Suspension Questions

Mr Hardware · 17-12-2009, 11:43 PM

So i've got an idea to change the suspension (shocks and springs) on my AUII to make the ride smoother, and i've got a lot of questions about it.

For arguments sake, lets say my springs and shocks are all the same age, 200,000k+.

I currently have a good one to one and a half inch gap between the top of the tread and the bottom of the wheel arch, ie standard Forte ride height.

For my driving style, I cannot accept the inconveniences associated with a lowered car (SL's, SSL's etc), for the same reasons i refuse to have any lower than 60-profile tyres, i mildly disregard speedbumps and i gutter-hop far too much (it's a falcon, it can handle it).

I also like an extremely smooth ride and don't really care about handling performance, most of you here see your Fortes as budget XR6's, i see mine as a budget Ghia, for want of a better analogy.

My questions are this:
1. Do springs sag over time? If so, is it by much?
2. If i replace my springs with standard height springs, will that improve the ride, and if so, what way and by how much?
3. If i replace my shocks (struts?) with entry level units, will that improve the ride, and if so, what way and by how much?
4. Are Kings 'Low' Springs the same height as factory XR6 springs?
5. How much lower would King Lows be than standard forte height springs?
6. If i do decide to go with King Lows, would i need to go with shortened/different shocks, or would standard ones be okay?
7. Would i lose much(any?) ride comfort by going with King Lows?

Thanks in advance guys, and yes if I go ahead with this I will be doing it myself, I have spring compressors on hand (ref Grandpa_Spec).

grandpa_spec_F6 · 17-12-2009, 11:55 PM

Well just speaking from the little knowledge I have, the lows you can use with standard shocks, I only needed the shortened ones for the rears (SL)

The ride is smooth as your mothers left nipple on the road however I am in need of a spinal adjustment after trying to tackle a dirt road out near Veriadale on the weekend :(

Mr Hardware · 18-12-2009, 12:05 AM

Oh okey doke.

Windsor220 · 18-12-2009, 12:11 AM

Yes I'm pretty sure lows are around the XR6 height. Probably around 1 inch lower. You wont need shortened shocks for these.
Ride would be ok. My SLs arent even that bad. But mine is IRS so may be different.
New shocks will firm up the ride if the old ones are on the way out.
Springs do sag overtime but it varies on the use of the car.

T3man · 18-12-2009, 12:12 AM

1. Springs sag over time but depending on how "hard" your car has travelled I wouldn't be replacing them at 200k km. Plenty of taxis do up 500k and original springs are still serviceable. Of course many do a lot more and you can tell just by looking at them that their springs are sagged.

2. answered above

3. new shocks (struts) will improve ride - but not necessarily the way you want. They will definitely make low speed bump and rebound firmer than your currently tired units. This may not be to your liking. However in harder driving where shock piston speeds are increased the new units will dampen the springs better and give a more controlled and comfortable ride. Again from what you have said, you may not drive hard enough to get the benefit.

4. yes, pretty much

5. about 30mm

6. standard length shocks will be OK

7. not a lot provided you match them with a good quality shock. The lower springs are also stiffer so your low speed bump and rebound is going to be harsher than at present. You've said you don't want to go this way so don't even consider it is my opinion.

Now, to offer a suggestion based on what you have said you need from your car ...

Basically you need to replace only the shocks to get what you want BUT you have to be very careful that you don't "overkill" the springs you have. Rule out any high pressure gas shock.

This leaves you with three basic choices - a) standard fare (low pressure gas) which will give the result in 3. above. At least you know what you're getting - standard Forte ride which is comfy enough; b) aftermarket performance hydraulic shock - this will give a softer ride and will only stiffen up when driving spiritedly. Only downside is they don't last more than 100k km (but they are cheap); c) aftermarket high performance low pressure gas - Koni Series 82 would be perfect as they are very compliant at low speeds, stiffen up at higher speeds, and they last forever (well, virtually - they will most likely outlive your car). They will cost you up to $1500 (full set) supplied and fitted but in the long run it is money well spent. They are an adjustable (off the car) unit and should be fitted initially on their softest setting - this will give you the ride comfort and control you are looking for.

Mr Hardware · 19-12-2009, 09:19 AM

Oh wow, that's really good information T3man, and i'm not terribly surprised at a lot of it, as it was sort of my very uneducated opinion that was the case, however i had been previously informed otherwise, and i was going "......i dunno hey..." in my head.

Thankyou so much T3man for the good info, and I'm pretty sure i'll give it all a miss, because no, i don't drive hard, almost ever, but i do drive rough, i treat it as the next best thing to a 4wd. Rep added.

GK · 19-12-2009, 10:12 AM

T3man, I also found your suspension information really useful. Great post.

I added to your rep, but the window closed, so I only got to say Gr..........! LOL! It should of say "Great Post".

Perhaps a Mod can fix that for me?

GK

Mr Hardware · 19-12-2009, 12:10 PM

Yeah i'm really grateful for the help on here, and i like the rep system.
So much good, proper information. What T3man said was very similar to my own limited knowledge.

I had been told all manner of fibs from someone i know, i was dubious as this is the same someone who told me that 18" wheels with rubber band tyres will give you the same ride as 15's with 65-profile tyres "because they run the same PSI".
Suuuuuuuuure they do.

mik · 19-12-2009, 06:23 PM

actually i put adjustable koni`s on mine the xr6 already has fairly stiff spring rates, replaced sway bar with the poly bushes, and with shocks set at 50% the ride still was`nt too bad , allthough some might say its a little on the firm side but after receiving 18" wheels as a gift (very sexy ones i might add

) the wheels made a huge difference to the ride......wow i`m still looking for my back teeth, mind you the tyres are 2nd handies and quite old even though tread is still ok, i`m hopeing some neweys will take some of the harshness out.