p3te Posted April 19, 2011 Share Posted April 19, 2011 Hi, I’ve previously set all the ride height on my hks hypermax II and had a full geo set up, but last weekend i fitted a 12" sub, 2 amps and a custom fibreglass box and now the back of my car sits lower (only about 1" gap between tyre and wheel arch, about 2" gap on front) I’ve also fitted a set of 10mm wheel spacers to my 19x9.5 rear wheels. The wheels now actually bottom out and rub on the rear arches so i was wondering if i lifted the back suspension up to the get the same gap in the arch as the front and 10mm wheel spacers will it affect my geo? Quote Link to comment Share on other sites More sharing options...
p3te Posted April 19, 2011 Author Share Posted April 19, 2011 Anyone know? Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted April 20, 2011 Share Posted April 20, 2011 If you are returning the ride height to what it was when you had the geometry set then I do believe it won't affect camber and toe so your geo should be as it was. However instead of just lengthening the strut body I think you may need to increase the preload on the springs (or a combination of the two methods) to regain the lost ride height to help counteract the effects of the added weight in the rear and the wheel spacers. Quote Link to comment Share on other sites More sharing options...
p3te Posted April 20, 2011 Author Share Posted April 20, 2011 If you are returning the ride height to what it was when you had the geometry set then I do believe it won't affect camber and toe so your geo should be as it was. However instead of just lengthening the strut body I think you may need to increase the preload on the springs (or a combination of the two methods) to regain the lost ride height to help counteract the effects of the added weight in the rear and the wheel spacers. Im not sure exacrly what it was set at but if i put it the same height as the front that ehould be it? Also how do you adjust preload on the hks suspension? Quote Link to comment Share on other sites More sharing options...
p3te Posted April 20, 2011 Author Share Posted April 20, 2011 Should front and back ride height be the same. Or rear lower? Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted April 20, 2011 Share Posted April 20, 2011 how do you adjust preload on the hks suspension? By winding up the bottom spring perch, effectively compressing the spring while the weight of the car is OFF it. This gives you a stiffer spring rate, which you need to offset the heavier load. (This is all based on the assumption that whatever coilovers you have fitted have these adjustment features) But I'm no expert (or anything even close) so a balance may need to be found between stiffer spring rates and increasing the strut length (again, if this option is even available) to keep the car from becoming rock hard at the rear. Should front and back ride height be the same. Or rear lower? That may depend on what type of set-up was dialled into your car. Was it track or drag strip biased or simply returned to a stock value? But to begin with I'd just adjust the rear to get the car sitting level, take a level reading from the doorsill, then test the ride height to see if there is any rubbing at the rear. Most of what I've just written may be used to wipe your arse with. The problem may be so small that simply adjusting the ride height will produce totally satisfactory results. In other words, you need someone who knows what they are talking about! Quote Link to comment Share on other sites More sharing options...
Scott Posted April 20, 2011 Share Posted April 20, 2011 The pre-load won't change regardless of how much you wind up the spring so best to leave that as it is unless you have no other way of altering the height. The Spacers will have made a little bit of a difference to your geo as will the height difference. You can get the height roughly to where it was previously, by measuring it with the kit out or guessing, but there is no way to alter the camber properly for the spacer addition. To be honest I don't think it will make a noticeable difference if you put the height back to where it should be. If you want to be safe rather than sorry you could get the geo re-done though. Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted April 20, 2011 Share Posted April 20, 2011 The pre-load won't change regardless of how much you wind up the spring so best to leave that as it is unless you have no other way of altering the height. Scott, would increasing the height of the bottom spring perch not increase the preload on the spring there by stopping the spring from compressing as much when the weight of the car is put back on it? Quote Link to comment Share on other sites More sharing options...
Scott Posted April 20, 2011 Share Posted April 20, 2011 Scott, would increasing the height of the bottom spring perch not increase the preload on the spring there by stopping the spring from compressing as much when the weight of the car is put back on it? Adjusting the pre-load height will lift the car up yes, but it won't change the spring load (it will still drop the same amount), it only decreases the amount of play before it bottoms out (I think this is the reason Tein SS are so solid on the roads, they bottom out). If it's the last option then you can do it that way. I think the HKS are bottom adjustable though are they not? Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted April 20, 2011 Share Posted April 20, 2011 Yes, yes, I see where my understanding was lacking now. The springs won't be any stiffer with the weight of the car on them, they simply wont compress as much if the preload is adjusted. But by ignoring preload and simply adjusting the length of the strut body isn't there a chance that the damper/suspension could bottom out? I have no idea what type of adjustment is on the HKS units. Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted April 20, 2011 Share Posted April 20, 2011 (edited) Adjusting the pre-load height will lift the car up yes, but it won't change the spring load (it will still drop the same amount), it only decreases the amount of play before it bottoms out (I think this is the reason Tein SS are so solid on the roads, they bottom out). If it's the last option then you can do it that way. I think the HKS are bottom adjustable though are they not? Should that not be increases? As in extra damper travel? EDIT: Nevermind I was reading your post arse about tit Edited April 20, 2011 by pedrosixfour (see edit history) Quote Link to comment Share on other sites More sharing options...
aman00123 Posted April 20, 2011 Share Posted April 20, 2011 You could always just take it to Revolutions and get the geometry checked for free Quote Link to comment Share on other sites More sharing options...
p3te Posted April 20, 2011 Author Share Posted April 20, 2011 You could always just take it to Revolutions and get the geometry checked for free thats wherevi got it set in the first place, i might just lift the back ride height to see if ot stopa rubbing then if they check it for. Free ill see what its like Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted April 20, 2011 Share Posted April 20, 2011 Actually I'm still at odds with what you said Scott. Surely a spring that has preload on it will resist a weight better (that is to say, will compress by a smaller amount) than a similar spring with no preload on it? Quote Link to comment Share on other sites More sharing options...
Scott Posted April 20, 2011 Share Posted April 20, 2011 Actually I'm still at odds with what you said Scott. Surely a spring that has preload on it will resist a weight better (that is to say, will compress by a smaller amount) than a similar spring with no preload on it? Sorry, I'll explain it better. I've been mixing up names for things in my hurry lol.. The pre-load can of course be changed and this will effect the height of the car when the weight is put onto it. If you increase the pre-load the car will get higher as it will already have xxkgs of force into it, thus negating the first xxkgs of weight the car has. The downside to this is that the spring will be in a compressed state while still having exactly the same spring rate. This means when you hit a bump or go over a pothole the spring will still travel exactly the same amount meaning that if you have compressed it too far, the spring will bottom out and give a VERY harsh ride. If you have a look at the tein ss springs they are fairly close together. Couple in with that the very low spring rate (to make them comfortable) and the fact that you need to pretty much max out the limitations of pre-load to get the supra off the deck it means that they bottom out a lot hence the harsh ride. Oh, this is IMO by the way as I haven't actually tested out the theory. I was in a discussion a few months back and myself and another member were talking about spring rates, I thought they were dynamic on the height adjustable range but it was pointed out they are infact static. This lead me to the question about the tein SS as they have a very very low spring rate yet are as comfortable as a cart with square wheels. Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted April 20, 2011 Share Posted April 20, 2011 Now we are singing from the same hymn sheet! Although I never realised that the spring rate remained unchanged regardless of the compression. Is that the difference between a linear and a progressive spring then, to increase the rate as the spring compresses? Quote Link to comment Share on other sites More sharing options...
aman00123 Posted April 20, 2011 Share Posted April 20, 2011 thats wherevi got it set in the first place, i might just lift the back ride height to see if ot stopa rubbing then if they check it for. Free ill see what its like Yea they check for free and if you want any adjustments to be made they charge but only if you ask them to make them Quote Link to comment Share on other sites More sharing options...
Scott Posted April 20, 2011 Share Posted April 20, 2011 Now we are singing from the same hymn sheet! Although I never realised that the spring rate remained unchanged regardless of the compression. Is that the difference between a linear and a progressive spring then, to increase the rate as the spring compresses? Yup, I always assumed they were all progressive until I looked into it during that discussion. Quote Link to comment Share on other sites More sharing options...
p3te Posted April 20, 2011 Author Share Posted April 20, 2011 So whats the best way to lifi it then? Turn the full thing with the hks spanners? Quote Link to comment Share on other sites More sharing options...
Scott Posted April 20, 2011 Share Posted April 20, 2011 Just googled it, am I right in saying yours only has the one locking collar? If so then you have no choice but to adjust the pre-load to raise the car. Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted April 20, 2011 Share Posted April 20, 2011 Yeah, from what I've just found on the web it looks as if the strut is on solid piece. You'll have to adjust the bottom spring perch upwards until you reached the desired ride height. Quote Link to comment Share on other sites More sharing options...
p3te Posted April 20, 2011 Author Share Posted April 20, 2011 Should front and back ride height be the same. Or rear lower? That may depend on what type of set-up was dialled into your car. Was it track or drag strip biased or simply returned to a stock value? But to begin with I'd just adjust the rear to get the car sitting level, take a level reading from the doorsill, then test the ride height to see if there is any rubbing at the rear. Most of what I've just written may be used to wipe your arse with. The problem may be so small that simply adjusting the ride height will produce totally satisfactory results. In other words, you need someone who knows what they are talking about! just for road use really? will be used 99% of the time on the road with the occasional 1/4 mile run Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted April 21, 2011 Share Posted April 21, 2011 just for road use really? will be used 99% of the time on the road with the occasional 1/4 mile run Well a proper drag setup would see the rear a fair bit higher than the front, the idea being that when the car launches and the rear suspension inevitably compresses because of weight transfer the drag biased suspension geometry holds the rear tyres as square to the road as possible to allow maximum traction off the line. But as you will spend 99.99% of your time on shitty roads with the rest of us I'd set the car up level and then see how it feels. Or better yet how about a picture of your car as it sits now, there are a few heads on here than can advise on ride height from a few well taken photos, paying particular attention to the gap between wheel arch and tyre and some steady side-on views. Tyre size and wheel type are major factors in settling on a suitable ride height so for me to simply say "set it level" was/is a bit simplistic. Quote Link to comment Share on other sites More sharing options...
p3te Posted April 22, 2011 Author Share Posted April 22, 2011 ok i have taken a few photos, all i have was my phone so they are not the best you can see though the gap at the back has much less of a gap than the front, i have took the spacers off but the wheel still rubs a bit, think I’m going to have to take my sound system out of the boot and see how it sits. http://img651.imageshack.us/g/dscf0001jy.jpg/ Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 22, 2011 Share Posted April 22, 2011 Good luck adjusting those, they look like they have been at the bottom of the sea for years If HKS adjusters are corroded they often split when you try to turn them. I am not sure why you are adjusting ride heights when the real issue is you have the wrong wheels and tyres on the car. The suspension should articulate from full droop to sitting on the bump stops with the springs off, without the wheels or tyres touching anything at all. Quote Link to comment Share on other sites More sharing options...
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