lost, entirely lost with suspension desperate

[Guest Anonymous]

 

i have a dilemia, i have a 81ZXT producing about 450bhp. and i have no suspension in the car, i have no idea what i should about spring rates coilovers, camber plates, adjustable this adjustable that. I plan on getting 16x8 and 16x9.5 wheels (also have mild 2.5" front flares and 3.5" rear flares) I want to autocross this sucker, and play on running in the 12's. I want a stiff ride that handles like a dream. I want to lower the car as much as possible. im thinking 2" could be resonable. anyone with pics of a 2" drop with 16" wheels? I kidna dont know what to do. Im guess coilovers is the best bet. Just looking for some direction... i need some input before i go wasting money on stuff i dont use for my car....

[Guest Thurem]

Just cut some coils off your springs until it sits a the right height. just kidding. coilovers is propably your best option because they are easily adjusted for rideheight and the springrates are easily and somewhat inexpensively altered ( I have seen new coils in summit for about 37 a piece)

Thure

[BLKMGK]

Go coilovers. I did using th eones MikeSCCA sells and wow, I love them. More room for tires plus I can change ride height in just a few minutes. Springs are harder to change but suspect I'll be swapping them around some too here soon

 

I'm running 225lbs up front and 200lbs in back. I believe the rear should be stiffer as hopping on the gas gives MAJOR squat I'm considering 250 for the rear - it rides pretty good now I think but with a T56 it's likely a little heavy.

 

Hope that helps!

[Modern Motorsports Ltd]

In another thread Chase passed on that he's also wondering if sectioning his struts is needed with his anticipated ride drop. How many here running 1.5-2" lowered and was sectioning req'd in your opinion? I'd be concerned about running out of adjustment room up top with shortened struts, larger rims and rubber...Mike's commented on this before as well.

 

right around 225-250 out back seems to be the range for decent ride and greatly reduced rear squat. My dad has 225 with his 240, Andrew is running same, and in my heavier 280ZX I run 250 out back. I wouldn't run stiffer out back in my ride FWIW. Minimal squat such that it doesn't bother me at all and the rides plenty 'stiff' to harsh on poor roads.

[BLKMGK]

Good point Ross, I was remiss in that aspect. My struts are NOT sectioned however I suspect that I'm riding on the bumpstops occasioanlly as I find my bumpers pushed up to the top when I pull the wheel. Previous struts looked prettyy new before being replaced but were DEAD as a doornail - possibly from bottoming... DO consider sectioning while it's apart, I probably should have considered it...

 

Hrm, not heard from SCCA lately - Mike you out there?

 

Oh, I'm running a 240Z so this might not be quite apples to apples

 

[ October 24, 2001: Message edited by: BLKMGK ]

[Guest Anonymous]

Ahh thank you very very much Ross and BLKMGK, i believe sectioning the strut an inch would prevent any bottoming out. Great, i think now im ready to jump into the suspension thing, thanks guys, ahh i love the internet.

[Modern Motorsports Ltd]

"My struts are NOT sectioned however I suspect that I'm riding on the bumpstops occasioanlly as I find my bumpers pushed up to the top when I pull the wheel."

 

OEM length bumpstops or have you already sliced them in half or similar? stock length is toooo long for us performance pushers

 

" Previous struts looked prettyy new before being replaced but were DEAD as a doornail - possibly from bottoming..."

 

some tolerate bottoming much better than others......tokico's are alright, someone was talking about 'old' konis or KYB's being shot after one bottoming

 

"Oh, I'm running a 240Z so this might not be quite apples to apples "

 

so's Chase, it's a 280ZXT motor he's referring to, in a 240Z chassis...I had to reread it the first time tooo

 

another spot to 'gain' strut travel is in the upper spring perches....their might be 1-2" alone to gain their in using a simply made (ie. caster/camber but cheap) upper mount to replace the coilover top mount, I've thought of making them as I know I'd prefer that to sectioning the struts myself but I don't have a welder or chop saw so my preferences can differ from others

, allows you to stay with easier to replace components if needbe

[Guest Anonymous]

hmmm, hmmm, okay im looking at ground-controlss coilover right now, shows the sleeve, spring then upper perch and then theres the camber thing, how would the upper perch be more simplistic than just cutting an inch of the strut? seems like the most straight forward to do it... but im open for ideas...

[Modern Motorsports Ltd]

"how would the upper perch be more simplistic than just cutting an inch of the strut"

-as mentioned, I don't have a welder so bolt on options are preferred. Top perch pictured by GC is thinner/shorter overall than your OEM, this is where the travel is gained (ie. your lower spring perch would not have to be set as low with thinner upper plates..)

-if welding/sectioning is easy for you to do then it's easiest....I just wanted you to beware of the options/pros/cons (ie. if you goto caster camber plates later it may be too short...but you can just use other strut housings in that case)

[DavyZ]

Havok, you can also go to www.modern-motorsports.com to get a coil-over kit as well.

 

Ross, isn't that your company? Doh! Yes, I see it in your signature, my bad!

 

Davy

[johnc]

The amount you section the strut depends on where your designed ride height is and what inserts you're going to use. What you are trying to do is get back some of the compression travel that you lose when the car is lowered. Lowering the car 2" at the rocker panel works out to a loss of about .75" in shock travel at the strut tube (I forgot the actual ratio, hopefully someone has it on the top of their head). But you're limited by the available strut inserts so you really can't cut off more than about 2.5".

 

I cut 1.75" off my strut tubes with a designed ride height of 5" measured at the front of the rocker panel. This is for an autocross/track car.

 

[ October 25, 2001: Message edited by: johnc ]

[jeromio]

I would think that lowering the car (with springs) results in a 1:1 ratio in loss of suspension travel. If you have 5 inches of travel, lower the car by 2 inches, then there's only 3 inches of travel left.

 

However, strut sectioning will not necessarily yield a 1:1 gain in lost travel. It depends on the amount sectioned and the cart. For instance, I have removed 1.5 inches from my strut tubes, but I used a Rabbit cart that was ~2.75 inches shorter than the stock cart (extra space taken up by section of pipe, see http://240z.jeromio.com/frontsusp2.html). BUT, since the rod is shorter too, it gets complicated. I haven't lost the 1.25 inches due to the whole cart being shorter, I've only lost about half that (but not exactly half because the rod to car ratio is not 1:1) because the shorter rod will allow not be compressed as much at the lower ride height. I think I'm even confusing myself after re-reading that.

 

IOWs, if I jack up my car to "normal" height, my carts will be almost maxed out, that is, "topped". Maximum travel.

 

It's all very confusing. But I have not hit the bump stops on my car.

 

If you have the bucks, I would go the camber plate route. It avoids the labor and hassle of the sectioning, gives you back your travel, AND gives you the camber (and sometimes caster, depending on the design of the plates) adjustment.

 

And Mikelly is selling a set too (if he still has them).

[johnc]

If you measure a car's lowering at the rocker panel (let's say 2") and then you measure how much travel has been removed from the strut there is a difference in the two numbers. In my example above, I overstated the difference - my guess it would be more like a reduction of 1 3/4" measured at the strut.

[jeromio]

Well, okay, Suspension Travel is the distance the wheel can move up or down. But what we're really concerned with is the UP part. If you take into account the full range of travel, then lowering the car with spring doesn't affect suspension travel at all! But, if you lower the car 3 inches, try explaining that to your kidneys.

 

So, when you lower the car with springs (by which I mean to include shortened springs or coilovers with the perch adjusted) you are lowering the car by effectively removing travel.

 

It's the exact same process as when the car hits a bump. Except that it's permanent. One inch lower = 1 inch less effective (bump) travel. As you crest a hill at speed, with say a 2inch "all spring" lowered car vs. my 2inch sectioned strut car, my tires may leave the ground because I have less over all travel, while the other car's tires may stay on the ground (although unloaded). But after that, my car would most likely be able to smoothly absorb the impact, while the other car would hit the stops and give its driver a nice headache.

 

If you leave the springs alone and "shorten" things by either cutting down the isolator or switching to camber plates (which are shorter), then travel is unchanged.

 

But, the whole issue of regaining travel on a lowered car by altering the strut (either the car or the tube and cart) brings in all kinds of strange ratios.

 

For instance, you could gain back some travel by only changing the cart and not cutting the strut tube at all!

[Modern Motorsports Ltd]

OK, I'll bite, how can you increase bump travel for SAME height setup by ONLY changing strut cartridges and not altering strut tubes? Without altering top plates or tubes etc even if 'new' cartridge as 5" extra stroke you'll only gain 'droop' travel assuming swaybards allow that range which isn't of interest to anyone here AFAIK (I don't know anyone with a lorider/hirider on hydraulics). You'd have to have compressed the 'new' strut to same remaining 'bottoming' travel to achieve same ride height correct??? Or am in left field here?

Jeromio wrote: "For instance, you could gain back some travel by only changing the cart and not cutting the strut tube at all!"

[Guest Anonymous]

hello, just got back from school, was reading up, and you guys are way to far ahead of me, im lost, i have no idea where this is going either, so far i understand that lowering your car will affect how much travel the suspension has up, so the lower the car is lowered the less travel the suspension has. To counter this, you would want to create a shorter strut/shock to compensate for the lowering of the car... so if i dropped the 240 2" then i have 2" less for the supsension to travel upward. thats why you would section the strut, to bring the strut assembly closer to the upper perch. but you also need to get the correct cartigdes that will fit the modified strut assembly. Jermino used rabbit tubes that were 1 1/2" shorter (i think) so he cut 1 1/2" off the strut assembly. Am i anywhere close???

[jeromio]

Jermino? Ouch.

 

Yes, I cut 1.5 inches out of the strut, but the carts I used (85 Rabbit GTI fronts) have bodies that are actually about 2 3/4 inches shorter than the stock 240 front carts. So, I had to make up some room with a spacer - 1.25 inches of 1 1/4 inch ID pipe. But, just to reiterate my earlier point: I sectioned my struts because I have more time than money. I think you'd be better off going with coilovers and camber plates.

 

As to the possibility of gaining back travel on a lowered car by using uncut strut tubes and a shorter cartridge: If you lower the car 2 inches, and find a cart whose fully extended length is 2 inches less than the standard one, then you've only lost 1 inch in travel vs. 2 with the standard unit (assuming 1 inch shorter body plus 1 inch shorter rod). So, you lose "droop" (overall) travel but gain "bump" (effective) travel.

 

That's in theory, anyway. In practice, even if you found that magic cartridge, you probably don't get that exact ratio due to the placement of the internal bump stop, the amount of susp. compression at static ride height, etc., etc. But you're sure to gain back some fraction of bump travel vs. using the standard cart.

 

[ October 25, 2001: Message edited by: jeromio ]

[Guest Anonymous]

yeah i butchered your name....... .... . oy.. im going to sit in the corner with my dunce had on now.

[Modern Motorsports Ltd]

"As to the possibility of gaining back travel on a lowered car by using uncut strut tubes and a shorter cartridge: If you lower the car 2 inches, and find a cart whose fully extended length is 2 inches less than the standard one, then you've only lost 1 inch in travel vs. 2 with the standard unit (assuming 1 inch shorter body plus 1 inch shorter rod). So, you lose "droop" (overall) travel but gain "bump" (effective) travel."

 

Disagreed, just installing the cartridge that's 1" shorter in extended length lost you 1" in bump with an uncut tube. Frame of reference is still top of strut tube to top of strut housing which wasn't improved, regardless of insert body length or extended length, no bump gained IMO unless that cartridge is more suited in that range of travel but still no effective bump/length gains IMHO.

 

I've been curious how close an MR2 or rabbit cartridge is to the Z designed cartridges (tokico). Be interesting to see compression/rebound test comparisons.

[jeromio]

Well, the dunce hat corner sitting does me no good unless you post a picture as evidence .

 

And I know this side discussion that Ross, JohnC and I are having has nothing to do with your original question, but I'm going to egg it along even further here (so perhaps I should wear the cap).

 

I made a little diagram to illustrate my point (I just don't know when to stop, do I?):

This is an oversimplification, but hopefully you'll get the idea of what I'm trying to state.

 

I think the key is

 

"Frame of reference is still top of strut tube to top of strut housing"

 

My little scenario, un-obviously (oops) is assuming the unusual, top spacer.

 

ALSO, it is assuming that there's enough "extra" shaft length to poke up over the spacer. Not all that real world I must say.

 

All in all, I started out trying to clarify that there is a general lack of straight forwardness in regaining lost travel via cart/tube length alterations. The very complexity of this discussion more than backs that up.

 

To answer that final question, I've been very happy with the performance of the GTI carts. BUT, not only have I not raced the car, this is with the stock L28 motor. Had I to do it over, I would've chosen the MR2 carts.