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Diagnosing a chirp can be infuriating. Old school method to find a noise like this is a piece of rubber hose, one end held up to your ear, the other end directed to the suspected area until it you hear it in the hose.
 

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Diagnosing a chirp can be infuriating. Old school method to find a noise like this is a piece of rubber hose, one end held up to your ear, the other end directed to the suspected area until it you hear it in the hose.
The car wizard used that trick in this video (though for a different issue)
 

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Nothing like resurrecting an old thread. I have the same squeal/chirping/repetitive pulley noise with my Evora 400. I am trying to formulate a strategy to diagnose and fix this. The design is ridiculous with 7 idler pulleys and a tensioner. The noise sounds as though its coming from the upper idler pulley assembly which makes sense because presumably all of the other pulleys are Toyota parts and unlikely to fail. Am I correct that the upper pulley bracket is also the upper engine mount? Can this be removed without taking the clam off? Once I get it off can the pulleys be replaced? Is there a better systematic approach to identifying the failed pulley(s)? The supercharger idler pulley bracket doubling up as an engine mount and a single belt with 7 idlers sounds like something Colin Chapman would have come up with...I wonder why they didn't just leave the Toyota serpentine belt as is and just have a separate belt for the supercharger like my old Audi S4? Any help or advice would be appreciated. I have a lift and a lot of tools including some thin wrenches and sockets and I don't drive the car much in the winter so I am planning on self isolating in the garage to work on this over the holidays.
 

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From the service notes: "From September 2019 (approximately) a ‘Gatorback’ type belt with grooves running at acute angles to the internal ribs replaced the original multi-rib belt. A service interval for belt change by age and mileage was also introduced at this time which is 36,000 miles (58,000km)/4 years, whichever is the soonest)."

My 17 Evora 400 has the old belt. Is there any particular advantage of this gatorback belt?
 

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From the service notes: "From September 2019 (approximately) a ‘Gatorback’ type belt with grooves running at acute angles to the internal ribs replaced the original multi-rib belt. A service interval for belt change by age and mileage was also introduced at this time which is 36,000 miles (58,000km)/4 years, whichever is the soonest)."

My 17 Evora 400 has the old belt. Is there any particular advantage of this gatorback belt?
Gatorback belts are basically supposed to help with squeal because of the design. I do wonder if they moved to this because of the squealing.

I have heard that Lotus doesn't sell the pulleys and need to get the full thing as a unit like so 2018 Lotus Evora 400 Idler bracket/mount assembly. Engine - A132E0161F | Lotus, Indianapolis IN

BUT eliseparts.com has some that should work (not sure if its been tested) Lightweight V6 Idler Pulley A132E6514S | EliseParts V6 Exige & Evora Idler Pulley A132E6515S | EliseParts
 

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Gatorback belts are basically supposed to help with squeal because of the design. I do wonder if they moved to this because of the squealing.

I have heard that Lotus doesn't sell the pulleys and need to get the full thing as a unit like so 2018 Lotus Evora 400 Idler bracket/mount assembly. Engine - A132E0161F | Lotus, Indianapolis IN

BUT eliseparts.com has some that should work (not sure if its been tested) Lightweight V6 Idler Pulley A132E6514S | EliseParts V6 Exige & Evora Idler Pulley A132E6515S | EliseParts
It seems as though the gatorback belts are now branded as Continental Elite belts. Does anyone know the part number for the continental elite Evora Belt?

The lower pulleys are Toyota parts. The upper pulleys and mount are specific for the evora 4xx/GT models with the edelbrock S/C. For some reason Lotus want to sell the mount and pulleys as one assembly but it does appear as though if you get the mount off you can replace or rebuild the pulleys. I am not sure about how to get the mount off though. Some of what I have read indicates that you may have to tilt the engine. I am also sure this is much easier with the clam off. I am thinking about swapping the belt and while I have it off going over all of the pulleys to see if I can identify which ones are worn. From the service notes it appears as though the belt can be changed with access from the bottom and through the wheel well.
 

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Discussion Starter #47
I can only speak for the S1 ... You can replace/overhaul the upper pulley assy. with the clam on, motor will need to be raised. 8hr job. 10-12 if doing everything. You will need slim profile bars. Not fun without a lift. And as mentioned above, I now know why Lotus will not sell the bearings (although proper mechanics will now how to obtain them). The machining on the pulleys is borderline rubbish... and after finding mine with a spun outer race, I spoke with others that had the exact same issue. So all installed with Loctite 660.
 

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I can only speak for the S1 ... You can replace/overhaul the upper pulley assy. with the clam on, motor will need to be raised. 8hr job. 10-12 if doing everything. You will need slim profile bars. Not fun without a lift. And as mentioned above, I now know why Lotus will not sell the bearings (although proper mechanics will now how to obtain them). The machining on the pulleys is borderline rubbish... and after finding mine with a spun outer race, I spoke with others that had the exact same issue. So all installed with Loctite 660.
Does the pully have enough meat to turn the ID on a lathe to a slightly larger OD bearing? Where I could do the machining properly?
 

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Discussion Starter #49
Does the pully have enough meat to turn the ID on a lathe to a slightly larger OD bearing? Where I could do the machining properly?
Depends on the side... I/O they each carry 2, and they are not the same. For sure one side has more then enough. I think your restriction would become finding oversize bearings... they are not common sizes to start. (coating would be an option) Properly cleaned, loctite 660 should work magic both. I also measured one of the pulley supports and found that to be slightly over machined... so in the end I just used the retainer on both inner and outer races.
5k kms no issues so far with mine.

In the end, if one spins again... I will attempt to fuse/weld them in. The pulleys are steel.
 
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Thanks for the information. I have a lift and a low profile socket set so I will give this a go, probably with the loctite approach unless I can find an alternative part. Its disappointing that Lotus went with what sound to be poor quality bearings, particularly given the difficulty in servicing them. Does anyone know where to get the gatorback belt- I might as well swap that at the same time.
 

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Thanks for the info Viper Guy. I've also had success welding the ID of a spun race and turning it back down to the proper size.

As long as the tempering isn't an issue, and I don't imagine it is on a pulley.
 

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If you do go the bearing replacement route, insist the bearing house you use supplies you with top name brand bearings such as SKF, ***, NSK. Plain box or brands such as "Consolidated" are third world bearings or they are repackaged aged out surplus that the grease inside the bearing has separated into oil and thickener. Using Loctite 660 or Red is good practice. The bearings can be pressed out afterwords by heating to about 300F. The loctite melts and acts as a lubricant to press it out.

I worked for SKF Reliability for 5 years.
 

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My local house always sells Axis bearings. I've had nothing but good luck with them, though my oldest application may only be about 14 months.
 

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Thanks again for the information. I may have lucked out and only need to fix the upper/external pulley bearings. Why on earth would Lotus use sketchy parts on what is such a difficult part to service?
 

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Discussion Starter #55
Thanks again for the information. I may have lucked out and only need to fix the upper/external pulley bearings. Why on earth would Lotus use sketchy parts on what is such a difficult part to service?
The Factory assy. uses SKF......
Like I said... pay attention. It may not be a bad bearing, just a spun Pulley race. The bearings I replaced were not bad,worn some, but minimal drag... just had spun do to both a poorly machined pulley and poor machined Bracket Assy.

Some other people may be confused. The replacement Bearings are SKF.
 

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Discussion Starter #56
If you do go the bearing replacement route, insist the bearing house you use supplies you with top name brand bearings such as SKF, ***, NSK. Plain box or brands such as "Consolidated" are third world bearings or they are repackaged aged out surplus that the grease inside the bearing has separated into oil and thickener. Using Loctite 660 or Red is good practice. The bearings can be pressed out afterwords by heating to about 300F. The loctite melts and acts as a lubricant to press it out.

I worked for SKF Reliability for 5 years.
They are in fact SKF... I'm with you, always have used SKF, F*AG or NTN.
 

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Hmm... This is an interesting thread.

I have a high pitched constant squeaky noise I can hear while at higher speeds but only with the windows down. It doesn’t sound like the typical belt squeal, though. Almost like a wheel bearing or something.
 

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Hmm... This is an interesting thread.

I have a high pitched constant squeaky noise I can hear while at higher speeds but only with the windows down. It doesn’t sound like the typical belt squeal, though. Almost like a wheel bearing or something.
If its the belt or the pulleys it will vary with engine speed but not road speed. Push the clutch in and see what happens.
 

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I can only speak for the S1 ... You can replace/overhaul the upper pulley assy. with the clam on, motor will need to be raised. 8hr job. 10-12 if doing everything. You will need slim profile bars. Not fun without a lift. And as mentioned above, I now know why Lotus will not sell the bearings (although proper mechanics will now how to obtain them). The machining on the pulleys is borderline rubbish... and after finding mine with a spun outer race, I spoke with others that had the exact same issue. So all installed with Loctite 660.
I think I am going to remove the pulley assembly- when you say the motor has to be raised once I have removed the bolt that attaches the pulley assembly to the upper engine mount is there enough play in the other mounts that I can jack the engine up a bit from the bottom to get the pulley assembly out? Or do I have to loosen or remove some or all of the other engine mount bolts?
 
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