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This issue occurs on my 95 LS400 and I'd appreciate anyone who has experienced similar issue to respond with 'valid' ideas. I'll be as detailed as possible.
The issue is an annoying harmonic vibration that occurs at around 70km/hr, and a slight vibration at 40kmh. It's worse under load but is still apparent if I back off acceleration and coast at that speed. However, if I disengage the gear and select Neutral, the harmonic vibration disappears. Therefore I suspect it's a drive train issue.
Mechanic #1: Checks play in engine and transmission mounts and is satisfied with them. Notices some degradation to the tailshaft dampeners but is not convinced. Doesn't do anything without my approval.
Mechanic #2: Checks play in engine and transmission mounts and is satisfied with them. Removes the 2 piece tailshaft and also notices the degradation to the tailshaft dampeners. Sends the tailshaft off to a specialist to check balancing. Tailshaft is rebalanced, and dampeners replaced. Checked centre bearing, and is satisfied it doesn't need replacement. Outcome.
The 70km/hr harmonics is the same in fact the range has broadened to between 60 & 80km/hr. But now the 40km/hr is much worse and particularly under load. Mechanic #1 charges me 2hrs labour but I get slugged around $500 for the tailshaft balance and replacement of the dampeners at each end of the tailshaft. Next Step.
Take back to Mechanic #1 for further investigation with a strict instruction that I don't want to drop another $700 unless the investigation unearths something that they positively recommend to fix. They spend some time with the car up on the hoist, inspecting with engine revving but can't put their finger on it. And I wouldn't expect they could if the car is not engaged in gear and hitting similar revs as per normal driving conditions. No charge to me. They recommended I reach out to Lexus to see if they can provide some advice before taking next steps. They also suggested if i didn't want to drop too much coin, maybe start with OEM engine and tranny mounts and go from there.
On reading forums, there was also mention of the harmonic balancer. I understand a bad harmonic balancer can also cause other issues and I have a sneaky suspicion that this could possibly be the answer as I have a weeping power steering pump, and a whirring noise coming from the AC pump, both symptons of a bad harmonic balancer. Mechanic #2 believes there was some very minor vibration but it wasn't obvious, so I'm no more confident that is the issue.
There is 272,000kms on the clock. I've just registered it. I have to deal with the power steering pump and the AC pump, I have a rear main seal minor leak and this issue. With some TLC, I'll get her back to being the beautiful smooth car she is. I don't want to let it go just yet, but how much do I put into a car of this age and kms?
What would you do next? Do you understand my dilemma?
This issue occurs on my 95 LS400 and I'd appreciate anyone who has experienced similar issue to respond with 'valid' ideas. I'll be as detailed as possible.
The issue is an annoying harmonic vibration that occurs at around 70km/hr, and a slight vibration at 40kmh. It's worse under load but is still apparent if I back off acceleration and coast at that speed. However, if I disengage the gear and select Neutral, the harmonic vibration disappears. Therefore I suspect it's a drive train issue.
Mechanic #1: Checks play in engine and transmission mounts and is satisfied with them. Notices some degradation to the tailshaft dampeners but is not convinced. Doesn't do anything without my approval.
Mechanic #2: Checks play in engine and transmission mounts and is satisfied with them. Removes the 2 piece tailshaft and also notices the degradation to the tailshaft dampeners. Sends the tailshaft off to a specialist to check balancing. Tailshaft is rebalanced, and dampeners replaced. Checked centre bearing, and is satisfied it doesn't need replacement. Outcome.
The 70km/hr harmonics is the same in fact the range has broadened to between 60 & 80km/hr. But now the 40km/hr is much worse and particularly under load. Mechanic #1 charges me 2hrs labour but I get slugged around $500 for the tailshaft balance and replacement of the dampeners at each end of the tailshaft. Next Step.
Take back to Mechanic #1 for further investigation with a strict instruction that I don't want to drop another $700 unless the investigation unearths something that they positively recommend to fix. They spend some time with the car up on the hoist, inspecting with engine revving but can't put their finger on it. And I wouldn't expect they could if the car is not engaged in gear and hitting similar revs as per normal driving conditions. No charge to me. They recommended I reach out to Lexus to see if they can provide some advice before taking next steps. They also suggested if i didn't want to drop too much coin, maybe start with OEM engine and tranny mounts and go from there.
On reading forums, there was also mention of the harmonic balancer. I understand a bad harmonic balancer can also cause other issues and I have a sneaky suspicion that this could possibly be the answer as I have a weeping power steering pump, and a whirring noise coming from the AC pump, both symptons of a bad harmonic balancer. Mechanic #2 believes there was some very minor vibration but it wasn't obvious, so I'm no more confident that is the issue.
There is 272,000kms on the clock. I've just registered it. I have to deal with the power steering pump and the AC pump, I have a rear main seal minor leak and this issue. With some TLC, I'll get her back to being the beautiful smooth car she is. I don't want to let it go just yet, but how much do I put into a car of this age and kms?
What would you do next? Do you understand my dilemma?
Do you know whether both engine mounts and transmission mount were ever replaced?
If not, do so...the engine mounts are 23 years old. (Your transmission mount is probably settled...inexpensive)
If so, were OEM mounts used?
If, not replace with OEM mounts....the aftermarket product is crap.
What event led the indy mechanic to conclusion your driveshaft was out of balance??
Also, were propshaft guibos replaced (front and rear)?
If so, was OEM used?
If not, have the mechanic who installed random aftermarket guibos (couplers) to install OEM.
Why did your mechanic, after extracting driveshaft, not replace Center Bearing??
Did the driveshaft shop (you know of the existence of a driveshaft shop invoice?) matchmark the front-rear driveshaft sections to insure they are in phase?
Did your mechanic adequately loosen driveshaft collar nuts so that driveshaft could be easily extracted? (telescoped in)
Waa nut (s) tightened after telescoped out.?
Ask your indy mechanic how, after extracting and reinstalling driveshaft, managed to set driveshaft angle... .where is his Lexus shop manual depicticting correct angles?. .what angles did he set?? What shims did he use?
Pay Lexus for an hour of time to evaluate and verify this and the remainder of your concerns
Do you know whether both engine mounts and transmission mount were ever replaced?
If not, do so...the engine mounts are 23 years old. (Your transmission mount is probably settled...inexpensive)
If so, were OEM mounts used?
If, not replace with OEM mounts....the aftermarket product is crap.
What event led the indy mechanic to conclusion your driveshaft was out of balance??
Also, were propshaft guibos replaced (front and rear)?
If so, was OEM used?
If not, have the mechanic who installed random aftermarket guibos (couplers) to install OEM.
Why did your mechanic, after extracting driveshaft, not replace Center Bearing??
Did the driveshaft shop (you know of the existence of a driveshaft shop invoice?) matchmark the front-rear driveshaft sections to insure they are in phase?
Did your mechanic adequately loosen driveshaft collar nuts so that driveshaft could be easily extracted? (telescoped in)
Waa nut (s) tightened after telescoped out.?
Ask your indy mechanic how, after extracting and reinstalling driveshaft, managed to set driveshaft angle... .where is his Lexus shop manual depicticting correct angles?. .what angles did he set?? What shims did he use?
Pay Lexus for an hour of time to evaluate and verify this and the remainder of your concerns
These are some great questions. I have been thinking about the engine and transmission mounts as a next step, in fact my mechanic suggested same. I have asked him to verify that OEM rubber couplers were used and posed all relevant questions to confirm. Mechanic also suggested paying Lexus to investigate issue.
In the meantime, I think my next step will be to have my mechanic replace the rear main seal and while the transmission is removed, replace engine mounts and tranny mounts, new oil and filters. If issue persists, then I may seek Lexus intervention as recommended. Thanks for the advice.
Hi Losiracer,
Both rubber couplings (Front & Rear) were replaced and slop was eradicated both ends.
I think you might have misunderstood. I'm speaking about the drive axles that insert into the rear differential. Replacing the boots on those is one thing but the CV joints also develop slop overtime from the engine loading and unloading power through them.
I'd stop using mechanic #2 immediately. I can't imagine going through such an expensive ordeal with your driveshaft without simply replacing the transmission mount first. $50 bucks for the part and without knowing your mechanical capabilities I'd bet you could have, and still could, do the job yourself. Start there (1237150060 ) you may be very surprised...
I think you might have misunderstood. I'm speaking about the drive axles that insert into the rear differential. Replacing the boots on those is one thing but the CV joints also develop slop overtime from the engine loading and unloading power through them.
Oh I'm sorry, yes I misunderstood. Haven't checked these...yet.
I'd stop using mechanic #2 immediately. I can't imagine going through such an expensive ordeal with your driveshaft without simply replacing the transmission mount first. $50 bucks for the part and without knowing your mechanical capabilities I'd bet you could have, and still could, do the job yourself. Start there (1237150060 ) you may be very surprised...
Sounds like an option. Not a lot lost in the event that doesn't sort it out.
Just ordered an OEM transmission mount on eBay (new). Toyota Australia and Lexus Australia do not have single unit in stock in the country, need to order from Japan 2-3weeks. $110AUD. $95AUD ebay purchase. Will advise outcome when the part arrives.
Out of phase and or bound drivelines make huge vibes at highway speeds. Because it no worse, I can't imagine it is out of phase. For the record, balance vs driveline loading rarely overlap. At highway speed if the driveline were shaking from out of balance, it would continue while trans is in neutral.
After the mounts are replaced, please pull the spark plugs and confirm all holes have a clean burn. The fact that this is load related makes me wonder if all cylinders are making equal power.
11-23-17, 01:23 PM
Another annoying vibration issue
