[goatjacket]

Resurrecting this thread for a question on cradle jack placement. I'm installing the BK063 tomorrow but want to understand a few things. Instructions state place jack under front of the cradle. Is there a central spot on the front, or do you jack it for driver side and then move to passenger side? I'm thinking placing the jack just behind the front cradle bolt to lower? Just not familiar with how the cradle is connected and what may come down if not placed correctly. Hoping for any tip before install tomorrow morning. Of course I could feel foolish if it really makes sense once on the jackstands

[Xaxas]

Originally Posted by goatjacket

Resurrecting this thread for a question on cradle jack placement. I'm installing the BK063 tomorrow but want to understand a few things. Instructions state place jack under front of the cradle. Is there a central spot on the front, or do you jack it for driver side and then move to passenger side? I'm thinking placing the jack just behind the front cradle bolt to lower? Just not familiar with how the cradle is connected and what may come down if not placed correctly. Hoping for any tip before install tomorrow morning. Of course I could feel foolish if it really makes sense once on the jackstands

I don't remember the install beside it being easy if you follow the instructions, as for the cradle, lift the rear and support with stands so you can free your jack, the cradle is connected in 4 points which is where you install the lockout (duh), and doing 1 point at a time should lower it enough to install the lockout, takes around 30-40 mins, very easy and the results are insane.

[goatjacket]

Originally Posted by Xaxas

the cradle is connected in 4 points which is where you install the lockout (duh), and doing 1 point at a time should lower it enough to install the lockout, takes around 30-40 mins, very easy and the results are insane.

Thanks! I've read the various reviews and was hooked based on positive responses. I've only been under the car once during pre-inspection, so was just unclear on connection points. In my head I was envisioning the entire diff just lowering as if i disconnected the rear of the car

Looking forward to getting through the upgrade!

[Xaxas]

Originally Posted by goatjacket

Thanks! I've read the various reviews and was hooked based on positive responses. I've only been under the car once during pre-inspection, so was just unclear on connection points. In my head I was envisioning the entire diff just lowering as if i disconnected the rear of the car

Looking forward to getting through the upgrade!

You will absolutely notice it, it's quite insane how connected the rear feels with such a simple mod, switching from a V6 with them to the V8 and I can not notice the rear end "wiggle" when taking sharp turns or corners, you might also go with the 3 control arms, when I replaced them, they were quite easy to flex with a screwdriver between them and very little force from my part, imagine how much the car is stressing that! The car just GRIPPED after changing all of them.

[Scargoes]

Originally Posted by Xaxas

you might also go with the 3 control arms, when I replaced them, they were quite easy to flex with a screwdriver between them and very little force from my part, imagine how much the car is stressing that!

When testing a part and looking at it's 'strength' you have to know what direction the forces travel thru the part and test in that axis. Putting forces into a part in a direction that the part does not normally experience those forces yields no beneficial information. One would never instrument a drive shaft for compression and tension forces because it never sees those forces. It sees torsional forces. Same with instrumenting a suspension link and testing for torsional force is useless when the input forces are compression and tension.

[TRZ06]

Originally Posted by Scargoes

When testing a part and looking at it's 'strength' you have to know what direction the forces travel thru the part and test in that axis. Putting forces into a part in a direction that the part does not normally experience those forces yields no beneficial information. One would never instrument a drive shaft for compression and tension forces because it never sees those forces. It sees torsional forces. Same with instrumenting a suspension link and testing for torsional force is useless when the input forces are compression and tension.

THIS!!!

GM used stamped arms when they didn't need the additional weight. BMR's video makes me laugh when they twist them and show the flex. That is not the directional force that is applied to those parts.

The benefit you get from the BMR stuff is from the solid or teflon bushings, not the increase weight and ridgness of the arms themselves. Maybe they need to increase the stiffness to counter the solid bushings though. Anytime you increase the stiffness you have to continue down that path and stiffen the next weakest link in the chain, all the way to the tires.

[Xaxas]

Originally Posted by Scargoes

When testing a part and looking at it's 'strength' you have to know what direction the forces travel thru the part and test in that axis. Putting forces into a part in a direction that the part does not normally experience those forces yields no beneficial information. One would never instrument a drive shaft for compression and tension forces because it never sees those forces. It sees torsional forces. Same with instrumenting a suspension link and testing for torsional force is useless when the input forces are compression and tension.

I recall reading that the arms were stamped because they need to crumple during impacts, which just tells me that GM made the least expensive part that also functioned as wanted, which is ok but it's still a weak point in the design; I agree with you and you are 100% correct, but the BMR parts are arguably better and also have better bushings while not being that expensive

[TRZ06]

Originally Posted by Xaxas

I recall reading that the arms were stamped because they need to crumple during impacts, which just tells me that GM made the least expensive part that also functioned as wanted, which is ok but it's still a weak point in the design; I agree with you and you are 100% correct, but the BMR parts are arguably better and also have better bushings while not being that expensive

That is an interesting point.

If the car is designed that way for safety reasons as well as just not needing the extra weight, then you have to consider what the consequences would be in a collision with the BMR stuff, both the occupants of your vehicle as well as those in the other vehicle.

[Scargoes]

Originally Posted by Xaxas

I recall reading that the arms were stamped because they need to crumple during impacts, which just tells me that GM made the least expensive part that also functioned as wanted, which is ok but it's still a weak point in the design; I agree with you and you are 100% correct, but the BMR parts are arguably better and also have better bushings while not being that expensive

But replacing a link that is perceived to be weak because you can twist it, when it would never normally see any of that type of force, doesn't mean the replacement part is better. Take the upper control arm, it looks weak compared to the BMR replacement part. But the factory part is lighter and it uses a spherical bearing instead of a poly bushing. Guess which one distorts more when force is applied? I can tell you that it's not the spherical bearing. Sure, the spherical bearing wobbles in the end of the link really easy, but that link wasn't designed to control rotational movement.

[Msquared]

Originally Posted by Scargoes

But replacing a link that is perceived to be weak because you can twist it, when it would never normally see any of that type of force, doesn't mean the replacement part is better. Take the upper control arm, it looks weak compared to the BMR replacement part. But the factory part is lighter and it uses a spherical bearing instead of a poly bushing. Guess which one distorts more when force is applied? I can tell you that it's not the spherical bearing. Sure, the spherical bearing wobbles in the end of the link really easy, but that link wasn't designed to control rotational movement.

This ^^^^^, 100%. And I'll add that in many locations, replacing a torsionally weak link with a torsionally stiff one and also adding poly single-axis bushings is going to introduce bind (rising wheel rate) because the links move in more than one plane. This is a decades-old struggle. Back in the 80s and 90s guys were replacing their "weak" rear control arms on Mustangs and Camaros with tubular designs and poly bushings, not realizing that the factory stamped pieces and rubber were intended and required to allow twist when the suspension moved. The result was a lot of cars with snap-oversteer and eventually a lot of broken suspension mounts. If a link is only intended to react longitudinal forces, it doesn't matter how stiff it in lateral bending or in torsion.

[Craig]

Some of these parts are engineered to be the weak link in the chain because they’re cheap and easy to replace. If you’re in a mixup it’s better to damage a $40 control arm than the parts it connects to up the line.

[TRZ06]

Originally Posted by Craig

Some of these parts are engineered to be the weak link in the chain because they’re cheap and easy to replace. If you’re in a mixup it’s better to damage a $40 control arm than the parts it connects to up the line.

Yep, this is also used in the snowmobiling world as well. Better to bend a trailing arm, then destroy the bulk head or chassis.

[carguy55]

Originally Posted by Xaxas

I don't remember the install beside it being easy if you follow the instructions, as for the cradle, lift the rear and support with stands so you can free your jack, the cradle is connected in 4 points which is where you install the lockout (duh), and doing 1 point at a time should lower it enough to install the lockout, takes around 30-40 mins, very easy and the results are insane.

Did you get yours done? I did mine today.

[Xaxas]

Originally Posted by carguy55

Did you get yours done? I did mine today.

I did them myself on my previous 2LT and it removed all the squatting and wobbling when cornering, def one of the best mods for our platform, however for the price (and convenience) I've been thinking about getting the ZL1 1LE solid bushings as they also come with all the bolts and mics hardware, might even try to coerce the dealership into giving me regular shop rates to keep the warranty if possible.

I saw a post here where someone managed to get the bushings off themselves but I don't trust myself with a flame, woulda done it on my previous car since it was learner car and I beat the shit out of her, bless this platform, it's so much fun to work with, except the control arms, that's a pita.