BMR Tech Tip: Clock those bushings after lowering your S550!

[zahimrad]

It is hard to clock the bushings with the tires on specially in the rear. I have 305 tires back there. the tech did it by putting a support lift under the lower control arm and raising it to simulate the car weight without having a tire on that side. He told me it should be fine and I didn't wanna argue with him because he did it for free lol.
Tell me what you think because It does not look like an accurate method to simulate the car weight on each side.

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[JKL1031]

It is hard to clock the bushings with the tires on specially in the rear. I have 305 tires back there. the tech did it by putting a support lift under the lower control arm and raising it to simulate the car weight without having a tire on that side. He told me it should be fine and I didn't wanna argue with him because he did it for free lol.
Tell me what you think because It does not look like an accurate method to simulate the car weight on each side.

You could debate the support point not being at the hub and having a shorter moment arm --> not full compression, but it shouldn't be a huge difference.

If anyone decides to do it wheels off I would take a measure from the fender to hub center on the ground and simulate it with a jack, etc..

 

[Norm Peterson]

I think the bigger issue is whether he lifted only one side at a time or lifted both hubs together. One at a time means that the sta-bar (I'm assuming it was left connected) would be introducing some error, most likely also leading to less than full static compression of the suspension.


Norm

 

[DuRsT]

Appreciate this getting bumped, I can definitely have my alignment guy do this when he is under the car. Ordering some springs to install myself today.

 

[TheLion70x77]

Just wanted to add a fact. I did the Steeda Bump Steer and Roll Center correction kit with stock PP struts and BMR SP080 springs (will change over to SP083 + FP Track Dampers once the PP struts are worn out). Had alignment done according to BMR recommendations but with 1/16th toe out for better dynamics (works extremely well with Pilot Sport 4S tires, car is very responsive in twisties).

I also clocked my rear OE vertical links, OE RLCA bushings and OE camber links appropriately. Then recently I added a the BMR 35mm front sway bar (stock PP rear, car doesn't need more rear bar than the stock PP one) and Steeda Tensions links up front with the higher durometer rubber bushing. I avoid open spherical bearings when possible due to the effects of salt from the winter driving months. Booted spherical bearings are fine, but right now open is a no go unless there is no other choice (as with the bump steer tire rod end links, but those at least have wipers on them and are pretty easy to replace when worn). I also wanted to have at least one bushing deflection point for road impacts to avoid breakage of any parts. You always need a point of flex, or something is going to give, just control how much flex is possible.

Anyway, I clocked the front tension links since they are higher durometer bushings and not spherical bearings, but also did some testing to see how much the bushings really affect roll and spring rates. I can say the stock tension link bushings are so darn soft, I could push the entire arm down when the outer end was disconnected from the front hub with just one finger. I was absolutely shocked at how soft they were. We are talking maybe a one or two ft-lbs or resistance at best....it's meaningless in the grand scheme of things. So if anyone says they reduce "artificial spring rate"...well technically it's true but it's so darn small there's no benefit in that area by going to a spherical bearing.

If anyone is going to argue and say that a bushing that is so soft I can use just one finger to move it 6 to 8 inches is crazy. The steeda rubber bushings in their tension links are much stiffer and will add some small amount of artificial anti-roll, anti-dive and spring rate, but even then, I can still move it with just one arm pushing up or down.

It's not much compared to the rate of the roll bar and the springs. In fact, it's again pretty meaningless and would result in barely a few 1/10ths of a percentage of the total roll rates or spring rates. People can say it affects that all they want, but the reality is the effects are pretty meaningless because they are so small even with the high durometer bushings. So don't shy away from their bushing versions of the tension links it you want a more dual purpose balance. Nothing wrong with spherical bearings, but more it NOT always better.

Now the spherical bearing in the tension link still has benefits over the high durometer bushing, there's no deflection at all with the spehrical bearing, so for a hard core track car that may be the better route. But for a dual purpose car the high durometer bushing gets you 90% of the way there to the spherical bearing but for a lot less and without exposure to salt corrosion issues. Case in point, after just one winter, I can see a few spots of minor pitting on the exposed tie rod end links from steeda. Obviously they can't be booted because of their design, but open bearings will wear out a lot sooner than booted ones. And tension links are a much bigger pain in the rear to replace than tie rod end links. Just keep in mind the Steeda High Durometer tension links are a very good alternative for a dual purpose car.

 

[TheLion70x77]

You don't have to clock if you have bearings instead of rubber?

I would make sure they aren't way out of orientation. Some of the rubber boots on the end links (like the tension links or lateral links) are wire tied to the spindles. So the boots twist as the link rotates. If you don't install them straight, the boot will be extremely bound up and fail much sooner, exposing the ball stud. Some of the spherical bearings are also like that. I would still clock them for the sake of the life of the dust boots. Once that boot goes, all of the moly grease will be exposed to moisture and dust, so it will go from an EP film to sand paper causing bind in the bearing and rapid failure. Moly is highly sensitive to moisture and becomes abrasive when exposed to it. A good seal on the boots is imperative and the dust boots on some of the ball studs and spherical bearings have wire locks on them and cannot rotate.

 

[BmacIL]

Just wanted to add a fact. I did the Steeda Bump Steer and Roll Center correction kit with stock PP struts and BMR SP080 springs (will change over to SP083 + FP Track Dampers once the PP struts are worn out). Had alignment done according to BMR recommendations but with 1/16th toe out for better dynamics (works extremely well with Pilot Sport 4S tires, car is very responsive in twisties).

I also clocked my rear OE vertical links, OE RLCA bushings and OE camber links appropriately. Then recently I added a the BMR 35mm front sway bar (stock PP rear, car doesn't need more rear bar than the stock PP one) and Steeda Tensions links up front with the higher durometer rubber bushing. I avoid open spherical bearings when possible due to the effects of salt from the winter driving months. Booted spherical bearings are fine, but right now open is a no go unless there is no other choice (as with the bump steer tire rod end links, but those at least have wipers on them and are pretty easy to replace when worn). I also wanted to have at least one bushing deflection point for road impacts to avoid breakage of any parts. You always need a point of flex, or something is going to give, just control how much flex is possible.

Anyway, I clocked the front tension links since they are higher durometer bushings and not spherical bearings, but also did some testing to see how much the bushings really affect roll and spring rates. I can say the stock tension link bushings are so darn soft, I could push the entire arm down when the outer end was disconnected from the front hub with just one finger. I was absolutely shocked at how soft they were. We are talking maybe a one or two ft-lbs or resistance at best....it's meaningless in the grand scheme of things. So if anyone says they reduce "artificial spring rate"...well technically it's true but it's so darn small there's no benefit in that area by going to a spherical bearing.

If anyone is going to argue and say that a bushing that is so soft I can use just one finger to move it 6 to 8 inches is crazy. The steeda rubber bushings in their tension links are much stiffer and will add some small amount of artificial anti-roll, anti-dive and spring rate, but even then, I can still move it with just one arm pushing up or down.

It's not much compared to the rate of the roll bar and the springs. In fact, it's again pretty meaningless and would result in barely a few 1/10ths of a percentage of the total roll rates or spring rates. People can say it affects that all they want, but the reality is the effects are pretty meaningless because they are so small even with the high durometer bushings. So don't shy away from their bushing versions of the tension links it you want a more dual purpose balance. Nothing wrong with spherical bearings, but more it NOT always better.

Now the spherical bearing in the tension link still has benefits over the high durometer bushing, there's no deflection at all with the spehrical bearing, so for a hard core track car that may be the better route. But for a dual purpose car the high durometer bushing gets you 90% of the way there to the spherical bearing but for a lot less and without exposure to salt corrosion issues. Case in point, after just one winter, I can see a few spots of minor pitting on the exposed tie rod end links from steeda. Obviously they can't be booted because of their design, but open bearings will wear out a lot sooner than booted ones. And tension links are a much bigger pain in the rear to replace than tie rod end links. Just keep in mind the Steeda High Durometer tension links are a very good alternative for a dual purpose car.

For the tension link bearings or rear LCA bearings, a good dose of fluid film will protect them pretty well. It's not a direct or high spray area.

While the tension links may not so much, the rear LCA bushings bind the F out of the rear suspension. 60+ lbs to move it less than 1/4". The ride and handling improvements from those is astonishing, to say the least.

 

[Bobombo]

I think the bigger issue is whether he lifted only one side at a time or lifted both hubs together. One at a time means that the sta-bar (I'm assuming it was left connected) would be introducing some error, most likely also leading to less than full static compression of the suspension.


Norm

Can you rest the brake discs on some wooden blocks?

 

[Norm Peterson]

Don't think so. Not without doing a whole lot of extra work, anyway.

You'd have to start by running some open-end nuts down the studs to fix the discs against wobbling . . . and you'd still have the sideways scrub as you lower the car onto the blocks holding the suspension height up artificially high (I don't know how you'd eliminate that and be sure that you got it right).


Norm.

 

[HoosierDaddy]

Don't think so. Not without doing a whole lot of extra work, anyway.

You'd have to start by running some open-end nuts down the studs to fix the discs against wobbling . . . and you'd still have the sideways scrub as you lower the car onto the blocks holding the suspension height up artificially high (I don't know how you'd eliminate that and be sure that you got it right).

Ahh, and if the blocks aren't the height to put the front and rear disks at relative ride height would the weight distribution be changed enough to matter?

And since tires have more lateral grip than wood, you would have that same sideway scrub if you clocked the bushings with the car on the ground if it had been off the ground by jacking and lowered back down as opposed to doing it after driving the car to where you are doing the clocking. I realize that jacking the car up and down before clocking wouldn't be a common scenario; always more things to think about.

 

[Norm Peterson]

Ahh, and if the blocks aren't the height to put the front and rear disks at relative ride height would the weight distribution be changed enough to matter?

At some amount of difference, yes. I haven't tried to do the math yet.

And since tires have more lateral grip than wood, you would have that same sideway scrub if you clocked the bushings with the car on the ground if it had been off the ground by jacking and lowered back down as opposed to doing it after driving the car to where you are doing the clocking. I realize that jacking the car up and down before clocking wouldn't be a common scenario; always more things to think about.

Yup. If you don't have access to a drive-on lift, you'd probably want to stack longer lengths of 2x10 or 2x12 than you'd normally use for most other undercar work.


Norm

 

[JKL1031]

Ok guys too far..

 

[Biggsy]

Quick question, do you have to reclock the bushings every time you get an alignment? or only after lowering for the first time?

 

[Dr. Norts]

Quick question, do you have to reclock the bushings every time you get an alignment? or only after lowering for the first time?

After lowering or anytime the vehicles height is adjusted.

Going from lowering springs back to stock should be clocked as well.

Essentially any time the static ride height is changed.

I just had a weird thought as I was typing this. Lots of higher end vehicles have comfort / sport settings. I'll use my buddy's porsche cayenne as an example.

From sport to comfort mode the ride height raises / lowers the ride height approx 4" from low low (on a track) to off-road mode. How do these systems mitigate having to clock bushings when the ride height is adjustable as often as one wishes and has 4x the range a simple 1" drop on our cars has?

 

[HoosierDaddy]

I just had a weird thought as I was typing this. Lots of higher end vehicles have comfort / sport settings. I'll use my buddy's porsche cayenne as an example.

From sport to comfort mode the ride height raises / lowers the ride height approx 4" from low low (on a track) to off-road mode. How do these systems mitigate having to clock bushings when the ride height is adjustable as often as one wishes and has 4x the range a simple 1" drop on our cars has?

Don't know about those cars but clocking is only needed if the bushings bind. So, for instance, with bearings you don't need to clock. I doubt those cars use simple bearings but maybe they do but with bushings around actual bearings for NVH.

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