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BMR LCA and UCA screeching noises

Hi,
I just installed on my boss 302 2013 some BMR parts here under listed :

Adjustable upper control arm with upper control arm mount
Differential bushing kit
Lower Control Arms, Boxed, Non-adj, Poly Bushings

Car is not lowered.
Parts are filled with sylicone grease

Every thing went well during installation phase but after about 50 miles when the car or parts became warm I have huge screeching noises coming from the rear.

I stopped the car for a while and started again and no more noise.

Does someone faced the same issue and could you fix it?

Is it possible that the noise is coming from the poly bushings and what can I do to get rid of these noises?

Thanks for your help

Chris
 

Norm Peterson

Corner Barstool Sitter
939
709
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
Does it sound like the screeching is coming as the suspension moves? Did you lube the flat faces of the bushings? When you installed the lower arms, did you notice whether the poly was longer than the inner sleeves or were the sleeves a tiny bit longer than the poly?


Norm
 
Does it sound like the screeching is coming as the suspension moves? Did you lube the flat faces of the bushings? When you installed the lower arms, did you notice whether the poly was longer than the inner sleeves or were the sleeves a tiny bit longer than the poly?


Norm
Yes it's coming when suspensions are moving but only after some miles like if the parts became warn.
I did not lub he flat faces from the bushings, was not mentioned on the installation book!
I do not remember if there was any difference between sleeves and bushings size.

I will remove, lub and reinstall, will check the size.
Will do it this weekend.
I keep you posted.

Thanks
 
634
201
Spider69 - Does it sound like it is coming from all over or just one side of the car? Does it happen on smooth roads, sharp pavement cracks, on undulations or all of the above?

Here is a trick I used to diagnose a weird creaking noise I could not figure out: drive the car until it makes the noises, then jack the rear of the car up and use jackstands under the rear pinch welds to let the axle droop down. Then get your quick action floor jack and put it under one side of the axle and raise the axle up a bit. You might start to hear the noise but if not, once you have some tension on the axle, give the jack a quick push down - just sort of punch it down quickly. It might help to have a friend help you with either listening or handling the jack while you try to listen. This is the sort of jack I am referring to:


But yes as Norm pointed out it's probably the bushings needing to be lubed where they mate up to the metal brackets.
 

Norm Peterson

Corner Barstool Sitter
939
709
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
I did not lub he flat faces from the bushings, was not mentioned on the installation book!
I'm a bit surprised - the poly has to slide against the bracket, and poly against many substances is a rather sticky-slippy combination (read: squeaky). Put the poly under compression, it's generally worse.

I do not remember if there was any difference between sleeves and bushings size.
This is definitely worth a look, as when the poly is longer than the sleeve it will be getting compressed as you torque the fastener. This can also lead to 'clunks' when engaging the clutch or sometimes when hitting the brakes in a fairly hard stop, because the sleeve is not as securely located when the poly is under compression and the whole business can slip until the bolt to hole clearances are taken up.

There is a DIY solution to both of those items if you're willing to accept the possibility of slightly/somewhat shorter poly life (poly bushings really should be considered "wear items). It's much more applicable to street and autocross/road course/canyon driving than drag racing. And it normally allows far less frequent re-lubrication.


Norm
 

Norm Peterson

Corner Barstool Sitter
939
709
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
Make sure the suspension is loaded when you torque the bolts
As long as neither bushing on any given control arm is an OE-style bonded rubber kind, there is no need to have the car at its static ride height with full weight on the tires. The sliding surfaces in either the typical polyurethane bushings or any sort of spherical joint permit the kind or bushing rotation that the OE rubber can only accommodate via compliance where the bushing material distorts in torsional shear.

OE bushings need to be torqued down at static ride height to avoid preloading the bushing material, which could cause them to be overstressed in shear and fail under extreme amounts of suspension travel in the direction opposite to the incorrect suspension position used. Usually this means the suspension was in 'droop' when the arm fasteners were torqued, where lots of bump travel would be the 'bad' direction of suspension movement as far as the bushings are concerned.


Norm
 
I'm back on my post regarding the noise on my boss302.
i have replaced the shocks with a set of Bilstein not adjustable but really good.
I have to say that this shocks are great, comfortable on the road and seems controlling very well the car.
In 2 weeks I will be able to test them on a race track, I keep you posted.

On another hand, since I've replaced the shocks, the screeching noise has gone and I'm really happy to have found the issue.
Nevertheless, I have some noise, I guess coming from the rear end of the car when realaunching the car in 1st or 2nd gear.
Not coming from the shocks, because no noise when driving on a bumpy road.

I thought this can come from the body of the car, with LCA and UCA and stiffer shocks the car is more stressed when accelerating.

What do you guys mean?
 

Dave_W

Cones - not just for ice cream
546
609
Exp. Type
Autocross
Exp. Level
20+ Years
Connecticut
It could be normal gear whine from the differential under a hard launch, being transmitted to the bodyshell more now due to the harder bushing material. If you track it down to that, you can try putting a 12" or so square piece of dynamat or similar asphalt/rubber soundproofing mat on the inside of the car where the upper control arm attaches, under the rear seat.
 

carver

breaker of wrenches
428
563
ontario
Since I removed the back seat I hear more rear end noise . Whining rear end and mild clunking from the stock drive shaft when decel or excel.
Do you run the stock driveshaft ?
 

302 Hi Pro

Boss 302 - Racing Legend to Modern Muscle Car
2,009
438
Southeast
Check the 2 piece DS hanger joint for slop.

Also UCA’s induce more noise than LCA’s. There is also a Press fit bushing on top of the pumpkin housing.
 

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