BMR BK048 and BK049 review

[Hoblick]

Sunday i decided to get the suspension work done in the car, because i have the Procharger and Long tubes on way this week.

I installed the BMR BK048 Delrin Cradle bushings, and BK049 Poly Diff Bushings. Install was pretty much a PIA, a lot of work to change some bushings out. I have been working on cars and motorcycles pretty much all my life. It was definitely not a fun job lol, but i digress.

while i was at it, i installed Eibach ProKit Springs and Steeda Transmission mount bushing.


after it was all buttoned up i took it for a test drive. Immediately noticed the increase in noise. I have diff noise at pretty much any speed, but most annoyingly at cruising speed, it has a nice wine to it. not much more in the way of vibration, but definite increase in noise. the rear feels more solid though, more of a piece of the car than it was. The Trans bushing made an increase in noise as well, i can hear every gear change inside the car, like the actual transmission, not just the shifter. he springs made a huge difference on the looks of the car, and it definitely feels more even through the corners.

now the bad news, id say wheel hop was decreased by 50% at best. (this is on stock 19" pirellis) and now the car has a weird wiggle to it. i can be cursing off throttle and then get in the gas and the car will do a little right then left movement and then pull straight. really have no idea what that is about. followed the install to a T on everything, all bolts torqued properly, etc, etc.

definitely feels like its coming from the back end. never felt it before putting in the bushings. Not sure if this is normal behavior for the bushings or what. Not super impressed with the performance or lack there of of the bushing kits, seeing the amount of time put in to installing them. price is not terrible on them, but price to performance outcome, and now this wiggle i got going on makes me regret the purchase/install. i won't send them back, because i really don't want to drop the cradle out of the car again.

i havent gotten an alignment yet, so maybe that has something to do with it.

but now ill be chasing down another part to buy in hopes to help cut down the wheel hop. i almost ordered the Spherical bushing kit for the LCAs, but glad i didn't yet, because i don't think that is going to help remedy my issue. Ill probably break down and buy the Viking Shocks in hopes that they along with the bushings will cure my woes.

but i still need to figure out what this wiggle is about. BMR got any ideas? :shrug:

Sponsored

 

[Cheezebandit]

Check your alignment. . Dropping the rear sub frame and doing Springs I bet it's not centered anymore.

 

[BMR Tech]

You will definitely need an alignment after installing the BK048 and 049.

The BK048 perfectly centers your cradle, and it is highly unlikely that your cradle was centered before the install.

I recently upgraded mine similarly, and the rear toe was substantially off (catered towards the passenger side post install) and my car pulled really bad, and wiggled. After the alignment, perfect. I set the rear toe at .07 in each side, total toe .14.

As for the NVH, unfortunately we cannot do much about that with a full bushing upgrade. The majority of it is coming from the BK049 bushings - BUT I will say, after you get an alignment and put a few hundred miles on the car (preferably hard miles) the NVH level "should" decrease slightly, as you put those poly diff bushings through some abuse.

Start with an alignment and lets go from there.

 

[Hoblick]

Good to hear it is an alignment issue. I'll get the alignment done after the car is tuned. NVH although annoying, I can live with as long as the car performs better. I'll report back after the car gets an alignment

 

[Gearhead]

OP, let me know if you figure it out, my car does the same damn thing, left right wiggle, its dangerous and starting to piss me off. I had the Eiback sportline springs in my car, the rears are progressive and was what I thought the cause of the problem. I put my stock PP springs back in the rear and it still does it. I think these cradle and diff bushing tighten those parts up so much that the next weakest link is getting all of that power to it and deflecting the suspension parts a lot more than anyone thinks here.

Bottom line, this car is the coolest piece of junk of ever bought... Not going to give up on it but lets figure this shit out so I can enjoy my "sports car"

 

[Hoblick]

OP, let me know if you figure it out, my car does the same damn thing, left right wiggle, its dangerous and starting to piss me off. I had the Eiback sportline springs in my car, the rears are progressive and was what I thought the cause of the problem. I put my stock PP springs back in the rear and it still does it. I think these cradle and diff bushing tighten those parts up so much that the next weakest link is getting all of that power to it and deflecting the suspension parts a lot more than anyone thinks here.

Bottom line, this car is the coolest piece of junk of ever bought... Not going to give up on it but lets figure this shit out so I can enjoy my "sports car"

Atleast I'm not the only one with this problem. Did you have your car aligned? And it still does this after alignment ?

 

[Gearhead]

I did a few alignments but like I said in a different post, I don't think it has anything to do with that, I can be going 120 mph and the car will track straight but the second you play with the gas peddle its all over the place. The rear of the car is deflecting just enough somewhere and steering the car into the other lane.

For me at least it does this under any type of acceleration, loads up hard to the left under acceleration, push the clutch in and it darts right... same with all gears.

 

[Hoblick]

I did a few alignments but like I said in a different post, I don't think it has anything to do with that, I can be going 120 mph and the car will track straight but the second you play with the gas peddle its all over the place. The rear of the car is deflecting just enough somewhere and steering the car into the other lane.

For me at least it does this under any type of acceleration, loads up hard to the left under acceleration, push the clutch in and it darts right... same with all gears.

That's pretty much spot on to what mine is doing, I haven't gotten the alignment yet though.


So BMR what say you?

 

[BMR Tech]

I did a few alignments but like I said in a different post, I don't think it has anything to do with that, I can be going 120 mph and the car will track straight but the second you play with the gas peddle its all over the place. The rear of the car is deflecting just enough somewhere and steering the car into the other lane.

For me at least it does this under any type of acceleration, loads up hard to the left under acceleration, push the clutch in and it darts right... same with all gears.

I would like to see your alignment sheet.

 

[BMR Tech]

For those who are reading, here are my recommendations for alignment out back with this IRS system.

Camber:

Out back, ME personally...if you are not road course / autocrossing - I recommend going more positive. For example, I run -0.10 on each side. From the factory it was at -1.1

The closer to positive, the better for traction and also everyday driving characteristics.

For "handling" applications....-1.5 to -2.5 seems to be the winning range. Just remember, the more negative...the more often you are going to buy tires.

Toe:

Very crucial on these cars. From what I have seen and experienced, these cars like a little more toe in. My car is set to 0.15 in on each side, and total toe at 0.30. I usually suggest .12 to .15 in on each side and total toe range at 0.24 to 0.30.

Thrust Angle:

Zero! Always try your best to get this to 0.00.

Ford will usually get crazy on their allowance for thrust angle. On most Mustangs they go for a range of -0.50 to 0.50.

If you are anywhere near that, it needs to be fixed. I recently drove my car around on 0.36 thrust angle (within OEM spec) and it was absolutely horrid.

 

[Hoblick]

thanks for the input Kelly, nice chatting with you on the phone. ill let you know how things go in a month after i can get the car aligned.

 

[MtnBiker]

The BK048, my only mod on the IRS so far, has been installed for about 5 months now. Had the car aligned shortly after installation. My experience has been positive - the back end seems more stable than before. Less "floaty" in corners and more stable under acceleration. Irrational exuberance on throttle brings on the nannies and you can feel the tires hooking up / unhooking without much drama. Side note: not that impressed with the P-Zeros. I see Pilot Sports in my future.

As for NVH I'd explain it this way. On freshly paved roads the BK048's are almost stock quiet. Hard to even notice. On our South Texas standard chip seal the noise floor ramps up faster than stock bushings but not horrible. We also have a wretched, super-coarse version of chip seal (bigger gravel but sparsely applied) on some of our rural roads and the noise is a little silly to be frank. Very loud. That said, very happy with the mod.

Alignment sounds like a good idea. Sorry you guys are having issues. Not fun.

 

[Hoblick]

Got the alignment done, toe and camber way out of spec. My friend who runs a tire/alignment shop got me damn close to the BMR specs. On the drive home the car was still doing the same wiggle. Called Kelly at BMR, who suggested I should crack the control arm bolts loose to loosen tension off the rubber bushings. As I was doing this I bumped my left rear wheel withy shoulder,and heard a noise, investigated the noise and saw there was movement In one of the links, saw a gap in it like bolt wasn't tight, even though I just torqued that bolt. Looked to the right rear wheel and noticed the link on that side had a different bolt.

So apparently I had mixed 2 bolts up on the left suspension, and the one bolt for the link on the bottom had about 2-3mm of slop. That little bit caused the car to wiggle, dance around, and pull on accelerate/decell. Fixed that mix up and all is good! Now I can really see the difference the bushings made!


Great product, great support! Kelly at BMR was a great help!

 

[Hoblick]

Oh just for heads up this was my align before the put it in spec

 

[POOPonYOU]

Got the alignment done, toe and camber way out of spec. My friend who runs a tire/alignment shop got me damn close to the BMR specs. On the drive home the car was still doing the same wiggle. Called Kelly at BMR, who suggested I should crack the control arm bolts loose to loosen tension off the rubber bushings. As I was doing this I bumped my left rear wheel withy shoulder,and heard a noise, investigated the noise and saw there was movement In one of the links, saw a gap in it like bolt wasn't tight, even though I just torqued that bolt. Looked to the right rear wheel and noticed the link on that side had a different bolt.

So apparently I had mixed 2 bolts up on the left suspension, and the one bolt for the link on the bottom had about 2-3mm of slop. That little bit caused the car to wiggle, dance around, and pull on accelerate/decell. Fixed that mix up and all is good! Now I can really see the difference the bushings made!


Great product, great support! Kelly at BMR was a great help!

Very cool that you caught this. Probably had a lot of people staying away from this mod. Update your title with FIXED! :clap2:

Sponsored