Change in sound? RS mounts/LSD?

[Edmundo2]

Hi.

 

After a few grocery runs to get the car out since recent work I've noticed a recent change in sound..

 

The work included LWFW, Sachs sprung clutch plate, Wavetrac LSD, 964RS trans mounts and a deeper baffled sump..

 

Initially the car sounded the same but part way through the previous outing, ( having covered circa 50 - 100 miles since fitting ), it seemed to take on a deeper more gutteral/thrum together with a different feel by way of subtle/faint vibration through the seat..

 

Now the noise/sensation seems permanent. It's a nice noise/sensation and the car seems to go just as well all be it with a tighter feel..

 

My only query is as to why the change came about after say 100miles rather than instantly..? Does this happen as engine mounts settle down? Could it be the LSD bedding in..etc..? 

 

The brand new LSD brings with it a more mechanical/taughter feel, the flywheel has brought a livlier rev rise and blip but no discernable extra rattling etc..Everything I was hoping for..

 

So my question is - is the change in noise just a result of the new trans mounts holding things more firmly and transmitting a different pitch of noise/harmonics/vibration etc? Or is it the LSD that's just more aggressive and it's being transmitted through the car..Bit of both?

 

Just wondered what others experiences have been so I can sleep easy that this change is as it should be and that it changed after 100 miles or so due to things settling down/bedding in rather than anything being out of balance, loose, too tight etc..? 

 

Obviously that's quite a few changes all at once that stand to alter the feel and all likely to bring a more mechanical sensation..Just want to be sure that everything is right..

 

Any thoughts appreciated.. 

[jcm987]

Sounds like a combination of the diff and engine mounts. When I fitted RSS engine/trans mounts I didn't notice any noise changes, just some more vibrations and less movement.

 

After fitting the LSD (Quaife) and new clutch there was a bit of a whining a low revs and more mechanical noise. Now it seems to have died down and I don't notice it. But my experience is similar, overall the tone is clearly more guttural and mechanical, possibly slightly deeper, especially at low revs in traffic.  

 

I've removed the carpet in the boot and engine cover, so any new noises are easy to pick up. 

 

 

[Edmundo2]

Thanks for that. Sounds consistent with my description and helps to allay any concerns. I didn't want to be enjoying this new found mechanical feel only to find I've actually been enjoying the sound of a spun bearing..😟

[Beanoir™]

Its not unusual to have more vibration through the car if you've fitted uprated engine or gearbox bushes.  That will reduce a bit over time, and depending on whether you've fitted poly or rubber versions makes a difference too.  (I think the RS ones you've fitted are rubber).  

 

Lightened flywheels are also known for introducing vibration back through the car too as you've removed a vibration limiting device in the DMF.  

 

I'd say it was probably a combination of things, all of those modifications you've listed will introduce different noises thats for sure.  

 

 

[Edmundo2]

Thanks Been our and yes I was expecting them all to have an effect, all of which was positive in my mind providing they didn't add up to too much NVH.., ( which it hasn't)

 

I ended up leaving out the yellow powerflex engine mount insert just in case this tipped things too far..It could possibly take this as well but I'll see how the car feels in another 500 miles or so..

 

I understand the effect each part/mod has on paper but didn't have previous before and after first hand experience of how the mods feel in practice so was wanting to see if others described the effect as I did..The main concern was the fact it seemed to change after 100 miles or so rather than from the get go? Not sure why but assume things just settling down/bedding in ..

 

The result is really nice..A sort of mechanical gruff turbine noise/smooth vibration as you build from low rpm that gradually gets drowned out as the rip from the exhausts starts to take over at about 4k onwards.. 🙂

 

PS. I have a spare set of yellow powerflex inserts if anyone wants them, ( I ended up with x2 sets ). £25 delivered. Drop me a line if so