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Sloppy/rubbery driveline - bushings or mounts to replace?
Hi guys, today is my 3rd day of IS-F ownership and am loving this car.... 2010 White on white with 97k miles.
But, I am realizing there is more slop in the driveline than I would like. Not to mention, when hard accelerating from a stop I feel a clunk at the rear end. If I rock the car back and forth in Park, I can see quite a bit of movement at the rear diff, so i'm thinking at minimum I need all new diff mounts? I see 4 total that might need replacement. Has anyone just done stock replacements? I fear FIGS or the like as I don't want to make the car uncomfortable. Thoughts?
Are there any other bushings in the driveline I should look at replacing at this mileage? I want to minimize this rubbery on/off throttle feeling but the last thing I want is to introduce NVH - I'm getting old and particular. I have driven other IS-F's that felt a bit tighter so I know there is room for improvement but I'm not sure where on these cars just yet...
Thanks
I put in all polyurethane bushings when I put the OS Giken spool in the diff. There was no change in NVH.
The OEM bushings are pretty challenging to change, they are much more difficult to install correctly because they are very tight in the rear mounts.
Sounds like this car was abused if the diff is moving as you describe.
If there is no change in NVH I'd go with poly. On my other non-Lexus cars, they added diff whine and vibrations which got really old.
Which bushings did you go with and did you feel a difference in on/off throttle and shifting?
SuperPro bushings from Figs. There is a very slight whine on neutral throttle, but I chalk that up to the Giken spool as much as anything. If the audio system is on, you will never hear it even with the volume at 4.
I would have to say a whine is not product of bushing change. A whine is more apt to come from incorrect gear setup that was there all along.
If OPs car has been baking in the sun all along it may not be an abuse issue rather sun baked dried failing busgings. That said these don't see a ton of heat so even that seems unlikely. Any chance its been apart and someone left out something? A washer, a spacer?
OP, could u please post the link? And review? I feel my neutral to drive shifting are followed up with little bump and sometimes when I am cruising and accelerating I can feel little delay before I can feel a power to the wheels!
SuperPro bushings from Figs. There is a very slight whine on neutral throttle, but I chalk that up to the Giken spool as much as anything. If the audio system is on, you will never hear it even with the volume at 4.
Yes, the slight whine sound on neutral throttle is coming directly from the OS Giken TCD as that's one of its mechanical characteristics (it sounds like a turbo spooling).
To the OP, the SuperPro differential polyurethane bushings that Figs offers is what you would need to minimizing rear end slop. If you want to go for a solid aluminum option, Titan Motorsports has a set available for the MKIV Supra but it is also compatible with the IS-F differential (this is what I'm using on my IS350 and it really helps to keep the rear tires planted): http://www.titanmotorsports.com/sodiearmof.html
I found even with just the poly bushings wheel hop disappeared. That alone is worth the effort, but to be very honest, replacing those front mounts isn't for the faint of heart. Lexus has the bushings pressed in and getting them out is not easy even with the diff removed. I did it with an air chisel. It would be extremely difficult with just hand tools.
Having set up some 50 differentials and only having one kick my but I have to disagree about any spool/carrier/center section, LSD, open, or locker being the source of a whine.
While in motion applying throttle on, off, or coasting, at best you get clunking from *whatever* mechanism is connected to the axles. The the carrier itself being what it is does not whine when both axles are turning the same speed!
Gear mesh, pinion depth, heel toe contact are what make a hypoid gear whine when set incorrectly. The lack of backlash or excessive backlash are also a factor.
Lets take a snapshot of what **typically happens** during a spool/carrier swap.
Maybe they check the gear backlash of original gear setup. Maybe not.
They have no means of checking carrier preload other than turning the pinion with a beam style inch pound torque wrench and record the value.
Remove the carrier and ring gear. Measure pinion torque again and subtract the removed carrier bearing.
**Maybe** a good shop would drop the carrier minus the ring gear into the housing and at least get a sense of bearing preload imposed by the case and OEM snap rings. Most will not!
That gives them a ball park figure of carrier bearing preload. If fitted with all new bearings and a pinion seal, those old torque values mean nothing. Too much preload makes heat. Too little preload allows deflection.
They likely:
Hammer new bearings onto LSD carrier.
Transfer ring gear.
Drop carrier in applying OEM snap rings. Verify backlash meets OEM spec (not As Found value) and call it done.
My point is the oem carrier and any replacement carrier being another open carrier, LSD unit, or whatever is not going to be exactly the same span bearing to bearing or offset from bearing to ring gear mount and that more than anything +/-0.0005in matters to a used ring and pinion. They are a work hardened married couple and do not accept change very well or someone will whine!
Lets say they also install new pinion bearings and muck with the pinion depth. Do you really think it goes back to the exact same depth and establishes the same exact contact patch on the gear set??? No way. This is where noise comes from.
Your whine comes from the gear mesh, not the carriers center section. They fed people a line of BS saying its the LSD unit to escape the truth. 99% of them throw the OEM snap rings right back in there and if the backlash meets spec; SHIP IT!
Why do you assume this is what happened with mine? Your assumptions are all incorrect. Mine was setup by a guy who has setup thousands of differentials over his 70+ years for both street and competition (including a whole lot of dirt track racers). He just happens to be my dad. Everything got measured and checked including tooth engagement and bearing preload per the factory service manual. No new bearings, the original bearings were just fine, and they were removed with great care. Whole spool was frozen and ring gear heated to install, and the whole unit was frozen for final installation to ensure the bearings were not damaged installing the snap rings that retain the outer races for the spool and to avoid stretching the diff housing (the factory specified method). The only thing we didn't do that the manual tells you to do is replace the ring bolts.
The whine ISN'T gear noise. The Giken makes a very small noise only on neutral throttle when the mechanism inside is switching between lock and unlock. Gear whine from improper fit/assembly is present all the time. This sound is quite literally on and off by either lifting or pressing on the throttle.
/ thread derail...
Is this documented somewhere? Expect a whine at cruise? I'm glad you have someone who gives a damn about doing it right. Sadly that does not apply to all installers hence the words 'most' and 'typical'.
And being the newb I'm essy to discredit; so be it. We may have to agree to disagree until facts are presented or I install mine and it whines... lol
What case did you use? A non LSD needing ground out? Not that this has anything to do w this, just curious.
Yes, the slight whine sound on neutral throttle is coming directly from the OS Giken TCD as that's one of its mechanical characteristics (it sounds like a turbo spooling).
To the OP, the SuperPro differential polyurethane bushings that Figs offers is what you would need to minimizing rear end slop. If you want to go for a solid aluminum option, Titan Motorsports has a set available for the MKIV Supra but it is also compatible with the IS-F differential (this is what I'm using on my IS350 and it really helps to keep the rear tires planted): http://www.titanmotorsports.com/sodiearmof.html
OMG $250 for these!! looks like ill be ordering some 7075-T6 stock and dusting off my lathe.
I do appreciate all the insight here. My last car (Audi S4) developed a whine under throttle and a little at cruise after installing poly diff carrier bushings. It was tolerable, but my tolerance has changed to close to zero. In those cars, changing to poly was hit or miss with NVH and the consensus was that you should expect it and be thankful if you don't get it. Whatever the reason, its how it was. That was a different car obviously but my experience nonetheless.
With the ISF I discovered a broken trans mount which i swapped out yesterday. Slop is slightly improved but thud from the rear end when I mash the throttle from a stop still persists. I may just go with the softest poly bushings I can find for the diff. Again, looking for a better feel with zero to trivial increase in NVH.
OP - just don't go cheap on your materials as some poly simply deforms over time as it lacks elasticity. This can lead to the same type of noise/thud problem.
02-09-18, 11:10 PM
Sloppy/rubbery driveline - bushings or mounts to replace?
