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Discussion Starter #1
I have a black 2014 S touring Hatchback. Originally I was using the Eibach springs on stock struts. Then I switched over to the H&R springs. At that time I decided to reuse the Eibach front bump stops, thinking that they were a better fit for lowering springs. What I noticed was that the H&R springs were alot more bouncy, and had a vague feeling like the car was always unsettled. After a bunch of reading here, I read that H&R did confirm to someone, can't remember who, that their springs were designed to work in combo with the stock bump stops. So, I put the stock bump stops back on, and it was a very noticeable improvement in stability and handling.

The car did sit a little lower with the Eibach bump stops. I'm guessing the stock bump stops are always in contact, and actually raise up the front a bit. It's not a huge difference.

The H&R springs with the stock struts and bump stops is definitely a better handling setup than the Eibach springs. But, it does scrape the front more.

I also have the Racing Beat rear sway bar. Running a little toe-in on the rear, and a little toe-out on the front. 37psi all around.
 

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So I got curious about my slightly increased ride height with the stock bump stops. Seeing that new ones were only $30 I decided to cut them.

With the stock bump stop at full length it is completely in contact with the strut and the top hat. I decided to cut off the smallest nub to bring the height back down to where it was with the Eibach bumpers. They still aren't as short as the Eibach s but the ride height did come down. I'm guessing the stops are now just barely away from full contact, where before the stock length was actually lifting the front.

That first nub is so small and thin that I didn't believe it could make a huge impact one way or another.

I can't feel any difference in handling or bounciness. I'm sure there is a slight change because there has to be when making a mod like this, but I can't feel it.

So I got my nice stance back with the front a little lower than the back, and still have the nice firm handling I wanted.

I'm not cutting any more.

PS. The stock bump stops are tougher to cut than other bump stops I've cut in the past (while on the car anyhow). A brand new blade was needed and even that had to saw through slowly. Others I've done were like butter or maybe a lower density.
 

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So what you are saying is that your cars suspension is comprised of just bump stops, nothing more? If the car is sitting on the stops the shocks and springs are not really doing anything. There should be a couple inches of shock travel before hitting the stops. Bump stops should have nothing to do with ride height. Your suspension is screwed up. Get professional help.
 

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Discussion Starter #4
Well then everyone on H&r springs have screwed up suspensions if they're using the stock front bump stops.

The stock bump stop is very tall and the suspension has very little travel.

Nobody has a few inches of exposed strut shaft with lower springs. There is very little with stock springs.
 

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I have H&Rs, no issues with the bump stops. If you are riding on the stops something is wrong no matter what you believe. You can't lower the car almost 2" and not change the bump stops accordingly. The stock shocks seem to have enough compression travel to accommodate the shorter springs, but you can't use the same length bump stops because the distance between the upper and lower shock mounts has changed but the shock body hasn't. Its just not going to work.
 

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Discussion Starter #6
All of the lowering springs I've purchased in the past have either came with new bumpers, or had instructions on how to modify the stock ones. My H&R instructions came with no mention of them. So, I was inclined to believe they intended for me to leave them alone. I now believe cutting them is worth while. I did have a 95' 626 that was fine on stock bump stops that also used H&R springs, so it's not totally out of the question.
 

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I have H&Rs, no issues with the bump stops. If you are riding on the stops something is wrong no matter what you believe. You can't lower the car almost 2" and not change the bump stops accordingly. The stock shocks seem to have enough compression travel to accommodate the shorter springs, but you can't use the same length bump stops because the distance between the upper and lower shock mounts has changed but the shock body hasn't. Its just not going to work.
So what exactly is the correct method here? I have a 2016 Mazda 3 sedan with the 2.5 and am installing H&R springs. Do I cut both front and rear stops? If so, how much?
 

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Follow the installation instructions from the spring manufacturer. In the first generation Miata, Mazda designed the OEM spring to work in conjunction with the OEM bump stop. The design used the bump stop as a higher rate spring in the rear. If the aftermarket spring you have for your 3 does not call to shorten the bump stop, don’t shorten it.
 

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I am purchasing the springs off someone else and there was no instruction sheet provided. I have also read from others the H&R springs don't mention shortening the stops but others suggest to shorten them. I only want to do this once and not twice. I can't imagine dropping the car 1.2"/1.8" and not shortening the stops.
 

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I am purchasing the springs off someone else and there was no instruction sheet provided. I have also read from others the H&R springs don't mention shortening the stops but others suggest to shorten them. I only want to do this once and not twice. I can't imagine dropping the car 1.2"/1.8" and not shortening the stops.
The H&Rs lower the car quite a bit, the rear a lot more than the front. There is plenty of travel in the suspension but generally the rule is remove about the same amount as you lower in order to stay off the bump stops.
I'll be helping somebody install a set of H&Rs with stock dampers tomorrow. I'll take a quick look at how much might actually be required.
 

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Follow the installation instructions from the spring manufacturer. In the first generation Miata, Mazda designed the OEM spring to work in conjunction with the OEM bump stop. The design used the bump stop as a higher rate spring in the rear. If the aftermarket spring you have for your 3 does not call to shorten the bump stop, don’t shorten it.
The NA Miata is a totally different car with a completely dis-similar suspension. It has very little suspension travel. The stops are progressive so hitting them isn't so harsh as it might be otherwise but the bump stops are not designed to be used as a spring. They are there to prevent the damper from bottoming out and being damaged.
If you really want to see what you need for a bump stop, jack up the the suspension one corner at a time to full compression, measure what you have left and go from there......
 

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The H&Rs lower the car quite a bit, the rear a lot more than the front. There is plenty of travel in the suspension but generally the rule is remove about the same amount as you lower in order to stay off the bump stops.
I'll be helping somebody install a set of H&Rs with stock dampers tomorrow. I'll take a quick look at how much might actually be required.
Thanks @arathol , this is what I figured was the case but I've run into so many competing views. Definitely keep me updated, I appreciate it!
 

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The NA Miata is a totally different car with a completely dis-similar suspension. It has very little suspension travel. The stops are progressive so hitting them isn't so harsh as it might be otherwise but the bump stops are not designed to be used as a spring. They are there to prevent the damper from bottoming out and being damaged.
If you really want to see what you need for a bump stop, jack up the the suspension one corner at a time to full compression, measure what you have left and go from there......
Sorry, but you are incorrect here. Yes, the Miata is a different suspension, but I am challenging your view that bumpstops are not used as part of the spring of the car. I worked at Flyin' Miata from 2000 through 2004. When we were reviewing our lowering spring design we were surprised to find that the NA version of the rear suspension used the bumpstop along with the very soft rear spring to provide a progressive spring rate. To make our 200% stiffer springs work properly, we had to remove 80% of the bump stop. It only came into play right before the shock body contacted the top hat.

The point, I'm trying to make here is that some manufacturers use the bumpstop in part of the normal suspension travel. And that the OP should consult with the manufacturer of his aftermarket springs to get the correct information on what to do with his bumpstops. H&R is a reputable company who's best interests are met when customers install their parts properly. Therefore, H&R's instructions are the best place to find the correct answer.

Another option, is to refer back to the hardworking business owners who help us all by selling aftermarket performance parts for installation assistance. But that is another topic for another thread...
 

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The thing with the Miata is the bump stop has to be progressive like that or the suspension would not work. Setting the suspension on the stops under the least bit of compression is part of what makes the NA Miata handle like it does - decent ride but in a corner the springs are right on the stops, the suspension stiffens up and you can get the rear end out pretty easily. These bumps stops are not springs though, and in part because of this the NA bump stops generally didn't seem to last too long.
The Mazda 3 has somewhat more suspension travel than the MX-5 did, so the stops are totally different.
Thanks @arathol , this is what I figured was the case but I've run into so many competing views. Definitely keep me updated, I appreciate it!
When I did my car, the stock parts were not working as intended. I finally ended up using shorter bump stops (5X Racing bumpstop kit, 47mm F and 76mm R) on all four corners. The OEM bump stops are fairly long and somewhat progressive, and with the H&Rs they engage too soon. Hitting large bumps at speed produces some pretty jarring thumps....
You can get away with using the OEM parts with H&Ns, but you won't see the full potential of the spring set because the suspension hits the stops too early. We did a 2018 S GT hatch today, H&Rs with a Progress rear bar. The owner chose not to cut the stops for now but that may change. After quick test drive he thought it seemed ok, there was no unusual or new bumps or noises but its going to take some miles for any problems to become apparent.
 

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When I did my car, the stock parts were not working as intended. I finally ended up using shorter bump stops (5X Racing bumpstop kit, 47mm F and 76mm R) on all four corners. The OEM bump stops are fairly long and somewhat progressive, and with the H&Rs they engage too soon. Hitting large bumps at speed produces some pretty jarring thumps....
You can get away with using the OEM parts with H&Ns, but you won't see the full potential of the spring set because the suspension hits the stops too early. We did a 2018 S GT hatch today, H&Rs with a Progress rear bar. The owner chose not to cut the stops for now but that may change. After quick test drive he thought it seemed ok, there was no unusual or new bumps or noises but its going to take some miles for any problems to become apparent.
Thanks for the update! I can't see spending another 80$ on bumpstops so I think I'll just trim the OEM ones down a bit. I've heard you can always cut them some more later on without removing springs or anything. My roads tend to be fairly smooth and I really don't drive her as much since I work from home. 2016 S GT sedan with 27k miles so I consider everything to still be fairly new and functional.

On a side note, I am also planning on installing the Progress rear bar while I do this so realistically how much time should I plan to replace all 4 springs and the RSB? I'll most likely be by myself and limited to jack/jack stands. No air tools or lift.
 

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A few hours. Depends on how nice the nuts and bolts are to you when you try to get them off.

Make sure you have a 1/2" and 3/8" socket set, a breaker bar, 1/2" & 3/8" ratcheting wrenches (get a few different sized ones), a mid length 14mm socket (1/2" & 3/8") (for the RSB.. standard socket is too shallow for the exposed thread and a deep socket is too long to fit over the top nut with the wrench on it).. pinch weld pads.. spring compressors.. offset wrench set for the strut top and an allen wrench socket set to hold the center in place.. screwdriver (for prying brake hose clip).. needle nose pliers (for abs line clip).. liquid wrench (just in case).. LOTS OF LIGHTS!
CK
 

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Thanks guys. Seems easy enough, most of the headache seems to be around the RSB due to space limitations. Never done springs before so I'll have to rent a spring compressor but I definitely have multiple sized torque wrenches.
 

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Thanks for the update! I can't see spending another 80$ on bumpstops so I think I'll just trim the OEM ones down a bit. I've heard you can always cut them some more later on without removing springs or anything. My roads tend to be fairly smooth and I really don't drive her as much since I work from home. 2016 S GT sedan with 27k miles so I consider everything to still be fairly new and functional.

On a side note, I am also planning on installing the Progress rear bar while I do this so realistically how much time should I plan to replace all 4 springs and the RSB? I'll most likely be by myself and limited to jack/jack stands. No air tools or lift.
Further update...The owner says he wants to swap the OEM length stops and use the shorter ones. Seems its bumping some on rougher roads.
You can't really cut the stops without removing them as the boots are in the way, and if you want shorter stops usually its better to use shorter bumps stops....Most are progressive so they engage gradually. If you cut them you can end up with a more or less solid stop that engages abruptly or a stop thats too soft.
Installing the springs and rear bar can be done in an afternoon, 4 hours maybe if you don't rush and are at least familiar with the car and what you need to do.
The front springs are easy, maybe an hour or so to do both sides, you'll need a compressor to disassemble but not to re-assemble. Do not use crappy ones. I destroyed a set of those suicide sticks doing a set of springs, the threads just seized up..... Get a decent safe set.....with safety hooks....
You'll want both tires in the air to make it easier to disconnect and reconnect the sway bar. This will be much easier to do if you have a good pass through ratchet set. The sway bar link ends and the tops of the struts use allen keys in the ends of the studs to keep them from rotating when you loosen / tighten them. Make sure these are clean before using and the allen keys seat well, you don't want to strip them..... A set of 3/8 drive allen keys for your ratchet wrench (6mm I think specifically for the endlinks) will help you torque everything properly afterwards. The best way to torque the OEM end links is hold the nut with a wrench, put an allen key on the torque wrench, then use the torque wrench in the reverse position to turn the stud. Its far easier than trying to hold the stud while trying to tighten the nut.
You will need a couple torque wrenches, one for the larger bolts, 70+ ft/lbs, and a small one for the end links etc, 50 ft/lbs or less. Most wrenches don't have that sort of range capability. Torquing properly is important.....improperly tightened fasteners on suspension parts will make lots of noise, and on an increasing level as they loosen even more...and you don't want to over tighten and strip the end links or anything else for that matter......

Doing the rear springs and bar isn't difficult but its time consuming. Both wheels off the ground so the sway bar swivels freely, you'll need two good jack stands and a jack that reaches fairly high. You'll need to remove the end links completely then disconnect the outer end of the LCA (use the jack, put a bit of pressure on the outer end, remove bolt and lower slowly) to remove the spring. Once that is done remove the shocks. Remove the springs first, install them last as they will be in the way when doing the rest..
To get the shocks off you need to remove the nut then the stud using an 8mm socket, you might need an impact to loosen it. Its easier this way, believe me, as the shock won't always just slide off the stud, and if you try to pry it off you can damage the rubber bushing...just use the impact to remove it...usually the shock frees up during the process... Re-installing the shocks is easier if you thread the stud in first, then slide the shock over the stud. (Use never seize when reassembling.....on everything....)
The rear bar is a bit of a hassle. You need a small ratchet to remove the nuts from the brackets as its tight fit, especially on the right side where there is stuff in the way... The drivers side is fairly easy if you reach in through the wheel well after the shock is removed. Remove the bracket shells and bushings from the bar before you pull it out, much easier that way....
Make sure you attach the upper ends of both end links to the bar and torque them before attaching either side to the LCA. If you do one side top and bottom before you do the other you won't be able to access the upper nut on the opposite side to tighten it properly.
Here is where you really need a small torque wrench as a larger wrench won't fit in the space around the mounting brackets. I use a small Snap-on 3/8" drive swivel head torque wrench (a swivel head can help a lot) to torque the bracket bolts.
The other part of this that nobody ever mentions is that you'll need to have the headlights re-adjusted afterwards. If you have the AFS lights, you'll also need to re-initialize the auto-leveling system before re-aiming.
 

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Thanks for the write up! Definitely helps. And I'm assuming to re-initialize the auto-leveling lights I just hold down the AFS button for a number of seconds and after that, manually raise the lights to where they need to be?
 

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Thanks for the write up! Definitely helps. And I'm assuming to re-initialize the auto-leveling lights I just hold down the AFS button for a number of seconds and after that, manually raise the lights to where they need to be?
No, I don't think that button will do this. The sensor needs to be reset to the neutral position to make the system function properly. There is an easy means to do this in the manual though. Use the Procedure Not Using M-MDS part.



 
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