Adding some compliance & softness back in

[Gibbo205]

Hi there


Clearly getting soft in my old age, current car is 2015 UK GT PP M6 with following suspension work:-
- FRPP dampers
- FRPP swaybars set to softest
- Steeda Ultralite linear springs
- FRPP toe knuckle bushes
- GT 350 strut brace
- BMR CB006 front lower 4 point brace
- Steeda transmission bracket
- Steeda differential bushing insert support bushes *red ones*
- BMR CB005 cradle lockout kit
- BMR SPHERICAL Vertical links
- 20" MRR FS02 forged wheels 275 fronts and 295 rear PS4S tyres


Car handles and grips insanely well but for street use as a daily it's almost too sharp and the rear seems overly harsh. Plus too much noise is being transmitted into the cabin from the rear of the car which I guess is a combination of the CB005 and diff inserts? The faint transmission thud turned into a more noticable clunk after CB005 and diff inserts.


My first thought are to first try removing CB005 as it's quite easy and put in the steeda alignment pins to keep cradle centred in place.

If still to much noise from the rear then to try removing the furthest rear diff inserts as they are easy to access and see how things are.

I know to get better overall softer ride would require spring change.

Anyone else done similar or thoughts?

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[dev1360]

Most noise is probably coming from the transmission insert and differential bushings. The cradle lockouts on my otherwise stock suspension are silent.

 

[BmacIL]

I would keep the IRS stuff (maybe not the diff bushings though) and go softer on springs and bars, and also get rid of the transmission mount insert to bring noise down. Lighter bars will make a big difference in ride over single wheel bumps. Perhaps go back to stock PP bars and see what you think? If you need more compliance, try BMR SP080s with your dampers.

 

[s550v6]

The differential inserts seem like they would cause the the biggest gain in NVH that you currently have. The CB005 adds very little NVH by itself.

Hi there


Clearly getting soft in my old age, current car is 2015 UK GT PP M6 with following suspension work:-
- FRPP dampers
- FRPP swaybars set to softest
- Steeda Ultralite linear springs
- FRPP toe knuckle bushes
- GT 350 strut brace
- BMR CB006 front lower 4 point brace
- Steeda transmission bracket
- Steeda differential bushing insert support bushes *red ones*
- BMR CB005 cradle lockout kit
- 20" MRR FS02 forged wheels 275 fronts and 295 rear PS4S tyres


Car handles and grips insanely well but for street use as a daily it's almost too sharp and the rear seems overly harsh. Plus too much noise is being transmitted into the cabin from the rear of the car which I guess is a combination of the CB005 and diff inserts? The faint transmission thud turned into a more noticable clunk after CB005 and diff inserts.


My first thought are to first try removing CB005 as it's quite easy and put in the steeda alignment pins to keep cradle centred in place.

If still to much noise from the rear then to try removing the furthest rear diff inserts as they are easy to access and see how things are.

I know to get better overall softer ride would require spring change.

Anyone else done similar or thoughts?

 

[Gibbo205]

Most noise is probably coming from the transmission insert and differential bushings. The cradle lockouts on my otherwise stock suspension are silent.

It's not the insert I have, that went a year ago as even with a hole drilled in it was terrible NVH.

The bracket I have added no NVH when fitted.

Biggest culprits seemed to be CB005 and diff inserts and springs.

 

[tj@steeda]

Hi there


Clearly getting soft in my old age, current car is 2015 UK GT PP M6 with following suspension work:-
- FRPP dampers
- FRPP swaybars set to softest
- Steeda Ultralite linear springs
- FRPP toe knuckle bushes
- GT 350 strut brace
- BMR CB006 front lower 4 point brace
- Steeda transmission bracket
- Steeda differential bushing insert support bushes *red ones*
- BMR CB005 cradle lockout kit
- BMR SPHERICAL Vertical links
- 20" MRR FS02 forged wheels 275 fronts and 295 rear PS4S tyres


Car handles and grips insanely well but for street use as a daily it's almost too sharp and the rear seems overly harsh. Plus too much noise is being transmitted into the cabin from the rear of the car which I guess is a combination of the CB005 and diff inserts? The faint transmission thud turned into a more noticable clunk after CB005 and diff inserts.


My first thought are to first try removing CB005 as it's quite easy and put in the steeda alignment pins to keep cradle centred in place.

If still to much noise from the rear then to try removing the furthest rear diff inserts as they are easy to access and see how things are.

I know to get better overall softer ride would require spring change.

Anyone else done similar or thoughts?

Was there a certain point of installation where you noticed more NVH than before? Or ... did you have all the parts installed at the same time?

Our alignment kit does not increase NVH ... so if you go that route, it could help things.

You would almost have to work backwards to see what works.

TJ

 

[Gibbo205]

Was there a certain point of installation where you noticed more NVH than before? Or ... did you have all the parts installed at the same time?

Our alignment kit does not increase NVH ... so if you go that route, it could help things.

You would almost have to work backwards to see what works.

TJ

Your diff bushing inserts and CB005 certainly causes more NVH and clunks from transmission. Guess I'll start there.

 

[Bluemustang]

Your diff bushing inserts and CB005 certainly causes more NVH and clunks from transmission. Guess I'll start there.

Definitely. I've experienced the same thing. Maybe go to softer springs and shocks and remove the CB005 and the diff inserts. Maybe go to BMR SP080s and PP shocks.

 

[jabrax]

Gibbo, have you thought about progressive springs?

 

[Gibbo205]

Gibbo, have you thought about progressive springs?

Will do the easy no cost stuff first. Gonna try:

- Remove just two rear bushing inserts as easy get too.


If still bad, shall remove the two front diff bushing inserts.

After this shall try removal of CB005.

Final option is spring change as that is expensive and timely, if I went down that route think I'd go with KW V3 coilovers as then I can set the car up as I want it for ride quality and ride height.

 

[West TX GT]

The diff inserts are what's causing the noise I didn't have any noise increase with cb005 the diff added a lot of noise. At least start with that. As for the stiff ride I would guess springs would make the biggest change.

 

[Rebellion]

I think that, if you still have your stock parts and don't want to buy stuff, you could follow this approach:

1. Change back to your stock sways. I'm not even sure the car requires more than PP sways to get proper handling, and I think they can make some lateral displacement which can contribute to harshness.

2. Remove the diff inserts, which doesn't really impact handling per se.

3. Now, this is going to sound stupid but hear me out...change your shocks back to PP. The rear definitely contributes more to harshness, and the FRPP shock might dampen too much for the Ultralites, from a ride comfort perspective. This is an easy swap and you'll be able to gauge if you want less spring or less damper, I'm guessing it's the latter (because I'm using the FRPP shock with SP085, and the amount of underdamping is about right).

4. Swap the CB005 arms for the black sheetmetal thing. I think you can gain some NVH reduction while still keeping most of the functions of the CB005.

 

[Gibbo205]

I think that, if you still have your stock parts and don't want to buy stuff, you could follow this approach:

1. Change back to your stock sways. I'm not even sure the car requires more than PP sways to get proper handling, and I think they can make some lateral displacement which can contribute to harshness.

2. Remove the diff inserts, which doesn't really impact handling per se.

3. Now, this is going to sound stupid but hear me out...change your shocks back to PP. The rear definitely contributes more to harshness, and the FRPP shock might dampen too much for the Ultralites, from a ride comfort perspective. This is an easy swap and you'll be able to gauge if you want less spring or less damper, I'm guessing it's the latter (because I'm using the FRPP shock with SP085, and the amount of underdamping is about right).

4. Swap the CB005 arms for the black sheetmetal thing. I think you can gain some NVH reduction while still keeping most of the functions of the CB005.

1. I fitted the sways seperate to everything else as I tried to do as much as one thing at a time. The sways really had no impact on ride quality, handling not so much but had a lot more confidence inspiration in the car with sways fitted.

2. Shall give these a go first as think you are indeed correct.

3. Great idea, swapping out the rear dampers is very easy job, worth a try.

4. Also great suggestion, I can try this for sure and again pretty easy to do.

 

[Southview]

Definitely. I've experienced the same thing. Maybe go to softer springs and shocks and remove the CB005 and the diff inserts. Maybe go to BMR SP080s and PP shocks.

Ryan. Call me if you haven't already sold them. :cheers:

 

[Jmeo]

I experienced the exact thing as you and I can tell you from experience the diff inserts are the culprit. I will say they do their job and work well at what they are intended to do, they just add NVH unfortunately. I am not sure if you did LCA bearings but I when I had CB005 in my last car and then added BMR LCA bearings the combo itself gave me NVH. I then switched to Steeda subframe braces and their aluminum subframe inserts instead of CB005 and it was slick, smooth and quiet from there on.

I can say I learned a lot from my last car and went out of my way on my current car to not allow any NVH in and I have succeeded. Check out post #1 of my build thread if your interested to see what I have done

Good luck and keep us posted

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