tube80z

And if you have a cage you can tie the pedal box into the front cross bar. If you do this then you will really notice a difference. It's always good to have someone push really hard on the brakes while you watch the pedal box/masters. Many times you'll be surprised at how much all this moves around. Removing that will help with brake feel. And then you just keep going down the line. best, Cary

It should work fine and I like it. Another option you might consider is to link both sides with cable and use some rollers to allow the cable to move back and forth. What this does is allow you to droop limit when you lift the end up but not constrain roll. And then you can start doing tricky things like keeping the amount of lift limited when you hit the brakes or drop the throttle but still have full travel for roll. If you're playing with underbody aero or a diffuser that might be useful. Or if you hillclimb and deal with a lot of road crown this can help to better put the power down. And you can also use the helper springs. Cool idea though. Cary

The one thing you'll want to add if you haven't already taken it into account is a pinion snubber. The ears will not hold the front of the diff from lifting and will eventually break on a V8 car. Just a piece of square across the top with a basic rubber block should be good enough. Cary

Let the splitter be the skid plate. Put a few tubes to capture the back of the splitter on the crossmember and then use this as the mount. Cary

Nice car, now I need to come up with 5K for that awesome manifold.

Looks really good Jon!

That's awesome Cameron. Harold Knoebel is a multi-time national DMOD champion and you beat a host of other people in really fast cars. From watching the video it looks like a couple of sections are pretty rough. It doesn't look like you're that far from being able to fight for King of the hill. Looks like a great venue and sounds very similar to what we have in the PNW with regards to event atmosphere. Great job! Cary

Having been around that car for a long time I can tell you it had nothing to do with the motor placement. It had a lot of other issues. A local racer put the motor even further back in his 510 (Larry Nelson) and it was one of the best handling 510s I've ever had the pleasure of driving. Put another way, the 510 has heaps more PMOI than most sports racers or formula cars and normal humans don't have issues with those. Claude Rouelle shared a number of stories in his seminars about weight distribution and PMOI. Up until the Pirelli tire era most F1 teams arrived and the track and only changed weight distribution according to him. They had sophisticated simulations to determine all the other parameters before they even showed up. Claude shared one story where moving two 7.5 pound blocks was worth three quarters of a second. You can do some simulation based on either data or by guessing by using the free version of Bosch Lapsim. If you have data you can build your own track and create a model of your car. From there you can play with certain parameters and see what happens to laptime. The free version assumes a perfect driver and doesn't really take suspension into account. From what I recall it's predictions matched what John said, which is what you would expect. So if you want to try and optimize you can have lots of fun with that tool. It was fun to build that 1000 HP Z and see what my 0 to 60 time would be. Cary

Sorry, I should have called it a hydraulic release bearing. These are stiffer and easier to drive. The engagement point will be something you'll want to work on. The small clutch will bite very quickly so any flex makes this harder to manage. Your definition of free play is correct. You need a specific distance from the bearing to the clutch cover. You also need to have a precise pedal stop so you don't over push the cover. That can also damage them. The crank thrust is the bearing area that takes the pressure when you push down the clutch pedal. If the bearing doesn't have the specific free play and is tight these surfaces can be under pressure most of the time. And over time the bearing wears down and then the machined area on the crank. And then things get expensive. As long as you follow the directions you should be good but make sure the free play is correct and the travel doesn't over extend (pedal stop recommended). Then it's just a matter of getting used to how easy these grab when you let out the pedal. Luckily with the V8 you have extra torque so it won't be as easy to kill the engine. Cary

Sorry I missed this part. For the small clutches you will probably need to remove the arm and go to an annular style bearing. These either replace the end on the transmission where the sleeve for the throwout bearing would normally sit or they can be mounted to the bellhouing. These clutches need a smaller bearing and a precise amount of engagement for release. You also need to be very careful you have the prescribed amount of free play or you can run into crank thrust issues down the road. Take a look at what's offered for the LS engines and the T56 conversion. This will give you an idea of what you need to do for the VK56 and G35 gearbox. Hope this helps, Cary

Hi Dave, A button is what they call a friction surface with no ring gear. You use a the stock flex plate and then sandwich on this friction surface (using normal flywheel length bolts), which is exactly what you're looking to do. Only change is longer bolts will be needed for the crank hub. Take a look part way down the page on this forum to see a CADed up view of how this works http://www.audizine.com/forum/showthread.php/333627-GURU-s-official-LS-B5-Quattro-Swap-for-under-5k/page11 The flex plate is usually about 0.125 and the button is around 0.25 or so. This gets you to the normal flywheel thickness. The cool thing in all this is the buttons are usually around $125 new from the speed shops but even a custom one shouldn't be too bad. For a button all they really need to do is take a standard one and put eh VK56 crank pattern on it. They may even sell blanks that you could do this your self. Or I'm guessing that Taylor would do this for you. On the clutch I'm not sure if you found a good deal on this one and that's driving the purchase. You'd be better off with the newer v-drive style as they run cooler. On a friends Z the older style like this in 5.5 needed a rebuild before the year was out. The newer v-drive (optiumum V) has shown less wear. I only gently nudge in the 7.25 range as they are all over e-bay for around $200-$250 for units in good shape. That's what I did for the LS one I have. BTW, as you probably know there's no loading your car on the trailer without a wing with one of these. Cary

Is there a reason you're not using a button and the VK56 flexplate? OR is it a problem with the G35 6-speed tranny not aligning the starter to the flexplate? I had a custom flywheel built years ago for a 510 conversion. For it I sent them the flex plate from the engine to establash crank pattern and general spacing and then a flywheel that fit the other tranny to get the starter gear spacing correct. So with those two and working back from the block mating face you could come up with your dimensions. You'll need to know if the VK56 is flat on the back or has any offset to figure that in. If this is a track only car the 5.5 will probably be okay but if you autox you may find that you have to service the clutch every year or sooner. A 7.25 has a lot more heat capacity and is going to be a little easier to get started. Just my two cents. I went with the 7.25 on my LS swap. C

I'd check your alignment and make sure you don't have anything that's worn out (tie-rods, inner/outer), worn rack bushings. And obvious things like the wheel is round. If all that checks out then it may be the tire. Over the years I've seen some weird wear patterns on tire from autox. I can only assume caused by what's under the rubber. The new GoodYear production slicks get a wear pattern that looks like massive toe-out. You run them once and then flip to take care of it. So another suggestion would be to check with other Nitto owners to see if they see a similar thing.

On most hills it takes a third of the way for them to really start working. One trick for any street legal car is to drive around at legal speeds but use a lot of brake gas to build heat into the tires/brakes. As you sit in line that latent heat can make a huge difference. If you have a hill where you all drive to start make sure you do real work to get heat into the tires. Often that can make a second or two up in the bottom third of many hills. Driving at normal speeds on the course can help you at times. But many times the difference between legal and race speeds is so much that it seems completely different. Almost all hills have a required novice program where they often take all of you up the hill in a truck and talk about key areas (usually safety related) and show movies of the course. No matter how many times I've ran a hill I always go to these often taking crap for where I went off on what year and so and so. I'd look for vids on youtube and make sure to record your own. You can watch them at night to help memorize what it looks like at speed. Just make sure the car still drives after the event. At some point we all have a moment when pushing really hard.

I've done a number of hillclimbs in the Northwest. Assuming the roads are similar your setup sounds reasonable. One thing to make sure is that your alignment doesn't make the car follow ruts/lines and that road camber changes in the road aren't a major issue. In general you won't be using your brakes as hard as you might on a track/autox course for most hills. For us a lot of corners have apex speeds in the 45 to 60 range and only a few in the 75 to 80 range, which is usually major pucker when a tree or rock is very close to you. I lost a door mirror on a rock wall at Bogus Basin (Boise ID). At hills you'll probably see more suspension travel than anywhere you race. So make sure you don't hit bumpstops or that could make the car very nervous. My only other advice would be to drive the hill as you see it at about the 95% level. As you learn it you can know what areas you can really keep the throttle down. But be careful you don't try and gain too much time each run. Keep each run close and inch up. I've seen too many people do a few slow runs and then really go for it only to crash. Generally it takes 2 to 3 years before you know the hill well enough to start chasing records, at least for an amateur like myself. And then mother nature often has her say. Hillclimbs are probably the most fun thing I have done in a car. You may go faster on a track but the feel from a hill is something else. And when you're done and talking very quickly or foot won't stay still you'll know it was a good run. Cary

I think a lot of this depends on how high you rev your engine. In most of the cars I've ran we typically used a 3.70 to start with and launched in second and then used third for most of the course. I found that quicker for me than dropping to second and having to deal with managing a lot of torque at the rear wheels. It also depends on whether your willing to change diffs for track/street versus autox. If you don't want to change diffs then I'd look at a lower ratio 3:55 or 3:36. If you're willing to change then maybe lower than what you have and start in second and go for third. As many others have written you want a gear that's good for 75 to 80. I wouldn't use a 4.38 for track days as they generate a lot more heat than a 4.11 or at least that's been what I've seen.

The only thing I saw I might change would be to use safety washers that has a built in conical spacer so the rod ends have more clearance to their bodies. To keep from trying to move the top of the strut you need this extra degree of freedom. Dan did an excellent job in the sticky discussing all this. That's why the majority of the aftermarket arms for the back of the Z aren't really a very good design. I did a quick and dirty set for a friend's car where we wanted to try adding some antisquat. While we never went down that road we did notice the car seemed to put power down a little better. This was on a car with 15 inch FA rears and 436 WHP. I know that's anecdotal but the toe-link arms do remove some stiction from the suspension and any where you can do that it will help. I think another area of development we haven't looked at too close is the outer mount on the rear strut. It would seem to me that we can do this in a more adjustable way that's a lot lighter and mount the heims flat so we're not rotating the bearing in the housing.

I've had good luck with real hammerite. I put it on with a roller and it holds up pretty well. Cary

That rule of thumb doesn't apply to race/high performance cars. It's really intended for ride (flat ride) for not causing discomfort. For racing we are more concerned with balance in the corners and control. As long as the car doesn't hop off the ground in a straight line it's okay. It's also perfectly acceptable to have the same frequency front and rear or the front stiffer. In a high HP car that often is quicker. Cary

You have a really nice car. It would be a shame to try and hack it up to run in EM. As mentioned below you have two options for classes, XP and SM. SM doesn't allow for any chassis mods outside of strut bars and a basic cage as I understand it. XP allows more freedom on the chassis but you can't mess with the firewall. Your car could fit in either class and probably be fun to drive and locally competitive. To be nationally competitive is a whole another story and would require a completely different direction I'm afraid. If you like to drive your car on the street and do track days then I'd look at SM. If you have to put it on a trailer and run on slicks and do autox/track days then XP is probably a better match. EM will require that fabrication become your hobby and you'll most likely end up with a silhouette of a car. If you really want to run in EM I'd either fund a rusted out junker or just build from scratch and put a fiberglass funny car style body on. As mentioned below the best way to pick springs is by frequency. For a more streetable car I'd look at springs in the 2.5 to 2.75 Hz range (most likely 300 to 400 lbs/in). You'll also need inserts that can deal with this and ideally you'd want something custom valved. It's not as big of an expense as you might think and money spent up front is going to be better than buying three of the same part. I'm sure you already know that pain. For an XP car on slicks it really depends a little on the tires. I'd probably start at 3 Hz for a sedan/GT based tire and look at going stiffer. If you run the FA tires then I'd look at springs in the 3.3 to 4.5 Hz range (that's very stiff and requires very good shocks). And to run rates that high you really need to have a cage that ties the car together. So the easy route would be to start in SM and then progress up. But truth be told you won't be much faster in XP than in SM unless you do some serious work to make all the new bits work together. There are a lot of really smart people on this board that can help point you in the right direction to go faster. But the ROI quickly goes south. For bushings you really want to look for other options than poly. The stiction is way to high and that hurts grip. Where ever you can it would be good to change over to rod ends/monoballs. Again this all depends on class. We're all happy to share what we know around here. Hopefully this helps. Cary

One option I haven't seen discussed is to put an X in the floor. Very common in the pro touring car categories (BTCC, V8 supers, etc.) For about the same weight as the subframe connectors a lot of people put in you can increase the stiffness a lot. Ideally this should tie into the cage completing the bottom. The rocker reinforcement shown on Dave's car was at my prodding. We had a hillclimb accident where the driver was seriously injured because this area folded up and struck him. The door bars did their job but the rocker and floor gave up. He now has a limp and was off work for about a year. If you look at newer cars this area has been massively reinforced compared to the Z. Cary

A friend glued the window on his 280Z chump car. It worked great and we saved a nice gasket from being wasted. Oddly the car drove very different before and after. Gluing in the windshield makes the car stiffer and at least in this old clunker you can feel it. cary

You've already gotten a lot of good info so far. One thing I found is that my car worked much better when running stiffer springs and less bar on surfaces that had less grip and/or when it was damp. I would be looking at 100 to 150 more in spring rate and a much smaller front bar and possibly no rear bar. You can then tune it using rake (lower the end for more grip/raise the end to take more roll stiffness). That's a better way to balance the car than reducing traction on one end. For autox the quicker the car will transition the faster it will generally be. I'd look at how much droop you have with the spring seated and see about removing some of that with a limiter. I'm guess you have somewhere around 1.75 inches of droop presently. Try removing 3/4 of an inch and see what you think. It should be an easy and cheap thing to try. And another things most people don't understand when changing only one thing at a time is a change in springs requires a change in ride height or you have not changed one thing at a time. BTW, to go faster you really need to start looking at reducing friction on the suspension. That means getting rid of poly and any bind you may have. That's where the next big gains will come from. Cary

I would see a couple of advantages to this. It should keep the tires flatter on the ground and if done correctly would have a roll center that moved with the car in a 1:1 relationship. Unlike the strut that moves at a different rate. I could see this making the car feel more stable in corners when putting power down or when trail braking. And I could see that making the car quicker just because the driver feels more confident. Cary

We use toe plates at the track and can get within a 1/16th with them. That's measured on an alignment rack after the fact. I can't see how you need to be more accurate than that. My preferred method is to use parallel strings. Tom Holt had a good design I stole from his site (thanks again Tom!).