JMortensen

Heh. L33 is an aluminum 5.3L V8. When my car was running with an L28, I used the Formula Atlantic front slicks. They were radial Yokohama A005s back then, 250mm wide. They were great, but a little on the hard side. One set would last a full season of autox and a couple of track days, and they would heat cycle out. Never even came close to cording one. They broke loose really progressively, easy to save, etc. From what I've read, the bias ply slicks like more slip angle and the radials are supposed to be more of a knife edge but faster overall, but my experience with the Yokohamas was that they were very forgiving. The one time out on the Hoosiers was OK. They wouldn't grip, but I never felt like I was out of control or like the car was difficult to control. I'm using Bassett wheels. They're 25 lbs each. Not too bad really. I had some stupid heavy steelies with the Yokohamas which were 23 lbs for a 15x8, and the Yokohamas were probably nearly as heavy as the Hoosiers, so for a couple lbs per wheel I've added a lot more rubber...

I've got the 15x13 R35 radial Formula Atlantic tires on mine on 15x14 wheels, using the same front and rear. I've only run them once, but I was having trouble getting heat in the rears. Found out my tire pressures were WAY off, so dropping pressure to 18-20 from 30 might help that issue a bit. Was surprised to be able to smoke those huge tires so easily though. I could smoke them for as long as I cared to, just by flooring it. 350ish whp L33 in mine.

10mm x 1.25. Most off the shelf 10mm bolts are 10 x 1.5, so they can be a bit hard to find.

Same here. Not permanent, just stronger locking than blue or purple. There is a green loctite that the diff shop I used to work for used to keep races from spinning when housings were worn. Apparently that stuff was a lot stronger than the red, so yeah, best not to just go by the color apparently...

Steve, that adapter has the control arm attachment points too. I bet it wouldn't be too hard to adapt that in and get the whole Miata front suspension. They have a shock tower that is very similar to our shock tower. Having spent a good deal of time under both I think the Z tower is taller, so might be able to run a longer bodied shock or cut the Z tower out completely and make a tower that fits the Miata shock.

Here's a drawing of a similar gauge:

In my case I moved up 7/16" to get rid of the bumpsteer. Used a similar homemade gauge, but I put a dial indicator on one side and nail on the other. That was me, not John. I put a tall slot in the xmember. When I went to the Woodward rack, I raised the LCA pivots as high as possible and moved the rack up to match. Now with 2" ground clearance on the front of my splitter the control arms are close to level.

^^^Agreed. This sounds pretty cool.

^^^This. That's one of the few things I really disagreed with John Coffey about. There was a post here where we were discussing bumpsteer and his take was that he could use two different bumpsteer spacers to get the "best" bumpsteer for a particular track if it turned more left than right, etc. My comment was just about the same as Keith's, paraphrased: "I want the car to go where I steer it, not to steer itself because of bumps in the road." Stock Z has too much bumpsteer. There was a rule of thumb that Cary (tube80z) used, want to say its .010" toe change for 1" suspension movement. If you get under that and it's toeing out under compression, you've got it handled enough to move on to the next thing. I did it and then moved on, which is why I can't remember exactly. You cannot completely eliminate bumpsteer on a strut system because change in caster as the suspension moves with change the angle of the steer knuckle and that affects bumpsteer, but you can get it to where it is no longer an issue. Dan (74_5.0L_Z) has used some software to figure out the exact length of tie rod that gives the absolute minimum amount of bumpsteer, I know in his simulation the tie rod is slightly longer than the control arm, but can't remember exactly what the spec is. It's in his very technical suspension FAQ post that also deals with motion ratios, roll centers, camber gain, etc. The rear of a Z doesn't have much if any bumpsteer, but bushing compliance could get you a decent amount of toe change without gemoetric bumpsteer.

When you use bumpsteer spacers, the curve is exactly the same. What part of the curve you're driving in is different. Moving the LCA pivot changes the curve.

You've got this backwards. Moving the pivot changes the relationship between the LCA and the tie rod, so it actually changes the bumpsteer. Using a "bumpsteer spacer" doesn't change the angles of the control arm relative to the tie rod it moves them down together the same amount, so it's a roll center corrector, but doesn't do anything with regards to bumpsteer other than to move what part of the stock bumpsteer curve you're driving in most of the time. I made a similar mistake when writing the Bumpsteer FAQ post: http://forums.hybridz.org/topic/38615-bumpsteer-faq/ and BlackBeaut posted an image to clarify, but it is a dead link now. FWIW, when I was running a stock steering rack and front xmember, I had to move the LCA pivot up about 7/16" to minimize bumpsteer.

Urethane at the TC rod tends to break the TC rods. A solid heims joint or inner tie rod end allows free movement without squishiness. Old thread with multiple broken TC rods: http://forums.hybridz.org/topic/22762-scary-tension-rod-failure/

It toes out under compression, which happens under braking. Stock TC and LCA bushings might allow more toe change than the bumpsteer creates, but who is running stock bushings???

IME adding caster probably added more front grip than just about anything else I did, and my Z understeered badly before I upped the caster. I pushed it up to about 5 degrees and it really made a nice difference. STB also made a huge difference. I like toe out for the front end too, but mine isn't a daily. When it was I had 2 marks on one tie rod, and I used to bring slicks with me and I'd move the tie rod from one mark to the other while switching tires. Different drivers like different setups I guess. Lots of autoxers running more than 3 degrees of caster.

NVH wasn't a problem for me when I was driving my Z daily. I had rod ends on the TC rods too, never minded it at all.

Less area to weld on the control arm? Mine plugged into the arm 3 or 4 inches, and the guy plug welded the tube to the arm in a bunch of spots, migged the end of the arm to the tube, then tigged around the end of the tube and the threaded insert. It might work without tubing. Never tried that or seen it done, but if it's welded well and the connection is solid, maybe that's enough. Maybe get someone better at fabrication to throw out an opinion. This would have been a perfect question for John Coffey.

Google "race car threaded tube ends" http://www.colemanracing.com/Tube-End-Threaded-P3952.aspx http://www.swracecars.com/store/Threaded-Tube-Ends-OSCAR_83.aspx https://www.summitracing.com/search/product-line/meziere-threaded-tube-ends?SortBy=Default&SortOrder=Ascending&tw=threaded%20tube&sw=Meziere%20Threaded%20Tube%20Ends The problem with the Z control arms is that the hole is fairly small. IIRC a 1" diameter tube fits inside the stock arm when you chop it, probably want to cut one and double check that... The problem is that the tube ends have different ODs. That Coleman piece is a 1" OD, so if you put a .083" wall tube on it it's now a little shy of 1 3/16" and won't fit in the arm. BJhines fixed that by cutting the arm lengthwise and then welding it all back together. The guy who made my arms turned the tube ends down to fit in a 1" OD tube IIRC. Either way works, obviously having a lathe helps if you're trying to use the right size tubing so that the arm doesn't need to be modified.

You have it right here. You had it wrong here: "The shorter the lever arm, the harder it is for the mount to hold it down." The lever arm is actually short on the long nose because there is not a big offset between the holes in the front of the diff and the holes in the chassis. The lever arm is long with the short nose because the mount is offset however many inches from the diff mount holes to the chassis mount holes, and the mount becomes a lever arm. To put it another way, there are plenty of short nosed diffs out there. The long nose is the oddball. You don't see a lot of cars ripping the chassis apart because the mounts are built correctly to handle the load. That's essentially the cradle idea that I suggested too. Some people here have done it, and it would be possible to tie into the mustache bar mounts as well and replace the whole thing, use bushings between the diff and the cracle to isolate NVH if desired, or just mount it solid. I was talking to a guy for a while about doing a bolt in setup for the F8.8, back when I had my diff biz running. Ended up folding the biz before I got to it.

I think you have that backwards. The shorter the lever arm, the less leverage. The problem with the S30 is that it was built for the long nose, so the mount is in the proper place for that length diff. When you put a short nose diff in, then you have to have a longer mount, which provides a longer lever arm. In essence, a Ron Tyler mount with a long nose takes the loads nearly vertically. I don't know exactly the length of most short nose mounts, but if it were theoretically 12" long, then you would DOUBLE the force applied to the chassis, and you're not putting those forces into the chassis vertically, the way they're designed to take it. You're trying to twist the mounts out of the chassis with all that force. I know I've seen at least one thread where a guy had ripped up the chassis. That's why I think the diff cradle is superior for a short nose install. Make it strong enough to handle the loads alone, then bolt that sub-assembly to the chassis.

The suspension doesn't bolt to the mustache bar. The uprights go right next to it but they aren't connected. IMO the big mistakes were the flimsy uprights and the stupid stock front diff mount.

Oh, I thought there was a bushing between the mustache bar and the rear diff hanger sheet metal thingy. Looking again, apparently not. That made me watch the video again and you can see the mustache bar tube flexing and the poly at the ends flexing. There is a reason the stock one is about 10mm thick and spring steel, it's supposed to twist. Maybe this is just what you're going to get with this combo. If you want it stiffer you could go to a thicker wall tubing on the bar itself and solid aluminum or stiffer (Delrin?) bushings on the end of the bar. If you stiffen things up considerably then you should do the same to the front bushings, swap them out for stiffer or solid too. If it ain't broke though...

Do they make a poly rear mount? That seems to be where your movement is.

Almost looks like a S130 or Z31 rear diff hanger setup. IIRC those have rubber in them, and that could be where the movement is coming from. Not sure how you could possibly use those hangers with the long nose R200. You must have some weird combo in there. Give us some more details and maybe we can help more.

You reminded me of one problem I had. In the rear with the hooks on the back the lengths are so short that a normal tie down wouldn't work. I have some straps with an axle wrap and those wouldn't work even if I did an X in back. I had to buy extra short straps from US Cargo Control. Mine are 6000 lb rated with 2000 lb operating. The fronts are 10K lb like yours, but I seem to recall I couldn't get the 10K short enough for the back.

With no hooks, I think most people either strap the tires down or they hook to the rear control arms. Not a fan of tire straps after yet another Coffey story: he told the story of a guy towing through I think it was Pearblossom Hwy, which has short hills lined up one in front of the other for about 20 or 30 miles. The guy had the tires strapped and the car hit a particularly bad oscillation on the trailer where the trailer and car extended and then bottomed at the same time for a bit and it ended up pushing the top of the strut through the strut tower. I believe it was a BMW that this had happened to, seem to remember pictures. Got to the track to find that the car was mangled. I didn't want to try and crawl under the car every time, so I avoided the LCAs, but they're pretty accessible on a stockish height Z, although I have to wonder if they'd get bent over time just from the ratcheting down. Some people use chains on one end and straps on the other. I guess if you had a convenient spot to weld loops to maybe you could set it up to hook chains to. Maybe add loops to the LCAs or something. I would think that the outer D rings would be OK for tire straps but I wouldn't use for tie downs in the middle of the car because you have the same problem as the X, but then it's really trying to pull the car off the trailer.