Hi everyone,
New member and while not a Lexus owner but rather a long time Toyota Owner (have owned several different Toyota's over the years including Supra's, MR2, a Taco, a 4 Runner and a Tundra). Anyways, recently decided to start a project that I had pondered doing several years ago and since I try to keep parts within a manufacture family, I am looking at possibly using IS or GS front knuckles for the front suspension of said project. I am however hoping that someone here could tell me what the difference is between them despite them looking the same.

The parts in question for example is say a 2010 IS350 front Steering knuckle (RWD model) and the one from a 2010 GS350 (RWD model also). I can plainly see the difference between the AWD models and the RWD models but I cant see any obvious difference from one car model to the next for the same drive type.
I see that Lexus has them listed as two different part numbers but what I'm hoping is that someone where might know the exact differences as to why they are listed as different numbers. From Photo's of them seen in Google Searches and Ebay sales ads, they look identical.

If anyone happens to know of differences and could shed some light on the subject, it would be greatly appreciated.

 

What are the part numbers?

 

Well these two for example,
2010 IS350 - 43202-53010 (Left Steering Knuckle)
2010 GS350 - 43202-30020 (Left Steering Knucle)

When you look at photo's of each of those pulled from wrecked / salvage cars, they look identical. I imagine that its a dimensional change for suspension geometry but what that change is is what I'm trying to figure out so I can see is maybe one is more usable than the other for what I'm trying to do with it.

I know that there is also a 43202-30031 listed for the GS but I know that that one is for the AWD model which I know that there is key differences for steering linkage connection and the hub bearing itself (different bolt pattern and different center bore) among possibly other things.

 

I see what you mean they do look the same. But Lexus rarely (I have not seen it) has two part numbers for an identical part there must be a difference. Maybe the casting process changed or maybe the machined holes are different something you won't pick up on in pictures. That's all I've got.

 

Based on what I know from working in the aftermarket:

OEM's change part numbers very frequently and have super-cessions. Changes can be very minor (such as they changed supplier, or a tool mold and want to keep track of the revised parts or supply chain) to moderate changes that don't affect the vehicle performance (such as a change in material, machining process, casting vs forging, adding a feature (such as an ABS or AFS bracket) etc, to major changes that change suspension geometry.

The fact that the IS350 and GS350 have completely different part numbers (I assume you've checked previous part number super-sessions) and they don't cross likely means there's a significant enough difference with them that they are not interchangeable at the OEM level. Nevertheless in the aftermarket, many parts that are similar are consolidated as long as they don't affect the fit or function on the vehicle, which is why you might find a control arm or knuckle sold with a bracket attachment to fit both AFS and non AFS Lexus vehicles, for example, as one part number. It might be worthwhile to check aftermarket catalogues to determine consolidations.

You can also look at other parts that attach to the knuckle to determine similarity. A quick search reveals that the 2010 IS350 uses a different upper control arm than the GS350. Perhaps the attachment at the upper ball joint (stud or taper size) is different and that warranted a different knuckle to mate to.

 

Yeah, I know what you guys mean as I've dealt with this same thing on the Toyota side of the family too..

I've seen / dealt with this with Chevy too. For example, the C5 and C6 steering knuckles are interchangeable and the C6 units are better (a few key areas strengthened) but GM / Chevy still has two different part numbers for them and does NOT supersede the C5 units to the C6 number.

While that would be a redundant waste to have two different ball joints, I wouldn't however put it past Toyota / Lexus to do such a thing as I've seem it done with other parts. I'd imagine thought that the UCA change had more to do with chassis difference but at the same time, that could have dictated a pickup point on the knuckle change too to keep the geometry correct.

Ironically, I was given a knuckle from an IS today and from the preliminary rough measurements, its really close to what I was hoping it was for the lower half so since I have a Right Hand one now that was free and its close, I think I'm just going to source a Left from somewhere and go with them and not worry if the GS is truly different or not.

If however someone does happen to see this and does know for sure, I would still be interested in knowing just for general knowledge. And to Lexus2000 and speedkar9, thank you for your replies.

 

In my experience Toyota and Lexus are extremely careful about supplying a part that matches or is better than the original. If a part differs they give it a new part number even if it is compatible, but if it is then the old number is superseded. In your case it isn't so I will assume the parts are not technically interchangeable even if the form factor is the same. There are rare cases where Toyota screws up and says a part fits a certain model when it doesn't, and they never fix their database because the car is too old.

 

Actually, Toyota / Lexus likes to play on the brand name for pricing so they create two different numbers for the same identical part just so they can sell it for a different price. This can be seen with the a lot of parts from the MKIV Supra's and the SC300 / 400. Many parts are identically the same but have a different part number and cost more when you by it from a Lexus dealer then when you get the "Toyota" part from a Toyota dealer. A perfect example is say the LCA for a 94 SC vs a 94 Supra. The Lexus Number is 48069-29165 and has an MSRP of $901.07 (yes, nine hundred $$$) the Supra on the other hand is 48069-14080 and has an MSRP of $390.96 and I know for fact that these are identically the same parts made from the same forging dies in the Honsha Plant in Japan (I've Toured that plant along with the 6 others of the 12 different Toyota plants in Japan when I lived there). Furthermore, if look up the OE part number for the "Toyota Saorer" which as you probably know is the same car as the SC's here minus the engine differences, its the same part number as the Supra.

I know that there is other parts / numbers that follow suit with this trend along with making minor / somewhat irrelevant changes, creating a new number and charging a totally different price because of rarity. A good example of this is the Rear wheel hubs on the SW20 MR2's vs the 90's Camry front hubs. Because of Toyota's practice with pinning the rear wheels on cars that come factory with staggered wheel so you can put the rear wheels on the front, the MR2 hubs and the Camry hubs are 99% the same hub except that the MR2's have the extra holes in the hub for the wheel pin. Basically, the raw forgings go to the same set of turret lathes that runs the same program other than the MR2 hubs get lug holes rather then 5 like the Camry's.The MR2 hubs are also more than twice the price as the Camry hubs. Sure it is extra machining steps because it is drilling and boring 5 extra holes but that is NOT worth more then double the price. Toyota could have easily just made all of them have the extra holes (for that matter, just 1 extra hole since there is only 1 pin in the rear wheels, charged a little more than the MSRP for the Camry intended units and had one part number across the board. This would also mean less overhead too.

All in all, Toyota / Lexus does do a pretty good job at superseding parts that they change the number for some reason or another but not always and regardless of that, they do like to issue different part numbers just so they can charge different prices because of the brand name (and even has been seen at least a time or twoo on some parts within the same brand but different car model...)