[jefrac]

I have been hearing a rattling or clattering noise that changes with engine RPM. I only hear it when driving the car hard on the track and only when slowing down, mainly when I blip the throttle for H&T shifts under heavy braking. I never hear this in spirited street driving.

My first thought was detonation-eek-, but the engine pulls great and smooth UP to redline without noise. Also, the noise has stayed consistent with my old tune and my new FastWorks Torque tune (love the new tune BTW).

My other ideas were:
1. Something with the belt tensioner
2. Supercharger lobes or bearing (another -eek-)
3. Alternator bearing

I have sport inserts in front and rear motor mounts. So far, I have removed the belt and turned the S/C and other pulleys by hand. They seem OK:shrug: Since it only happens on the track, it's hard to get someone to ride along and listen, well... at least anyone that knows something. Thought about sticking the GoPro in there somewhere, but it seems like that will just be too loud to get much. I have recently torqued my intake manifold bolts and S/C support bracket. It does not sound like my Lidbone.

Any thoughts or experience with something like this?

 

[jefrac]

Just for reference.... I found the noise. It was the bracket that holds the end of the alternator support. These are the brackets from an original Tripoint Engineering Supercharger kit. I believe they have all broken now and I have had to repair or replace each one. The top bolts for this particular bracket are right against the firewall and below the alternator so there was no way to see them. Everything in the area had to be removed.

When the car would heat up after some hard acceleration the sound would start. It was worse under hard braking I guess because the force would move the alternator forward and free things up to clatter. My advice is to use RED Loctite when bolting stuff like this together.

 

[Coyne]

I get a clattering noise every time I let off the throttle. It's a light noise, but it's a buzzing type clatter that makes me nervous.

 

[Twizzstyle]

After I installed a lightweight flywheel on my old car (Subaru WRX) I got a very light buzzing/rattling sound when decelerating in gear. After looking around online, it sounded like it was fairly common, so I never worried about it.

My Elise makes the exact same sound under the exact same condition. I'm not the original owner, so I have no idea if it has a lightened flywheel, but I've never been too worried about it.

(knock on wood)

 

[Coyne]

After I installed a lightweight flywheel on my old car (Subaru WRX) I got a very light buzzing/rattling sound when decelerating in gear. After looking around online, it sounded like it was fairly common, so I never worried about it.

My Elise makes the exact same sound under the exact same condition. I'm not the original owner, so I have no idea if it has a lightened flywheel, but I've never been too worried about it.

(knock on wood)

It definitely sounds like a gear/wheel noise. I know he kept everything OEM, so it's the stock flywheel. After a while you get used to the car, and I can remember if it had this noise before or not.

 

[kestrel74]

Everyone's first Lotus ?????? :tadts:

 

[KWYK]

I get a clattering noise every time I let off the throttle. It's a light noise, but it's a buzzing type clatter that makes me nervous.

yours sounds like a clutch release bearing not freeing properly

 

[4380r]

It definitely sounds like a gear/wheel noise. I know he kept everything OEM, so it's the stock flywheel. After a while you get used to the car, and I can remember if it had this noise before or not.

I've owned 3 Elises, 2 Exiges (one S220). Two of the Elise bought new, one of th Exige. ALL of them made this noise the entire time I owned each.