What Should I Do About My Suspension?

[luk3333]

So I'm in a bit of a dilema. My suspension sucks big floppy doodles. Currently it has stock ke70 suspension setup, chopped springs in the front and rear (probably sitting a bit below illegal height, but I don't scape on anything, 520mm from ground to highest point on front wheel arch), I think stock shocks in the front because they are the worst, the rears may have been replaced as they look fairly new. I have an adjustable rear panhard rod too which i haven't chucked in yet. I'll be getting my tax back and some uni scholarship so about 1500 i think soon and I'd like to sort out the poor handling.

 

I already have ae86 front gear that needs to be recondition. I have struts, brakes, calibers, p/s arms etc.

 

My first option is coil overs and that exhausts all my funds straight away pretty much, put on the ae86 gear and be done.

I'd also have to buy new pads for the brakes and brake lines, clean up the old rotors.

 

My second option is leave the back suspension as is, put new shocks ( cheap ones) in the ae86 gear, buy new brakes pads, rotors, lines, and change all the bushings, RCA adjusters and hopefully come out with some change.

 

To sum it up, I can invest a large sums in shocks, springs, and some camber plates and get the bonus of height adjustment or I can spend a moderate amount and get it riding right. Either way I'll get a brake upgrade.

 

So what are your thoughts? It is a daily, I don't get this sort of money often, but I'm not planning on selling this car until I'm at least off my p's (I love my KE even though it's slow and squishy haha)

Edited June 5, 2013 by luk3333

[altezzaclub]

The KE70 stock wet strut can be easily modified at home. We used to pull the Datsun 1600 ones apart and block a couple of holes in the foot valve, put in fresh oil and stick them back on. If you don't like the handling you pull it out the next weekend and do something more. The little circular shims can be removed or stiffened too.

 

Other than that, I'd say 99.9% of people with adjustable coilovers set them to a happy height and never adjust them. So you can do what we did and reset your spring perch to the height you want and leave it there. That way you get a good spring rate with travel. 520 is pretty low, I think I'm on 610mm.

 

I'd go for either playing with the stock struts (you learn a lot!) or putting inserts in the AE86 struts and using those. I will admit my rears came from the wrecker, I found a KE70 with shiny new rear shocks just sitting there.

 

Really, there is years of research and learning about suspension before you can put something together that gives great handling and ride all at once, so I'd aim to spend small amounts of money in all areas rather than blow a lot of dough in one place like struts. When you know more you add better things, so start with bushes and balljoints and reasonable spring rates.

 

You never mentioned rear sway bars, yet I've gone from stock KE70 to stock Celica to aftermarket Celica with noticeable changes every step. Dirt cheap too, $15 from the wrecker and I stole the 3rd one off the spares car, and now I have great turn-in on corners.

 

Lots on shock rates and shock graphs for tarmac cars on the net, as I found as I was chasing data for dirt use. This guy was excellent-

http://farnorthracing.com/

[luk3333]

Thanks, you always give great feedback. I hadn't thought of modifying the stock inserts. What oil do you use? 520mm is quite low, its the height the car was when I bought it. I think it is too low as I get a fair bit of scrubbing even though i've flared the guard a fair bit.

 

Raising the perch is another idea I hadn't thought of. I wouldn't be changing the height very often, I thought that if I was defected for being too low though it would be handy to be able to just raise the car again.

 

Do you get ae86 wet shock cartridges new? I thought that most cartridges now are dry. Otherwise i suppose a used stock pair must be pretty cheap. Unfortunately I threw out the old ones assuming they were rubbish :bash:

 

On the front I am have the stock sway bar, on the rear I am running dual sway bars and it made a very noticeable difference. I think if i remember correctly, you said stiffness is proportional to cross sectional area. The stock sway bars are 13mm diameter. So 2 13mm swaybars are relatively equivalent to an 18mm sway bar, which is a 51% increase in stiffness over stock. I am actually pretty happy with the body roll compared to other issues such as bump steer and dampening.

 

Also, 510 may have been from wheel center to highest arch point now that I think about it. I'll check tomorrow.

 

Having a quick look at that link, there is a great wealth of information I will look through tomorrow, thanks.

[altezzaclub]

I hadn't thought of modifying the stock inserts. What oil do you use?

You can buy shock absorber oil, or if you're keen you can chat up an oil supplier for something with a slightly thicker viscosity and a high viscosity index. I had some stuff they used on sno-cats in Antartica, so it was a thin oil but held its viscosity very well at all temperatures. That is the killer, the shocks get hot when hammered in rallying and the oil goes thin. Not a problem on the road I suppose.

 

I don't expect you to be able to buy wet inserts new, everyone just uses dry cartridges now. So if you've tossed the original shocks out you might as well pick a KYB insert or whatever and fit it. Then pick a spring that gives you the ride you want, even if it is too low.

 

Once you are happy with the shock and spring rate, then move the perch to where you want it. It will let you use a longer softer spring rather than using a hard stiff spring to get ride height. Then sort out what will bottom first, shock, spring, bump stop... Its all a balance.

 

The twin swaybars would make a big difference!

 

so much to learn about.....

[ke70dave]

1500bucks hey, and you already have ae86 stuff.

 

you want to make sure that your ae86 struts (persumably stock shock length still?) has the proper amount of travel at the height you want run.

 

you want just as much bump travel as you have rebound travel, if your car is as low as it sounds, i assume you currnetly have bugger all bump travel, and loads of rebound travel.

 

This is no good!

 

(can you take a photo of your front strut with the car on the ground to show where the shock is sitting in its stroke?)

 

So you need to design it in such a way that at static height (car not moving, but on its wheels) the suspension sits about the middle of the shock absorber stroke.

 

Once you have figured that out, i reckon you spend your cash like this

 

4 new shocks - KYB excel G are around $500 a set

4 new springs - id go 5kg Front and 3kg Rear if you want it a bit spirited, or 4kg and 3kg if you want it a bit softer. last time i got 2 springs custom made through repco, it was around $200 a pair. see what you can find second hand.

 

so we're up to a potential of about 500 for shocks+ 400 for springs (unless you find some 2nd hand) - ~900

 

So 600 to play with.

 

what size wheels do you have?

 

if they are something reasonable sized, get 4 new tyres. 4 NEW tyres, something decent like a bridgestone RE002 or a Federal 595 RSR and a wheel alignment.

 

Then with any cash left over, an adjustable panhard rod, and a full set of bushes, a set of QFM brake pads and some new brake fluid.

 

(install bushes and panhard rod before wheel alignment tyres)

Edited June 6, 2013 by ke70dave

[luk3333]

Thanks, I'll get you a photo.

 

I'm running 14 x 6.5 mags +12. This is a good size I think, tyres are cheap, get a good width and suits the car.

 

They are stock struts, as in they haven't been shortened or had sleeves welded on. I know that SW20 shocks fit and a few others, but it's going to take some searching I can tell already. You assume right about short bump travel, it is very short. I just avoid pot holes very actively.

 

As for springs, I was hoping to continue to use the stock ones as they are quite stiff but manageable. I will measure the spring stiffness of them this weekend perhaps. I liked the idea of raising the perch to bring the front up a bit (cheap cheap cheap) and get the ride height right. Otherwise I'll invest in some used aftermarket springs, I don't see the difference between a used spring and a new one and can't justify the price difference.

 

I kind of wanted to avoid spending $900 on springs and shocks, because for $200 more I'll get camber tops, height adjustment, damper adjustment and a warranty for whatever it's worth. The rear shocks are clean with no leaks, and rear ride height is were I like it, the tyre is almost tucking but not quite. The top of the arch is level with the top of the tyre. The front is where the real issue is with bump steer, poor dampening, too low.

 

Tyres would make sense as mine are pretty shot. Although I don't experience any real bad understeer with them, I think that's more because I'm not confident in my car enough to push them.

 

Also, I've been reading that link and their is some really good stuff! Gold mine!

 

Thanks for the insight guys :y: