Rumble Research, Calling RS200 MT owners for a survey

Dual mass flywheels are there to dampen vibration from the engine, to prevent the vibration from transmitting through the drive train.
I'm pretty sure some Silvias run a dual mass, they are also a 2ltr 4 cylinder rwd set up.
The question is, what in the engine is causing the the rumble. Fuel air ratios, causing the engine to run odd on the overrun, or unbalanced mechanical parts, harmonics?

yip the S15 and also 350Z runs a dual mass flywheel

To all those who have the rumble on decceleration....

What are your driving habits?

1) Do you track the car?
2) Are you a stoplight warrior? (ie. Do you dump your clutch often)
3) Do you heel-toe often while street driving?
4) Do you use the gears to slow doen the vehicle?

Perhaps a trend will show here.

Here are my responses.

1) Yes
2) No
3) Yes. 50% of the time
4) Yes. 75% of the time

My rumble occurs on deceleration in 6th, 5th & 4th gears.

I believe that the bushings & the clutch throw out bearing needs to be replaced in the gearbox.

It's a definite possibility, but given the number of differing driveline configurations that suffer the same problem I've started looking elsewhere. As Skyline Guy mentions do intake harmonics play a role? That's why I was asking the induction question as part of my research. Perhaps I should be asking if anyone running an air/fuel controller (Apexi SAFC etc) who has changed the ratios that occur on the overrun have found any difference?

Here are my driving habit responces:
1) No
2) No
3) No
4) Yes

Rumble occurs in all gears 3rd and upwards. Strictly speaking I find it's more of a 2800 rpm rumble than a 3000 rpm one...

Looks like it will be early next month that I get my driveline overhaul, so I'll post some more findings then.

I dont think it matters what your driving habbits are, its something to do with the engine I reckon, maybe the computer, tuning, or another component, as with other vehicle makes and models, some do it and some dont, changing clutches and flywheels only makes it worse where it would normally be unnoticed!


Cheers

Did I mention that I only get the rumble once the car is warm? I've been intending to trick the car into thinking it's cold to see if the rumble is affected then (unplugging the water temp sensor makes the car think it's hot, so I have to do the opposite of that)... I looked at closed loop vs open loop operation for the fuel injection and thought unplugging one of the exhaust oxygen sensors might trick it into open loop, I didn't see any success with this approach tho.

Does the Altezza 3SGE shut off fuel injection completely during the overrun? If so, so it only do it when the engine is at operating temperature??

jasestu,

Your legend is screwed bro!!

BTW, my rumble existed when I had my TC kit on a couple of years ago.

At least someone is paying attention!! I've removed it for now and will re-post when I have time to do it properly

I don't really have a rumble on decceleration like you mentioned but something much worse

What happens is if you're on WOT and change gears so the rpms drop to just below 3000 and get on WOT again after the gear change, its a really loud flutter sound liket the car is spitting, not sure what it is but it sounds pretty terrible

Induction: HKS Intake & filter
Flywheel: Not actually sure, had a Cusco lightened one in but clutch was fucked as and cusco flywheel didn't bolt up to the new clutch so - its a mystery.
Exhaust: HKS Extractors through to some sort of japanese muffler with cat still in place.
Year: 2000
Rumble I guess?

One more for the stats...

Induction - Apexi Power Intake with Apexi heat shield
Flywheel - ORC 5.4kg
Clutch - TRD
Year - 2002
Rumble yes/no - YES
Exhaust - Factory

Here are my driving habit responces:
1) Yes
2) No
3) Yes
4) No

Induction - stock (tied flap)
Flywheel - stock
Exhaust - cat removed
Year - 1998 (rs)
Rumble yes/no - YESSSSS

Hi,

I just brought my RS200 Manual (Factory), and on deceleration and certain revs it rumbles.

I believe this is just caused by back pressure created by the exhaust (if this is mentioned any where else in this post sorry) this is because Toyota engines seem to like back pressure....my 10c worth anyway.

Changing the flywheel certainly changes the noise, so I don't think it is exhaust related.

At least Toyota engineers will recognise that it exists. See the comments from Toyota NZ here-

http://forum.altezzaclub.org.au/index.php?showtopic=1934

Argh!!!! ENGINES DO NOT LIKE PRESSURE ON THE EXHAUST SIDE!!!
(I prefer not to use the term backpressure, because there is no such thing - pressure does not have direction, so it back be back or forward pressure...)
Sorry for shouting, but this is one myth I get sick of hearing.

Anyway, here's some reading for you:

toymods.org.au
www.miata.net

It's all about velocity, not pressure...

Did I mention that I only get the rumble once the car is warm? I've been intending to trick the car into thinking it's cold to see if the rumble is affected then (unplugging the water temp sensor makes the car think it's hot, so I have to do the opposite of that)... I looked at closed loop vs open loop operation for the fuel injection and thought unplugging one of the exhaust oxygen sensors might trick it into open loop, I didn't see any success with this approach tho.

Does the Altezza 3SGE shut off fuel injection completely during the overrun? If so, so it only do it when the engine is at operating temperature??

Does the Altezza 3SGE shut off fuel injection completely during the overrun? If so, so it only do it when the engine is at operating temperature??

i think they do shut off the injectors 2 a pont but they dont stop flow Iv had a look on the scope at work will i was playing with my car the outer day. Tey drop off on dsell but the still pusle and i get flames on dsell so must be dupin fule in lol

I FIXED MY RUMBLE!!!

My rumble was extremely loud in the cabin and it was really starting to get annoying. It was from around 3000rpm to 2500rpm on overrun 5,4,3 and not as loud in other gears.

I just got an Exedy single mass full weight flywheel and a new Toyota clutch. The sound has vanished (not to mention everything else being a lot smoother).

Does anyone know if this flywheel can be lightened easily if I want to do it later?

Induction - TRD panel filter
Flywheel - Exedy fill weight single mass replacement
Clutch - Toyota new replacement
Year - 1998
Rumble yes/no - Not anymore!!
Exhaust - Decat only

now that's interesting..

Everyone I know who fitted the lightweight flywheel still had the noise, but the pitch & volume changed.

Easy to lighten anytime, about $100 plus the cost of getting it in & out.

Did the decat make much of a difference??

Hi Greeneyes,

I found that interesting as well. I had read that from people who had fitted the lightweight one. Am I right in thinking some people from the club lightened these flywheels? I take it that is what your talking about with the ~$100 lightening. Is it much roughter to drive with the lightening i.e. rutting, needing to heel-to at gear changes etc.? What weight can it be machined down to?

The Decat definitely made some difference but it also increased the exhaust noise. Does anyone know the best way of getting rid of the tinny sound from the exhaust without increasing the volume?

Thanks...

We bought a dozen of them through Manukau Toyota, proper TRD lightened ones. They were spun down on a lathe at the factory to about half the normal weight, about 7kg. Maybe 10kg would be an improvement and still not buzzy.

There must be racing guys down there that have had flywheels lightened somewhere in Dunedin.

Easy to drive with, no changes needed to your driving except you will stall taking off uphill if you have the revs too low. Happened twice or so in the first week, never again...

Quicker in 1st and 2nd gear, which I would never have believed until it was fitted!

Yeah I had this Toda one, think it was just for racing, and sure was 4.7 kg, it was the lightest one you could get!

Have a steep driveway at beach house and it didnt like it at all, burnt bit of clutch on two ocasions and didnt do that again!

Wasnt more noisey when driving apart from decelaration as per all others!

I did find that by choosing different gears sometimes higher etc I think it wasnt as bad, eg the noise nearly went away!!!

The tinny sound comes from the flap in the stock rear muffler.

Time for a new one!!

Hey RS200AT, sounds like you know something I don't. What flap are you referring to? I would be stoked to get rid of that tinny crap aye...

Off topic, so I've put the answer here: Creating a Free-Flow Exhaust

FIXED RUMBLE

Fitted new genuine Toyota:

• Dual mass flywheel
• Clutch plate
• Pressure plate
• Clutch release bearing
• Spigot shaft bearing

and Castrol VMX Gearbox Oil.

With the rumble gone there's a lot of other little rattles that were happening on the overrun that have also shut up. For example my accelerator pedal had a rattle (that I was getting around to fixing...) but has gone completely. Just goes to show how much of a vibration the rumble used to send through the car.

The gears now engage a lot more smoothly, there's no shudder on cold take-offs and the stick feels less notchy between gears.

The 'thud' when you push through from 1st to 2nd reasonably quickly still exists, as does the front shaft gear chatter in neutral. But you can hardly expect a clutch and flywheel change to fix those 'characteristics'!

Playing with the old dual mass when it was out apparently you could feel that the 'springiness' in one direction was not there, so the dampening effect wouldn't have been working. The question is, when you consider what Icarus has said above, was the worn dual mass the cause of the rumble, or was it just unable to dampen the rumble? Toyota must be using dual mass for a reason, and the reason is most likely to dampen such vibrations - but this makes Icarus' finding that the Exedy single mass full weight flywheel also stopped the vibration very interesting.

Anyway, no rumble, happy happy joy joy...

Stoked to hear you fixed it too! I just put some VMX in my Gearbox as well and it has made such a difference. The thuds are all but gone and the notchiness is also barely there now.

Just as an aside, there's more on my mission to stop the tinny exhaust noise here.

This post has been edited by jasestu on Nov 20 2005, 07:37 AM

Well done jasestu, that is one problem sorted out!

..and that info about the VMX oil is also something vital that should be read by all.


Now, about the tinny exhaust sound and the gearbox idle clatter....