Mazda 5 rear suspension improvements
 

Hi all. I’m finally going to try and make some improvements to my ‘12 Mz5’s rear suspension. It’s one of the weak points on this car, and has been from the beginning. The rear coil springs were updated for the 2nd gen (possible the second year of the 2nd gen), which apparently made improvements. Even still it isn’t fantastic. With the vehicle loaded up and back sometimes catches going over bumps, and sometimes even empty it will run into things while going super slowly (bad driveways, dirt roads, etc.). After several years of family trips in our 5 with the car all loaded down (three kids, three adults, loaded roof box and behind third row, hitch bike rack with several bikes, etc) and watching the rear end squat down I decided to look into it a lot more.

I’ve been looking for awhile at air helper springs.... just simple polyurethane air bags which go inside a coil spring and have an air line to a Schrader valve. You can pump them up to help support additional load in the vehicle, and use them to level side to side. There are no confirmed kits which fit the 5, so it would be a bit of trial and error to find bags which fit the springs on the rear end. The biggest complaint most people have about them is leaks and losing air. Still at $150 for the kit not a terrible kick to the wallet.

A member over on 247 posted shots of his Mz5, and I just ran across them today. He swapped in the rear coil springs from an AWD CX-7 years ago with no problems. They’re the same dimensions, but a little longer to deal with the ~600 pound heavier CX-7. The end result was his rear end ended up raised about 2”, and he also installed a spacer for his front struts to make the car sit level. Apparently he recently carried about 1,000 Pounds of soil in the back with a bit of sagging from ride height, but no issues driving.

I started looking around trying to find coil springs for a reasonable price. The ones for the 5 are about $50/side, and there are several aftermarket OE replacement swap in options. The ones for the CX-7 run $100/side, and I couldn’t find any aftermarket replacements for them. Then I ran across a close out on a set of H&R lowering springs for the CX-7 on tire rack for just under $200. They claim a 1.3” drop in the rear for the heavier CX-7, so I’m hoping that 1.3” drop extends to the 5 and takes away most of the 2” gain the stock CX-7 springs gave that guy’s 5. I don’t care about tucked wheels, and honestly I’d be fine with a bit more clearance. Still the car doesn’t always drive around with weight (though it routinely has two kids in the third row) so I didn’t want it canted forward a whole bunch.

I just ordered the H&R kit and will hopefully be installing them, and new rear shocks (91k on the OEM ones) next week. Went with KYB Excel-G shocks which I’ve used on several other vehicles without problem. Thought about the gas adjust, but I’m not looking for a stiffer performance ride, just something to take the weight in the back end better than stock. I’m not doing the front struts right now, but will likely get to them next month or so and stretch out the money falling into the car. Unless the ride height is severely thrown out of whack with the rear coils, I’ll probably just keep the OE Mz5 springs in the front...... I am a little curious what the CX-7 lowering springs would do in the front end though.

I’ll post up with what I learn from this experience. Here’s a couple of shots with our 5 loaded up for a trip. Without the roof box and the bikes it doesn’t do well with six people inside, even when half of them are kids!

https://cimg9.ibsrv.net/gimg/www.maz...ef034b5d7.jpeg
https://cimg2.ibsrv.net/gimg/www.maz...48a6061cc.jpeg

The air bags will NOT leak if installed correctly. I recomend the

Firestone "Coil-Rite" Air Bag Helper Springs

You may not find a listing for the MADZA
These are what I have used on a few none applicated rear coil spring car and currently a set will be going on my 2018 Mazda 3.

Firestone 4100 Coil-Rite Air Springs - 4100

https://www.mazdaforum.com/forum/maz...like-do-44018/
My Mazda 3 rear coil springs with the Firestone bags
https://cimg1.ibsrv.net/gimg/www.maz...1d45bcaf54.jpg
https://cimg2.ibsrv.net/gimg/www.maz...4231522262.jpg

The air controller,air pump and gauge are from other Firestone misc parts I have and will be using with the universal Firestone Coil-Rite kit.
This is also a DUAL-AIR CONTROLLER to allow for separate air pressure adjustments in each bag.
https://cimg3.ibsrv.net/gimg/www.maz...11f1d66962.jpg

Callisto, the firestone kit was the one I was looking at. What I ran across was firestone doesn’t list a bag that fits the Mz5. CarID lists a replacement Firestone bag which fits the 5, but does not list the 5 as compatible with any of their kits. Their kits also don’t state which bags come with the kit...... so while I might know bag “x” fits the 5, I don’t know if bag “y” comes with the kit I’d be buying. The replacement listing gave dimensions, but none of the kits listed the dimensions of the bags. Are there ways to find that out, sure. Still just annoying as hell. CarID did list a handful of other cars as also compatible with the same bag the 5 could use, and I did find kits for those cars (10-13 Audi A3 for instance). Like I said the only real negative reviews I read were leaking air, or people saying “I couldn’t slip it through the coils, this thing sucks!”..... I don’t put a lot of credence in those. For the leaking I think most of that can be blamed on not having clean even cuts to the air line. I also like the connection better on some of the other brand bag kits which actually have external nipples and a clamp vs the “push this line in” connection of the firestone bag. Maybe it’s perfectly fine and I’m worrying over nothing. Hmmm, looks like you bags actually do have external nipples for the connections. All the videos I’ve seen of the firestone bag installs it has some sort of friction fitting hole you stick the line into. If I’d been doing the bags I was just going to run the lines to a Schrader valve and manually pump them up. I don’t really need on the fly adjustment (at least I don’t think I do), and I really wasn’t wanting to drop too much into this. I just want the rear end to not bottom out or sag severely.

Since I already ordered the H&R springs I’ll see how those do. If I’m not satisfied with those then I may end up back with the air bags. I like the idea of having progressive springs, so that they don’t really kick in until there’s more compression on them, while hopefully they’ll be a little more forgiving on the first half of the spring.

Oh, and I said it in your other thread, but .... damn! I was not prepared for what I was going to see when I went into that thread. Nice work.

Random aside..... the forum’s censoring software is interesting. I was trying to describe the air connection of the bags using the word you’d describe wire fencing with sharp metal pieces on it. Apparently while I can type “nipple” I can’t type “b a r b e d“. LOL

Lot of good question.... CHECK YOUR PRIVATE MESSAGE!

H&R springs arrived this afternoon. New shocks should be here on Tuesday. Quick measure of the rear springs is 14” long. I’ll compare them to the stock springs when they come out.


https://cimg0.ibsrv.net/gimg/www.maz...05b1e550f.jpeg

Drove the 5 around this morning to try and get a feel for how it was actually driving currently. It’s not my DD, so it’s always a surprise when I drive it now. Definitely felt a little floaty in the rear end, and the right rear felt more bouncy. Almost but not quite the feel of oversteer, but I think that was the rear end drifting vs. the tires actually moving out. Hit some hard bumps, and didn’t manage to bottom it out (did get some good thunks though), but it was empty but for me and car seats. BTW the ride height measurements from before were 26.5” left, 26” right (as measured from the lower edge of the fender to the ground across the center of the wheel).

I got home and said “what the heck, let’s start working”. This is where things started to go wrong. The wheel lock key was missing. Looked all over the car, every cubby, under every seat, etc and nothing. Looked through my tool boxes, through my storage cabinet in my carport, nothing. Last time I used it was the beginning of April when I did my front brakes. It’s not anywhere I would’ve left it when cleaning up from that. Eventually went to the shop I used and had them use their lock remover and throw some extra open lug nuts from my winter wheels on. I’m not that worried about someone stealing my scratched up eight year old OEM wheels.

I started with the passenger side. Most everything came apart really easily. I did have a solid brain fart moment when I couldn’t get the control arm low enough to remove the spring. Ran back through everything and realized I didn’t disconnect the driver’s side of the sway bar, so it was still obstructing the passenger control arm. Once that was out of the way everything dropped away and the spring pulled right out.

The CX-7 spring is the same 14” as the OEM 5 spring, so hoping I’ll be close to stock height. It is of course a lot heavier, so won’t be surprised with some lift. Back to those height measurements, the passenger side shock was silly rusty and didn’t seem to have much oompf left in it. I think that accounts for at least some of the floaty rear end, and the 1/2” difference between the two sides. Anyway I got the passenger side back together and then went to work on the driver’s side. Everything was going well, but the lower bolt for the shock seems to be not quite seized. It still turns but it basically takes me doing a deadlift with my legs to move it about an 1/8 of a turn. I got everything else apart, and pulled the stock spring out, then sprayed the bejesus out of the threads with penetrating oil. Then it was dinner time, and now it’s time to get the kids to bed, so I’m done for the night. I’ll let it sit overnight and hopefully I can get that bolt loose tomorrow.

https://cimg4.ibsrv.net/gimg/www.maz...c03bd4adc.jpeg
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Good Show Old man hahaha! :p oh and great write up. Thanks for sharing, Look forward to the continue adventure read!:D

“adventure”. I’m like a kiddo pulling a little radio flyer wagon compared to you taking the Oregon Trail.

Still, things I haven’t done before. Would love to have the car on a lift right now so I could actually use a cheater bar on my breaker bar. As it is I can get barely a 1/2” of movement on the bar before the flex of everything runs it into the ground. Having another foot of space even would be awesome. Or an impact wrench. That would help too.

check private message ....

Small update..... yeah, that bolt isn’t moving. I got the second spring in pretty easily, but haven’t moved that bolt out more than 1/2” I got it to yesterday. Can’t get the bar on it with the angle I have, and , don’t have the leverage to put it back in.

I spent the afternoon finding a store around me that had a reasonably priced corded electric impact wrench. Went through a bunch of problems getting that because some asshat pulled a bait and switch and returned the one I purchased and stuck a $50 drill into the box for a full refund of the impact wrench. Involved two 50 mile round trips, and at this point I wish I’d just gone to the closer store and payed a little more money For what they had in stock.

By the time I got home it was dinner time again, so it’s waiting until tomorrow. Trying to hold off until I can chat with Callisto tomorrow before I go breaking stuff. Would be really nice to make the car drive able again, and even better to avoid shop service fees.