Al Keller Posted November 23, 2001 Share Posted November 23, 2001 Happy Thanksgiving all, I'm curious to know how much ground clearance I should provide for real world driving. What do you guys think? Thanks, Al Keller Quote Link to comment Share on other sites More sharing options...
DavyZ Posted November 23, 2001 Share Posted November 23, 2001 Al, What are the road like in your section of the country?? That would be my first question. Next, what kind of tire and rim combo are you running (what size of tire & wheel)?? Is you exhaust modified or is it stock? How far away from the ground is it now? Is the exhaust the closest thing to the ground on your car (excluding air dams)? Are you running stiffer springs or the stock softies? How was your Thanksgiving? Do I ask too many questions? Need more info before I can lend you some answers Davy Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 23, 2001 Share Posted November 23, 2001 As Davy said, road conditions are going to dictate how far you need to get it up off the pavement. Mines low, and I've seen lower and I fear repavement like you can't imagine. I'd say for my car and setup, stock height would give me quite alot of clearance, lowered 1" (plus gravity induced drop from cast iron chevy motor) mine will probably bottom out at anything over 3.5 - 4" inches I'd imagine (some that have seen it might say less ). I'll pose this question for you suspension Guru's, is suspension travel measured in the full range of motion of the part, or just from car rest to fully compressed? This would have a factor in the equation to. If you had 3" of travel, but the weight compression gives you a usable 2" then ground clearance (in a perfect flat world hahahahaha, and far away from the Baja like job they do on our highways here while repaving), then you'd need that amount plus a safety factor ride height to be determined by the engineer (you). I hope that puts a little lite on it, how well your exhaust is tucked in too will have a large effect on the above. Dogged determination (Being stupid and stuborn ) has made me do my own exhaust, but bucks permitted use a pro, it'll save you time and money building them again (and again and ....) Regards, Lone Quote Link to comment Share on other sites More sharing options...
Mikelly Posted November 25, 2001 Share Posted November 25, 2001 As usual, Don asked a GREAT question. Don, we call the setup "Sag" on mountain bikes... So it would also apply in cars as well. The only car I ever setup with scales, we made sure the car had the exact amount of gas the driver would use to race, and the driver with suit, helmet and all race/ safety gear in place and inside the car. With everything set properly it took over two inches out of the stroke of the piston on each strut at each corner...This was a B210 Datsun the guy had, with moderate springs and koni strut inserts. That setup told us that his springs were WAY inadequate on a "RACE Car". Stiffer springs were ordered.... How we can apply it in our "Real World" application is: You want to take a measurement of the cars four corners when you have two people in the car and the car FULL of all its fluids. If you use a stunt double for yourself, make sure that person is close to your body weight. Also, you can use steel weight plates, but the weight distribution will not be 100% accurate. Anyway, now you can check the setup on all four corners and measure from pre determined points at each corner to get your SAG ride height. From there, you do the math, but keep in mind, the # of your springs will play into the equation. The more stiff the springs, the lower you can go with less travel under suspension load. Mike Kelly Quote Link to comment Share on other sites More sharing options...
Guest SHARKMAN Posted November 25, 2001 Share Posted November 25, 2001 Lonehdrider Not all 1977 280z's are the same. Mine didn't have to have a cat. It has a sticker under the hood saying it is a non cat. All 77-78 280z cars have EFI All my car came with is the egr valve an the pcv. Most all others I have seen do have the cat. Anyway I would like to see your car sometime. I'm in sacto once a week or more. My car has a date of feb.1977 maybe it wasn't a calif,car to start with I don't know. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 25, 2001 Share Posted November 25, 2001 Sharkman, Send me a mail with your # and what days your in sacramento typically and sure we can meet somewhere and you can check it out, be my pleasure. You can email me at lone@cwnet.com. It may have been an out of state car. Thats a real sketchy area though in those years, I had a oregon spec 76 nova that had no smog pump and I was able to register it fine here. As far as I know 1975 was the start of cats in Cal on passenger cars, pickup trucks got cats a few years later. I'm no expert at smog though and its all real cloudy these days, those years were good to me (and bad for me).. Mike, Thanks for the explaination. I figured they must have to somehow put 'sag' into the equation to determine what your 'real world' suspension travel/ground clearance is. Much appreciated. Regards, Lone Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted November 25, 2001 Share Posted November 25, 2001 Passenger weight makes a big difference too FWIW. My RX7 NEVER scrapes with just me in it, put a passenger in it and I have to be MUCH more careful around speed bumps and driveways. Weird but 150lbs or so makes a noticeable difference! The Z doesn't seem to mind nearly as much though Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 26, 2001 Share Posted November 26, 2001 Heh, just don't say that out loud with the woman in the car.. "Gee, it never bottoms out on bumps with just me in it..." you will see they're expression go to this: ! , Lone Quote Link to comment Share on other sites More sharing options...
John Scott Posted November 26, 2001 Share Posted November 26, 2001 Lone, you got me rollin' on the floor with that one. Ahhh.. if I can wipe the tears from my eyes, I have less than three inches to my exhaust. A fraction more to my oil pan sump. As one friend put it. "John you won't clear a road apple in that thing" I havent hit anything yet in 5 years, but I do survey train crossings, speed bumps and avoid construction zones. I hope the V8 will have a little more. I get tired of scanning the horizon for debris at fast highway speeds. One truck retread or concrete chunk can ruin your whole day. JS Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted November 26, 2001 Share Posted November 26, 2001 Yup, I've mentioned it once or twice without thinking - not smart The RX is pretty low and I was going to have it raised but unlike coilovers with threads these use some sort of clips and raising it is a PITA so I've left it alone (shrug). I hear ya' on tire retreads and manhole covers! Both of those scare me silly no matter which of MY cars I'm driving All of them are low enough that hitting one of those suckers would do nasty damage. I've known a couple of guys who have actually ripped rears out on those manhole things when repaving is being done - NOT cool! Quote Link to comment Share on other sites More sharing options...
Al Keller Posted November 26, 2001 Author Share Posted November 26, 2001 Thanks for the info guys - you've given me a little more to think about. The new tube chassis is coming together on the chassis jig and I was concerned with the oil pan/exhaust/scattershield clearance. I've allowed 4 1/2 - 5". It sounds like I'll be ok. The total travel on the coil-overs is less than 6". The tires will be 245-40-17s in front and 315-35-17s in rear. The wheels will be 17x10 in front and 17x12 in rear. Unfortunately, some dumb a-- didn't measure the clearance before he started taking the car apart. Wait until I figure out who did that!!!! Again, thanks a lot. You always seem to come up with a question/s I didn't think about. Al Keller Quote Link to comment Share on other sites More sharing options...
pparaska Posted November 26, 2001 Share Posted November 26, 2001 Al, got any pictures of the progress on your car? Very interested! Quote Link to comment Share on other sites More sharing options...
pparaska Posted November 26, 2001 Share Posted November 26, 2001 How? Well, how about a wife that won't let me forget about it taking over a decade to finish, and me setting a crazy deadline to get it driveable to take it on a 6000 mile journey from Maryland to CA (MSA show) and back in May 2002? BTW, I'm still on target - my engine is coming together and should be back in the car and totally hooked up by Christmas 2001. Can't wait to see those pictures! Quote Link to comment Share on other sites More sharing options...
Al Keller Posted November 27, 2001 Author Share Posted November 27, 2001 Pete, Soon - very soon. How did you stay focused on your car? Al Quote Link to comment Share on other sites More sharing options...
Guest Glenn Parker Posted November 28, 2001 Share Posted November 28, 2001 Pete, Mine is up and running, I'm sorting out the jetting and advance. I was not getting but 16 total degrees at first. I'm going through the 30 dollars here, 50 dollars there, thing. It has a way of adding up and wearing you down. With my suspension setup I'm 4 in. from ground to frame rails. haven't noticed any problems with normal driving but I haven't gone looking for speed bumps either. I made the bumpsteer correction to the lower arms by moving the holes. Do you think the strut bushing kits make a difference and how much toe in are you running? Quote Link to comment Share on other sites More sharing options...
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