Rear Differential IS250

[Vintagesixtysix]

IS 250 / nov 2005 / MTM 

Ladies & Gents….. my differential story…. If you can get to the end…. a little help needed.

So I started to get a rumbling noise a couple of weeks ago.

It’s a constant noise from set off that seems to peak in the cabin at around 40mph.

The car is running fine, no engine issues, gear changes all fine, economy all normal. No dash lights. I can rev it hard at stationary doesn’t miss a beat.

If you drive with all the windows open, air con off there no exterior sound….. or when I got the wife to do a couple of passes past me in the local supermarket car park.

The rumble did not disappear if I put the clutch in and continues if I take it out of gear and coast along.

The rumble is a mechanical grumble/whirring if that makes sense….it’s not a rapid bump bump bump noise…..and not a high pitched whine.

I would have put my mortgage on that it was coming from the front end of the car…… so I stripped both front wheels, callipers, pads, discs, disc shields and replaced both hubs ( I was convinced it was the NS front hub ) and thought might as well do both while I was at it.

Went for a test drive…. Noise exactly the same!…… red face 🥴

I checked the exhaust to see if anything could be making a contact and everything looks ok…..including the heat shields.

I’ve had the wheels refurbed about six months ago so I know they are all straight and balanced, I have no sign of any adverse wear on the tyres. No steering wheel shake either, even at legal plus.

I checked both rear wheels and didn’t seem to have any play, drive shafts, joints and boots all seem to be in good order.

Couldn’t feel anything strange on the prop-shaft ( was thinking may be central carrier bearing??…. ) but it is hard to tell this diy styli on the drive.

While under the car I touched the rear diff case and thought it felt quite hot ( don’t honestly know what kind of temp it should be….warm I guess like a gearbox??) but it felt hot to touch.

First thought was low on fluid.

I cracked the fill plug and managed to get maybe a 100ml tops into it. The drain plug was dry no sign of any weeping.

I last had this changed at 60k ( now at 130k ) and was originally planning on doing it again around 120k with the plugs…. but like when I changed the plugs at 60k ( they still looked perfect ) the diff fluid was also still in great condition.

So I had put off both until the end of the year.

I’ve resisted dropping the diff fluid and having a look at what’s attached to the magnet mainly due to being a bit in denial at the time….. as this seems to be a reasonably rare occurrence.

Just for the record…. I’m not the burnout or doughnut drift king LOL…… far from it.

Finally had the back end up both sides, while a mate was turning the rear wheels you can hear the noise clearly from the differential. It’s toast….

 

Q) regarding a replacement ( used ) would any one fit from a 250 / 220d….ATM or MTM are they all the same ratio?

The part number I’m working to is :

41110-53191   09 2005.  Carrier Assy Differential Rear GSE 20 MTM FGR= 43:12=3.583

[Mihanicos]

The are special oils for differentials that whine, 80W140 and also an STP additive directly into the differential and then fill with  80W140 GL5 minimum specification.

I had Mercedes 280CE with a whining diffetential, especially when driving about 20 mph. Applied the above prescription and it was silenced forever. Clocked many thousand miles and had no problem.

It may work for yours.

Chris.

[Texas]

I would go with the above initially as if it is ‘toast’ then nothing to lose!

[Vintagesixtysix]

Thank you both….. I did start to have a look at some of these types of products, as you say Paul not much to loose.

My Indy managed to squeeze her in yesterday and get it up on the ramp and also spin the wheels under drive.

it’s a bit worse than I thought and he’s advised me to do as little as possible if I can’t take it off the road immediately.

I asked about using anything of the magic potions and he thought I’d be wasting my time and money……. We had a joke about sawdust too! 😆

Hes a decent lad and probably being over cautious….. but his rule of thumb is if its a whine try the greases etc…… rumblings is the bearings squaring off so recon or replace it ASAP.

Ive been offered a used diff that seems in good condition from a is250 2008 auto with this label. They cannot see any other stamping on it.

Anyone know if it would be compatible?
Thanks

phil

 

[H3XME]

On 9/14/2021 at 10:23 PM, Vintagesixtysix said:

Q) regarding a replacement ( used ) would any one fit from a 250 / 220d….ATM or MTM are they all the same ratio?

The part number I’m working to is :

41110-53191   09 2005.  Carrier Assy Differential Rear GSE 20 MTM FGR= 43:12=3.583

Auto diffs are 3.7 ratio. Manual are 3.9.. i've seen the prices of used ones and if i was to change the diff, i'd upgrade to GT86 diff (torsen lsd) with 4.1 final drive.. it'll give you a noticeable acceleration boost. I'm not sure which IS250 specs etc had open or lsd (torsen diff), but keep that in mind.. I've had my dealings with 2 manual IS250s, both pre-facelift and both with factory limited slip diff.. my 2 mates with auto facelifts also have LSD.. I presume maybe IS220d or very very basic spec 250s had an open diff. If you're going to replace the diff, make sure you don't downgrade 🙂 

[H3XME]

1 hour ago, Vintagesixtysix said:

Ive been offered a used diff that seems in good condition from a is250 2008 auto with this label. They cannot see any other stamping on it.

Anyone know if it would be compatible?
Thanks

phil

 

Y55 is auto and Y54 is manual diff IIRC. Different ratios, but compatible yes. If your car is auto, you won't make things worse. If you have a manual, you don't really want the auto diff due to lower ratio (3.7) so worse acceleration but higher top speed - downgrade in my opinion.

[Vintagesixtysix]

Thanks Lucas….. that clearly explains that.

I think I saw the GT86 diff discussion on a US site as I was looking for info…… and I believe interestingly the 350 & 400 series diffs being compatible in terms of fit ( push fit rather than the previous bolt on)

My car is the very basic spec ( & I mean basic )…… so was the LSD an optional extra I wonder rather than standard??

or are they all LSD??

I’ve also seen this label from an IS220……. Any clues on ratio?
 

 

[Vintagesixtysix]

Anyone know if I was to use a different diff to stock…… does it change the speedo reading?

[scudney]

As far as I am aware I don't think it will 

[H3XME]

1 hour ago, Vintagesixtysix said:

Anyone know if I was to use a different diff to stock…… does it change the speedo reading?

Don't think so. Speed will be accurate but different ratio final drive will increase or decrease your rpms. So like higher ratio final drive will make your 6th gear 70mph like 3k rpms compared to current 2.5k or so..hope it's clear

[ColinBarber]

6 hours ago, Vintagesixtysix said:

Anyone know if I was to use a different diff to stock…… does it change the speedo reading?

No. The speedo uses the ABS wheel sensors to calculate speed so the only thing that alters the speedo accuracy is the tyre circumference.

[Vintagesixtysix]

Ok thanks for confirming…..

I’ve got a call with a recon company tomorrow….. just to investigate another option.

Anything decent GT86 wise is £400-500 plus fitting.

Most of the Lexus stuff is old and difficult to know what condition it’s in….. but cheap.

Tricky….. as the car is not worth big money….. but otherwise running fine.

[Vintagesixtysix]

So as suspected the bearings are dealer supply only….. there are no pattern bearings available according to the recon specialist.

It is obviously possible to recondition but would have to order individual parts as there is no recon kit available.

The parts guys I’ve spoken to at Lexus/ Toyota confirmed that the oem is an LSD.

New oem around £2k ( ISF guys look after yours as £5k…. Gulp)
 

The 2008 auto I’ve been offered best guess is…… 41110-53211 FGR=43:11=3.909

[Guest bigbullhead]

Check your drive shaft if high mileage as mine dropped off after only having a small vibration 

[Vintagesixtysix]

Yes will do…..

D day next week as been waiting on seals order.

I want to know if the central carrier bearing is ok while under there.

 

[Vintagesixtysix]

So follow up to my diff issue.

My original was: 41110-53191   09 2005. GSE 20 MTM FGR= 43:12=3.583

Deciding on a replacement was a little tricky as I was not overly concerned about any kind of performance upgrade through different ratios, more around continued reliability and cost.

Going to have a look at any diffs in the flesh or discussions online, even with a video it’s still practically impossible to check how good it is out of the vehicle and at 35kg without fluids they’re not exactly lightweight.

So you have to trust your gut to what vehicle it came out of, age and mileage etc.

I previously mentioned that I was offered a diff from a 2008 auto which is a 3.9 ratio LSD.

At least I knew of the seller, it looked and felt ok and was in budget.

41110-53211 FGR=43:11=3.909

I was reasonably confident that mechanically it would fit dimensions wise, but my concerns were wether the car would throw a wobbly and give me an ESP issue through maybe the revs being different or the abs sensors.

New seals were ordered through Lexus, there were some significantly cheaper listings I found on eBay etc but decided to go with the real deal.

My Indy fitted the replacement without any major hiccups and I’m glad to report a couple of weeks later that all seems well.

No codes

There is definitely more pep to the acceleration.

Fuel economy ( using onboard computer ) doesn’t seem to be hugely different, maybe a fraction down mixed driving.  Although I went to a family event 60 odd mile round trip mostly motorway, filled up just before getting on and the trip went up to 40ish mpg at 70mph which is what I would of expected out of the old diff set up.

You can defiantly feel the power drop off more when you lift off the accelerator but it’s not jerky.

So she lives to fight another day!

I have an MOT in early Jan so we’re going to drop the diff oil then just out of interest.