Lowering rear end

10184 Views 15 Replies 11 Participants Last post by Pinan, Oct 15, 2016

eNigma17

Discussion Starter · Mar 3, 2013

I was going to use Smart Madness rear end lowering springs but after much research, a lot of people have mentioned not to do it for several reasons: need to realign headlights, "...front end lift at high speed", "...will ruin handling... need to maintain factory ratio front to rear", etc.

So my question is... How does this differ than H&R springs which drops 0.6" in the front and 1.2" in the rear? Isn't this essentially the same as "don't drop your car lower in the rear as so and so..."?

If that's the case, it may be better to go with Eibach since it lowers even all around at 0.8". Thoughts?

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Stretchmobile

· #2 · Mar 3, 2013

eNigma17 said:
I was going to use Smart Madness rear end lowering springs but after much research, a lot of people have mentioned not to do it for several reasons: need to realign headlights, "...front end lift at high speed", "...will ruin handling... need to maintain factory ratio front to rear", etc.

So my question is... How does this differ than H&R springs which drops 0.6" in the front and 1.2" in the rear? Isn't this essentially the same as "don't drop your car lower in the rear as so and so..."?

If that's the case, it may be better to go with Eibach since it lowers even all around at 0.8". Thoughts?

Bend your knees, your rear end lowers automatically.

Reactions: 1

GoFaster

· #3 · Mar 3, 2013

"Need to realign headlights" - So what? Just realign them and be done with it. Sure, a reminder that you have to do this is fine, but that's not a valid reason to not do the modification at all.

Aerodynamic lift? How fast are you going?? This is not a Formula 1 car. The floor pan is not close enough to the ground to have any meaningful effect and it's not exactly smooth underneath, either. F1 cars have an inch or so of ground clearance ... If you are worried about the effect of air getting under the car then just install a front air dam of some sort.

Rigid rear axle suspensions that have left-right symmetry are normally not all that sensitive to ride height. (Panhard rod can be a different story if it is too short.) Stock, the two links at the back have the chassis-end pivot about an inch higher than the axle-end pivot (I've already measured mine). Lowering the rear a little bit will just level them out. The geometric roll center will stay where it is relative to the chassis. If anything, I'd say lowering the rear a smidge will take out a tiny, almost unnoticeable amount of bump steer and side-kick on one-wheel bumps.

I'm not buying the naysayers in this case.

Independent MacPherson struts (i.e. front suspension) often don't like being lowered ... whole different ball game.

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Rustedwrench

· #4 · Mar 3, 2013 (Edited)

eNigma17 said:
I was going to use Smart Madness rear end lowering springs but after much research, a lot of people have mentioned not to do it for several reasons: need to realign headlights, "...front end lift at high speed", "...will ruin handling... need to maintain factory ratio front to rear", etc.

I don't know from whom you are getting this advice but they are as full of crap as a Christmas turkey. Lower it, adjust the headlights, done.

Reactions: 2

DrKillerBee

· #5 · Mar 3, 2013 (Edited)

The NTA (National Turkey Association)does not support your opinion on Christmas Turkeys and demands that you take back the last statement lest they will have to primary you off the forum. Most Christmas Turkeys come pre cleaned from the grocer.:wink:
That being said the cars look so darn good lowered that it is my first mod when I get the Bee back from the paint shop.

silverbrabus

· #6 · Mar 4, 2013

If lower, need to be stiffer or will be on the bump stops all the time. If higher spring rate at rear need similar increase at front to maintain "factory ratio."

H&Rs will do this. Changing only the rears won't.

GoFaster

· #7 · Mar 4, 2013

True, you need higher spring rates when lowering to preclude bottoming out. No idea how the SmartMadness spring rates compare to stock. Higher spring rates on the rear will increase roll stiffness at the rear which will tend to tip the handling balance towards less understeer. I won't say that it would promote "oversteer" because these cars have SO many factors promoting understeer that I don't see how they would all be overcome by some increase in spring rate. (Mine - stock - understeers like a pig under every circumstance I've yet found, despite me trying to provoke it a little.)

Stock rear springs aren't progressive rate. I just went downstairs to look. Also, there's only about 3 inches of front compression travel available before the tires would hit the fender liners, a little more in the rear. No doubt the bump stops are somewhat short of that. On the crap roads that we have around here, one wonders how much of the bumpy ride is actually coming from the suspension hitting the bump stops ... I won't be lowering the front suspension any time soon! If you have a situation where the suspension is hitting bump stops, springs with higher rates can actually give a better ride, by reducing the frequency with which that happens!

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eNigma17

Discussion Starter · #8 · Mar 4, 2013

Thank you all for your inputs. It's been very helpful!

elders08smart

· #9 · May 28, 2013

eNigma17 said:
I was going to use Smart Madness rear end lowering springs but after much research, a lot of people have mentioned not to do it for several reasons: need to realign headlights, "...front end lift at high speed", "...will ruin handling... need to maintain factory ratio front to rear", etc.

So my question is... How does this differ than H&R springs which drops 0.6" in the front and 1.2" in the rear? Isn't this essentially the same as "don't drop your car lower in the rear as so and so..."?

If that's the case, it may be better to go with Eibach since it lowers even all around at 0.8". Thoughts?

For what it's worth I just ordered the SM rear springs for my new 11. I'll be putting them on next week. I'll post pics and report ride quality. I've done a similar rear swap on PT cruisers with no ill effects so we'll see.

elders08smart

· #10 · May 28, 2013

I don't want to go through the hassle of doing the front springs. Lowering only the back end would increase the caster, if at all, given the length of a smart which would increase straight line stability. SM has spent some time developing these springs and I have no reservations saying that they wouldn't put their name on just any old spring. They are a progressive style spring with a polyurethane wrap on the center coils. I would think being a NASCAR fan that this is there as a type of spring rubber to increase the spring rate as the coil compresses and as light as a smart is a bit of a coushion as well. It is interesting to that the rear only spring is progressive in the center only and not on just the top or bottom but in the center. http://smartmadness.com/pdf/rearsprings.pdf
I would think this design allows the spring a constant dual rate. Similar to coil over shocks that run a small helper spring before engaging the larger absorbing spring.

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elders08smart

· #11 · May 31, 2013

eNigma17 said:
Thank you all for your inputs. It's been very helpful!

Well I installed the new rear leveling springs, I wanted to post some pic's but i can make my photos small enough to post them but anyways the car looks great! I have 2 finger clearance in the front and 3 finger clearance in the rear and it just looks so much better! Its rocks a lot less and the weeble-wobbel feeling is gone. Now time to get the stiff motor mount and she'll be set.

BB Benz

· #12 · May 31, 2013

The description of the Smart Madness variable rate springs could also be a description of the Brabus springs. They too have the restricting poly band on the center coils.

ilomax

· #13 · Jun 8, 2013

I'm very happy with my 3 Guyz... I mean Smart Madness upgraded rear springs.

About 10,000 miles now.

The big difference was wider front wheels....

ATL Smart alec

· #14 · Jun 8, 2013

i have a 09 Brabus Cabrio, running wedges, 17" Brabus rears on all 4 and a slightly taller than the stock Brabus rear tires all around. I would REALLY like to lower the back to match the front. It is my only vehicle, so I don't want to ruin the ride (stiff enough, and we have nasty roads in Atlanta) or handling (handles GREAT)... Are the stock Brabus struts ok with the SM rear springs ?

ilomax

· #15 · Jun 8, 2013

The rear upgraded springs ride like stock "should". It's a progressive spring so the harder you hit the corners the stiffer the spring. Normal driving it feels stock except for the rear being 3/4" lower.

Reactions: 2

Pinan

· #16 · Oct 15, 2016

Bumping this old thread because I just installed the SM rear-only springs, and it's great!

Immediately noticed the difference in ride and corning. Slightly softer when street driving, and much better at cornering! Also tracks straighter at HW speeds. Feels more secure, less wobbly, less wind push, etc. Plus she now sits about 3/4" lower. Headlight adjust was simple. No different over speed bumps, etc. Not worried at all about bottoming out.

I just got up to my mountain home, and after the 20miles of very curvy road I can say that I am very happy with this simple, inexpensive upgrade. Less than $150 OTD.

Total install time was about 45min. Nothing to it, following the youtube video by Randy Zimmer:

2008 Pure
121K
Stock rear wheels all four corners
Continental ContiProContact 175/55/15.

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