The definitive h&r / mm spacer lowering thread
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2004-2007 Cadillac CTS-V Performance Mods Discussion, The definitive h&r / mm spacer lowering thread in Cadillac CTS-V Series Forum - 2004 - 2007; Here's my attempt at answering some of the questions that I see asked a lot regarding this set up. In ...
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    EdmundGTP is offline Cadillac Owners Enthusiast
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    The definitive h&r / mm spacer lowering thread

    Here's my attempt at answering some of the questions that I see asked a lot regarding this set up. In all my searching I had yet to find a set of answers from people who've had these installed, that give a really good idea of what the installation process, and end result is really like.


    First off. The drop from these springs is not the widely advertised 1.2" Front and 1.0" Rear. It is significantly more than that.

    I took a lot of before/after measurements when I did the installation on these and the actual drop numbers are more like 1.6" front and 2.2" Rear. The extra drop in the rear may or may not be due to adding the MM spacer kit to the installation. I don't really have a way to verify that at this time. That being said, with the self-leveling shocks in the rear, I believe the rear drop amount changes from when the car is being driven to when it's parked for a period of time. The 2.2" drop measurement was made AFTER the car had sat idly in my driveway for about 12 hours and also after I spent some time in the trunk and back seat re-installing the seats and trunk paneling. I think 175 Lbs of me bouncing around in the back of the vehicle for 20 mins caused the rear to settle a bit more than usual. After driving around for a little bit, I believe that the rear shocks do in fact help the back of the car raise back up a little, but no more than a quarter inch or so. Either way, plan on a rear drop of 2" instead of the advertised 1". My car doesn't have headers, so the lowest point of the under body are the frame "rail bends" towards the front of the car, where you'd normally mount jacking pucks. After installing the H&R springs, the ground clearance here is approximately 4 inches. The rubber "lip" under the front bumper sits about 3.5" off the ground. I have a set of DIY Jack Pucks installed so as of now my lowest point gives me a hair over 3 inches of ground clearance. That's enough to clear MOST parking lot and residential speed obstacles, but I'd try to avoid them anyway. More on that below.

    How does it look? The drop looks awesome. The stance of the car after the HR/MM spring spacer combo is much more aggressive and better looking than the factory 4x4 off-road look. It literally creates an entirely new, and better, look for the car. It should have looked more like this from the factory, but I can see where an effort to cater to the "older" typical Cadillac buyer base resulted in what the V is.

    Installation. Installing these springs along with the MM spacers is really very straight-forward and simple if you're at all familiar with suspension components and how they fit together. Air tools are a HUGE help and I highly recommend that this installation be done where you have access to them. I did the installation over the course of 2 nights by myself. First night I did the rears, and second night, I did the fronts. I took my time with the install, and even ate dinner halfway through working each night. Total time spent ACTUALLY working on this was probably less than 6 hours, and I've never done significant work on a V before. Anybody competent with tools could easily bang this out in a single night with help from a friend. As far as instructions go, I used a combination of the steps outlined on MightyMouse's instruction sheet, and the instructions on the FAQ for the Ground Control kit and KW Coilover Kit installations. Between those, I ran into essentially zero hang-up's along the way. I found that the cup washers supplied with MM's kit were a very close fit to the shock's shaft and instead of beating them on with a hammer and deep well socket, I opted to use a round metal file to open them up to the point that they fit on with only a little force. The only area I was kind of "gray" on was the bump-stops. I trimmed about a half inch off of the rears and about 3/8" off of the fronts and I saved the pieces which I cut off since it seems like they can be re-stacked on the shaft if necessary. You only need spring compressors to remove the front springs from the front shocks. The H&R springs are short enough so that you can install them without having to compress them any. I can provide more details on the installation if anyone's curious but with the information that's already out there, a specific spring swap write-up really shouldn't be necessary.

    The shocks on my car are FE-4's with 28K miles on them and in the past few days I haven't noticed any rubbing, clunking, or any other sorts of odd noises from the installation. Nor have the shocks bottomed out at any point. That being said, I also haven't driven around with a full trunk and or full back seat either, so all encompassing observations remain to be seen. I don't suspect I'll run into any problems though. My car acts as more of a weekend/fair-weather cruiser than a daily hauler too, so odds of it seeing a full person/cargo load are slim. I should also mention that my tires are stock size 245-45-18. With current wheel-well clearances I doubt I'll ever go bigger than a 255-45-18 and if I want a wider tire, I'll probably go 255-40-18 and sacrifice a bit of diameter to get a wider contact patch, and hopefully remain free of rubbing issues. I saved my rear dust boots and I am actually considering a way to make them re-usable with the MM kit. I believe that if the top hole on the dust boot is drilled out, and a nylon bushing with an ID that matches the shock shaft's OD, is pressed in, they could be re-used. I may try this down the road at some point if I get ambitious.

    How does it ride? It seems like for every person you ask, there's a different answer and they range from "horrible" to "almost no change from stock". Here's what I can share about how the resulting ride is. It's definitely different from stock, but not in a bad way. Physics alone dictates that you cant subtract 1.5-2 inches of suspension travel from this car and have it ride
    exactly the same. It's just not possible. So the ride is definitely firmer. There is much less vertical movement of the vehicle relative to the wheels as it goes over bumps and "waves" in the pavement, and more of the contours of the road are felt as you drive over them. At the same time, the factory shocks do a very good job of dampening the springs so the ride isn't at all "bouncy" or erratic like I've experienced with lowering springs on other cars in the past. I was actually pleasantly surprised at how well the car rode immediately after installation. There's significantly less body roll and lean when making turns, and also less nose-dive when braking. All that is well and good, but at the same time you "feel" a lot more of the smaller imperfections in the road.
    Things like, pavement cracks, rough patches, edgy transitions from one pad of tar to another, sewer grates, man hole covers, etc etc. You feel and hear these things in the cabin more with the H&R springs than with the stock springs, but again, for a significantly lowered car, it's very tolerable. I've been driving a lowered car for the past 4 years now and it's essentially become ingrained in my driving habits that I make mental notes of where I come across pavement/road hazards as I drive, and make significant efforts to avoid them afterward. For example, I can tell you where every pot hole or crack in the road deeper than an inch is on my way to and from work. I also know and remember where every speed bump I've ever audibly scraped bottom (with my other car) on is, and also know where the ones which look too high to even bother trying are. I keep an eye out for those concrete drainage ways which sometimes cross major intersections and always drive slowly over them. If you're driving a lowered car it's really a good idea to adopt a mentality like this. Yes it may piss off some people behind you but that's always the better option than breaking something on your car.

    Now after all that, I know everyone always asks for pics so here are a few.

    Before (ones you've probably seen previously)





    After






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    CadzillaTN's Avatar
    CadzillaTN is offline Cadillac Owners Connoisseur
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    Re: The definitive h&r / mm spacer lowering thread

    good info, especially for those interested in the h&r.

    car looks great.

    I need to get the mm kit and give my spacers to someone.

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    JCaddyV's Avatar
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    Re: The definitive h&r / mm spacer lowering thread

    Good write up. I plan to do H&R's and maybe MM's but still not sure on shocks and

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    big reg is offline Cadillac Owners Member
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    Re: The definitive h&r / mm spacer lowering thread

    What color is the powdercoat on your wheels. Looks awesome!!

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    EdmundGTP is offline Cadillac Owners Enthusiast
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    Re: The definitive h&r / mm spacer lowering thread

    Extra dark hyper silver. Doesn't have an exact name. They just vary the darkness of dark hyper silver by the percentage of black powder content.

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    nlpy8b is offline Cadillac Owners Fanatic
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    Re: The definitive h&r / mm spacer lowering thread

    Can you post a close up of the wheel? I'm loving the powdercoat job.

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    EdmundGTP is offline Cadillac Owners Enthusiast
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    Re: The definitive h&r / mm spacer lowering thread

    Quote Originally Posted by nlpy8b View Post
    Can you post a close up of the wheel? I'm loving the powdercoat job.
    Damnit! Not the point of the thread but, here you go. Haha


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    Re: The definitive h&r / mm spacer lowering thread

    Thanks for the writeup and your opinions.. this is something i definitely want to do but have been putting off for awhile now. I'm running a series lower tire than you and hope i won't have problems in the northern virginia area but thankfully i dont really drive my car that much so as long as im careful i dont think it should be an issue. Do you have any pics of the MM spacers? just trying to wrap my head around how they work as opposed to the general spacers... Also, do you know if they can be made so the rear doesn't drop as much (so in effect, only relocating the mounting point half as much, if that makes any sense)... just curious as i take a few road trips every year with a few folks and a lot of golf gear and wouldn't want to hinder the ride anymore or have the rear dragging like crazy

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    EdmundGTP is offline Cadillac Owners Enthusiast
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    Re: The definitive h&r / mm spacer lowering thread

    I don't recall if I actually took pictures of the spacers while they were installed but I should have. Really, the only purpose of the MM spacers is to shift the fixed mounting point of the shock further up into the vehicle, to "fool" the shock into thinking that the rear of the car is at its "proper" height. Shocks by nature have a minimum overall length and maximum overall length and those lengths are determined by the amount of travel it has. The nimovat shocks are built to operate "optimally", and keep the vehicle level at a certain point somewhere between the min and max, say Point X. When an extra load is applied to the vehicle, which makes the rear sag, the shock works internally to raise the back of the vehicle up so that the shock is operating back at Point X. The spacers make the shock believe that it is at Point X even when the rear of the car is lower than its original height.

    Really, in a way, the MM spacers ARE and ARENT what determine the height of the back of the car. If you installed the H&R springs without the MM spacers, the back of your car would drop the same amount as if you did install the spacers. BUT when you drive the car, the rear shocks would try to raise the back of the car back up so the shock is operating at Point X. When you install the MM spacers with the H&R springs, the shock is theoretically always operating at or near Point X, and the back of the car doesn't raise.

    If you wanted to use H&R springs with MM spacers and have less of a drop, you need to figure out a way to shim the spring itself. The operating range of the spring is what ultimately determines how the suspension assembly behaves, and the best way decrease the amount of drop, is to make the spring's installed length longer. Obviously you can't make the H&R spring longer, but what you can do is create a spacer or shim of some sort that fits between the springs mounting pads and the lower control arm. This would effectively raise the suspension by whatever thickness the spacer/shim is. I toyed with the idea of creating hard durometer rubber washers to install between the lower spring pad and the control arm in the event that the drop was too much.

    There is a way to install these items and get less of a drop. You just have to be a little creative about it. Changing the dimensions of the MM spacers alone won't get you the results you want.

  11. #10
    Dan_Gurney is offline Cadillac Owners Fanatic
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    Re: The definitive h&r / mm spacer lowering thread

    what is the height from the ground to the center of your wheelwells?

    From the pictures it doesn't look like your car is lowered 1.6 and 2.2. My car has the eibach springs (which lowered the front 1.5" and the rear 1" from my measurements) and your rear looks lowered about 1 in, but your front doesn't look as low as mine. (part of the reason i have considered swapping to H&R Springs)

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    EdmundGTP is offline Cadillac Owners Enthusiast
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    Re: The definitive h&r / mm spacer lowering thread

    I actually have a series of before and after pictures of measurements I can post up at some point, but here are the numbers to the nearest 1/16th increment.

    Stock:

    Front Driver: 27.63"
    Front Passenger: 27.68"
    Rear Driver:27.75"
    Rear Passenger: 27.75"

    MM/H&R
    Front Driver: 26.06"
    Front Passenger: 26.13"
    Rear Driver: 25.63"
    Rear Passenger: 25.50"

    Relative Drops
    Front Driver: 1.56"
    Front Passenger: 1.56"
    Rear Driver: 2.13"
    Rear Passenger: 2.25"

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    Dan_Gurney is offline Cadillac Owners Fanatic
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    Re: The definitive h&r / mm spacer lowering thread

    cool, I am glad you had actual measurements before and after. Thanks for posting those

    I would love for another H&R owner to chime in about the drop, i was really hoping to use these springs to raise the front of my car a little...

    Did you buy these new? any chance there is a base CTS version? i'm assuming you didn't cut them.

  14. #13
    EdmundGTP is offline Cadillac Owners Enthusiast
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    Re: The definitive h&r / mm spacer lowering thread

    No problem. I actually just went out into the garage and checked the measurements again. The car has been sitting still since Sunday night, but it appears the suspension has settled even more. The front fender lips are both sitting at 25.93" and the rears are sitting at 25.5 on the drivers side and 25.25 on the passenger side. I'll measure them again right after a drive next time I take the car someplace.

    But yeah, the springs are new right out of the box H&R's, totally unmodified in any way. I'm not sure if there is a separate set for the base CTS though.

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    Re: The definitive h&r / mm spacer lowering thread

    So as far as shocks go. The mileage on my car is 43k should I replace my shocks when I do the springs or will I be fine?

  16. #15
    EdmundGTP is offline Cadillac Owners Enthusiast
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    Re: The definitive h&r / mm spacer lowering thread

    If your shocks are good now, I'd just keep them and use them with the H&R springs, and if you're worried about blowing one out, keep a set of spare shocks on hand and replace them when you need to. The spring rate of the H&R's doesn't seem to be drastically different from the stock springs so I have a hard time imagining that they would accelerate the deterioration of the stock shocks by much. No sense ditching them if they work presently. Aside from that, the struts are fairly easy to replace so it's not like it will be a job that you'll absolutely dread having to do at a later time.

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