IS300 M85/M98 rear diff - does it fit? - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

PantsDants · 08-11-2013, 02:31 AM

So I saw the thread about the Cusco final drive gear kit and it got me thinking that I'd like to up my final drive ratio. However, I would also like to be able to swap the diff as a unit rather than replace the internals of my stock one. I figured it might help cut down on labor costs to have a shop just install the kit with the diff already out and I could install the diff myself.

My idea was to find a compatible one in a junkyard or eBay and install a final drive kit in that, probably the 4.556 ratio offered from autofactory.jp (provided someone over there speaks English and they actually ship to the US

). Price point is awesome and they use Toyota parts.

Does anyone know for sure, 100%, without a doubt, that the IS300 M85/M98 differentials can just be bolted on to our cars? I've read that they're supposed to be the exact same housing but haven't found any threads with anyone actually performing the swap. I've also seen IS300 owners speculating they could use our diffs for the same purpose but without anything conclusive.

SportInjected · 08-12-2013, 12:03 AM

Don't have a concrete answer for you, but I ran across this craigslist post, and the guy states that the m98 is the same unit used in Fr-S and BRZ.

http://chicago.craigslist.org/chc/pts/3994245594.html

PantsDants · 08-12-2013, 12:46 AM

I actually kept digging and finally found this post from @Jeff Lange: http://www.ft86club.com/forums/showthread.php?p=302901

It looks like the carrier/differential assembly out of an IS300 is a direct fit for our cars. Good thing because I found a great deal on one at a local junkyard.

Now I just need to see if I can get the gear kit and required pinion seal through amayama or autofactory and I'm good to go!

Dipstik-sportech · 08-12-2013, 12:49 AM

I sure hope it turns out to bolt in. I'm eying up the m85 3.73 set out of a manual car....

Jeff Lange · 08-12-2013, 06:42 PM

It's definitely a completely bolt-in affair with a differential assembly from an IS300 or IS250.

Jeff

Captain Insano · 08-12-2013, 09:36 PM

This looks like a nice option if it's perfect fit.

NYCsubaruBRZ · 08-13-2013, 03:48 AM

soooo. is it?

NYCsubaruBRZ · 08-13-2013, 03:49 AM

what is the stock ratio? and has anyone done this and can say its a 100% direct fit?

ft_sjo · 08-13-2013, 04:31 AM

Best wait until someone actually does it themselves before rushing out and potentially wasting money.

PantsDants · 08-13-2013, 04:38 AM

For the record, I contacted a local shop to get an estimate on doing a final drive gear swap. As an alternative, they offered to sell me a differential that would fit... in a 3.91 final drive ratio. Hmmmm, that sounds like a familiar number... what diffs have we talked about that have that ratio already installed...

GTB/ZR-1 · 08-13-2013, 08:03 AM

Great info--this forum is awesome.

charged86 · 08-13-2013, 08:36 AM

Please let us know how this goes. What is the stock ratio? Does it have a similar lsd?

Jeff Lange · 08-13-2013, 06:12 PM

Stock ratio is 4.10:1.
IS300 AT is 3.91:1.
IS300 MT is 3.73:1.

Not all IS300's have LSD, so you'll want to make sure before buying one unless all you want is the ring and pinion.

Jeff

Dipstik-sportech · 08-13-2013, 06:35 PM

Or just swap our LSD into that case. I'm on the look out for a 3.73 third then.

08-11-2013, 02:31 AM	#1
PantsDants Senior Member Join Date: Jul 2013 Drives: Scion FR-S A/T, Whiteout Location: Seattle Posts: 334 Thanks: 57 Thanked 221 Times in 90 Posts Mentioned: 16 Post(s) Tagged: 2 Thread(s)	IS300 M85/M98 rear diff - does it fit? So I saw the thread about the Cusco final drive gear kit and it got me thinking that I'd like to up my final drive ratio. However, I would also like to be able to swap the diff as a unit rather than replace the internals of my stock one. I figured it might help cut down on labor costs to have a shop just install the kit with the diff already out and I could install the diff myself. My idea was to find a compatible one in a junkyard or eBay and install a final drive kit in that, probably the 4.556 ratio offered from autofactory.jp (provided someone over there speaks English and they actually ship to the US ). Price point is awesome and they use Toyota parts. Does anyone know for sure, 100%, without a doubt, that the IS300 M85/M98 differentials can just be bolted on to our cars? I've read that they're supposed to be the exact same housing but haven't found any threads with anyone actually performing the swap. I've also seen IS300 owners speculating they could use our diffs for the same purpose but without anything conclusive.

08-12-2013, 12:49 AM	#4
Dipstik-sportech Senior Member Join Date: Oct 2012 Drives: 2013 BRZ satin white pearl sportech Location: Thunder Bay Ontario Canada Posts: 1,813 Thanks: 842 Thanked 911 Times in 576 Posts Mentioned: 43 Post(s) Tagged: 0 Thread(s)	I sure hope it turns out to bolt in. I'm eying up the m85 3.73 set out of a manual car.... __________________ 2013 SWP BRZ sportech. 11.11sec@129.01mph, 511whp on e70. FullBlown base kit, FullBlown built 9.5:1 engine, GTX3076R GEN2 turbo, 1700cc Bosch injectors, FullBlown flex fuel kit, FullBlown radiator and oil cooler, FullBlown custom 3" dual exit exhaust, act xtreme clutch, whiteline diff and subframe inserts, BC Racing coilovers, hotchkiss 18mm rear sway, is300 3.73 differential ... Never finished

08-12-2013, 06:42 PM	#5
Jeff Lange Senior Member Join Date: Dec 2011 Drives: 1986 AE86 GT-S, 2011 Lexus IS250 6M Location: Calgary, Canada Posts: 661 Thanks: 136 Thanked 361 Times in 161 Posts Mentioned: 5 Post(s) Tagged: 0 Thread(s)	It's definitely a completely bolt-in affair with a differential assembly from an IS300 or IS250. Jeff __________________ 2011 Lexus IS350 F-Sport 6MT with LSD 1986 Toyota Corolla GT-S Supercharged

08-13-2013, 08:03 AM	#11
GTB/ZR-1 Senior Member Join Date: Oct 2012 Drives: '13 BRZ in WRB--let's mod!!! Location: Central, FL Posts: 1,224 Thanks: 317 Thanked 449 Times in 262 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	Great info--this forum is awesome. __________________ * ‘23 Corolla GR—AutoX/DE toy * '13 Toyobaru P&L Turbo WRB BRZ SCCA XS-A build starting. SOLD * '22 Z51 Vette--sold. * '09 Nissan GT-R--gone, but not forgotten... 10.63 @ 131+ on streeties. * '90 ZR-1 11.0 @ 130.2 & 11.2 @ 132.4 sprayed 120 shot.

08-13-2013, 06:12 PM	#13
Jeff Lange Senior Member Join Date: Dec 2011 Drives: 1986 AE86 GT-S, 2011 Lexus IS250 6M Location: Calgary, Canada Posts: 661 Thanks: 136 Thanked 361 Times in 161 Posts Mentioned: 5 Post(s) Tagged: 0 Thread(s)	Stock ratio is 4.10:1. IS300 AT is 3.91:1. IS300 MT is 3.73:1. Not all IS300's have LSD, so you'll want to make sure before buying one unless all you want is the ring and pinion. Jeff __________________ 2011 Lexus IS350 F-Sport 6MT with LSD 1986 Toyota Corolla GT-S Supercharged

08-12-2013, 12:46 AM	#3
PantsDants Senior Member Join Date: Jul 2013 Drives: Scion FR-S A/T, Whiteout Location: Seattle Posts: 334 Thanks: 57 Thanked 221 Times in 90 Posts Mentioned: 16 Post(s) Tagged: 2 Thread(s)	I actually kept digging and finally found this post from @Jeff Lange: http://www.ft86club.com/forums/showthread.php?p=302901 It looks like the carrier/differential assembly out of an IS300 is a direct fit for our cars. Good thing because I found a great deal on one at a local junkyard. Now I just need to see if I can get the gear kit and required pinion seal through amayama or autofactory and I'm good to go!

08-12-2013, 09:36 PM	#6
Captain Insano Senior Member Join Date: Sep 2012 Drives: 2014 Jeep Wrangler RubiconX Location: Midwest, USA Posts: 1,282 Thanks: 110 Thanked 292 Times in 224 Posts Mentioned: 7 Post(s) Tagged: 0 Thread(s)	This looks like a nice option if it's perfect fit.

08-13-2013, 03:48 AM	#7
NYCsubaruBRZ Banned Join Date: Sep 2012 Drives: 2013 Subaru BRZ & 99' Ford Explorer Location: NYC Posts: 709 Thanks: 94 Thanked 87 Times in 66 Posts Mentioned: 4 Post(s) Tagged: 0 Thread(s)	soooo. is it?

08-13-2013, 03:49 AM	#8
NYCsubaruBRZ Banned Join Date: Sep 2012 Drives: 2013 Subaru BRZ & 99' Ford Explorer Location: NYC Posts: 709 Thanks: 94 Thanked 87 Times in 66 Posts Mentioned: 4 Post(s) Tagged: 0 Thread(s)	what is the stock ratio? and has anyone done this and can say its a 100% direct fit?

08-13-2013, 04:31 AM	#9
ft_sjo Banned Join Date: Oct 2012 Drives: GT86 Location: The Motherland Posts: 1,398 Thanks: 140 Thanked 473 Times in 271 Posts Mentioned: 22 Post(s) Tagged: 0 Thread(s)	Best wait until someone actually does it themselves before rushing out and potentially wasting money.

08-13-2013, 04:38 AM	#10
PantsDants Senior Member Join Date: Jul 2013 Drives: Scion FR-S A/T, Whiteout Location: Seattle Posts: 334 Thanks: 57 Thanked 221 Times in 90 Posts Mentioned: 16 Post(s) Tagged: 2 Thread(s)	For the record, I contacted a local shop to get an estimate on doing a final drive gear swap. As an alternative, they offered to sell me a differential that would fit... in a 3.91 final drive ratio. Hmmmm, that sounds like a familiar number... what diffs have we talked about that have that ratio already installed...

08-13-2013, 08:36 AM	#12
charged86 Senior Member Join Date: Mar 2013 Drives: whiteout gt86 2015 IS350fsport Location: northern kentucky. cincy Posts: 1,931 Thanks: 2,154 Thanked 697 Times in 437 Posts Mentioned: 42 Post(s) Tagged: 0 Thread(s)	Please let us know how this goes. What is the stock ratio? Does it have a similar lsd?

08-13-2013, 06:35 PM	#14
Dipstik-sportech Senior Member Join Date: Oct 2012 Drives: 2013 BRZ satin white pearl sportech Location: Thunder Bay Ontario Canada Posts: 1,813 Thanks: 842 Thanked 911 Times in 576 Posts Mentioned: 43 Post(s) Tagged: 0 Thread(s)	Or just swap our LSD into that case. I'm on the look out for a 3.73 third then. __________________ 2013 SWP BRZ sportech. 11.11sec@129.01mph, 511whp on e70. FullBlown base kit, FullBlown built 9.5:1 engine, GTX3076R GEN2 turbo, 1700cc Bosch injectors, FullBlown flex fuel kit, FullBlown radiator and oil cooler, FullBlown custom 3" dual exit exhaust, act xtreme clutch, whiteline diff and subframe inserts, BC Racing coilovers, hotchkiss 18mm rear sway, is300 3.73 differential ... Never finished

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