Another Spring and damper question
Discussion
I've trawled the previous threads on this but not found what I'm looking for.
I'm not a trackday hero but use my 98 Chim for long distance cruising and weekends away.
Problem is when the car is fully loaded with 2 large adults, a load of luggage/shopping and a full tank of petrol, the back end squats a little low and a little too readily under acceleration. So much so that its got to the stage where I'm regularly flashed by oncoming drivers at night as my lights are obviously dazzling. I've had the headlight alignment checked more than once so I know that's not the problem, but obviously in the garage it's only only been checked when the car is unladen.
Car's done 36,000 miles and is still AFAIK on original springs/dampers. So what do I uprate to?. I understand that I can't change the rear without changing the front proportionatly as well, otherwise I'll adversely affect the balance of the car. So, do I just up the poundage of the springs or do I perhaps need to consider spring length? New dampers will obviously need to be matched to the new springs
I don't want to end up with someting spine jarringly hard, so what might be a good starting point?
I'm not a trackday hero but use my 98 Chim for long distance cruising and weekends away.
Problem is when the car is fully loaded with 2 large adults, a load of luggage/shopping and a full tank of petrol, the back end squats a little low and a little too readily under acceleration. So much so that its got to the stage where I'm regularly flashed by oncoming drivers at night as my lights are obviously dazzling. I've had the headlight alignment checked more than once so I know that's not the problem, but obviously in the garage it's only only been checked when the car is unladen.
Car's done 36,000 miles and is still AFAIK on original springs/dampers. So what do I uprate to?. I understand that I can't change the rear without changing the front proportionatly as well, otherwise I'll adversely affect the balance of the car. So, do I just up the poundage of the springs or do I perhaps need to consider spring length? New dampers will obviously need to be matched to the new springs
I don't want to end up with someting spine jarringly hard, so what might be a good starting point?
GreenV8S said:
How about loading the car up with two adults and the kitchen sink and then aligning the headlights?
Problem is that when the more vociferous of the 2 adults and all its travelling accoutrements were removed from the car, the adjusted lights would probably then only illuminate an area 3ft in front of the car.
All you need is your old springs onto a pair of adjustable platform dampers on the rear, and adjust the ride height according to how the car is laden .. ie after you've loaded your luggage, sit two people in the car and wind th spring seats up till you reclaim your ride height back. When you're unladen put it back to std height again.
325lbs at the rear is going to feel very stiff (and more so than the front which doesn't sound right to me). I have 300lbs which feels firm enough. Also, IMHO if you're going up on spring rates you'll want some decent dampers that move easily but still control it all. I noticed that I can bounce the front wing up and down more easily with 400lb springs and Nitrons than I could with the original set up. Makes it reasonably comfy whilst reducing roll/pitching etc. Increasing ride height each time you go out sounds like a pain but at least it wouldn't mess up the handling. Looks like the best bet is new springs and dampers all round 
GarryM said:
325lbs at the rear is going to feel very stiff....
It is very stiff!I've done a lot of different experiments with the spring rates,on the rear in particular.The best spring rate for grip is the softest one!!I found it interesting that Nitron only really recommend 250lb for the rear(their kit for these cars is 250 rear/350 front)std,which many would believe too soft,but it really works.I know that Julian(Trackcar)also recommends 250-275 at the back on his Protechs.By what i've now learn't i wouldn't go over 275lb to be honest,and if you have good quality dampers,you should be able to run this soft successfully.I take an opposite opinion on this one, I can't speak for other shock manufacturers but on Gaz with 400/325 springs we are on 15 clicks front and 25 clicks rear for a fast road set-up, this puts the damper bang in the middle of its range.
What I can tell you is that I have played with other shocks with much narrower adjustment bands and on full soft they still had significant bump and rebound.
I can also tell you that I can have my chim like a bouncy castle on these spring rates, or very hard.
I haven't added it up lately but I have in excess of 200 Chim/Griffs running on the rates recomended by by Guglielmi and adopted by all my dealers, do you hear the howls of dissatisfaction? I don't think so
>> Edited by the gazman on Monday 8th May 17:22
What I can tell you is that I have played with other shocks with much narrower adjustment bands and on full soft they still had significant bump and rebound.
I can also tell you that I can have my chim like a bouncy castle on these spring rates, or very hard.
I haven't added it up lately but I have in excess of 200 Chim/Griffs running on the rates recomended by by Guglielmi and adopted by all my dealers, do you hear the howls of dissatisfaction? I don't think so
>> Edited by the gazman on Monday 8th May 17:22
mongoose said:
325lbs at the rear is going to feel very stiff....
the gazman said:
Probably a good idea but for only £40 extra, I'd put some 325lb springs on the back as well. Written at 6.31 a.m.
the gazman said:
I take an opposite opinion on this one, I can't speak for other shock manufacturers but on Gaz with 400/325 springs we are on 15 clicks front and 25 clicks rear for a fast road set-up, this puts the damper bang in the middle of its range.
What I can tell you is that I have played with other shocks with much narrower adjustment bands and on full soft they still had significant bump and rebound.
I can also tell you that I can have my chim like a bouncy castle on these spring rates, or very hard.
I haven't added it up lately but I have in excess of 200 Chim/Griffs running on the rates recomended by by Guglielmi and adopted by all my dealers, do you hear the howls of dissatisfaction? I don't think so
Derek, just my observation but may I suggest thatyou may not have woken up fully and that you might want to amend/clarify your 6.31 a.m. statement? Rear/front spring ratios usually work out at between 0.66 to 1 and 0.75 to 1. Your standard set up is 0.81 to 1 so your opinion is slightly different but hardly opposite (especially when the bush/rose joint and ARB values should be added in as well.) Bearing in mind that the front springs may be as low as 275, then putting 325 on the rear and fitting new dampers would give you 1.18 to 1 which I doubt is what you meant really.
Cheers, Jonathan
So, the suggested stiffened springs may sort out my particular problem out, but if not, I may have to adjust the ride height from time to time as well.
Given that, are the spring rates that Gazman's suggested as good a starting point as any?
Am I right in understanding that all replacement springs have a linear rate of compression and the original ones were progressive? If so does this mean that the linear springs generally tend compress less under the same loading?
Given that, are the spring rates that Gazman's suggested as good a starting point as any?
Am I right in understanding that all replacement springs have a linear rate of compression and the original ones were progressive? If so does this mean that the linear springs generally tend compress less under the same loading?
sparkythecat said:
So, the suggested stiffened springs may sort out my particular problem out, but if not, I may have to adjust the ride height from time to time as well.
No, you seem to be muddling up two solutions: solution 1 fit new dampers with adjustable spring seats(no new springs) the spring seats can then be adjusted at times of heavy load. solution 2 fit new, stiffer springs all round(no new dampers) this will minimise the effect of extra loading but will only partially solve the problem. In short the adjustable spring seats and adjusting them as necessary will solve the problem; if you go down this route it would be better to buy a set of four new springs and match them to the dampers - these new springs will also lessen the problem if they are stiffer.
sparkythecat said:
Given that, are the spring rates that Gazman's suggested as good a starting point as any?
No, not on their own, only as a matched set of four - which I think is what he meant but it just appears to me that his original statement was misleading.
sparkythecat said:
Am I right in understanding that all replacement springs have a linear rate of compression and the original ones were progressive?
Not all but most.
sparkythecat said:
If so does this mean that the linear springs generally tend compress less under the same loading?
With the spring rates mentioned in this thread, yes.
JR said:
Derek, just my observation but may I suggest thatyou may not have woken up fully and that you might want to amend/clarify your 6.31 a.m. statement? Rear/front spring ratios usually work out at between 0.66 to 1 and 0.75 to 1. Your standard set up is 0.81 to 1 so your opinion is slightly different but hardly opposite (especially when the bush/rose joint and ARB values should be added in as well.) Bearing in mind that the front springs may be as low as 275, then putting 325 on the rear and fitting new dampers would give you 1.18 to 1 which I doubt is what you meant really.
Cheers, Jonathan
I take your point but I was thinking about my shocks with the springs, with softer rear valving on the damper a 325 spring can work ok with a front end working on a soft spring and hard valving and again I have a few examples out there.
the gazman said:
I take your point but I was thinking about my shocks with the springs, with softer rear valving on the damper a 325 spring can work ok with a front end working on a soft spring and hard valving and again I have a few examples out there.
Thanks. I'm glad that you're back - after saying that your post was unclear I don't think now that my last post was clear, lol. Time for a break? Jonathan
JR said:
So, the suggested stiffened springs may sort out my particular problem out, but if not, I may have to adjust the ride height from time to time as well.
No, you seem to be muddling up two solutions: solution 1 fit new dampers with adjustable spring seats(no new springs) the spring seats can then be adjusted at times of heavy load. solution 2 fit new, stiffer springs all round(no new dampers) this will minimise the effect of extra loading but will only partially solve the problem. In short the adjustable spring seats and adjusting them as necessary will solve the problem; if you go down this route it would be better to buy a set of four new springs and match them to the dampers - these new springs will also lessen the problem if they are stiffer.
sparkythecat said:
Given that, are the spring rates that Gazman's suggested as good a starting point as any?
JR said:
No, not on their own, only as a matched set of four - which I think is what he meant but it just appears to me that his original statement was misleading.
JR, thanks for your reply, but I'm not at all confused . I appreciate what you are saying, but, if you read my original post, you'll see that I was only considering the option of a a complete car set of 4 matched new spring/dampers as a solution. I hadn't really considered retaining any of the originals. My question was really about the spring specs necessary to achieve what I was after. I know there will be some degree of trial and error and involved, but I was trying to narrow the parameters down a bit before I started.
>> Edited by sparkythecat on Monday 8th May 23:06
sparkythecat said:
JR, thanks for your reply, but I'm not at all confused . I appreciate what you are saying, but, if you read my original post, you'll see that I was only considering the option of a a complete car set of 4 matched new spring/dampers as a solution. I hadn't really considered retaining any of the originals. My question was really about the spring specs necessary to achieve what I was after. I know there will be some degree of trial and error and involved, but I was trying to narrow the parameters down a bit before I started.
Right, I see now. In that case mongoose's reply looks like a good summary to me.
JR said:
Derek, just my observation but may I suggest thatyou may not have woken up fully and that you might want to amend/clarify your 6.31 a.m. statement? Rear/front spring ratios usually work out at between 0.66 to 1 and 0.75 to 1. Your standard set up is 0.81 to 1 so your opinion is slightly different but hardly opposite (especially when the bush/rose joint and ARB values should be added in as well.) Bearing in mind that the front springs may be as low as 275, then putting 325 on the rear and fitting new dampers would give you 1.18 to 1 which I doubt is what you meant really.
Cheers, Jonathan
ratios smatios. It doesn't really matter what front/rear ratios you end up with (it's just a number) as long as *it gets you what you want and doesn't compromise the car unduly for any avoidance/stability situations*
Most Tivs end up with spring rates in a certain range because that's what is found to work well for most people, but it's not always the case. And anyway it's not the spring rate ratio you want to be looking at, it's the wheel rate, and even then it doesn't translate into any specific handling trait per se except in a very general form.
If this guy wants uber stiff back springs because he doesn't want to adjust anything, then that's ok as long as the safety issue isn't compromised.
There's no right and wrong on spring numbers .. give the customer and the car what it needs to get the job done, that's all there is to it.
the gazman said:Not strictly true Derek,my experience does relate to more than one type and brand of damper
Mikes summary was clear and concise but related to his experiace with one brand of dampers, those rates suited the valving on his dampers and wouldn't be the case on all others IMHO.
.Part of the point i was trying to make though,was that i would rather have a softer spring rated combo,and feel that a shock designed/valved around a softer spring is better.You just cant get too much grip on these cars at the rear i feel,and at the rear is also where you predominantly feel the ride quality,which is why i squirm a bit at so many thinking that stiffer is always better.The front i like stiff,as i really like a sensative turn in,but then it doesnt affect the ride quality too much,so you can get away with it.My current combo is 250 rear and 375 front,and i cant see that changing much from now,if i do change,then its only going to be a little stiffer at the front,but i doubt i will.As Trackcars says though,its all down to personal preference at the end of the daymongoose said:
Mikes summary was clear and concise but related to his experiace with one brand of dampers, those rates suited the valving on his dampers and wouldn't be the case on all others IMHO.
Yeah, we all want the same thing, however I must say that when I sell springs only I do have to be a bit careful and find out what they are going on, there are some brands that I do drop 50lb on and particularly on the rear, so your point is probably valid.
Gassing Station | Chimaera | Top of Page | What's New | My Stuff