Runnig Coilovers with "low" spring rates

[agorge]

Hello,
I have a Mustang 04 GT convertible... good engine but I wanted to improve handling (street only and daily driver), everything is stock except (all mods done at Chicane, a Mustang shop in the LA area...good guys) :
- first mod was GW ladder subframe connectors and MM front strut tower brace: great improvement in the feeling of the car in corners
- second mod: MM Bilstein coil-overs; my objective was good handling and good ride quality...but this is where I am having problems getting the right setup
Initially I had 325 in the front and 200 in the back. The car is well planted but the ride is just too firm for the local freeways here, especially the rear is down right scary when hitting large uneven pavement at 75+mph. Also in some corners there was an incredible banging metal noise from the rear, adding a washer on the quad shocks helped but did not solve the problem; as well as very obnoxious squeaking from the rear (pretty much all the time). I ordered 175 (MM suggestion) for the rear but while waiting the shop installed a set of 225. The squeaking noise disappeared, and also the metal banging improved (but did not disappear). When they took off the 200, there was significant rubbing between the inner spring and the black sleeve around the shock, probably the source of squeaking (the guy also mentionned that the 200 spring seemed to be fitting looser than the 225).

So here is my question, if I install the 175 will the squeaking and the loud interference with the quads come back even worst? Is anyone running this with the the fully stock quad link?

I am contemplating also going down to 300 in the front...any experience with this?

At this point I really don't want to change anything else on the suspension, and since I am still running wheel rates more than twice stock, what do you feel is the lower end for spring rates, both front and back, on a similar coil-over setup?

Thanks for the Help!!!!

 

[Torinalth]

ehh.... i think you are on a slightly incorrect path. lemme re-read the entire post again to be sure though...

ok i am going to ask for some clarification, but still give my advice, and then alter later if i am assuming incorrectly.

i understand that you are looking for a good grib, but not wanting to sacrafice too much (i am guessing this) however your main point you brought up was noise and the scary back end when going over bumps...

i think you have made a very poor choice with downgrading springs. this will effectivly make the rear end less viable under stress, but it will give the offset effect of "feeling" more stable when NOT going full tilt in a corner. to elaborate, it gives a little more but hits the wall sooner. so if you dont like it, you will not like the lighter rate. i think you should go further into the suspension to correct the problem rather then trying to live with it.

the reason for that statement is that the quadlink is garbage, and is the reason for the event you cited as being scary. to assist with this i would MASSIVLY recommend staying with the 225 the shop installed in the rear, adding MM LCAs (poly/heim hybrid for your case, it eases road noise) and yanking the upper control arms for a favor of the EvM trilink or MM Torque arm, and add a panhard rod to the list.

the issue you have now is the fact that you have an incomplete system. this is the same crossroads i am at. at this incomplete stage you have all the noises, and large querks of the loss of OEM design... however we have not gone far enough in the design change to alter it over to the finished geometry yet. thus we have mild upgrade in handeling, and more noises then you can shake a stick at... let alone find. get to the end roads and most of your issues will be solved.

i cant help with the CO issue as i have heard thats just part of the demon you have to fight with COs... they do rub... however, with LCAs you can yank the quadshock and eliminate one issue. i do not recommend lowering the rate in the front either, i think you should REALLY think hard on this. these are common issues that you will face in the aftermarket. you either finish the goal or return to stock, because if you cant stand the noises then you only have those two options.

you can run wheel rates 3-4 times that of stock and still handle well... meaning not feel like a track car. again your project is not completed... regardless if you call it finished the suspension is NOT finished.

on a side note what bilsteins you using? specifically part numbers... makes a difference to the valving for them... and wiuth that how they perform with the COs.

Torinalth

 

[agorge]

Hi,
My purpose is how you stated: good handling without sacraficing too much (and paying double for another car without a V8...)
After the chassis stiffening I chose the coil-over because when you look at the price difference with a full kit it's not that much and I was hoping to get similar ride quality, but with a hjigher wheel rate.
In general I think what people say about CO is true, ride quality is better over small pot-holes and at lower speeds, even if you can feel if you're running over a quarter...and I can perfectly live with that.
At the moments my complaints about CO (except for noise and clearance with quads...) is not really in turns or real handling: the car is very planted and feels very good. But when you pick the pace in a straight line on a bad road there is something wrong (for example on LA freeways): the car is much worst than stock! It ends up jumping around and feels like it is losing contact with the road...very dangerous, and makes me go slower than before...! That's why my first thought was decreasing wheel rate (but then I am worried of all the problems I encoumtered with the CO).
So basically, ther are 2 directions I coul take:
1/ go all out like you are saying: I think it would work, but I feel it is just too much for a street car (noise for a tri-link, weight/clerance of a torque arm), and of course a lot of extra cost
2/ try and get back closer to stock (after all it was working): is it possible with a coilover? If not I might have to get a Bullit kit and try and sell the COs...it sure won't be free...
I am leaning for option 2/ right now, so any advice from people that might have been in this situation is usefull...
Torinalth, what spring rates are you running? Any complaints?

Thanks...

 

[san~man]

A CO system won't solve the wandering of the rear end.

To do that, you need to get some matching LCAs and the PHB. After that, you'll have a totally different handling car from what you have now.

 

[hotmustang331]

Im running 175 up front with drag shocks on setting # 1 (SOFT) lol...and really its not THAT bad. IMO just get some 225 or 250# springs and some stiff struts....that should be plenty for anyone and with adjustable struts you could tune it to how stiff you wanted the car.