Build thread

[lOOkatme]

Motion ratio is the ratio the wheel moves with respect to the spring.

so you move the wheel 1 inch (vertical, up and down), the suspension moves .68 inches. So think of it as leverage on the spring. Its just how the suspension is designed and the leverage on the spring. This is important because what matters is the wheel rate (the wheel rate is the resistance to bumps that the wheel/hub sees). Some suspension designs will require a lot higher spring rates than others because of the leverage the wheel puts on the spring to maintain the same wheel rate.

Frequency is just the term that desribes a mass on top of springs and the frequency that mass will oscillate at. Typically smaller frequencies will be more comftorable and offer more mechanical grip. The frequency depends on the sprung mass of the vehicle and the spring rate along with the motion ratio/wheel rate.

Finally you have the front and rear ride frequencies and giving a flat ride. typically you want the rear of the car to have a higher frequency (10-20%) than the front to maintain a flat ride which most people deem comftorable. If you have pretty high critical damping of the spring (think stiff damping) this becomes a little less important IMO.

Lots of opinions are being shared on rx7club about ride quality/handling/grip/etc. I am of the group that softer rate springs ride better, provide more grip, and offer only a little less handling left to right transitioning, but IMO not enough to justify the stiffer ride and less grip. I also think that going 70% stiffer in the front and 72% stiffer in the rear for spring rates is a substantial amount of stiffness added by spring rate. Others say that running 14KG springs are fine, but that is 784lbs/in springs which is 3X or 200% increase in spring rate which is substantial IMO. I just don't believe Mazda was that far off.

Damping does matter but so does spring rate for ride comfort and mechanical grip. It's definitely interesting and fun to see which set up provides the best ride for what we want out of the suspension. I do think the Ohlins DFV damping is great, so we definitely chose the right damper, I just think the spring rate for me is a little too strong for what I do.

The yoko AD08R's are awesome tires, go for them. whatever you choose just go a hair wider on the wheel width than the tread width. so the 285 has an 11" tread width and I would run a 11/11.5 wheel width and the 295's are 11.5" tread width so I would run a 11.5" wheel width.

[speedjunkie]

Cool, thanks for explaining all that. Although I'll have to dig deeper to understand some of what you said lol. I found a thread on 7club where you're weighing in on this stuff. In no way am I interested in going up to 14kg, or up at all actually. I'm thinking I'll do 10kg/8kg. I did confirm today that the range is 9kg-14kg for the valving. I am very happy I got the Ohlins and I'm excited to see how they feel and perform. Well, I've already seen them on your car, but I wasn't driving haha. I'll talk to you more about this in person, before I order the springs.

I'm not completely sold on the AD08Rs, I just figured I might get them since I've had the regular 08s and been pretty happy with them. I'm going to look at the Direzza Star Spec II again too. But really I need to see how wide I can go on the front first because of the brake ducting, then that will help me decide. I'm getting impatient about finally figuring this out haha.

Zico mailed off the wastegate springs today. They'll get there on Wednesday around 10am. Hopefully Chris can get it figured out and finished soon.

[Saul_Good]

Higher spring rates are good for autox where there are lots of lateral movements from all the transitions that happen. I agree with Andy on the somewhat softer rates for roadcourses, especially the tracks in Colorado.

As for tires the latest GRM tests go something like this, BFG Rival S/RE71R > Direzza II > Everything else.

[lOOkatme]

I would say anything in the extreme sports class is probably good enough, and then from there find the least expensive tire with the right size.

With 285 we are stuck with re-11, AD08R, RE71R and ZII, the 295's are AD08R and......Michelin pilot PS2? not much in this size.

[speedjunkie]

Higher spring rates are good for autox where there are lots of lateral movements from all the transitions that happen. I agree with Andy on the somewhat softer rates for roadcourses, especially the tracks in Colorado.

I'm not sure I'll do autox, mostly road course and spirited drives I think. But I might do autox at some point.

As for tires the latest GRM tests go something like this, BFG Rival S/RE71R > Direzza II > Everything else.

I would say anything in the extreme sports class is probably good enough, and then from there find the least expensive tire with the right size.

With 285 we are stuck with re-11, AD08R, RE71R and ZII, the 295's are AD08R and......Michelin pilot PS2? not much in this size.

What is the GRM test? Grassroots Motorsports?

I searched for the Direzzas last night again and it looks like they're discontinued, so that's one less option haha. Which is unfortunate because it was a lot cheaper than the AD08R, those are $357 for 295 and $347 for 285. I'm gonna dig into this some more.

[Shadowden]

I think they simply renamed the Star Specs. Not positive.

[Saul_Good]

I think they simply renamed the Star Specs. Not positive.

Yup. Direzza Star Specs.

[speedjunkie]

Ok, I did a search the other night for Direzza Star Spec ZII, or II possibly, and it said they were discontinued. I just did a search for Star Spec and it brought up the ZII Star Spec in the sizes I need, and IT'S THE EXACT SAME TIRE lol. They're more expensive than they were though, $312 on Tire Rack, and it says the tread width is 10.7", so I won't be able to use them on 11" or 11.5", whichever I end up with. I might look at the Hankook Ventus RS3 also. The only reason I hadn't looked at them before was because I was looking for 295/30 and I think their largest size is 285. I even thought about getting something even more track oriented like the Toyo R888. Or the ones Luis sent me a link for a while back, but I don't remember which ones they were. Hoosiers? lol

EDIT: Now I'm looking at the RE-11s and it says their tread width is 10". Maybe I'm supposed to be looking at section width lol. Andy, wanna chime in and refresh my memory? lol

[speedjunkie]

I'm filled with so much f**king rage right now. Chris just texted me and said he only got one set of wastegate springs. I thought I mentioned the other set was in the toolbox but I guess I didn't. He said he'd order another set from his distributor if he couldn't get a set locally, which would mean even MORE time until I get it back. He also said Syvecs sent him updated firmware that should solve the fuel pump issue, and I didn't know anything about that.

I'm really pissed about this issue with the springs. ARGHGHGHYGH*GYHGU!!!!~

[Shadowden]

That does indeed suck.

Would it be more cost effective to have Z send the other springs 2 day express mail? Probably cost another $7.00, but lost time.

Or are you more upset about not knowing their was a fuel issue?

Best of luck, it'll turn out good.

[Saul_Good]

Ok, I did a search the other night for Direzza Star Spec ZII, or II possibly, and it said they were discontinued. I just did a search for Star Spec and it brought up the ZII Star Spec in the sizes I need, and IT'S THE EXACT SAME TIRE lol. They're more expensive than they were though, $312 on Tire Rack, and it says the tread width is 10.7", so I won't be able to use them on 11" or 11.5", whichever I end up with. I might look at the Hankook Ventus RS3 also. The only reason I hadn't looked at them before was because I was looking for 295/30 and I think their largest size is 285. I even thought about getting something even more track oriented like the Toyo R888. Or the ones Luis sent me a link for a while back, but I don't remember which ones they were. Hoosiers? lol

EDIT: Now I'm looking at the RE-11s and it says their tread width is 10". Maybe I'm supposed to be looking at section width lol. Andy, wanna chime in and refresh my memory? lol

A 10.7in treadwidth will be a good fit on an 11in wheel. I look at treadwidth when I buy tires and ensure that it is 'slightly' like yours, narrower than the width of the wheel. My treadwidth on my Rivals was 8.5 and my rim width was 9in.... so basically you're good to go if you want to put a 10.7in tire on a 11in wheel. You might even get away with it on an 11.5in wheel too.

Keep with the ZII star specs. They aren't the same, just the same tread pattern with a better compound. Or you could hit up the race site and buy takeoffs.

EDIT: Tire rack review http://www.tirerack.com/tires/tests/tes ... p?ttid=202

[lOOkatme]

If you want max traction and steering response you will want to run a wider wheel width than tread width to create the most optimum tire shape where the wheel supports the tread of the tire in a "stretched" position. The "stretched" position holds the tread in place and isn't allowed to move around like it could with the tread width wider than the wheel width.

so a 10.7" tread width, you want to run it on atleast an 11" wheel width if you want max performance. Origionally tire rack showed the bridgestone RE-11 as an 11" tread width for 285/30/18 and changed it back to 10" (which it is) and I measured it. so I am running really wide wheels for the tread width. I will step up to a wider 285/30/18 tire when these are done. The reason bridgestone went with smaller tread width on their tires is most people run a 255/35/18 on a 9.5" wheel width. Bridgestone knows that running a 9.4" tread width on a 9.5" wheel stretches the side walls out a little and provides better steering response and grip, hence why these tires feel so good to many people. little do they realize that the tread width to wheel width is what is giving such a great feeling.

Run a 11 or 11.5" wheel width with a 10.7 or 11" tread width. This will give you the most direct steering response and most mechanical grip. It also will take out the damping from the tire which leads to a little stiffer feeling for the tire, but we suck out the harshness from the spring rate on the coilovers. The most important thing is creating predictable handling/grip/let go characteristics which this gives you. but it will only be this way if you have a wheel width wider than the tread width of the tire (think of the tire beads being outside of the tread width and how the tires tread width and sidewalls are supported in this shape of the tire installed on the wheel). Every single race wheel set up is done in this way for competitive race teams where lots of money is on the line.

If you go with a ZII 285/30/18 I would run it on a minimum of 11" wheel width for amazing handling.

[lOOkatme]

My one oil lines was leaking a little. I purchased another fitting and installed the new fitting. its leaking worse from the fitting itself than before. so I am purchasing a whole new line to make new with new fittings. You aren't the only one having problems with things running right;)

[Ranger]

If you're gonna go with an R comp, as in a track-only tire that you won't drive in the wet, I wouldn't do R888s. I can't believe Toyo still makes those. The R888 was supposed to be a replacement for the RA1, and while it was better in the rain, it failed in the dry compared to the RA1. Maybe they've fixed it, but when I ran them (back in 2010 so take it with a grain of salt), they'd heat up, do well for a short while, then get greasy and permanently lose grip. The RA1s had more grip and much better life. Then there's the RR, which was also supposed to replace the RA1. I've never used those, but it is the current standard for most NASA racing classes. And there's been a lot of controversy. Some like them, but some people even go as far as to say that Toyo is completely f***ing over racers with all these changes, and that NASA should switch sponsors. They haven't killed off the RA1 so that should say something. I'd do some research anyway because as you know, R comps aren't cheap

Side note I loved my Nitto NT01s, they're owned by Toyo and similar grip to the RA1, yet far cheaper. But, for 18s, they only come in 275 and then up to 305

[speedjunkie]

That does indeed suck.

Would it be more cost effective to have Z send the other springs 2 day express mail? Probably cost another $7.00, but lost time.

Or are you more upset about not knowing their was a fuel issue?

Best of luck, it'll turn out good.

Yes it does. Oh well, this stuff happens. Chris couldn't find springs locally so Z sent the other springs on Thursday after work, to the tune of $67 again, and this time they won't even get there until Monday, 4 days later, because they don't deliver overnight to Chris' address on Saturdays (Zico got out of work late again and missed the truck again). A lot of good it does to pay for overnight shipping when they get there 4 days later. That REALLY pisses me off. So I need to send Z money again and it cost me $130-ish just to send freakin wastegate springs that weigh no more than 1lb all together.

I wasn't upset about not knowing about the fuel issue. And that's fixed now anyway. Basically one of the fuel pump outputs was used to run the OMP but they fixed it. Chris also told me he sent my OMP to England along with his so they could kinda reverse engineer them and understand how they work so they can get the ECU to work with mine. I'm hoping they operate and are wired the same because the Mikuni that I have is harder to find and that way if it fails I can switch back to the regular one.

A 10.7in treadwidth will be a good fit on an 11in wheel. I look at treadwidth when I buy tires and ensure that it is 'slightly' like yours, narrower than the width of the wheel. My treadwidth on my Rivals was 8.5 and my rim width was 9in.... so basically you're good to go if you want to put a 10.7in tire on a 11in wheel. You might even get away with it on an 11.5in wheel too.

Keep with the ZII star specs. They aren't the same, just the same tread pattern with a better compound. Or you could hit up the race site and buy takeoffs.

EDIT: Tire rack review http://www.tirerack.com/tires/tests/tes ... p?ttid=202

Maybe I'll just get the Direzzas and then figure out how wide to go with the wheel when I get the tires lol. But that's kinda putting the cart before the horse.

My current setup has the sidewalls straight up and down. What do you mean "slightly" like mine, you mean a tad more stretched? Well, I should say a tad stretched since mine aren't stretched at all lol. I don't mind a little stretch, but I don't want to get crazy.

Which race site are you talking about, the one you've linked me to? What is it again, RMSolo or something?

Thanks for the link! I'll read that.

If you want max traction and steering response you will want to run a wider wheel width than tread width to create the most optimum tire shape where the wheel supports the tread of the tire in a "stretched" position. The "stretched" position holds the tread in place and isn't allowed to move around like it could with the tread width wider than the wheel width.

So a 10.7" tread width, you want to run it on at least an 11" wheel width if you want max performance. Originally tire rack showed the Bridgestone RE-11 as an 11" tread width for 285/30/18 and changed it back to 10" (which it is) and I measured it. So I am running really wide wheels for the tread width. I will step up to a wider 285/30/18 tire when these are done. The reason Bridgestone went with smaller tread width on their tires is most people run a 255/35/18 on a 9.5" wheel width. Bridgestone knows that running a 9.4" tread width on a 9.5" wheel stretches the side walls out a little and provides better steering response and grip, hence why these tires feel so good to many people. Little do they realize that the tread width to wheel width is what is giving such a great feeling.

Run a 11 or 11.5" wheel width with a 10.7 or 11" tread width. This will give you the most direct steering response and most mechanical grip. It also will take out the damping from the tire which leads to a little stiffer feeling for the tire, but we suck out the harshness from the spring rate on the coilovers. The most important thing is creating predictable handling/grip/let go characteristics which this gives you. But it will only be this way if you have a wheel width wider than the tread width of the tire (think of the tire beads being outside of the tread width and how the tires tread width and sidewalls are supported in this shape of the tire installed on the wheel). Every single race wheel set up is done in this way for competitive race teams where lots of money is on the line.

If you go with a ZII 285/30/18 I would run it on a minimum of 11" wheel width for amazing handling.

Yeah I understand. I'll probably do the ZII, but I still have to see how wide I can go on the wheel. I'm trying to remember for the section width measurement, is that the measurement from bead to bead on each side? I was looking back through old emails but I can't remember what you said before.

My one oil lines was leaking a little. I purchased another fitting and installed the new fitting. It's leaking worse from the fitting itself than before. So I am purchasing a whole new line to make new with new fittings. You aren't the only one having problems with things running right;)

One of your oil cooler lines? At least you have your car haha, but I definitely understand. I've about pulled my hair out dealing with issues like that, things that just won't go away. At least I'm not the one doing the work on my car right now so my frustration levels are still lower than they would be lol. With the new line, are you switching to a different type or staying with the kind you already have?

If you're gonna go with an R comp, as in a track-only tire that you won't drive in the wet, I wouldn't do R888s. I can't believe Toyo still makes those. The R888 was supposed to be a replacement for the RA1, and while it was better in the rain, it failed in the dry compared to the RA1. Maybe they've fixed it, but when I ran them (back in 2010 so take it with a grain of salt), they'd heat up, do well for a short while, then get greasy and permanently lose grip. The RA1s had more grip and much better life. Then there's the RR, which was also supposed to replace the RA1. I've never used those, but it is the current standard for most NASA racing classes. And there's been a lot of controversy. Some like them, but some people even go as far as to say that Toyo is completely f***ing over racers with all these changes, and that NASA should switch sponsors. They haven't killed off the RA1 so that should say something. I'd do some research anyway because as you know, R comps aren't cheap

Side note I loved my Nitto NT01s, they're owned by Toyo and similar grip to the RA1, yet far cheaper. But, for 18s, they only come in 275 and then up to 305

Ok thanks for the heads up! I never really wanted to get R888s, but it had crossed my mind before. I never did any research into their reviews.

I'm not really into Nittos anymore. I feel like they're all very tall tires and it made the car feel slower lol. I thought it was just the NT555s I had, but I've seen some others and they all seem pretty tall.



And with all of this tire talk, I still have to remember to get with Alvin about the wheel he's designing. He contacted me a while back and asked if I was ready to move forward yet, but I feel like this summer is just being sucked away with very little forward movement when it comes to these projects. It won't be long until I'm deploying again and again stuck in limbo. I need to do the brakes so I can install the ducting plates so I can figure out how wide I can go on the wheels and then I can figure out where I'm ordering the lips and barrels from so I can get him the exact measurements for the bolt holes on the outer edge of the faces. What I might do for now is just see if I can find a couple AD08s to replace the rear ones and keep driving on the current wheels for right now.

Also, Zico mentioned about getting an EFR 8374, so I might get in on that deal and go ahead and get one now haha. But if I do, I'd like to get one with investment cast housings if possible, and I'd really like to do internal wastegate this time, but we'll see.

I bought a Bushmaster ACR the other day too, and that got to a dealer in Colorado Springs today, so I'll go get that when I get home. One more checked off the list lol.