How-To: Change final drive ratio (relatively) cheaply

[Anthony]

There's a chart around here somewhere...

I'm actually serious. Think I'm probably going to do it. Eventually.

And yes, first gear's going to be bananas.

[uncivilised]

I can confirm that the M22 diff thats in the australian/european is300s fit the 86/frs/brz with no issues

Just got the 4.55 gears installed as well. its a good improvement but may look into 4.7 or 4.88 in the future.

so thankyou PantsDants and Jeff Lange for your help on this.

[JiB]

Originally Posted by uncivilised

I can confirm that the M22 diff thats in the australian/european is300s fit the 86/frs/brz with no issues

Just got the 4.55 gears installed as well. its a good improvement but may look into 4.7 or 4.88 in the future.

so thankyou PantsDants and Jeff Lange for your help on this.

how much u pay for install?

[uncivilised]

Originally Posted by JiB

how much u pay for install?

about 1k all up. I had the 4.55 diff gears already that i picked up very cheap from a GA70 supra diff.

[fooddude]

Originally Posted by uncivilised

about 1k all up. I had the 4.55 diff gears already that i picked up very cheap from a GA70 supra diff.

Does it really cost that much to install the FD?

Anyone know the going rates in SoCal for FD install? (both gear install and removing&reinstalling of pumpkin).

Tranny Shop recommendations in the LA/OC area welcome

Worse comes to worse and if it really costs that much, I think I would just drop the pumpkin myself and just drive it to the tranny shop so they'd just do the install of the gears (but I like the convenience of them having do it all..only if the price is decent of course). I know the actual gear install would cost a bit and requires special tools/skill; but swapping just the pumpkin itself is pretty easy and should only take an hour (or 2 at the very most if you're taking your sweet time). I swapped a junkyard Infinity(iirc) LSD into my S13 before; and I remember it was easy and fast.

[uncivilised]

Originally Posted by fooddude

Does it really cost that much to install the FD?

It only cost that much as i bought an is300 lsd carrier and paid a shop to setup the diff correctly. I would have saved $500 there abouts if i used my stock 86 LSD instead.

[suaveflooder]

WOW! GREAT post! Saving this for future reference.

[fooddude]

Originally Posted by uncivilised

It only cost that much as i bought an is300 lsd carrier and paid a shop to setup the diff correctly. I would have saved $500 there abouts if i used my stock 86 LSD instead.

Ah, I see. Nice! $500 sounds totally reasonable and like a good price for install labor.

Aside from wheels/tires & coilovers, I think a short FD would be my very first modification. I don't think there's any other better engine/drivetrain mod for less than $1k that would yield such a big and noticeable difference/improvement over stock.

[uncivilised]

I would recommend it, its a good improvement. I gave the car to my friends to drive without telling them I did this mod and they all noticed the difference.

[JS + BRZ]

Thanks for the awesome thread. So much valuable stuff in here.

So, just to confirm.. if we can source the rear differential carrier of an IS300, we can basically swap it with our stock rear differential, yes?

[PantsDants]

Originally Posted by JS + MS3

Thanks for the awesome thread. So much valuable stuff in here.

So, just to confirm.. if we can source the rear differential carrier of an IS300, we can basically swap it with our stock rear differential, yes?

Correct, the only thing to note is that the IS300 carrier will have axle stubs (half-shafts, wheel-looking things) that will need to be popped out. On the IS, the axles bolt onto these, but on the 86, our axles spline straight into the carrier.

...but JUST to make certain, you're talking about just swapping carriers right? Like drop pumpkin #1 from your car, install pumpkin #2 into car, done? If you're talking about swapping the actual differential out of the carrier, I can't say with 100% certainty that that will work. It SHOULD, considering the IS300 and 86 carriers both contain T2 Torsen differentials, I'm just not 100% on if they bolt up the same internally.

[Dustin]

@PantsDants what was your reasoning for using he IS carrier? Was it solely to limit down time? It just seems to me if you were paying a shop to do it, why incur the extra cost of the carrier instead of just buying a ring and pinion for the FRS. The setup time for uninstalling and reinstalling wouldn't be more than an extra day or two. Or did you have another reason for doing so?

[fooddude]

Originally Posted by PantsDants

Correct, the only thing to note is that the IS300 carrier will have axle stubs (half-shafts, wheel-looking things) that will need to be popped out. On the IS, the axles bolt onto these, but on the 86, our axles spline straight into the carrier.

...but JUST to make certain, you're talking about just swapping carriers right? Like drop pumpkin #1 from your car, install pumpkin #2 into car, done? If you're talking about swapping the actual differential out of the carrier, I can't say with 100% certainty that that will work. It SHOULD, considering the IS300 and 86 carriers both contain T2 Torsen differentials, I'm just not 100% on if they bolt up the same internally.

I thought I read somewhere that only JDM IS300's have the 4.56 in certain models and none of the USDM IS300s had 4.56; hence, you won't find any 4.56 pumpkins in american junkyards. I could be wrong though or may have thought incorrectly.

[PantsDants]

Originally Posted by Dustin

@PantsDants what was your reasoning for using he IS carrier? Was it solely to limit down time? It just seems to me if you were paying a shop to do it, why incur the extra cost of the carrier instead of just buying a ring and pinion for the FRS. The setup time for uninstalling and reinstalling wouldn't be more than an extra day or two. Or did you have another reason for doing so?

The main motivation was actually to have two working carriers as insurance against an improper gear setup or bad break-in period. The majority of gear wear happens during the first 500 miles, and if you don't do it right, you could end up with warped gears. At least, that's what I've been told.

But yeah, it also served to limit my time without the car. Considering it took the shop around two weeks to actually get my ring and pinion installed in the IS300 carrier, I think I made the right choice there. Additionally, I sold my FR-S carrier to another member here and made my money back, so it didn't cost me anything extra in the end.