Recaro trans am

iTrader: (1)

I need to replace the spohn coil over springs that came with there front and rear kit. I just cant get the car low enough without the spring coming loose in the seat during full suspension travel times (i.e large bumps or dips in the road). It has now damaged the thrust bearing and is beginning to rub against the thread collar. I want to put a shorter spring in and adjust the collar so the spring always has pressure on it. That was I can use the coil overs as there ment to be used, adjusting corner weight. My front end is almost all tubular, and my engine has aluminum heads. What I'm saying is the front end is much lighter than stock.

What rate springs would you suggest for the front and rear?

What length would you suggest if the spohn fronts are 12" and I think the rears are the same? If I set them so there is pressure on them at full travel (extension) I have about a 4" fender gap.

Thanks,
Will

//<86TA>\\

iTrader: (14)

A shorter spring wont help you, you will have the same problem. They make a kind of helper spring, made from light flat material and a few inches tall, that are made to keep pressure on the springs so they dont come loose when drooping. I believe ebiach makes them and im sure others do too.

Recaro trans am

iTrader: (1)

But this being a coil over suspension in order to maintainsome pre load when the suspension is at full extension like when its jacked up I need pressure on the spring with the thread collars. I want the ride height lower, so to accomplish that I need a shorter spring just like a drop spring would do for stock suspensions.

Recaro trans am

iTrader: (1)

So I think My only options after researching this is to make upper strut tower extensions to effectively raise the mount point of the top shock mount, this should effectively lower the front suspension but maintain proper shock travel and position.

The rears only option is to go from a 12" coilover to a 10" coilover. This should effectively lower my car the 2 inches I want and still maintain spring preload. So If anyone is looking for a rear set of coil overs I maybe selling these. lol

406TPI

iTrader: (1)

What is your rear spring rate now?

Recaro trans am

iTrader: (1)

My rear springs are variable rate. #130-240

Recaro trans am

iTrader: (1)

I got my new 10" rear coilovers and springs. Now my car should sit just right and still maintain proper shock position.


Also got the two 1" alum plates that I am going to mill out to act as spacers to effectively lower the front 1" and still maintain shock "sweet spot" position.


Just some other goodies, My new oil Road course oil pan.

Recaro trans am

iTrader: (1)

my new camber spacer plates to lower the front end.

DBLTKE

iTrader: (1)

Nice spacers! I just made some spacers myself but they're just round spacers that go under each bolt on the camber plates.

Recaro trans am

iTrader: (1)

Couple of views with the spacer plates in place for mock up. They still need final sanding and then either polish of powder coat.







Showing the fender gap before spring adjustments. This is just with the spacer drop.

Recaro trans am

iTrader: (1)

I got board so I polished the sides of the spacer plates.

morrow

what spring rate did you use in the rear

Recaro trans am

iTrader: (1)

Im currently running a 10" Coil with a 1" extension to get 11". I then used a 140-260 variable rate spring in the rear. I think I may need to increase it. I may go up to a 160-170 rate spring. Right now I have to run a lot of pre-load to get the height in the sweet spot.

morrow

how long is your shock eye to eye at ride hight... im worried that mine wont sit at the right hight with a 185 spring, idk if i should do a 175 or 185...ugh lolmaybe i should do the 175 so i have more room for pre load? what is your rear fender to the ground hight?

customblackbird

iTrader: (15)

I love these raised spacers. please make me a set!!

chad pickens

iTrader: (1)

I asked for these in the who wants billet parts thread didnt get a reply. Id love to get a set Im sure there would be a market for them. Send me a pm if you are willing to sell a set

SlickTrackGod

Much more beneficial to have a shorter strut assembly then to lengthen the geometry with these spacer. you loose beneficial gains by lengthening the ball joint to strut mount distance. Why not just by a racing strut cartridge and weld tabs to it to make yor own shirtened racing strut like from Koni. Less jacking leverage, better camber gains, better static camber range. Better static caster range. More dynamic caster build.

A shorter strut overall working length is far better benefits.

customblackbird

iTrader: (15)

Can u illustrate what your describing? Or pics of the parts your referring too?

It would be super easy to make a solid plate with a hole for the strut to pass through and weld tabs to mpunt the top of a universal shock, shorter and with a spring cup u can get more adjustment since the spring would be below the hole kinda. Still doesn't address the spindle mount area or the fact that the strut/shock and spring would be very short.

SlickTrackGod

Buy a race cartridge and weld your own tabs to them. Make then the length you need rather than trying to extend a strut mount up higher. The shorter distance from the ball joint to the sturt mount bearing is what the rear "jacks" upon as in lift or anti lift as the front brakes are applied and the motion weight of the car carry's through the front suspension.

The shorter distance in a lateral stand point allows for better negative camber range for racing application. The lower the top mount the less camber loss through articulation as the car sits and rolls to that side. The lower the top strut distance the higher the caster gain in suspension travel as well countering nose dive wandering due to increased scrub radius of wider front wheel cars

http://www.koniracing.com/8611.cfm#8611

Recaro trans am

iTrader: (1)

PM me if you want a set of the plates. They work perfect on my set up.

The issue I was having was with the spohn coil overs, to get the lowered ride height I wanted I had to lower the spring on the adjuster so much that it left the spring dancing around on the strut. This lead to a damaged thrust bearing and an anoying bong noise on big bumps. So I made the plate, This lowered the front and inch, did not loose any suspension travel to worry about bottoming out the strut, and I still have full adjustablity with my caster and camber at the top.

I dont quite understand what slick trackGod is talking about since the caster and camber was easily brought back into specs and even a little further for my occasional track days and I have no ill effects. Its a compromise thing I guess, I wanted the car lower, I lowered it probably close to 3" all said and done.

SlickTrackGod

I guess I should start back at the top with your first post.

You state you need shorter springs because the long spring you have are coming out of the pocket (in your terms-"Coming loose in the seat during full suspension travel" Just upon reading this I knew this was not your problem. Why? A shorter spring will only fall out of the pocket easier- yet your new shorter spring you had already bought prior to my response are not.

So what is the problem? you have too long and heavy rate a spring for your application. The strut body iis too long for your coilover application at the height you are trying to make it WHY? Because the Spohn setup reduced the strut body-to-strut mount clearance because of the need for the upper spring perch under there. You are slamming the strut body into the coilover spring perch.

As for the rubbing of the spring on the strut coilover threads? springs naturally do that. The spring bends with compression loads and the spring will rub the inside diameter- this is the beauty of barrel shape 2.5 spring design, it eliminates conventional spring bending- YET- a 3rd gen setup does not permit room to run a barrel shape spring design that is more stable for a 2.5 ID setup/

I knew all this upon just reading your first post.

Where I came into the topic, you were talking about using a spacer to raise the distance of the upper strut so as to not "go bong" against it in travel. What this does is lengthens the distance from the strut mount pivot ball-to- the ball joint. Of course youc an get static camber and caster settings, but what you are leaving on the table is not having as much dynamic gain in those readings and the benefits in tire footprint as a result of those dynamic gains. You raising the strut mount to allow for that coil over perch is hurrting overall ultimate geometry potential.

What I suggested for a better fix and better performance levels is to shirten the strut body via using a racing sturt cartridge that is shorter then the standard 3rd gen sturt.

so mow you know...even though you most likely still have no idea about the benefits of dynamic caster gain and how it pertains to camber curve and straight line braking footprint with less staitc camber.

Recaro trans am

iTrader: (1)

I dont mean to insult Slick TrackGod, I know that race suspension dynamics gets very complicated very quickly. The problem I am having is the geometry of the suspension has not changed. The whole upper mount was raised, that means the hypothetical upper ball joint (since it is a modified McPherson ) was raised the same as the lower ball joint. As far as the suspension knows its in the same place. The car was lowered around it. Am I making any sense? lol This is why I am confused as to how I changed/ lost dynamic caster and camber?
Obviously I could have achieved the same thing with a shorter strut, but would have then lost suspension travel, and since this car is still mostly a street car I wanted to maintain that long travel so that I had a more comfortable ride.
You also mention not enough spring rate, but there has been recently a lot of really good results with softer springs and faster track times. The reasons why are far beyond my scope of understanding.

If you could explain in more detail how its changing with moving the top perch I'm all years.

Will

SlickTrackGod

You didn't insult me. I was giving friendly advice and I explained twice already how your geometry changed. You still say it has not changed. You are only understanding static geometry, Ive said twice I was trying to explain dynamic geometry. It's a complex thing so If you do not understand it then donlt feel bad, most people don't understand this stuff. have a good one.

Recaro trans am

iTrader: (1)

You say your not insulted, but your response to me asking to explain in more detail is you explained it twice. lol I understand it much better now, thanks.

After doing so inter web related searching on this it still does not look as if it is changing. The geometry has not changed, the upper point is just moved away from the car. The upper mounts give a very far range of adjustment so that the caster can be dialed in just the same as it would 1" lower.

Even with that McPherson suspensions it seams are notoriously bad when it comes to adjusting for dynamic changes. The arc that is created as a result takes away from the overall caster during compression. But by lowering that point, then resting Static adjustments, the change to dynamic will still be the same as it would be without the plate. This is why I'm confused.

Perhaps someone else can explain this a bit better so that I understand. T

Thanks, Will

SlickTrackGod

For the 3rd time (note that I am not upset, I am trying to point you to read what I have already wrote twice. It is the relation of the lower ball joint pivot "in length" to the upper strut mount pivot. You increased this. You are trying to run the chassis liw like anon coilover car, yet the coilover upper oerch underneath the strut mount does nit alliw you ti do so like a convenruonal sper ng car does. Your strut is hitting it. Yoy had to lift the strut mount even more then the spohn unit already lifts it compared to oem. You increased this distance. A shorter strut woyld be better (just like you did on the back by getting a shorter shock ti properly fit the ride height. )

SlickTrackGod

Sorry im on a phone typing with big fingers.

Now take two senerios. The 1st is 18 " between the two points on a line resting 5* from vertical. The next is also 5* but is longer at 19".
Now- keepibg both upper and lower points at fixed x and y axis. Shorten the length of both by 3 inches. The shorter of the two will have a greater dynamic angle gain.

SlickTrackGod

There is several more things going againat dynamic geometry performance by raise the top pivot mount on a 3rd gen also. Rear jacking effect, front roll center heght, camber gain through caster multiplication, camber curve. This stuff get very complex. You are not simply extending a shock mount, you are moving suspension geometry point.

Recaro trans am

iTrader: (1)

Well thanks for the example and nice explanation. I understood what you were talking about the two ball joint points, I guess what confused me all along is that the length of the shock was never changing with the 1" plate. It just changed the position of the end point. All things being equal its hard to see how this changes. But I can defiantly see how a shorter shock would be a better solution. I just happen to have access to the needed material and machinery so it was a much cheaper option then $800 worth of front struts. Im a visual learner so I need to see it for my self to understand. There are many good explanations of this and race setups on the web it those helped a lot.

It was a way to adapt the poorly designed spohn coil over kit for a real use instead of just a way to lower the vehicle to look good. I wanted it to perform well as well.

I saw your link to the koni struts, is that what you run in your car? What length do you run?