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BMR's "CB005" S550 IRS Cradle Bushing Lockout Kit - PICS & INFO!

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Mike K.

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I just finished up the install of the SP8080 rear CB005, plus TCA048 vertical links. I had my exhaust off because I was ( still am ) installing the Roush Active Quad tip. I used a scissor jack plus a hydraulic jack and my pry bar fit perfect. Here is some tips. One plus about lowering the cradle is it makes it damn easy to do springs :). I just took my time with the cradle bolts and made sure I could turn them in a good amount by hand before I really tightened down on them, between that and the pry bar it wasn't so bad to install.

Attached some pics, and as soon as I can drive it I will post back with how it feels, I barely get time to work on it and I had to order the stupid 17/32nd drill bit as I couldn't find anywhere :(.
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BMR Tech

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Awesome!

I cannot wait to hear your feedback, SP080 / CB005 / TCA048 is an absolutely awesome combo.
 

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Awesome!

I cannot wait to hear your feedback, SP080 / CB005 / TCA048 is an absolutely awesome combo.

Got the knuckle and lca bearings also but I am gonna have a shop do those, something tells me its a bad idea to do myself :)
 

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Have you taken her out yet for a spirited drive to see the difference? I'll probably end up with tca048 too, can't beat the price and they're better than stock.
Not yet still finishing up the roush active and gotta do the front springs, I will soon though and report back
 
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Not yet still finishing up the roush active and gotta do the front springs, I will soon though and report back

....patiently waiting! :headbang:
 

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This car keeps on pushing the CB005 further and further!

Absolutely insane.

[ame]
 

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Is it just me or did Ford hurt the first gen S550 performance substantially with the excessive use of rubber bushings in the rear end? Their paranoia over NHV got the best of them and I think they took it too far.

All that sub-frame movement in the rear really holds back the performance of the car with regard to it's handling. I know a lot of people say the Alpha Chassis on the Camaro is "much better", but in reality I see nothing radically different other than much better tuning on the Alpha.

Base model 1SS = 3685 lbs
Base model GT = 3705 lbs

SS uses a multi-link front with coil over struts, so does the GT. PP GT's uses spherical bearings, so there's very little flex up front on PP GT's, I'd imagine SS is similar in it's use of spherical bearings up front, I KNOW it uses them in the back end from the factory, you can see all of the details in the following video.

Here's a great detailed video of the gen 6 Camaro's hind quarters: [ame="[MEDIA=youtube]u0CsG6Q9CRI[/MEDIA]"]

So the real reason why the SS handles better than a PP GT from the factory has to do with suspension tuning. Stiffer spring rates and higher damping on the struts, the extensive use of spherical bearings all over the rear end unlike Ford, which uses rubber bushings on EVERYTHING in the rear end. This is why the car feels like it "wallows" compared to the SS or other tighter handling cars.

Worst offender are the IRS bushings in the S550, they are very soft, while they do an awesome job at NHV isolation, they substantially hamper the car's ability to not only put down power, but corner. There's a ton of movement in the S550 hind quarters, where GM does a much better job from the factory. BMR's video shows nearly twice as much movement of the stock IRS assembly in the GT as compared to the SS. Kudos to GM for finding a better balance of NHV vs. performance.

The track, turn in, length of these cars is nearly identical as is the weight. There's really no magic reason the SS handles better from the factory other than that was their goal in chassis tuning and they were willing to tolerate a moderate increase in NHV for the substantial performance improvements, where Ford's goal was more of the grand tourer with sporty attributes rather than the other way around. The real question is, can we blend the two cars together from a chassis standpoint?

The GT is much more livable from a daily driving standpoint, it's just a more comfortable and practical car to drive, period. But it's "wallowy" rear end holds back it's potential for spirited driving and light track use. The potential is there from a chassis standpoint, but you need to do a little work to get there and BMR as well as others offer all the bits and pieces.

That might explain why the sub-frame kit, performance springs and vertical links seem to be a golden street combo. They address the worst offenders of movement in the rear and lower the ride height a little more like the SS, which sits a bit lower down. I think we can learn a little from GM's ground work on chassis tuning and apply it to the GT. Sure, Ford has the winning combination from a sales standpoint, there's just no arguing with the massive sales discrepancy between the Camaro and the Mustang. Mustang wins hands down.

But for those that want the excellent tuning GM did on the latest generation Camaro, but in a more practical (and far better looking) chassis design, a little tweaking is in order!
 

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So the real reason why the SS handles better than a PP GT from the factory has to do with suspension tuning.
Pretty much, but I believe the Alpha+ is also stiffer than the S550 which helps handling by itself, plus it allows the suspension to be designed in ways that could be a problem with a more flexible chassis. So yeah, suspension tuning mostly but even if the S550 had identical geometry, weight distribution, spring rates, damping, tires, etc., I believe the Alpha+ would probably still be a little better.
 

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Here's a mechanical specification comparison just to illustrate my point:

SS (2016-2018) GT (2015-2017)
15.8:1 electric steering 16.0:1 electric steering
2.3 turns to lock 2.6 turns to lock
38.4 ft turning circle 40.0 ft turning circle
strut-type, multi-link front strut-type, multi-link front
13.6-in vented front rotors 15.0-in vented front rotors (testes note the GT has better braking ability in general, this is why)
4-piston fixed calipers 6-piston fixed calipers
13.3-in vented rear rotors 13.0-in vented rotors
4-piston fixed calipers 1-piston sliding calipers

All steel chasis Steel / aluminum chassis
188.3x74.7x53.1 in 188.3x75.4x54.9 in
110.7 in wheelbase 107.1 in wheelbase
Track-F/R 63.0/62.9 in Track-F/R 62.3/64.9 in (nearly identical, wider rear track creates more over steer, wider front track creates more under steer)
Cargo Cap 9.0 ft^2 Cargo Cap 13.5 ft^2 (I love the trunk space for a sports car!)
Base Weight 3685 lbs Base Weight 3705 lbs (20 lbs difference and people call the mustang a pig...I don't get it)
Fully Optioned 3760 lbs Fully Optioned 3810 lbs (GM does a better job of weight control)
Weight Dist: 54/46 Weight Dist: 54/46
Weight-To-Power 8.3lb/hp Weight-To-Power 8.8lb/hp (put on lightweight wheel / tire setup (38 lbs less) and an aftermarket cat back (30 lbs less), GT increases to 8.36 lb / hp, same as SS)
EPA 16/26 EPA 15/25
Tank 19.0 Gallons Tank 16.0 Gallons (1 gallon of gas weighs 6.3 lbs, GT would gain only 19.8 lbs if it had the same sized tank, but trunk space or rear seating would suffer)
 

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Pretty much, but I believe the Alpha+ is also stiffer than the S550 which helps handling by itself, plus it allows the suspension to be designed in ways that could be a problem with a more flexible chassis. So yeah, suspension tuning mostly but even if the S550 had identical geometry, weight distribution, spring rates, damping, tires, etc., I believe the Alpha+ would probably still be a little better.
Do we have any numbers to quantify flex comparatively? Remember the S550 was 20~25% more rigid than the S197 which wasn't too bad itself. I don't know if one can with any validity say this car's chassis is actually stiffer than this car's without measuring the four corners and looking at deflection under load. Alpha is 28% more rigid than the previous gen 5. Doesn't sound so different to me either.

But none of the mfg's publish exact torsional flex number. At most you get this chassis is xx% stiffer than the last....if the alpha is substantially more rigid than the S550 chassis then yes, it would provide a handling benefit, but given how similar their dimensions are, including A pillar placement engine placement, increased rigidity from the previous generation, I have a hard time believe there's a substantial difference there either. If that's the case, then why did they need another 100 HP on their 1LT to beat out a GT350 on a track? That's a great example of what the chassis can do with all the tuning applied to it.

Anyway, the point is, there's a lot to be learned from GM's chassis tuning or also looking at Ford, in the GT350, but relating to the point of this thread, it would be the IRS bracing, vertical links and use of spherical bearings in place of the rubber bushings on the lower control arms as well as the upper link. The lower control arm bushings could also be replaced with spherical bearings and you would have a completely solid rear end, much like the Alpha's. With a little weight reduction on the GT and a FP Power Pack, the GT would be a track master as well without loosing much of grand tourer prowess. A better blend than either of the two cars by themselves.
 
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Do we have any numbers to quantify flex comparatively? Remember the S550 was 20~25% more rigid than the S197 which wasn't too bad itself. I don't know if one can with any validity say this car's chassis is actually stiffer than this car's without measuring the four corners and looking at deflection under load.

But none of the mfg's publish those numbers. At most you get this chassis is xx% stiffer than the last....if the alpha is substantially more rigid then yes, it would provide a handling benefit, but given how similar their dimensions are, including A pillar placement and engine placement, I have a hard time believe there's a substantial difference there either. If that's the case, then why did they need another 100 HP to beat out a GT350 on a track? That's a great example of what the chassis can do with all the tuning applied to it.

Anyway, the point is, there's a lot to be learned from GM's chassis tuning, but relating to the point of this thread, it would be the IRS bracing, vertical links and use of spherical bearings in place of the rubber bushings on the lower control arms as well as the upper link.
Chassis stiffness requirements are more important when you have significantly different total roll stiffnesses front and rear. If you have equal roll stiffnesses there is minimal torsional load having to be resisted by the body of the car. This is all in theory, of course, but there is definitely real world application. When I was looking chassis stiffness requirements some years ago for racecars, we settled on a rule of thumb of 10:1. The chassis must be at least 10 times stiffer than the difference between the front and rear roll stiffnesses. This ratio makes sure you have a tunable chassis.

On the practical sense, this car is not lacking in body stiffness. Small tuning changes are able to be felt and there is no obvious lack of response because of load being absorbed by the body. This is especially true once a lot of the rubber compliance is removed.
 

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Here's an example of the massive re-design of the S550 chassis: https://www.mustang6g.com/forums/showthread.php?t=15917

Showing a 38% increase in rear end torsional stiffness...overall torsional stiffness is up 31% from predecessor. Alpha is up 28% from it's predecessor. It is quite difficult to quantify the Alpha in comparison to the S550 directly as there are no over all numbers. Saying this chassis is stiffer than that chassis is nothing more than speculation without hard numbers in directly comparable testing.

Where the loads are applied and how much flex is there...I get tired of people saying the Alpha is better but never see anything to actually prove that other than inter net here say. I do know however, which is easily provable and a known certainty, that GM does use hard motion points in their hind quarters (heavy use of spherical bearings) and it results in a noticeable improvement in handling compared to a stock S550 which is nearly all rubber bushings.

For all you know the S550 may actually have a greater overall torsional rigidity than the Alpha which is an older design that entered production back in 2012...in fact it looks like Ford's chassis development is quite well thought out, they were able to build in the rigidity without sacrificing substantial amounts of the driver's functionality unlike the Alpha which has some very undesirable blind spots. It's quite interesting how similar the roof line is to the Porsche 911's. Maybe they are onto something regarding an architecture that is used in the higher end car design. But I digress, I'm only after two things here:

Improving the rear end feel and debunking some inter net here say about the Alpha. Until I see some direct numbers, it's nothing more than two different floating potentials that cannot be directly measured relative to each other.
 
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Do we have any numbers to quantify flex comparatively? Remember the S550 was 20~25% more rigid than the S197 which wasn't too bad itself. I don't know if one can with any validity say this car's chassis is actually stiffer than this car's without measuring the four corners and looking at deflection under load. Alpha is 28% more rigid than the previous gen 5. Doesn't sound so different to me either.

But none of the mfg's publish exact torsional flex number. At most you get this chassis is xx% stiffer than the last....if the alpha is substantially more rigid than the S550 chassis then yes, it would provide a handling benefit, but given how similar their dimensions are, including A pillar placement engine placement, increased rigidity from the previous generation, I have a hard time believe there's a substantial difference there either. If that's the case, then why did they need another 100 HP on their 1LT to beat out a GT350 on a track? That's a great example of what the chassis can do with all the tuning applied to it.

Anyway, the point is, there's a lot to be learned from GM's chassis tuning or also looking at Ford, in the GT350, but relating to the point of this thread, it would be the IRS bracing, vertical links and use of spherical bearings in place of the rubber bushings on the lower control arms as well as the upper link. The lower control arm bushings could also be replaced with spherical bearings and you would have a completely solid rear end, much like the Alpha's. With a little weight reduction on the GT and a FP Power Pack, the GT would be a track master as well without loosing much of grand tourer prowess. A better blend than either of the two cars by themselves.
I think then numbers have been published and seem to recall that he Alpha is stiffer. Improvements from previous chassis are apples to oranges without knowing the stiffness of the previous.

Now the CTS and Camaro are not pure alpha, they are Alpha plus. The only pure alpha (so far) is the ATS the alpha plus is not quite as good as the pure alpha in a few ways but damn close. I have first hand experience with a pure alpha because I have an M6 ATS and an M6 S550. And while not scientific, my perception of them both matches the published stiffness, i.e. the ATS feels better from a handling perspective aside from factory rubber grip. Think about the ridiculous Stallone movie Driven; I believe I could pick up the quarters better in my ATS than in my Mustang PP. Then again the pure alpha ATS has lower weight and perfect 50/50 weight distribution which the Camaros and Mustangs do not.
 

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....patiently waiting! :headbang:
Finally have been driving around, yeah 90% of the wheel hop is gone now which is awesome !! Feels nice and tight with the Sp080s, next thing to decide is if I want to do the lca and knuckle bearings, it's pretty damn good like it is now and I'd hate to make it harsher for the sake of eliminating the the tiny bit of hop that's left. Awesome product , no clunking or nvh with this setup. Highly recommend :headbang:
 

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Finally have been driving around, yeah 90% of the wheel hop is gone now which is awesome !! Feels nice and tight with the Sp080s, next thing to decide is if I want to do the lca and knuckle bearings, it's pretty damn good like it is now and I'd hate to make it harsher for the sake of eliminating the the tiny bit of hop that's left. Awesome product , no clunking or nvh with this setup. Highly recommend :headbang:
The SP080s are soft enough that I don't think you'd have significant harshness from them. The toe knuckle bearing won't give you any at all.
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