rear springs & ride height

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350matt
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rear springs & ride height

Post by 350matt »

So gents

driving out the other day there was a 'SPROING' kind of noise and upon stopping to check I found a rear spring had snapped a top coil on the driverside

So I got Mr Bigpete to send me another stock 231 spring , and having fitted it I now have about 20mm difference in rear ride height from side to side

the new and old springs have the same number of coils and are the same wire diameter so I was just wondering if its just my originals were quite sagged ( car is 92K miles and 14 years old) or could it have some other flavour of spring on it

as the rear ride height is now right at the top of the limit in the Mazda manual ( 400mm measuring from wheel centre to top of arch)

what ride height does the PZ have?
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Re: rear springs & ride height

Post by mrspiller »

350matt wrote:So gents

driving out the other day there was a 'SPROING' kind of noise and upon stopping to check I found a rear spring had snapped a top coil on the driverside

So I got Mr Bigpete to send me another stock 231 spring , and having fitted it I now have about 20mm difference in rear ride height from side to side

the new and old springs have the same number of coils and are the same wire diameter so I was just wondering if its just my originals were quite sagged ( car is 92K miles and 14 years old) or could it have some other flavour of spring on it

as the rear ride height is now right at the top of the limit in the Mazda manual ( 400mm measuring from wheel centre to top of arch)

what ride height does the PZ have?
PZ is a totally different spring - can’t Pete send the other spring from the pair ?


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Re: rear springs & ride height

Post by Conan »

It’s not a PZ spring as these are ground flat at the base rather than fitting a slot in the spring seat.
PZ rear measurement is 350 - 355
I believe there were two different springs for sun roof or not variants, there is a coloured dab of paint on all springs to check compatibility.
I assume you loaded the suspension before tightening or the bushes will keep it high.
It’s always best to fit a pair
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Re: rear springs & ride height

Post by 350matt »

Pete may not have the other one of the pair but he's going to check for me

and yes I tightened the lower bush when the car was on the ground

so the sun-roof cars are heavier then?
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Re: rear springs & ride height

Post by 350matt »

So I now have a matched pair of stock ride height springs on my car and it turns out I have / had a set of -25mm springs on the car already

so I now have a low front and very high back and I have to say its not nice, roll oversteer being the order of the day and the car feels a bit wayward...
as its 400mm height on the back ( mazda top limit) and 360mm on the front (mazda bottom limit)

So are these any good? about 1/2 the price of Eibach's which are my usual go-to spring manufacturer

https://www.direnza.co.uk/direnza-lower ... a-rx8.html
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Re: rear springs & ride height

Post by warpc0il »

Those Direnza springs are -25mm from Mazda Standard Suspension (as fitted in the US and JDM) not Mazda Sports Suspension, which was fitted to all UK-spec 8s

I wouldn't be looking to just replace the rears unless you know what's on the front and can match them.

Hold fire for a couple of weeks and the forum will be flooded with ads for good (slightly used) lowering spring kits, as people get around to fitting their PZ suspension sets.
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Re: rear springs & ride height

Post by Conan »

OR !!!!
You could buy a brand new PZ set from me and find out what Mazda really intended this car to feel like :)
You're only just up the road.
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Re: rear springs & ride height

Post by 350matt »

thanks for that chaps
whats the ride height of 'sports suspension then ?
and i was very happy with how the car rode and handled before the broken spring
so I should try and measure that spring rate next I suppose
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Re: rear springs & ride height

Post by Deathaga »

Sorry to Frankenstein this thread a bit but was wondering when Dave I think it was mentioned the PZ measurements which measurements they were.

I’ve just had my car alignment done and as part of that the system asks for heights from arch to wheel centre. My car was out of spec all round. I assume that is because his system only had sport suspension not prodrive like I’ve got fit.

However I thought prodrive suspension was only 15mm lower and I’m more than that from the min spec

Car measured 335mm front both sides and 336mm rear both sides (I did have some stuff in my boot but not loads)

Can anyone else with prodrive suspension take some measurements for me to make me think mine arent shot.

Car still drives lovely and feels planted now my alignment is all done

Cheers
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Re: rear springs & ride height

Post by 13Black »

I have new PZ springs on used PZ shocks on an S1.

Some inconsequential lightening here and there, and possibly some tools etc scattered around the car, which probably evens it all out.

Usually I get about :-
Front: 360 mm
Rear: 340 mm

So at the low end of Mazda's tolerances at the front... and slightly below min at the rear (I may have had tools in the back at the time).

I plotted them on a graph before, Mazda's recommendations are quite linear, so you can extrapolate out a little without needing bare Maths skills. But with that said... Mazda's recommendations are quite broad, and might not be ideal for your driving style and use case etc.
For example: you could have massive toe in at the front (uurrgh) and slight toe OUT at the rear (eek!) and (according to Mazda) that's A-Okay. Sure, whatever floats yer boat!
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Re: rear springs & ride height

Post by Deathaga »

Thanks for the measurements, I seem to remember last time I had my alignment done the front wasn't anywhere near as low as it is now, I've had a lot of parts apart and replaced most of the front end and tightened bushes with the suspension compressed which it might not have been before.

hopefully nothing for me to worry about, I never liked the front sitting higher anyway just worried if I'm too out of spec I'll damage something.
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Re: rear springs & ride height

Post by 350matt »

Usually you want to run some rake so the rear is higher than the front, you don't need much

at the moment I'm running 355 front and 370 back which suits me
however this is Tein S springs on PZ shocks with homemade platforms..... so a bit of a weird reference point
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Re: rear springs & ride height

Post by warpc0il »

My car is currently running Mazda oem sports shocks with Eibach Pro-sport option springs.

These give a slightly more nose-down stance than the original setup.
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Re: rear springs & ride height

Post by NeMFO »

This probably isn’t the right place for this post but I need some help. I bought a set of PZ suspension from the club a while back and am finally getting round to fitting it. The problem I have (like I have only had one with 15 year old nuts and bolts lol) is that I don’t know which pair of springs to put back on the rear. I suspect it is the slightly shorter pair or is it the longer ones with the partial clear plastic covering. I don’t appear to have any instructions so has anybody got any pertinent experience please?
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Re: rear springs & ride height

Post by Ollie »

Plastic coverings are the rears.
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Re: rear springs & ride height

Post by NeMFO »

Thank you 👍🏻

I don’t mean to be rude but I have to ask how you know because I think they are a bit longer so I thought they would be for the extra weight at the front ? Thanks again.
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Re: rear springs & ride height

Post by NeMFO »

Actually , I just checked the Eibach website again and that suggests there’s more weight on the back axle and the recommended rear springs have an HA suffix which I saw on the springs so thanks again for your help 👍🏻
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Re: rear springs & ride height

Post by Volmars »

Long shot ...while we're talking suspension... anyone know the Eibach product code for the rear coil springs on a PZ please?
(I.e. what did Eibach send over to Prodrive to tweak)
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Re: rear springs & ride height

Post by warpc0il »

Pete [Conan] may know, as he arranged the PZ suspension group buy, but I'm 99.9999% sure that they aren't any off-the-shelf Eibach part.
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Re: rear springs & ride height

Post by Volmars »

Thank you sir.