Hello all,

I recently bought a '1994 Gen4 Honda Prelude 2.2 Si vtec LSD' to work on as a project. I am also using it as my everyday car.

Yesterday it started making a horrible clattering/chattering noise under low rev deceleration. The noise kind of spins up when I slow down and the engine reaches low revs, then fades down once I either get back on the throttle, or come to a complete standstill.

The noise only occurs when the vehicle is in motion - slowing down at low revs to be specific, and can happen whether the brakes are being applied or not. Coincidentally, the noise is exactly the same regardless of whether the brakes are being applied or not.

The clattering is also accompanied by what I can only describe as a 'background electrical whining'.

Perhaps most importantly, the 'spinning up' & 'winding down/fading away' characteristics are not consistent with either engine speed, or wheel speed. But the sound seems to be coming more from the r/h/s of the vehicle. Possibly close to the right front wheel. Car is R/H/D if this makes any difference.

Now, I don't know much about how LSD's work, hence my post. But the reason I believe it to be a problem relating to the LSD, is that it sounds like how I'd expect it to sound if I could hear it working. It sounds like it's working correctly, just one of the internal components is grinding, or worn out.

It sounds like gears grinding, or if you were to spin up a cog of sorts really fast, then touch it with a piece of metal or plastic.

My best guess would be a problem with overrun, and something relating to the coupling perhaps?

I really don't know much about LSD's, so I could be completely wrong about this. But either way, it doesn't sound healthy.

*It may be worth noting that the ABS light is on. I would assume that the brake pads are just low because the brakes feel a bit spongy, and perhaps slightly out of balance. But no brake related warning indicator noise to speak of. The only reason I mention it, is that where as far as I know the brakes have nothing to do with the operation of a LSD, is it conceivable that it could in some way be interfering with the normal operation of the system? Or does that simply confuse matters further? Just throwing it out there.*

Does this problem sound familiar to anybody? Is there something else obvious that it could be?

Any help would be gratefully received.

Thanks

 

Well i dont completely understand the noise.. Was the car purchased like this? Is there a noise when it idles or just moving? Is this a m2b4 tranny? Is there any aftermarket parts in the tranny that you know of? Have you checked the fluid? Do you know what fluid is in it?

 

Noise is only there when the car is slowing down under load, at low revs. Then stops either when I apply the throttle, or dip the clutch to disengage the drive. Yes it is the M2B4 transmission, and no I have not checked the fluid. I have no idea what fluid it has in it I'm afraid. It wasn't making this noise when I bought it two weeks ago.

 

It's worth noting that when I disengage the drive or reapply the throttle, the noise doesn't stop immediately. There is a short delay while the noise 'fades away'/'winds down'.

 

Check the fluid and see how low it is if its a m2b4 you could just change it they only hold 2 qts.. If you do put fluid in it make sure it is not a thick 80w oil.. Honda transmissions take light weight oils.. Honda makes there own mtf fluid but you also have a lot of choices i recommend torco mtf.. To me it sounds like a bearing my guess would be input shaft bearing.. But there is a few bearings inside the tranny hat could all cause a problem.. It winding down thought sounds like something to do with the main shaft.. Hope ive helped you post what you find..

 

Is the car 100% stock? If you have a set of miss matched gears you could develope a whine or a aftermarket final drive can also whine..

 

Tbh, I have no idea if it's stock or aftermarket. I would assume stock, but I don't know what I'm looking for. Regarding shafts & bearings; if it were to be one of these, are they replaceable or would it mean a new transmission?

 

They are replaceable but the transmission does have to come out.. But check the fluid first make sure its not thick gear oil or low..

 

my guess is input shaft bearing only because I experienced the same issue on my m2y4 and I decided not to fix it because I was currently in the process of rebuilding a m2b4 that i just threw on. The input shaft bearing is a very large possibility. Good luck and post your findings.

 

Will do, thanks for your help.