BMR IRS Lockout and BMR Red Diff insert NVH question ???

[Conekiller88]

As many of you now by now I told my dad to add a BMR lockout kit to get rid of that horrendous wheel hop and while I was shopping for these parts I decided to add BMR Red Diff inserts. I did this without searching forum ( I have a ZL1 so dont spend that much time on other forums ) but I am just finding out about clunks/gear whine noises from combination of these two.

All suspension work was done at the same time and it included:
FP X pipe
Roush Mufflers
FR Strut brace
Koni Yellows
Steeda Sport springs
BMR IRS lockout kit
BMR Diff Inserts (Red)
PP Wheels with PZero

After driving a car NVH is kinda horrendous, clunks whine gets little bit ridiculous and the car only has 8k miles on it.

1.Clunks when going from Neutral to 1st or 1st to 2nd while parked
2. clunks when starting of slowly between 2 or 3 gears
3. Gear Whine is very noticeable starting at 60mph even with Aftermarket exhaust
4.Seems like a driveshaft or diff has way too much backlash (feels like it)

Question I have, if its BMR DIFF bushings causing all this NVH , can I take out the 2 rear bushings and see if it helps? Do all 4 need to come out or can I leave two front ones to see if it helps with stuff? Is it gonna affect the lifespan of the diff if I only leave two in?

Just trying to see what everyone else did to help improve ride quality in their GTs. We do love in Ohio so the roads are pretty crappy. This was added mainly because of AutoX events but I just cant justify NVH over performance of these inserts.

Let me know what you guys think.

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[Rustang]

Clunks and whine was likely there before but now being transmitted to the cabin more as you firm up the bushings. Most likely the diff bushings. The BMR I believe are 95 durometer which is pretty stiff and will transmit more. I wouldn't reccomend running only 2, all or nothing. I have the Steeda which are 80 and it increased gear whine but not much and I can live with it vs wheel hop.

 

[Bluemustang]

Yes absolutely its the diff bushings. 100%

Living in Ohio, well we can't help you with that LOL

 

[Bluemustang]

Also the diff bushings don't do anything for handling. I'm going to take mine out. I just haven't had the time.

What happens is the IRS mods tightens up the rear end and with the combination of the diff bushings it exposes the sloppy driveline. It will be a good bit better IMO when you take those out.

 

[Conekiller88]

I just cant believe the driveline on GT is so sloppy. I had and drove Evos with 600hp and full poly black bushings and it was tight , even after 50k and handful of autox race seasons and daily driving.

 

[PoppinJ]

Tons of clunks with the Steeda red bushings installed. Not much more gear wine but I do notice it every now and then on the highway. Very livable though. I also have the Steeda subframe bushing support system. Dont know if its the lockout kit making it much worse or not but all the diff bushings seem to cause the clunking sounds.

 

[wbrownie]

I have the same issue. Installed the BMR subframe lockout and diff bushings at the same time. Noticeable clunk over low speed bumps and drive off. I too suspect it is the diff. Going to remove them.

 

[Bluemustang]

I can almost guarantee you the diff bushing inserts are the offender. The worst suspension product for NVH you can buy on this car.

 

[Conekiller88]

How is the gear whine ?

I have the same issue. Installed the BMR subframe lockout and diff bushings at the same time. Noticeable clunk over low speed bumps and drive off. I too suspect it is the diff. Going to remove them.

 

[Conekiller88]

I can almost guarantee you the diff bushing inserts are the offender. The worst suspension product for NVH you can buy on this car.

I cant believe BMR qould sell such a prosuct. From what i read and I dod days of digging , Steeda guys at least can get away with low gear whine. On BMRs whine is loud as hell

 

[wbrownie]

I don't notice the gear whine much. But then again I run Toyo R888R since I use the car mostly on track. The tire noise is crazy.

 

[Bluemustang]

I cant believe BMR qould sell such a prosuct. From what i read and I dod days of digging , Steeda guys at least can get away with low gear whine. On BMRs whine is loud as hell

Sometimes NVH is the cost of performance. A lot of people don't realize that this product isn't necessary for them and they buy it anyway. I have the Steedas. Mine whines loud as hell too. Both products are essentially the same. Take em out. You live and learn.

If you ask Kelly, he'll tell you. The diff bushing inserts are the very last IRS mod he will ever recommend. Only for drag racing and once you've upgraded literally everything and chasing that every last bit.

 

[BMR Tech]

Re-enforcing the differential mounts with any material that increases rigidity will increase NVH levels. This is true on any vehicle.

NVH level increases are not the same from car to car, nor person to person. For example - my base model 2015 GT with Auto trans and 3.15:1 rear gear had a much lower NVH increase than my 2016 GTPP with 3.73:1 and Torsen diff.

What I usually find is that the manual transmission cars will show higher increases in NVH due to exercising the driveline tolerances more, AND they typically have a higher numerical gear ratio. Higher gear ratios seem to always emit more NVH.

When I deal with a customer directly, I always shoot them straight. Diff inserts/bushings, Toe Links and Vertical Links are (3) parts that are usually always towards the end of the list and I typically only suggest them if I think the end user needs them for their specific goals.

OP; I would suggest removing them and seeing the difference. Some people do not feel there is enough improvement to settle for the level of NVH increase that they experience.

 

[Mazman]

I have diff bushings as well, opted to have them installed as lowering springs and CB005 was being installed.

My car is a daily and the NVH is killing me .

I will try to get them out myself, I only have jack stands I guess it is going to work out.

 

[BmacIL]

only suggest them if I think the end user needs them for their specific goals

Very few do.

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