DIY - Differential and Ring & Pinion Swap

[kodyo]

Alright, so here's the scoop. I got sick of waiting a week+ in between emails with Spence at Weir Performance, so I went about finding an alternative gear solution. Based on some stuff I was reading, I decided to buy a set of Motive Gears for a V6 toyota (People were saying that pretty much any 8" ring/pinion for a toyota would fit). I went with the V6 over the 4 cylinder version because it had the correct tap size for the ring gear attachment bolts. Here is the link if anyone else wants to go that route.:

http://www.jawsgear.com/Ring_And_Pin...s-Toyota-8-V6/

That being said, after a quick comparison, it is quite clear that the Weir Performance pinion gear has MUCH thicker teeth than the Motive Gears. Probably on the order of 20%+ if I had to put a number to it. So if you want to go higher power than stock, I think that is probably the safest route. For a stock-ish FRS, I'm guessing the motive gears will work just fine.

I put the OEM differential back in yesterday so I could choose not to rush this rebuild (the car feels hella slow now). I bought a 12 ton press from harbor freight, which made the process go so much faster. If you don't want to buy a press, there is a trick for quick setup. What you do is you take an old/scrap pinion bearing and sand down the ID so it can be easier to put on/take off. Use this bearing for setup and then once setup is done, use the new bearing to get final position and for install.



Here is the progression of pattern I saw as I went through setting up the gears. Measured the backlash to be .011 (.007-.009 being preferred), so I will be buying new shims along with new seals (noticed some diff oil on the under side of the car upon removing the 4.56 diff last).

First Setup:



Second Setup:




Final Setup:


(180deg from first image)


After correcting backlash, I'll recheck mesh again before install. Relatively happy with where it sits right now.

[kodyo]

Got the Motive Gears setup and in the car. I've basically become an expert at getting the differential in and out, haha. Took me 2 hours to get old one out and new one in this time, a new record.

Anyways, no more whine from the gears, so I think they are setup right this time. Going through a more extensive 100 mile break in (20 miles at a time, no speeds above 60 mph), then no heavy acceleration for 500 miles with an oil change at the end of that.

I did kind of figure out the difference between the Motive Gears and the Weir Performance Gears. See the drawing below, but basically the motive gears are positioned further into the ring gear than the weir performance gears, and thus, operate on a smaller tapered section of the cone defined by the pinion gear. What this means is that the ring gears are basically identical, but the teeth on the pinion will appear smaller on the motive gear than on the weir gear since the gears are designed to operate at a different depth relative to the ring gear. What this means for the actual strength of the gears is anyone's guess. I'm not sure now if that necessarily means one set is inherently stronger.

[Joeyk]

I was trying to call/e-mail Spence @ weir but no reply or phone calls getting thru.

when I call it goes straight to voicemail.
Should have bought the set when I could get in touch with him.
going to get the 4.8 gear set.

[Joeyk]

Got the 4.88 gear from weir. Can't wait.
I love the added tq feel on my s2k after the 4.7 Fd.

Waiting on the Tomei LSD to get them all installed at same time.

[kodyo]

Originally Posted by Joeyk

Got the 4.88 gear from weir. Can't wait.
I love the added tq feel on my s2k after the 4.7 Fd.

Waiting on the Tomei LSD to get them all installed at same time.

Manual or auto?

[mrk1]

I finished my 4.44 install the other day with MFactory gears and Weir install kit. I am getting a slight whine, I mean no radio, windows down, stock exhaust, and listening for it slight. If it persists past break in I maybe concerned but for now its not on my mind.

[mrk1]

I contacted MFactory about the slight whine I'm hearing, here is there response.

"whine is normal due to the different tooth angle on the final drive."

[kodyo]

I got whine on mine, as you can read earlier in the thread, from a poorly setup gear mesh. I'm not saying that is the issue you are getting, but once I got a new set of gears and meshed them correctly, I had no issues. So if you had a shop set it up, it might be worth contacting them about. I have hard about aftermarket final drives whining due to the tooth angle. It all comes down to how loud it is. Mine was fairly loud and was on decel only.

[Joeyk]

Mine is Manual.

little whine can occur since you are turning more per rev now and is not used to the sound. Too much whine can occur from improper set up.
Weir seemed like he knew what he was doing so I doubt its the install error.

[Lunatic]

I have 4.88s from Weir in mine and it makes no noise at all.

[Joeyk]

What speedo calibrator are you guys using?

[mrk1]

Originally Posted by kodyo

So if you had a shop set it up, it might be worth contacting them about. I have hard about aftermarket final drives whining due to the tooth angle. It all comes down to how loud it is. Mine was fairly loud and was on decel only.

I built this diff myself so thats why I asked the manufacture and they said it was the tooth angle. I bet if I reinstalled my back seat I wouldn't even hear it, its that quiet.

On a side note I've been taking the long way to work just because its so much more fun to drive this car now.

[kodyo]

Originally Posted by Joeyk

What speedo calibrator are you guys using?

No speedo calibration needed. Speed is taken at the wheel sensor.

[GT86drifter]

@Dustin @kodyo where you able to measure the pinion depth spacer?