough this is easy to do with just a 14mm, 12mm and 10mm socket, torque wrench, soft mallet or plastic hammer, a tube of gasket goo and replacement gearbox oil. Naturally you will need to get permission from the owner of the gearbox before you attempt this procedure, but it will guarantee that you are getting what you paid for. I assume that the box is out of the car for this as it can't really be done in the car.

1. Drain the gearbox of oil (you were going to replace that anyway weren't you?). Replace the drain plug and tighten.
2. Using a 12mm socket, remove the tab from the speedo drive on the side of the extension housing.
3. Wiggle out the speedo drive. You may end up with oil coming out of this hole, so plug it with a *clean* rag.
4. Remove the shifter by unscrewing the 4 x 10mm headed bolts at the base of the shifter. This may vary from gearbox to gearbox as I have seen a couple of different types. Make sure the gearbox is in neutral (makes it easier later) and remove the shifter.
5. Undone the 6 x 12mm headed bolts holding on the cover plate for the shifter. Note as you remove these bolts, there are 6x 1mm spacers in the neoprene cover underneath the aluminium. Don't loose these! See attached picture (shifter1.jpg)
6. Remove the aluminium coverplate carefully and retrieve the 6x 1mm spacers in the neoprene. Remove the neoprene.
7. You will now see a 12mm bolt on the shifter arm. Remove this bolt so the shifter arm slides freely on the shifter rod.
8. Around the extension housing end of the steel sandwich plate, you will see 9 x 14mm headed bolts. Remove all of these.
9. Using a rubber mallet or plastic hammer, tap the extension housing gently away from the sandwich plate. I found the best way was to stand the gearbox up on the bellhousing and hit the rear gearbox mount in an upwards direction. It may take a few hits, but it will release eventually.
10. Lift the extension housing clear (straight up), making sure you grab the shifter arm (don't drop it).
11. Note where the selector rod is positioned and remove.
12. Now you are at the point where you can start counting teeth. Using the atatch picture as a reference, mark a starting tooth on each of the layshaft 5th gear and the mainshaft 5th gear. Count each tooth on the main shaft (the long one), write it down and then count the layshaft gear. When counting, always use a clean pointer (e.g. screwdriver) to count each tooth. It is *very* easy to lose count here. Double or triple check if necessary.

Because the w57/58 has an input shaft tooth count of 46 on the layshaft and 34 on the input shaft, that creates a 1.352 ratio going into the gearbox. With a 5th gear count of 57 teeth on the main shaft and 33 teeth on the layshaft, it makes a final output ratio of 0.783


Input Layshaft count divided by Input Main count
46/34 = 1.352

5th gear layshaft divided by 5th gear mainshaft
33/57 = 0.579

1.352 x 0.579 = 0.783 5th gear ratio

So the long and the short of it, if you have 57 teeth on the main shaft and 33 teeth on the layshaft, congratulations you have a W58 box!

To reassemble:

1. Place the selector rod previously removed back into the same position.
2. Clean old gasket goo from extension housing and sandwich plate. Do NOT let any get into the gearbox!
3. Place a bead of fresh gasket goo on the sandwich plate and smear with finger. Do not place too much on here as it will squeeze its way into the gearbox.
4. Slide the extension housing over the top of the main shaft. This is where you have to slide the shifter arm back onto the selector rod as the extension housing is going back into place. Insert and tighten the 12mm bolt into the shifter arm. Torque to 38Nm or 28ftlb
5. Insert the 9 x 14mm headed bolts and torque down to 37Nm or 27ftlb.
6. Place the neoprene cover over the shifter arm and insert all 6 x 1mm spacers in holes.
7. Replace aluminum shifter cover and tighten 6 x 12mm headed bolts to 16Nm or 12ftlb
8. Insert shifter and tighten 4 x 10mm headed bolts.
9. Carefully insert the speedo drive and reinstall lock tab with 12mm headed bolt.
10. Replace gearbox oil

Job is done.

If you have gotten this far, thanks for reading and I hope this helps you out. If there are any questions, feel free to ask.

Cheers,
Dave

* Gearbox ratios taken from toymods FAQ (http://www.toymods.org.au/~rod/Techn...0GEARBOXES.htm) and toyota supra manual. Torque specs taken from Toyota W58 gearbox manual. Teeth counts are from my own experience.

[CrUZida]

Just like to point out to be VERY VERY careful not to knock the selector rod while putting the rear housing back on, and to make sure NO GEAR is selected at the time.

Failure to do so will result in the gearbox being locked into gear, which you really can't tell until its mostly reassembled

[ed]

Now since these ratios are very close to each, it is quite difficult to get accurate by marking the input and output shafts and rotating the input shaft 1 turn and seeing how far the output shaft goes. This may work for you, but if you want to be really sure, you have to count the teeth of 5th gear..

um, why not just get a friend, and turn the input shaft, say 20 times, and get your friend to count the output shaft, then divide!!?? piece of piss!! much easier than pulling the box apart!!

if you want to be more acurate, turn it 50 times...

[dave368]

Thanks for the input CrUZida - good advice.

um, why not just get a friend, and turn the input shaft, say 20 times, and get your friend to count the output shaft, then divide!!?? piece of piss!! much easier than pulling the box apart!!

if you want to be more acurate, turn it 50 times...

Yeah you're right. I also took the opportunity to check the condition of the syncros (I actually split the case as well) and thought that others may find it useful. You hear so many stories of people being sold a w58 when it was actually something else...

Cheers,
Dave

[brett_celicacoupe]

so whats the difference in ratio/gears for the W55 vs 58?

[CrUZida]

http://www.answers.com/topic/toyota-w-transmission

[brett_celicacoupe]

handy indeed

[wilbo666]

um, why not just get a friend, and turn the input shaft, say 20 times, and get your friend to count the output shaft, then divide!!?? piece of piss!! much easier than pulling the box apart!!

if you want to be more acurate, turn it 50 times...

Umm, yeah I'm with ed

Cheers
Wilbo

[Cameron_Datto]

Because the w57/58 has an input shaft tooth count of 46 on the layshaft and 34 on the input shaft, that creates a 1.352 ratio going into the gearbox. With a 5th gear count of 57 teeth on the main shaft and 33 teeth on the layshaft, it makes a final output ratio of 0.783


Input Layshaft count divided by Input Main count
46/34 = 1.352

5th gear layshaft divided by 5th gear mainshaft
33/57 = 0.579

1.352 x 0.579 = 0.783 5th gear ratio

So the long and the short of it, if you have 57 teeth on the main shaft and 33 teeth on the layshaft, congratulations you have a W58 box!




Do you know the input Ratio / teeth count of a W55 gearbox ?

[dave368]

Do you know the input Ratio / teeth count of a W55 gearbox ?

Sorry mate, only have access to W57/58 box but I've had a quick look in the EPC and it looks like the Soarer MZ2# (86-88) (supposed to have a w55) and the JZA70 Supra (88-93) (supposed to have a w58) share the same input shaft and counter gear as far as the part numbers go.

So it would be a safe bet to say that they are the same number of teeth. I've attached the pics from the EPC so you can do your own research though to verify what it tells me (or to say that I'm smoking crack because the part numbers don't match and I can't read )

Maybe someone else will be able to help with a confirmed sighting on a w55?

Cheers,
Dave

[mike1980ra40]

What about a listing of gearbox part numbers?, thought it might be simpler to quickly
identify one eg. in a wrecking yard.

cheers.

[CrUZida]

There are no identifiable part numbers on the box.

[Steve M]

We found Ed's method to be very accurate when we wanted to see what box we'd bought (turned out to be a W55).
Works like a charm and was easy.

[wilbo666]

... I've had a quick look in the EPC and it looks like the Soarer MZ2# (86-88) (supposed to have a w55) and the JZA70 Supra (88-93) (supposed to have a w58) share the same input shaft and counter gear as far as the part numbers go.

Looks like GZ20 and GA70 to me (to split hairs )

Cheers
Wilbo

[mike1980ra40]

I came up with an idea based on ed's idea, if your own your own and no one to help you.

grab this degree wheel
http://www.toymods.net/forums/showthread.php?t=1635
cut a hole in the middle just big enough for the output shaft to go through and mark a
tooth on the shaft with a paint pen and get that lined up with zero on the degree wheel.
put a mark on the input top center.

put gear box in 5th, turn the input one turn and the mark on the output should line up
fairly closely with 282 degrees (.783 if w58). I haven't tried it yet, I just thought of it while
having a coffee 20 mins ago.

If it's a W55 output should line up with 306 degrees.

cheers