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Boss S LCA Clunk & Relo Bracket Question.

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7500RPM_Ben

TMO Clueless
I have a stock Boss with Boss S LCA'S with relo brackets and they clunk, is the clunk from the rear axle rotating or the spherical bearings?

Question 2, since I am stock ride height with Relocation Brackets will my pinion angle be off?

I do not want to pull off parts I put on a few days ago. In the future I would like to put on T springs and a spherical bushing UCA. I have searched this forum and asked on FaceBook and have received no direct answers. I also have the FRPP Adj. PHB.
 
There should be additional NVH but no clunking. Check your install.

Installing the relocation brackets shouldn't change your pinion angle if you used the holes that kept the LCA angle the same and lowering the car is usually what changes the angle. Others will have better info on this.

What is the goal of your suspension changes? Are you going full track mode, occasional HPDE or trying to get rid of wheel hop? They're are differing opinions on this but I wouldn't change the UCA unless you're going full track mode. It adds a lot of NVH.

@Grant 302 @modernbeat
 
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Grant 302

basic and well known psychic
Make sure everything is tight and properly torqued first. Can you describe when you hear the clunk noises? The noise should be associated with some particular movement or condition.

I wouldn't worry about pinion angle until you lower the car, like Rick suggests.

If there's nothing wrong or loose with your LCAs, then a UCA with spherical bushings won't make you happy noise wise.
 

7500RPM_Ben

TMO Clueless
There should be additional NVH but no clunking. Check your install.

Installing the relocation brackets shouldn't change your pinion angle if you used the holes that kept the LCA angle the same and lowering the car is usually what changes the angle. Others will have better info on this.

What is the goal of your suspension changes? Are you going full track mode, occasional HPDE or trying to get rid of wheel hop? They're are differing opinions on this but I wouldn't change the UCA unless you're going full track mode. It adds a lot of NVH.

@Grant 302 @modernbeat

Everything is torqued and the top of the two holes on the FRPP brackets were used. My goal is to make my Boss a Boss S for the street. Well, with the exception of T springs.

Make sure everything is tight and properly torqued first. Can you describe when you hear the clunk noises? The noise should be associated with some particular movement or condition.

I wouldn't worry about pinion angle until you lower the car, like Rick suggests.

If there's nothing wrong or loose with your LCAs, then a UCA with spherical bushings won't make you happy noise wise.

Every time you get on the throttle and get off the throttle on the street at normal street speed. I hit the gas, clunk, I hit the brake, clunk. I do not mind it once I know what exactly it is. This week I will probably put her back on the lift and retorque the arms.

Once I lower the car I guess I will find an adjustable UCA.
 
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That clunk could be anything, to be honest. Swaybar endlinks, UCA, LCA, LCA brackets, etc. I would start by just pushing, pulling, yanking, etc on everything under the car and see if anything makes a clunk. If not, then definitely go retorque everything.

As for needing an adjustable UCA, Steeda makes shorter fixed length ones for lowered cars. I have one and it has been great (and I am lowered on coilovers, have LCA, LCA relos, Dynotech driveshaft, etc). As much as I lust after the gigantic adjustable BMR one, I haven't found a need for it.
 

Grant 302

basic and well known psychic
Sounds like something loose. If those are the only new items, looks like you should check the LCAs before driving it again. If it clunked only on tip in/tip out throttle, I would suspect the driveshaft. Nothing over bumps and dips? Noise with the brakes could still be loose LCA or bracket or other suspension connection.
 

7500RPM_Ben

TMO Clueless
Sounds like something loose. If those are the only new items, looks like you should check the LCAs before driving it again. If it clunked only on tip in/tip out throttle, I would suspect the driveshaft. Nothing over bumps and dips? Noise with the brakes could still be loose LCA or bracket or other suspension connection.

DS would make sense, that is why I am wondering about pinion angle. I know guys run -2.5 degrees and I should probably check it this week when I have a chance. That is also why I wonder about a UCA. One thing is that I can barely twist the LCA's when they are torqued because of the spherical bearings. Should they not be moving at all?

@wwilde001 did you have any funky clunking noises when these LCA'S where on your Boss?
 
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If the rear is ALL spherical bearing ends, you probably might want to think about running alot less than 2.5 degrees pinion angle.
There is not much to rotate anymore.
 

7500RPM_Ben

TMO Clueless
If the rear is ALL spherical bearing ends, you probably might want to think about running alot less than 2.5 degrees pinion angle.
There is not much to rotate anymore.

@DocB only the LCA's have spherical bearings, I have a stock UCA still on the car. What pinion angle would be best? I think I should of waited to install everything at once lol.
 
So I had a similar issue for a couple of years. When I'd back up I'd get a clunk on the back end. Almost sounded like the tire rubbing but it wasn't. I'd checked several times for something being lose and couldn't find anything. Just dealt with it.

This spring I put in a single piece aluminum drive shaft and the clunk was gone. That was the only change so...

Not saying this is your problem but it solved mine.
 

7500RPM_Ben

TMO Clueless
So I had a similar issue for a couple of years. When I'd back up I'd get a clunk on the back end. Almost sounded like the tire rubbing but it wasn't. I'd checked several times for something being lose and couldn't find anything. Just dealt with it.

This spring I put in a single piece aluminum drive shaft and the clunk was gone. That was the only change so...

Not saying this is your problem but it solved mine.

Hmm, down the road an FRPP DS is on the list. I think it may be the stock UCA rubber bushings are allowing the axle to rotate because that is the only soft control arm connection to the chassis. I think I saw where a guy on here had the same LCA's with a Steeda UCA with the spherical bearing. I want to see how that acted for him. I think his name is cloud9 or something.
 
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Since you are at stock ride height, I would not worry about your Pinion angle. As a matter of fact, I would put it out of scope since the adjustable upper arm seems to cause more concerns on the street that they "fix". Spherical bearings in the upper control arm really suck on the street....

I would focus on finding the source of the clunk. I ran these arms on a 600+rwhp GT500 and they did not clunk. This car also had the Ford Racing relocation brackets. In my opinion, you should remove them as they are meant to correct the control arm angle of a lowered car. Reinstall when and if you install the T springs. BTW, the T springs really lower the rear for looks but don't really improve handling (my opinion). I have driven a stock boss with these springs vs a Laguna with stock springs; that's how I came to this conclusion.

Find that clunk; Something is definitely not right. Good luck!
 

TymeSlayer

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That clunk could be anything, to be honest. Swaybar endlinks, UCA, LCA, LCA brackets, etc. I would start by just pushing, pulling, yanking, etc on everything under the car and see if anything makes a clunk. If not, then definitely go retorque everything.
As for needing an adjustable UCA, Steeda makes shorter fixed length ones for lowered cars. I have one and it has been great (and I am lowered on coilovers, have LCA, LCA relos, Dynotech driveshaft, etc). As much as I lust after the gigantic adjustable BMR one, I haven't found a need for it.

Have the BMR LCAs and adjustable UCA with poly bushing and their mounting bracket and I have no discernible noise coming from the rear. BMR says the UCA bracket keep the clunk away.
 

TMSBOSS

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Could be rear gear noise transferred through the solid bearings. I would definitely hunt for something loose before swapping parts.
I had same sort of observations when I installed the Ford LCAs with poly bushings. Then the one piece driveshaft. Clunking went away with the new shaft.
 
I had some clunking noises too after installing FPP Boss S LCAs and relo brackets. I also installed a Steeda UCA spherical diff bearing. The clunking is pretty much gone now but with all the spherical bushings you get a lot more NVH transmitted into the cockpit anyway, including a lot of rear diff gear noise.
 

7500RPM_Ben

TMO Clueless
Since you are at stock ride height, I would not worry about your Pinion angle. As a matter of fact, I would put it out of scope since the adjustable upper arm seems to cause more concerns on the street that they "fix". Spherical bearings in the upper control arm really suck on the street....

I would focus on finding the source of the clunk. I ran these arms on a 600+rwhp GT500 and they did not clunk. This car also had the Ford Racing relocation brackets. In my opinion, you should remove them as they are meant to correct the control arm angle of a lowered car. Reinstall when and if you install the T springs. BTW, the T springs really lower the rear for looks but don't really improve handling (my opinion). I have driven a stock boss with these springs vs a Laguna with stock springs; that's how I came to this conclusion.

Find that clunk; Something is definitely not right. Good luck!

I may look into different springs then, I like the drop of the T springs and they were made specifically for the Boss. I will have to figure that out later.

Have the BMR LCAs and adjustable UCA with poly bushing and their mounting bracket and I have no discernible noise coming from the rear. BMR says the UCA bracket keep the clunk away.

BMR LCA's with the spherical bushings and their UCA with the poly bushing? I think the actual problem may be the stock UCA.

Could be rear gear noise transferred through the solid bearings. I would definitely hunt for something loose before swapping parts.
I had same sort of observations when I installed the Ford LCAs with poly bushings. Then the one piece driveshaft. Clunking went away with the new shaft.

Someone mentioned a new DS, I may pick one up.

Like TMSBOSS said, you could now be hearing your gear backlash. I know I do, but I also have a one piece driveshaft and other stiff suspension components.

It may be the backlash, it feels like more of the whole rear end rotating though.

I had some clunking noises too after installing FPP Boss S LCAs and relo brackets. I also installed a Steeda UCA spherical diff bearing. The clunking is pretty much gone now but with all the spherical bushings you get a lot more NVH transmitted into the cockpit anyway, including a lot of rear diff gear noise.

Ok, I am down to it being the stock UCA. I may go ahead and order the one with the poly bushing. I may go with the spherical bearing one, I do not mind gear whine.
 
...I do not mind gear whine.

There's gear whine and then there's GEAR WHINE. Be careful what you ask for! lol. I have the latter and I can't carry a normal conversation in the car. Yelling is required. But if you dont have any gear whine at the moment, then I'm going to guess it won't increase that much when you go spherical.
 

7500RPM_Ben

TMO Clueless
There's gear whine and then there's GEAR WHINE. Be careful what you ask for! lol. I have the latter and I can't carry a normal conversation in the car. Yelling is required. But if you dont have any gear whine at the moment, then I'm going to guess it won't increase that much when you go spherical.

Haha, as long as it is a slight whine I do not mind. If it is loud as crap I will go with an upper poly unit. This is a street car that will play in the mountains and will possibly never see a road course. I had a '98 GT that screamed at you that I daily drove for years that got me used to gear whine haha.
 

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