Minimize Lean for AutoX

[johnc]

If you have the CV joint axles you can't use the rear mount ST bar Jon reccommended, it won't clear the axles.

 

I see people post this a lot and I don't understand. I've installed 6 ST rear ARBs on 240Zs running CVs (both 280ZXT and 300ZX) and there are no clearance issues if:

 

1. You shorten the end link.

2. You plate the stock LCA and drill a new link mounting hole futher forward or use the MM LCAs.

 

[Leadfoot321]

Bart,

The Falkens are very good tires if you don't get them to hot, when hot they get a bit greasy. Most of us use water sprayers to cool them between runs. If you can find a set of Falken RT-215s get them. Falken doesn't make them anymore but they handle hot temps better. The hard part will be finding a new set that has been stored correctly.

Wheelman

 

Actually, I've had the very opposite experience with the 215's. I, along with most people I know that have run these tires, feel the 615's handle the heat better. They will overheat, as you stated, but I feel the 615's are more forgiving regarding heat. The 215's have a much stiffer sidewall, and are heavier because of it, but they have a better turn-in response. I have also run a shaved Kuhmo MX and the 615's are a better tire. You also might check out the Bridgestone RE-01R, supposedly a very sticky street tire. Just became available in a size that I can use on my autocross car and I'm going to try it this weekend.

 

My experience with these are on a STS Civic for the past 3 years. I'm now just starting to build an XP 240z.

[Bartman]

I forgot to mention I've replaced all the bushings with urethane. Have you replaced any of yours?

You don't need to spend $800.00 for tires. I got my Falkens from Edge Racing for ~$500.00 shipped to my door.

Right now the RT-615s are listed on their site in 225/45-17 for $110.00 each, same price I paid for mine. The site says their sold out but you could call and ask.

 

Wheelman

I have upgraded my bushings with urethane.

 

The wheels and tires are a big item, and I'm still trying to figure out the best combination of size, cost, compound, weight, etc. I think I'm going to stick with 17", but I haven't decided on the width. There are a few people running 8" shod with 245's on the front and 9" shod with 275's on the back (like 2fiddyz and Clifton). Others are going with 8.5" 245's all around (like what John Coffey posted on another thread). The more expensive route for tires would be something like V700's and the more economical route would be something like the RT-615's.

 

Decisions, decisions...

[Clifton]

2fiddy drove my car and I drove his at msa's last autoX. He runs a 245 wide rt-215 on the front and I run a 235 wide ra1 on the front. There is a huge difference in grip. I'm sure he will agree. They aren't much more and last almost as long as a Falken and longer than a v700. IMO they are the best dual purpose tire when you want mileage (8/32" tread depth). I've had mine on for about 2 years and they are finally getting down there. If you were closer I would give you a ride.

[uccreepanddrums]

sway bars, strut bars(surprised at how much this helped me), and lower springs w/ struts.....that should get the handling down

[Leadfoot321]

2fiddy drove my car and I drove his at msa's last autoX. He runs a 245 wide rt-215 on the front and I run a 235 wide ra1 on the front. There is a huge difference in grip. I'm sure he will agree. They aren't much more and last almost as long as a Falken and longer than a v700. IMO they are the best dual purpose tire when you want mileage (8/32" tread depth). I've had mine on for about 2 years and they are finally getting down there. If you were closer I would give you a ride.

 

That's so true on the RA-1. The tread lasts so long they will basically heat cycle out before you run out of tread. Excellent DOT r-compound to learn on and great bang for the buck.

[Bartman]

I have the strut bars already and the framerails will be installed soon, so I think I'll get the sway bars then the new tire and wheel package (possibly in conjunction with stiffer springs...especially if I need to switch to 8" in the rear). So I need to determine which specific bar's to get. Will the MSA 240Z kit work with my rear end setup?. If you think I need the ST setup, which one's?

 

MSA Sway Bar Kit 70-73 Z, 1" Front, 7/8" Rear

 

ST

50095 240Z 70-73 1" Front

51075 240Z 70-73 3/4" Rear

52095 Front and Rear Kit

 

Both MSA and ST have different bars for 74 and up Z's but I don't know if they would fit on my car. The ST bars bump up 1/8" in size for the later Z's.

 

The ST's are definitely more, but are they worth it?

 

P.S. - I appreciate all the advice I've gotten so far and the compilment from Ben, but I've still have a long way to go! The journey is fun...but expensive.

[Clifton]

Summit has ST bars pretty cheap. I would go larger.

 

240 http://store.summitracing.com/partdetail.asp?part=stq-52095

 

280 http://store.summitracing.com/partdetail.asp?part=stq-52100

[Bartman]

Summit has ST bars pretty cheap. I would go larger.

 

240 http://store.summitracing.com/partdetail.asp?part=stq-52095

 

280 http://store.summitracing.com/partdetail.asp?part=stq-52100

Thanks Clifton, that is a much better price than I found. So the 280Z kit will fit on my car? If so, I'll buy it.

[Clifton]

So the 280Z kit will fit on my car? If so, I'll buy it.

 

I've never seen the under side of a 280 but it will if the 280 rear mount is the same as the 73's which it sounds like they are.

[ARZ_]

2fiddy drove my car and I drove his at msa's last autoX. He runs a 245 wide rt-215 on the front and I run a 235 wide ra1 on the front. There is a huge difference in grip. I'm sure he will agree. They aren't much more and last almost as long as a Falken and longer than a v700. IMO they are the best dual purpose tire when you want mileage (8/32" tread depth). I've had mine on for about 2 years and they are finally getting down there. If you were closer I would give you a ride.

 

Yea Cliftons RA1's were way stickier than my Azinis, I couldnt believe the difference. I had a little too much negative camber based on Cliftons Pyrometer readings but not enough to mess with it (I was kinda lazy) since we slammed a bunch of negative camber in just for this event and I was getting tired of messing with it, I just wanted to enjoy the day.

[z-ya]

A good quality drivers seat and harness will make a huge difference in your times. If you still have the 280Z seat and seat belts in there, get a decent race seat and a 4 point harness. It should be tight enough so that you don't need to use any effort on the dead pedal to stay put. It is amazing how much faster you are when you don't have to waste energy and thought trying to stay in the seat.

 

I used to be 3-4 seconds slower than a good friend of mine. After a new seat and harnesses, I'm consistently 1-2 seconds faster than him (even in the same car).

[Flexicoker]

I've never really put too much thought into spring rates vs vehicle weights before, but now I'm thinking since the car and the suspension is heavier, why wouldn't you be able to run a heavier spring than in a 2000 lb Z. To state in another way, if the car is 30% heavier shouldn't a 30% heavier spring act the same as the lighter spring in the lighter car???

 

The relationship you're talking about is called undamped natural frequency. Its defined by:

 

1/(2pi) * sqrt(k/m)

 

Where:

 

k is your wheel rate in lbs/ft, NOT lbs/in. For a car with struts its going to be very close to the same as your spring rate. Its motion ratio^2 * spring rate. I would probably just use the spring rate if I was doing basic calcs for a Z. You'll just need to multiply by 12 to convert from lbs/in to lbs.ft

 

m is the mass of one corner (note: mass = weight in lbs/32.17, the unit is slugs)

 

Your answer will be in Hertz, and should be between 1 and 3, although thats a very broad range. The higher the number, the stiffer your car. This number is basically the number of times per second at which your car would oscillate if disturbed and there was no damping or friction. Alot of people believe that equal natural frequencies front and rear will create a neutral car... alot of people don't.

[johnc]

Alot of people believe that equal natural frequencies front and rear will create a neutral car... alot of people don't.

 

Assuming no longitudinal weight transfer while driving on a perfectly flat surface I can see how that would be true.

[Flexicoker]

Assuming no longitudinal weight transfer while driving on a perfectly flat surface I can see how that would be true.

 

I should have said 'statically neutral car' like in a skidpad.

 

I also realized that I made an error, you need the wheel rate, not the spring rate for that formula. Which, with struts, is going to be close to the same number. The wheel rate is going to be motion ratio^2 * spring rate.

[Bartman]

Here's a pic from last weekend:

I am not crossed up in this picture and it's from the front. You can see I'm still leaning quite a bit. So here's my plans so far:

• I have the sway bars on order through Summit (they're on backorder though)
  
• I'm in the process of getting wider rims and stickier rubber.
  
• I'm going to install Bad Dog Framerails (I've already received them).

After I get everything done above I need to adjust some toe in and camber on the rear. I think I already have what I need to do that with adjustable lower control arms and eccentric bushing already installed. I also need to get some camber plates for the front to allow adjustment on the front as well.

 

Does it sound like I have the bases covered?

 

Edit: One more thing; Im thinking of moving the 225 lb. springs from the back to the front and installing 250 lb. springs on the back.

[Clifton]

I would try the bars first before swapping springs. I would then only swap the springs around if it has too much push, assuming the camber is set were it needs to be for optimum traction.

[tube80z]

Here's a pic from last weekend:

I am not crossed up in this picture and it's from the front. You can see I'm still leaning quite a bit.

 

Here's a pic from a friends car. It has a one inch front swaybar and is at maximum turn-in. Based on this I'd say go for swaybars first then see what it looks like. He's running stock springs BTW.

 

Why are you trying to climb into the passenger seat

 

C

[Cethern]

I'm running in BSP right now and I have a long way to go yet with car and the nut behind the wheel. So far I have 200lbs Quickor spings in the front and a ST front bar along with some poly bushings the back so far is still stock and to top it all off the car still has the Automatic:rolleyesg.

 

The motor is stock for now I have a few parts waitting to go on which will happen when the 5sp goes in.

In BSP I can not upgrade the brakes to the 4x4 or do a rear disc setup I can change the rotors though. I also can not use the weld in camber plates. I'm going to have to give Mr Coffey a call and talk with him about his coilover setup and maybe a few ideas on set up.

 

The pic's are from my first Auto-x this year down in the Springs.

 

Cethern

[buZy]

I'd be careful with the MSA rear bar on a 240. I don't think the 280 is a problem because the mounts are further away from the frame rails, but the 240 is not right in my experience. Mine bound on the frame like crazy and I would pick up inside rear tires when slaloming. Of course at the time I was too lazy to take the time and figure it out, so I only really realized the true extent of how bad it was when I went to make the bars adjustable last year. Get the ST rear bar and then space it back off of the uprights about 1/2" would be my suggestion, parroted from John Coffey. Whatever you decide to put on there, you should take the time to push the suspension all the way through its travel and make sure the sway bar and the end links are not binding. You can also shim under the bushing straps to minimize the squeeze of the swaybar bushings and free it up a bit, and it's really really simple to add zerks to the straps and drill a hole in the bushings so that you can grease them up. Teflon tape as suggested will go away in short order, and grease dries up fairly quickly too. Adding the zerks means you can maintain the sway bar bushings instead of just waiting for them to get worn out and replacing them.

 

EDIT--Actually now that I think about it didn't the 73 come with the later style mounts? If so maybe you can use the 280 bar... then your only disadvantage is that it weighs about 3x as much as the ST bar.

 

Hey Bartman, After waiting a month finally got the ST bar kit last week (1" front and 3/4 rear early style) and installed it using these tips. Checking suspension movement and looking for binding. Ended up using 3/8 alum shims between uprights and bushings and .06 shims under the bushing clamps. Added the grease fittings too. I'm not running cv's but what I wanted to say is that I feel these tips really did prove to be effective and worth the extra time to do. More than anything it made the car drive much straighter at higher freeway speeds. The rear end is compliant as it was but the car has a more confident feel. So thanks Jon and Johnc for the info as I would have never figured that one out myself. The front I was not too impressed with the bushing clamps. Without shimming these bushings will be over stressed and distort tremendously! Used .10 shims on the front and added grease zerks. Also had to grind down the bar ends to clear the non-sectioned strut tubes while on jacks at full droop. No big deal really. It appears the oem front bar has similar features to accomodate for this, so it might be something to watch out for when installing any aftermarket bars. The front frame rails are still oem but I don't plan to autox the car anytime soon. Heck i'm just happy its off the jackstands. Everyones setup is unique but I hope maybe some of this will help you what I experienced.

 

Brian