Solid Everything? Yes. Yes Solid everything.
03-31-2010, 06:30 PM
#1
Solid Everything? Yes. Yes Solid everything.
Just wanted to share with the hardcore guys out there what's going on with our race car. Kuah from SPL sent us his new rear spherical kit, and along with all of his arms everything from the subframe out will be solid, with the exception of the upper camber arm - which I will have to machine my own bearings for.
The front of the car is already full solid thanks to Kuah's lower control arm sphericals and our compression rod spherical bearing.
The only piece of the puzzle missing were the rear subframe bushings which don't seem to be available anywhere in aluminum, despite being very popular for the 240sx chassis. After pressing out the factory bushings I drew some simple aluminum ones and had the machine shop next door churn them out for me. They are also designed to raise the subframe a wee bit to help a little bit with suspension geometry. I would have loved to go higher but with the way the subframe is you would need to machine the entire rear of the subframe to get it any higher, and my fuel cell is already mighty close to the driveshaft!
If you're looking to be doing a lot of lapping / time attack or performance driving, I wish I could explain to you the difference sphericals make. In the front steering response time becomes seemingly negative, and the crazy wiggles from the back of the car at high speed are all but a painful memory!
Here are some pictures:
And the front arms from last season:
The front of the car is already full solid thanks to Kuah's lower control arm sphericals and our compression rod spherical bearing.
The only piece of the puzzle missing were the rear subframe bushings which don't seem to be available anywhere in aluminum, despite being very popular for the 240sx chassis. After pressing out the factory bushings I drew some simple aluminum ones and had the machine shop next door churn them out for me. They are also designed to raise the subframe a wee bit to help a little bit with suspension geometry. I would have loved to go higher but with the way the subframe is you would need to machine the entire rear of the subframe to get it any higher, and my fuel cell is already mighty close to the driveshaft!
If you're looking to be doing a lot of lapping / time attack or performance driving, I wish I could explain to you the difference sphericals make. In the front steering response time becomes seemingly negative, and the crazy wiggles from the back of the car at high speed are all but a painful memory!
Here are some pictures:
And the front arms from last season:
I likes it a lot.
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04-01-2010, 05:09 PM
#13
Thanks Guys!
Jason, you can buy the front compression rod bushings from Kuah at SPL Pro Suspension, combined with the lower control arm bushings it makes an incredible difference.
I'll be assembling the subframe shortly but first I've got an engine to assemble tomorrow! High compression should make some sweet sweet jam.
Edit: Hopefully we'll get down to the Glen this year. Road Atlanta is my next favorite US track that I have to visit soon!
Jason, you can buy the front compression rod bushings from Kuah at SPL Pro Suspension, combined with the lower control arm bushings it makes an incredible difference.
I'll be assembling the subframe shortly but first I've got an engine to assemble tomorrow! High compression should make some sweet sweet jam.
Edit: Hopefully we'll get down to the Glen this year. Road Atlanta is my next favorite US track that I have to visit soon!
04-05-2010, 06:14 PM
#15
Hey Sharif,
We'll make it to the states for a time attack event when it has enough horsepower to not embarrass itself on the straights
As far as lapping days or regional races go, I would love to get down to the some of the larger tracks this year. All this iRacing training, I want to try the real thing now, god knows Mosport was 100% spot on!
Back to the car-
Got the subframe back in today and everything looks good. Because of the raised subframe, special upper spring pickups, SPL Mid-Link arm, and relatively low ride height we run, the rear spring options are going to be very difficult to sort out indeed. At the full compression I want to have in the suspension I'll have less than 3" between the upper and lower spring seats. That's not really enough for a blocked tender, spacer and 1000lb/in spring! Coil bind is bad news, so I'm going to look at making a custom insert for the SPL mid-link that will allow me to use a 2.25" spring and sit it down lower in the arm.
Here are some pictures with the new 18x10.5 RPF1s all around with 280/650/18 yok's
Just less than full droop
~Ride Height
2" Bump:
~3.5" Bump:
I haven't had it on the alignment machine yet to measure the bump steer in the rear, but it looks like at extreme bump it starts to go from toe in to toe out, so we'll want to avoid that much compression. Either way, the damper bump stop should stop the wheel NOT coil bind!
Looks like testing this weekend maybe, don't want to rush things though!
We'll make it to the states for a time attack event when it has enough horsepower to not embarrass itself on the straights
As far as lapping days or regional races go, I would love to get down to the some of the larger tracks this year. All this iRacing training, I want to try the real thing now, god knows Mosport was 100% spot on!
Back to the car-
Got the subframe back in today and everything looks good. Because of the raised subframe, special upper spring pickups, SPL Mid-Link arm, and relatively low ride height we run, the rear spring options are going to be very difficult to sort out indeed. At the full compression I want to have in the suspension I'll have less than 3" between the upper and lower spring seats. That's not really enough for a blocked tender, spacer and 1000lb/in spring! Coil bind is bad news, so I'm going to look at making a custom insert for the SPL mid-link that will allow me to use a 2.25" spring and sit it down lower in the arm.
Here are some pictures with the new 18x10.5 RPF1s all around with 280/650/18 yok's
Just less than full droop
~Ride Height
2" Bump:
~3.5" Bump:
I haven't had it on the alignment machine yet to measure the bump steer in the rear, but it looks like at extreme bump it starts to go from toe in to toe out, so we'll want to avoid that much compression. Either way, the damper bump stop should stop the wheel NOT coil bind!
Looks like testing this weekend maybe, don't want to rush things though!
04-05-2010, 07:06 PM
#16
You think you will see a 3.5 inches of compresion with 1000lb springs? From the pics, it looks pretty extreme to see that on track.
Also, Sash, has anyone seen/heard of any issues of control arm failure due the solid mounts? This looks really compelling but just thinking out loud.
Also, Sash, has anyone seen/heard of any issues of control arm failure due the solid mounts? This looks really compelling but just thinking out loud.
Last edited by Sharif@Forged; 04-05-2010 at 07:12 PM.
04-06-2010, 05:20 AM
#17
Hey Sharif,
I doubt we'll see that much - but here is my concern with spring bind in this situation:
The inboard toe control arm uses a spherical rod end which can only take so much bending load. If the spring coil binds @3500lbs (which is about 2100lb at the wheel, or 3G's vertically - not that much!) It's going to send any further force through the rod end and possibly break it. If the damper hits the bump stop first, then I know the maximum load the rod end will ever see and as long as I test it to be OK with that load (and I suppose some for saftey!) it should be just fine.
Today I'm going to see exactly where the bump stop is in the back of the suspension, but last year with 800lb springs in the rear I was tucking tire in a few videos I've seen from some big bumps on the outside rear wheel while on throttle and you'd be amazed how much the wheel compresses!
Kuah from SPL also sent me some much larger rod ends that I can use on the toe arm to give me a larger safety factor which I think I'll use. As far as the other arms go, as long as there aren't any impacts there should be no reason for them to break. But it's racing so anything possible!
I doubt we'll see that much - but here is my concern with spring bind in this situation:
The inboard toe control arm uses a spherical rod end which can only take so much bending load. If the spring coil binds @3500lbs (which is about 2100lb at the wheel, or 3G's vertically - not that much!) It's going to send any further force through the rod end and possibly break it. If the damper hits the bump stop first, then I know the maximum load the rod end will ever see and as long as I test it to be OK with that load (and I suppose some for saftey!) it should be just fine.
Today I'm going to see exactly where the bump stop is in the back of the suspension, but last year with 800lb springs in the rear I was tucking tire in a few videos I've seen from some big bumps on the outside rear wheel while on throttle and you'd be amazed how much the wheel compresses!
Kuah from SPL also sent me some much larger rod ends that I can use on the toe arm to give me a larger safety factor which I think I'll use. As far as the other arms go, as long as there aren't any impacts there should be no reason for them to break. But it's racing so anything possible!
04-06-2010, 06:16 AM
#18
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04-06-2010, 04:02 PM
#20
If Kuah is busy working on other things I'm sure it would be possible to have a one-off set of those compression rods custom machined, but if I told you the price I paid to have them made by hand not counting the time i spent measuring and drawing you would be in shock for at least 6 hours. If you're really itching for them and don't mind seeing a shocker price tag I would be happy to buy you new compression rods, burn out the old bushings and have mine machined and pressed in for you - unless you have a good machine shop you trust to press the old ones out and properly measure and press in the new ones.
Back to the race car.
I measured the Koni's and the way they sit now I only have 1.8 inches of bump travel from ride height! This is because the Unitech guys were running the cars a lot higher, so shortening the bodies will be a certain requirement soon. After seeing a destroyed shock sensor from not only hitting the bump stop but smashing it (the shock sensors should over travel the bump stops, but were installed backwards!), it showed me that even with the limited downforce and r-compounds we're running, the ~900lb springs I was using last year weren't going to cut it with larger, real slicks with more aero to come.
So I've upped things to 1300lbs. At the wheel that's only an increase of ~240lbs/in from the 900. To balance the chassis I'll likely be around 1500-1600lb/in, but I'll worry about that another day.
Now the problem. No one makes a 1300lb/in spring in 2.5" ID, certainly not in 5" length. Luckilly I had some 1100lb 6" long springs laying around. Figure cutting 20% off the spring you'll gain 20% in rate, the spring should be 1320lbs if cut to 5".
I called the guys at Hyperco to see if they could cut a 6" spring for me and bend the tip down and grind it, since I didn't really have the equipment to do that here. They said they don't offer that service, but gave me a bit of a pep talk - enough for me to have a go at it anyway.
So here I was, a blacksmith of springs cutting torching and grinding them down. Would you believe it, our ghetto spring tester shows them to be less than 5lb/in apart in rate, and just over our goal at 1338lb/in and 1341b/in!
Since pictures are all that matter, here they are:
Torching a spring after cutting it to bring the tip down
Slowly cooling the spring to keep it from becoming brittle
Flip it over and push it down on the ground! This is what it looked like after being flattened
Ground and wire-wheeled
The cut was real close to the goal! Maybe a bit short
Ghetto spring compressor, just a corner balancing scale and a press. Zero at a reference height, compress one inch and that's the rate!
So hopefully this extra inch will be enough to fit the tender and the spacer, plus Kuah told me that I can reverse the spin in perches with minor machining which should give me roughly another inch to work with.
Knowing now that my bump travel isn't quite what I thought it to be, and having another 2 inches to work with, I think we'll be ok!
Back to the race car.
I measured the Koni's and the way they sit now I only have 1.8 inches of bump travel from ride height! This is because the Unitech guys were running the cars a lot higher, so shortening the bodies will be a certain requirement soon. After seeing a destroyed shock sensor from not only hitting the bump stop but smashing it (the shock sensors should over travel the bump stops, but were installed backwards!), it showed me that even with the limited downforce and r-compounds we're running, the ~900lb springs I was using last year weren't going to cut it with larger, real slicks with more aero to come.
So I've upped things to 1300lbs. At the wheel that's only an increase of ~240lbs/in from the 900. To balance the chassis I'll likely be around 1500-1600lb/in, but I'll worry about that another day.
Now the problem. No one makes a 1300lb/in spring in 2.5" ID, certainly not in 5" length. Luckilly I had some 1100lb 6" long springs laying around. Figure cutting 20% off the spring you'll gain 20% in rate, the spring should be 1320lbs if cut to 5".
I called the guys at Hyperco to see if they could cut a 6" spring for me and bend the tip down and grind it, since I didn't really have the equipment to do that here. They said they don't offer that service, but gave me a bit of a pep talk - enough for me to have a go at it anyway.
So here I was, a blacksmith of springs cutting torching and grinding them down. Would you believe it, our ghetto spring tester shows them to be less than 5lb/in apart in rate, and just over our goal at 1338lb/in and 1341b/in!
Since pictures are all that matter, here they are:
Torching a spring after cutting it to bring the tip down
Slowly cooling the spring to keep it from becoming brittle
Flip it over and push it down on the ground! This is what it looked like after being flattened
Ground and wire-wheeled
The cut was real close to the goal! Maybe a bit short
Ghetto spring compressor, just a corner balancing scale and a press. Zero at a reference height, compress one inch and that's the rate!
So hopefully this extra inch will be enough to fit the tender and the spacer, plus Kuah told me that I can reverse the spin in perches with minor machining which should give me roughly another inch to work with.
Knowing now that my bump travel isn't quite what I thought it to be, and having another 2 inches to work with, I think we'll be ok!