My final gear swap project

[charged86]

Originally Posted by PantsDants

By carrier I mean the "pumpkin" or housing that contains the differential. The two terms are often conflated so I figured I'd try to be as specific as possible. What I bought was a factory IS300 rear differential carrier, it comes with the differential inside obviously.

im just used the redneck version the "diff" "pumpkin"

[8686]

Originally Posted by Dustin

I'm not 100%, but I believe doing this will be the only way to do all the OEM final drive part numbers I posted before. From what Spence @ Weir Performance was saying, the internals in the stock FRS rear end are not compatible. Maybe @8686 can clarify with the OEM 4.56 he just purchased.

As the mechanic just told me over the phone. The install went OK.
I will be receiving the car on Thursday as I am away on business trip.

[accelerated]

So between this and a modified VB / TCM software, these should help these cars turn some good times at the track.

[PantsDants]

Something of an update: Using the list of installation parts that @37 kindly provided us with, I've got all of my required small parts on order. I've ordered everything in the list with the exception of the shims, washers, and pinion bearing.

My reasoning was as follows:

• I plan to have this done by a dedicated differential rebuild shop; they'll likely have the tools to get my pinion bearing off without damaging it and probably have shims/washers laying around.
• The carrier I've got is basically brand new, so I'd be very surprised if the bearing was less than pristine.
• If I DO actually have to order those parts after all, I'm not without my car while waiting for the parts to arrive anyway.

$100 for the required (OEM) installation parts beats the hell out of the ~$300 I've been seeing for "master installation kits" online.


My plan for now is to enjoy my road trip to Montana, and when I get back, place an order with Weir Performance for a 5.29 ring and pinion kit. Go big or go home, I guess.

[mtsui]

nice, please keep us updated!
btw, I saw it in thread, someone said "I have been looking for a Lexus IS300 or 250 differential to swap in as a way of getting the 4.55 final drive. THEY WILL NOT BOTH WORK. They differ in the way they bolt up. The axles are also different. At this point I am stuck.... Even if I get a unit that bolts up I cannot be sure the axles will fit. Any advice would be appreciated. I don't mind doing the leg work so the community can find a source of parts and even a DIY... But I can't buy both of them on a gamble."
and "The IS300 and IS250 have different differentials as well as different axles. There is no way both of them will bolt on to the 86. It would have to be one or the other as they bolt up differently and have different axles. "
anyone can confirm that?

[PantsDants]

Originally Posted by mtsui

nice, please keep us updated!
btw, I saw it in thread, someone said "I have been looking for a Lexus IS300 or 250 differential to swap in as a way of getting the 4.55 final drive. THEY WILL NOT BOTH WORK. They differ in the way they bolt up. The axles are also different. At this point I am stuck.... Even if I get a unit that bolts up I cannot be sure the axles will fit. Any advice would be appreciated. I don't mind doing the leg work so the community can find a source of parts and even a DIY... But I can't buy both of them on a gamble."
and "The IS300 and IS250 have different differentials as well as different axles. There is no way both of them will bolt on to the 86. It would have to be one or the other as they bolt up differently and have different axles. "
anyone can confirm that?

I actually PM'd him (wootwoot) about that. During that exchange he never told me the carrier couldn't bolt in.
I deleted the messages like an idiot, but I remember there were two distinct issues going on:

The first was in that thread you mentioned, they were speculating about how you might just be able to find a carrier from one of those IS cars with a 4.556 in it from the factory and just swap it onto your car and be done with it. The fact of the matter is neither of them are available with a 4.556 final gear from the factory; I know the biggest final drive available in the IS300 from the factory is 3.9, not sure about the IS250. The IS350 is a totally different beast all together and doesn't work at all. However, both the IS300 and IS250 carriers are bolt-ons for our cars. The man to talk to about that is @Jeff Lange.

The other issue I recall was that the way the differential itself bolts into the carrier (pumpkin) is different between various models, despite the fact that the carriers are the same on the outside, AND they even share the same sized ring and pinion gears. I don't know the specifics, but this part is less relevant though as I'm not doing this sort of swap. I'm keeping the IS300 carrier and differential intact with the exception of the ring and pinion.

[Turkish]

Originally Posted by JimmyMac

You should post some of this info in the final drive thread. I've seen the Cusco 4.56 for under $900 here in the US. But I like your deal much better. Hmmmm maybe they gave automatics that ratio to keep them slower than manuals... hehe... just kidding...?? Thanks for the info.

Funny, I was told by a service manager at a Subaru dealer that the auto was given the "fuel efficient" ratios to keep the auto from being faster than the manual.

Sent from my SCH-I535 using Tapatalk 4

[PantsDants]

Just stumbled across a fun fact! 41110-30A03 is the part number for the FR-S carrier; it's the same number as the AWD IS250's rear carrier.

[Stay n/a]

Originally Posted by PantsDants

Just stumbled across a fun fact! 41110-30A03 is the part number for the FR-S carrier; it's the same number as the AWD IS250's rear carrier.

may want to double check I see the frs carrier listed in toyotas system as part # 41110-18021

[37]

Originally Posted by Stay n/a

may want to double check I see the frs carrier listed in toyotas system as part # 41110-18021

41110-18021 ... Carrier Assy, Differential, Rear, Manual/Auto w/ LSD
41110-30A03 ... Carrier Assy, Differential, Rear, Auto w/o LSD (Not applicable to our cars)

@PantsDants is correct since the part he found is for a slushbox, which is correct for his particular application. Looking at the gear ratios both in the trans and rear end, I can see why 6AT owners might want to swap their gears.

We just have to be careful when relaying part numbers and note if a part is specific to a 6MT or 6AT.

[448hpsti]

Originally Posted by 37

41110-18021 ... Carrier Assy, Differential, Rear, Manual
41110-30A03 ... Carrier Assy, Differential, Rear, Auto

@PantsDants is correct since the part he found is for a slushbox, which is correct for his particular application. Looking at the gear ratios both in the trans and rear end, I can see why 6AT owners might want to swap their gears.

We just have to be careful when relaying part numbers and note if a part is specific to a 6MT or 6AT.

direct swap?

[TouchMyHonda]

In for read later

[OrbitalEllipses]

Your Price:$1761.83
Toyota's Retail Price:$2402.09
You Save:$640.26

Yeahhhh that's definitely gonna be a You-Pull-It part if I decide to do it.

[PantsDants]

Any guesses as to why the part numbers are different between AT and MT? They both have the same final gear ratio...