scarp Posted April 19, 2000 Share Posted April 19, 2000 Why is it that everyone seems to be hung up on keeping the irs rear? just what do you have over solid axle besides pike's peak hill clime ect. for norm pavement ect isnt a solid just as effective ne:NASCAR ? Stan Quote Link to comment Share on other sites More sharing options...
Drax240z Posted April 20, 2000 Share Posted April 20, 2000 Generally speaking, an independant rear suspension will give you better road holding and handling characteristics than a solid rear axle. There are of course ways to have a great handling solid rear axle vehicle, as well as lousy IRS vehicles. For most applications though, you will have a better cornering vehicle with an IRS. Not to mention that a lot of people think it just feels and drives better! Drax240z Quote Link to comment Share on other sites More sharing options...
scarp Posted April 20, 2000 Author Share Posted April 20, 2000 I dont agree I just got off the phone w/my brother who works w/ nascar peeps it is all in the setup.... and durability versus handling there is a trade off but when running over 600 hp it is advisable to run solid axle as irs has many weak componets.... and NASCAR runs solid only at 200 mph but he did say that the ride would probly be better on a normal street car..... and that if you did the proper setups on both they would be very close except for like dirt or very rough roads then the irs would be a little better just a thought... where I need very good durability..... Stan Quote Link to comment Share on other sites More sharing options...
Michael Posted April 20, 2000 Share Posted April 20, 2000 I think that for many of us, the main problem with switchng to a solid rear axle is cost and complexity of the operation - and not an aversion to the setup itself. Most of the engineering challanges encountered in our V8 conversion projects are a matter of how to construct something. The "design" aspect comes down to how to make things strong enough, to make everthing fit together and stay together. Changing suspensions, however, involves a conceptual design change, and that includes textbook calculations. In other words, you essentially have to know how to design cars from the ground up. And that, at least to me, is a little scary. Independent suspensions have their main advantage in road holding over poor surfaces, and not in getting power to the pavement. As a somewhat relevant comparison, many people consider that the Z28 Camaro (solid rear axle) handles as well as a Corvette (I.R.S.) - at least, up to its traction limit, launches considerably better, but has problems on rough pavement. Obviously, most of us have no intention of racing on bad pavement. I.R.S. of course also has less unsprung weight, though it seems to me that this too is more of a ride quality than a performance issue. Quote Link to comment Share on other sites More sharing options...
scarp Posted April 20, 2000 Author Share Posted April 20, 2000 great point on irs vs solid thanks I will be going solid for my application due to high HP. but will not be afraid of SCCA comp.... as curves is one thing but coming out of a curve with brute power is an other....... Stan Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted April 20, 2000 Share Posted April 20, 2000 Out of curiosity, for those with solids, can you give a brief description of your rear end setup and the cost, including the rear end. Scottie Quote Link to comment Share on other sites More sharing options...
Drax240z Posted April 20, 2000 Share Posted April 20, 2000 Well put michael. Though I wouldn't really put either the camero or the corvette in the "good handling" area. Now there is a flame war ready to begin. In extreme hp situations, it is probably cheaper to get a solid rear that will hold up. But almost every race car, or race-bred street car has had a IRS. (and I'm not talking nascar or drag racing) If you want a high strength IRS, I have heard good things about the Jag rear end, used often in cobra kits... Drax240z Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted April 20, 2000 Share Posted April 20, 2000 I'm going to be running IRS but I'm "taking the road less traveled by"...Ford 9" 3rd member, custom 3rd member case, toronado CV shafts, Titanium Stub axles. This setup will be bulletproof and definately original. My 3rd member has a posi-trac unit and 3:1 gears. I am confident that this setup will be as strong as most of the solid axle setups out there and I'll still have the benefit of the tunability associated with IRS. I'll have pics of this setup on my website in a couple months if everything goes well (money donations accepted). SpencZ MonsterZ Cont. http://members.xoom.com/SpencZ/index.htm Quote Link to comment Share on other sites More sharing options...
Mike kZ Posted April 20, 2000 Share Posted April 20, 2000 Scottie, I'm running (or will be, the engine is not in yet)a shortened 12 bolt Chevy with disc brakes. 295-15-50 on 10 inch wheels tucked under the stock fenders. narrowed frame and tubbed wheel wells. I'm using Jeg's Street/Strip suspension. Street mode - right bar functions as a torque bar, lift bar is a suspension link. Strip mode - Both bars function as adjustable ladder bars. Plus i have coil overs and a panhard bar. The rear cost aprox - $1300.00, the suspension, - $400, coil overs - $200. As you can see it's not cheap. There is a pic of it under "members rides" Quote Link to comment Share on other sites More sharing options...
Mikelly Posted April 20, 2000 Share Posted April 20, 2000 Also you must remember that with an IRS you have multiple points of pivot (Hence the broken Ujoints and Axle shafts) where a solid axle pivots on the right or left corner. People often argue that the IRS is not the way to go, and I think durability is the only bases for their argument. IF Spenc gets his built the way he wants, I'd say that would truly be the best of both worlds... But for my money, the IRS is still the most tunable, and best handling suspension on the market except for the durability issue. As for the comment about Vettes and Fbodies..I think the new C5 is a good example of GM getting it right...Finally. That car is the car the C4 should have been.... I'm keeping an eye on your rear suspension setup Spenc... Keep me posted! I plan to duplicate it! Mike ------------------ "I will not be a spectator in the sport of life!" mjk Quote Link to comment Share on other sites More sharing options...
Ray Posted April 20, 2000 Share Posted April 20, 2000 Another issue that you guys totally missed is ride quality. Go ride in a stiffly sprung solid axel car then a IRS car the IRS car will ride alot better. Handling should be equal on a flat surface if both are setup properly. On a rough surface the IRS will shine big time not only in ride but in handling. Now this is only for those of us who drive our cars enough to notice freway expansion strips and potholes. The rest of you a solid axel will work great. [This message has been edited by Ray (edited April 20, 2000).] Quote Link to comment Share on other sites More sharing options...
Mikelly Posted April 21, 2000 Share Posted April 21, 2000 Also, not only ride quality, but launching a stiffly sprung Z with IRS is much easier to do than with a live axle car set up with the same stiff (Read: Road Course type) setup. One of the characteristics I love about the Z is the rear squatt when I launch it... Mike ------------------ "I will not be a spectator in the sport of life!" mjk Quote Link to comment Share on other sites More sharing options...
SpeedRacer Posted April 23, 2000 Share Posted April 23, 2000 Great thread guys and I think most pros and cons where covered except maybe one. On a normal straight axle car the rear wheels are maintained at a 90 degree angle to the road. So, for a drag car, you get the most traction. For an IRS unit the tire travels through an arc which changes the camber (more positive). Since this helps against side forces on the tire and counter acts body roll it is a good thing and improves handling. As Mikelly noted, an IRS car squats on take-off but when it does it adds camber and the tires are no longer flat on the road which reduces traction. It is interesting to note that the NASCAR boys actually bend the rear axle tube to provide positive camber. This is really rough on the rear axles and bearings which is why you see them fail once in awhile. Quote Link to comment Share on other sites More sharing options...
Cyind Posted August 24, 2000 Share Posted August 24, 2000 quote: Originally posted by SpeedRacer: Great thread guys and I think most pros and cons where covered except maybe one. On a normal straight axle car the rear wheels are maintained at a 90 degree angle to the road. So, for a drag car, you get the most traction. For an IRS unit the tire travels through an arc which changes the camber (more positive). Since this helps against side forces on the tire and counter acts body roll it is a good thing and improves handling. As Mikelly noted, an IRS car squats on take-off but when it does it adds camber and the tires are no longer flat on the road which reduces traction. It is interesting to note that the NASCAR boys actually bend the rear axle tube to provide positive camber. This is really rough on the rear axles and bearings which is why you see them fail once in awhile. Speed Racer, If you let enough air out of the tires they should sit flat... LOL NASCAR puts the hubs (end plate) on with an offset and fine tunes the angle with heat on the top or bottom of the axle then cools with water to fine tune it. Do you know how big the cheater pipe would have to be to bend the housing... LOL IRS Vette rear end is hard to beat and has not broke yet... ------------------ Z U V8ter http://cyind.com Rspencer@satx.rr.com Quote Link to comment Share on other sites More sharing options...
Guest Smooth Operator Posted October 16, 2003 Share Posted October 16, 2003 Ive always heard that handling in a car with solid rear axle on crappy roads is horrible. Especially in acceleration. Quote Link to comment Share on other sites More sharing options...
Guest Zachb55 Posted October 16, 2003 Share Posted October 16, 2003 ok, call me suspension ignorant but i have some thoughts i need to clear up and im sure you smart folks can do that for me. first off, this may sound dumb, but to run a solid axle in back must you install leaf-type springs or can you keep a strut suspension on there? i guess i've never seen a solid axle with spring like our cars have.. maybe i have, i dunno. also, what is a ford 9 inch? is it a solid axle or a rear differential that connects to half shafts or what? sorry about my stupidity guys, just bear with me... lets see do i have any other dumb questions... oh, what exactly does it take to put in a solid rear axle? would you take out the A-arms and connect the suspension right to the axle housing or what? ok im done, thanks in advance guys, i gotta learn sooner or later and these questions have been bugging the crap out of me! -Zach Quote Link to comment Share on other sites More sharing options...
Tim240z Posted October 16, 2003 Share Posted October 16, 2003 Comparing NASCAR suspension setups with a road going Z car is ridiculous. I think of it this way: HP cars=IRS, sedans =Live axle Corvette=IRS Camaro=LA M3=IRS pickup=LA. Tim Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 16, 2003 Share Posted October 16, 2003 There are a number of different ways to mount a solid axle, but the one you're going to see most often around here is 4 link with panhard bar and coilovers, I'm not even going to try to explain that, look it up on the web and the pictures will be better than a description. Leaf springs are not the best, so people wanting to swap probably won't go that way. The Ford 9" came in lots of performance cars and light trucks from the 60's to '86 in the Bronco. They come in 28 and 31 spline from Ford, but you can order aftermarket 35 spline, and if memory serves I seem to remember seeing a 45 spline once (more splines means thicker axle=more strength). The stock cast iron housings tend to crack over about 350 hp, especially if you can put it to the ground. Aftermarket nodular iron and aluminum 3rd members can address this issue. Also the axle tubes tend to flex, but there are weld in braces you can buy to fix that as well. The 9" is good because the axles bolt in, which is required at some level (I think it's once you get into the 11's) in NHRA competition. By comparison, 12 bolt Chevy rear ends come with C-clips, which are excluded once you hit that break point. You can modify a 12 bolt for bolt in axles, but you don't need to if you start with the 9". The 3rd members are very easy to set up, and since road racers, circle track, drag racers, and off roaders all like them there are a HUGE number of gear ratios available, and parts like ring and pinions and lockers and spools are cheap. They do have a really low pinion, so problems with pinion angle are common (at least in 4x4's). Anyone care to expand further? Jon Quote Link to comment Share on other sites More sharing options...
awd92gsx Posted October 16, 2003 Share Posted October 16, 2003 So...is it the axles that are the weak point in our Z's? Hmmm.... I've seen DSM's put out over 500hp with the stock rear end and 4 bolt axle set (from 92-94 Eclipse GSX's/Talon TSi's)...plus, they're limited slip and use a stronger CV type axle...I wonder if it'd be possible to fit one of those suckers up there... They're pretty bulletproof as long as you use the 4 bolt axle... In any case, is there anybody that makes a stronger aftermarket axle for use with the stock Datsun rear end? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 16, 2003 Share Posted October 16, 2003 BRE put VW CV's in the original 510. Not too far from there to get a 930 CV from a Turbo 911. I've seen rifle drilled chromoly custom axles for those too. Lightweight and super strong... Couple more things on the 9", you can set up 3 or 4 3rd members and swap them out fairly easily so you can change your gear ratio from one track to the next. The have a 3rd pinion bearing called a pilot bearing after the ring gear contact point which keeps the pinion from flexing away from the ring gear. This is better than the standard bearing setup which only holds the pinion behind the head. Jon Quote Link to comment Share on other sites More sharing options...
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