Coil conversion problem

[get it up there]

Hello!!!!! I have just put a custom 4 link coil setup into the back of my sierra. I know of people using nissan 180sx coils in the rear of their vitaras, this giving them a 2" lift, and a nicer ride. I then decided to use these coils also, which all worked out good.. untill now!!!!!!!!!! I got the cab back on today and the coils are sagging waaaaay to much :( Now i just have to figuire out what to do about the sagging.. coils spacers would fix it, but i think the coils are still to compressed, even while just sitting in the shed!!! I have been told a bit about custom coils... can anyone shed some more light on these? Well, any thoughts would be good about now!! Thanks heaps

[big lux]

https://www.suspensionstuff.com.au
2/3405 Pacific Hwy, Springwood, Qld
Free Freight Vic, NSW, Qld, Perth & Adelaide
1300 048 991

known as suspension stuff on here shoot him a pm maybe, heard good things

[Tiny]

try calling lovels or dobinson, someone who manafacture coils, give them unsprung and sprung weights, coil diamater, compressed coil length required and see what they have that is suitable

[spamwell]

honda crv rear coils, can get standard or 50mm lifted from pedders, probly suit your application, see my build on auszookers

[76patrol]

hey bud, when i first did my conversion i went and raided the scrap bin at tjm. got a heap of different coils and worked out what would suit. i ended up usin gq 1 1/2 lift coils. but surf coils were great but didnt like haulin my trailer. its a cheap way to get a heap of different setups till you find what suits. less wasted money and more for fuel lol. nice build by the way. ray

[get it up there]

sweet.. thanks for the feedback. I will try and get more details of the 180sx springs so i then have something to tell some of these suspension places... im hoping they will be able to roughly work out how much the coils will sag etc, to be able to get the ride height back normal again?

[TWISTY]

The previous owner of my old zook had a couple sets of custom coils done by Dobinsons....they seemed to work really well.

[joeblow]

mmm.....i do believe i said that will happen

[lukes4x4]

At LUKEYS 4X4 CUSTOMS we can work out custom spring rates and supply coils to suit. give us a call on 0409 991742 . cheers lukey

[lay80n]

Do you have corner weights? if you can get these coil rates/heights etc are not too hard to work out.

Layto....

[get it up there]

sweet.. thanks everyone!!! At this stage i think it all may be sorted... if it is i'll post up the outcome.. for when/if that search button is ever used!!!

mmm.....i do believe i said that will happen

hhhmmmmmm, and i do remember you saying this.. and it did cross my mind whilst building everything... dozens of times!!!!!!!!!!!!!!!

[Gwagensteve]

Back looks about right to me.... Its height of the front that's the problem IMHO.

Here's mine sitting about 2.5" above ride height. I'm on stock Vitara SWB rear springs.



PS got bumpstops?

[get it up there]

I do agree with you there Gwagen..
As for the bump stops, nope... havent got them yet, caused i havent flexed it up whilst having the cab on... just gotta see where it will hit etc

[1MadEngineer]

if you haven't noticed from the replys, the guys that don't have problems generally run FACTORY springs! We NEVER run aftermarket springs! ever, its just a waste of time. They are crap, the steel is made in 'farknowswhere' and has bits of old ships and leftover coke cans in it (ok so it might not be that bad ).
You just have to think, you go to a wrecker and get a spring that hasn't sagged after being in a car for 200000km, so it aint going to get any worse!

The trick is to find something that fits the specs you need, this is usually just a bit of trial and error, but generally pretty easy to take a reasonable guess at. plus most time a wrecker will give you a bag of springs for $100.

[Nelso]

Back looks about right to me.... Its height of the front that's the problem IMHO.

Have to agree. I would drop the front to match the height of the rear. Those springs look like slinky springs. They would give you heaps of down travel.

[get it up there]

I have managed to loan a pair of heavy duty CRV coils. They are a beatiful fit in the lower mounts, but the upper mounts are going to need re-fabbing. They are heaps flexier than what i first thought.. and it appears that i will even be able to have them retained in the top and the bottom But i have it all pulled apart again, and have started grinding off the upper mounts, and will be replacing them with something different, and at the same time i'll be lowering the back a bit. When i go coils in the front, i will also aim to lower the entire vehicle by a couple of inches or so. Ggrrrr, never bloody ends!!

[chimpboy]

Back looks about right to me.... Its height of the front that's the problem IMHO.

Yep, you need a much heavier engine.

[Tiny]

Back looks about right to me.... Its height of the front that's the problem IMHO.

Yep, you need a much heavier engine.

lol, commo V6

[Gwagensteve]

Get it up there,

You might have designed your suspension a bit back to front. When I did mine, I made a quick estimate that a back of my sierra weighs about the same as a lightly laden vitara. As such, I worked out my spring position and bumpstop location based on the length of a vitara rear spring at ride height in a vitara.

If my car weighs more, I can use GV, XL-7, aftermarket, or even jimny front springs to tune in ride and height.

The important thing is that I can't overcompress the springs - I'm not compressing them more than they were compressed in a vitara - and that I have a known reference point. I'm also not trying to achieve more vertical travel out of them than suzuki intended. Bumpstops are an integral part of this design. They weren't positioned afterwards based on clearance, they were placed based on spring travel.

Lowering bumpstops is fine to create clearance - so long as you know where you reference point is. Those 180SX springs look cool - and it looks to me like they are sitting about the way they were intended (they are clearly a progressive rate spring) but you have no idea how much compression travel the rear of a 180SX would have loaded the same way you sierra is, so it's hard to know whether you have 2" of compression travel or no compression travel in those springs.

Personally, I'd throw some vitara rears in there, and measure the bumpstop clearance on a stock vitara at ride height. then you know where you should be putting your bumpstops, what height the car sits with a known spring designed for a similar application, and what you stock replacement and aftermarket options are.

I think it's a terrible idea to design a suspension around an aftermarket spring. You want to start at the softest stock spring you can and then all your options add load capacity and height.

PS did you design your links around the height the rear is at now, or the height the front is at? AFAIK link geometry really only solves for a set ride height, and without bumpstops how do you know your desired compression travel won't have the links binding?

Just some thoughts. I'm not trying to be negative, I just think it's interesting the springs, and especially bumpstop placement looks like an afterthought.

Steve.

[get it up there]

Your probably right with most of what your saying mate.. but this is comes down to experience.. and considering this is the first time i have EVER had much to do with coils, i think im going all right so far!! I designed it to suit what the rear ride height was when it was leaf sprung.. so ideally to match the front. Now you have said it, it will make it hard to lower the ride height down when the time comes, but i'll get the 4 link calculator out again for that and see how we go. Also, you are correct - the bump-stop and springs have always been a bit "unsure" during this conversion.. it will all work out eventually!! As for the travel.. this is the up travel it had with no bump stops - and on the 180 springs... so if i use these CRV coils, i will have no probs with the links binding up

[get it up there]

In those pics you will also note that i wasnt running retainers on the top of the coils... if i can use these CRV coils i am playing with, i should be able to have them retained top and bottom.. fingers crossed!!

[Gwagensteve]

From what I can see, you've done a great job of the link geometry but your shock placement and coil choice is where the work is required.

Your flex shots show how sound your link geometry is. However, have a look at the way your spring is compressing - basically, it isn't. There's probably 3" or more compression left in that spring, and you want that - that's a 3" lower COG when you are crossed up on an obstacle. It looks like the limitation there is that the tyre is on your shock crossmember. that's understandable - even leaf sierras have to have that area clean for the tyre to clear. However, you might want to try raising the roll centre a bit by raising the upper link mounts on the diff. This will roll the diff "out" further under articulation on the compressed side and add clearance against the chassis, helping you to get that spring compressed. Note how high my panhard rod is - I tried to run the roll centre as high as feasible considering the length of the bar.

If you get the compressed side 3" higher, you'll get much more articulation out of the same spring without it going loose. There's very little relationship between spring travel and articulation, and having the springs go loose, especially unless you are HARD on the bumpstop on the compressed side.

If you move the bottom shock mount further outboard you'll get shock shaft travel closer to wheel travel - this will be good for handling. At the moment you're not using much shock travel and that will mean you'll have limited damping.

Just some ideas.

Steve.

[get it up there]

Thanks for the detailed info steve.. it all makes heaps of sense, and i will take it all on-board.

I just went up and chopped off the upper mounts (they were bundera lowers).. this lowered the back by around 2" If i measure off between the top of the tire and the gaurd, the back is still 40mm to high. You can sort of see in these pics. So, 2 questions:

* These coils are brand new, will they "settle" once used, and loose a bit of height?

* If not, can you get coils lowered at a spring shop, and is this a good idea?

What the plan is now is to continue using the lower (vitara) mounts, and have the coils retained to these. As for the uppers, im planning to have a ring (50mm deep) around the outside of the coil, and the bump stop will be inside the coil. If all goes well, i'll also use a retainer in the uppers. Please everyone.. share your thoughts!!

Currently:





This is where the ring will be.. it obviously needs some prepping first though..

[chimpboy]

Please everyone.. share your thoughts!!

Your bonnet scoop looks crooked

Just kidding, I wish I had more to contribute but wanted to say thanks for sharing the build-up including all the issues, it is interesting and good to see a discussion and exchange of ideas for once instead of just shitfighting.

[get it up there]

True true chimpboy!!!!! It has been a very interesting process!! After 100,884 different ideas/methods, I am now using a bundera housing, hilux centre, vitara coil mounts, CRV coils, and extended GQ patrol control arms.. all under a sierra!!! hehehehe