SUNNY Z Posted October 1, 2012 Share Posted October 1, 2012 (edited) So if you've been following, my car is hard on rear end parts (LS1 - 6 speed - slicks). I just broke an input shaft to the diff, and I don't plan on changing how I drive the car - so don't even suggest that. I'm curious if an R230 is even beefy enough? I've seen a handfull of LS1 240sx guys making a little more power than me, but having the same issues with an R230 axle. I'm leaning more toward a ford 8.8" IRS from a cobra/t-bird/explorer pumpkin due to the vast availability of gear ratios and LSD's. I know there's been threads started on this before, but no one seems to ever follow through, so theres no info!!! I'm going to try to source one locally and start experimenting this winter I think. Edited October 3, 2012 by SUNNY Z Quote Link to comment Share on other sites More sharing options...
SUNNY Z Posted October 1, 2012 Author Share Posted October 1, 2012 (edited) Doing a little reading about the 8.8 and swaps. I found this on an S2K board Its a 2007 ford explorer diff cover. Could prove useful. this is part number 7L2Z-4033-B From V8S2000 board: "Ford 8.8 IRS Info ALL 99/01/03/04 Cobra axles have a 28 Spline outer that goes into the hub 99 Cobra axles have a 28 spline inner that goes into the diff 01 Cobra's came with stronger axles than 99 01/03/04 Cobra axles have a 31 spline inner that goes into the diff 03/04 Cobra's came with stronger axles than 99/01 03/04 Cobra's came with Carbon kevlar clutch packs 03/04 Cobra's came with larger pinion flange than 99/01 All Cobra's came with limited slip There was not a 2000 or 2002 Cobra released on the american market. The 8.8 IRS was offered in the following vehicles 99/01/03/04 Cobra 1989-1997 Thunderbird Supercoupe (All Posi-traction) 1992-1997 Thunderbird V-8 models with rear disc brakes(some posi-traction)3.08, 3.27 1992-1997 Lincoln Mark VIII (All aluminum carrier, most non-posi-traction) 3.07, 3.08, 3.27, 3.55, 3.73 1989-1992 Mercury Cougar XR-7, supercharged V-6 (All posi-traction) 1993-1997 Mercury Cougar V-8 02+ Explorer/Mountaineer = 3.55 and 3.73 open, 3.73 LSD , 31 spline To determine the gear ratio, and whether or not the unit has posi-traction, look at the tag that is attached to one of the differential cover bolts. The first 4 spaces signify the gear ratio and whether or not it has posi-traction. If the unit has posi-traction, then the second space will have an L in it representing (limited slip), the remaining spaces specify the gear ratio. For example, 2 L 7 3 means posi-traction with a 2.73:1 gear ratio. Most people pay a salvage yard between $300-$400 for the donor parts. Also, Ford Motorsports sells a 15lb. lighter aluminum carrier with gears and posi-traction for around $650. Edited October 3, 2012 by SUNNY Z Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted October 1, 2012 Share Posted October 1, 2012 I thought I posted this but the post didn't go. Check in with 1QUICKZ; he has an 8-second (1/4-mile) IRS 280z with a 12-bolt Corvette diff and his own custom adapters. He's best buds with jnjracing, the guy who only puts front wheels on his z so he can park it easier in the pits. Quote Link to comment Share on other sites More sharing options...
SUNNY Z Posted October 1, 2012 Author Share Posted October 1, 2012 (edited) C4 IRS swap Edited October 1, 2012 by SUNNY Z Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 1, 2012 Share Posted October 1, 2012 (edited) Looks like your R200 is strong enough. Axle upgrade? Seriously though, maybe the Technotoy R230 with upgraded stub axles would be a good upgrade... Edited October 1, 2012 by SleeperZ Quote Link to comment Share on other sites More sharing options...
SUNNY Z Posted October 1, 2012 Author Share Posted October 1, 2012 (edited) What do you suggest I upgrade to? Billet input stubs? FORGET that. I'm not spending a dime more on custom one-off parts that are still inherently weak by size. Also, I'm pretty much done with the nissan diffs. Way to hard to find parts for, suuuuuper limited gear selection, even worse LSD selection. Also, I'm not done with this car - it will get more power in the future, so I'm not just going to put a band-aid on it, I want to FIX the problem.... Which might be more of a project than I can justify right now. However, I'd at least like to look at other diff options. Edited October 1, 2012 by SUNNY Z Quote Link to comment Share on other sites More sharing options...
Michael Posted October 2, 2012 Share Posted October 2, 2012 Hp/torque at the rear wheels? 1/4-mile times? I am curious what power level would cause the input-shafts to fail thus. Perusing other threads of breakage of rear-end parts, the OP's reported mishap strikes me as rather unusual. For maximal availability of ratios, the Ford 9" appears to be the favorite. There are vendors such as Kugel Komponents who make hot-rod-oriented IRS using the 9". Their stuff is pricey and the setup is like a Jaguar or C3 Vette, with the halfshafts as active suspension-linkages. But their approach to a "narrowed" Ford 9" center-section could be adapted to a Chapman-strut suspension. Then your problem would be finding halfshafts of the proper length. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 2, 2012 Share Posted October 2, 2012 The text you posted on the 8.8 axles, about the halfshafts getting stronger from one model year to the next tells me they are weak too. If you are looking to put even more power and shock into your driveline than you have now, screw the IRS, go get the Ford 9" and a 4 link. Quote Link to comment Share on other sites More sharing options...
SUNNY Z Posted October 2, 2012 Author Share Posted October 2, 2012 (edited) Hp/torque at the rear wheels? 1/4-mile times? I am curious what power level would cause the input-shafts to fail thus. Perusing other threads of breakage of rear-end parts, the OP's reported mishap strikes me as rather unusual. For maximal availability of ratios, the Ford 9" appears to be the favorite..... Approximately 450hp/450lbft. This was a 4500RPM launch (not clutch dump) on slicks. I have the 39 spline stub axles and companion flanges, and a 3" steel driveshaft. It makes sense to me that the weakest part would fail? There are several guys on LS1tech with ~500whp breaking R230 input stubs. The text you posted on the 8.8 axles, about the halfshafts getting stronger from one model year to the next tells me they are weak too. If you are looking to put even more power and shock into your driveline than you have now, screw the IRS, go get the Ford 9" and a 4 link. Well with that logic, I should probably skip the 8.8, skip the 9" and go straight to a Chevy 14 bolt, or strange S60 - because they're both stronger. Ford 8.8 Axle diameters -28 Spline axle shafts with a 1.29" diameter -31 Spline axle shafts with a 1.32" diameter R200 Axle diameter (splined diameter) -30mm = 1.18" diameter R230 Axle diameter? - someone lend me a hand here? Even the 28 spline has a .1" on the r200 stubs, which is 9.3% increase in diameter. the 31 spline is a 12% increase in diameter. This doesn't even factor in the availability of upgraded materials. I plan on doing this swap with a budget in mind. I know I can pick up an 8.8 housing for $300 max, with the cover i need, or for less, +75 for the cover. I will be able to make all the mounts I need. The only other component will be the Inner CV joint, which I have already talked to the Driveshaft Shop, and they said that they have an input stub with a CV joint on the shelf - which can be mated to the bars that I already have - If the length is compatible. However, they can always be shortened, which I believe will be the case, since the 8.8 is ~11" wide, where the R200 is (narrower). Edited October 2, 2012 by SUNNY Z Quote Link to comment Share on other sites More sharing options...
akeboshi Posted October 2, 2012 Share Posted October 2, 2012 OK, Well it sounds like you know what you want to do despite the input so just do it already. Take some pics too please. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 2, 2012 Share Posted October 2, 2012 Well with that logic, I should probably skip the 8.8, skip the 9" and go straight to a Chevy 14 bolt, or strange S60 - because they're both stronger. Point taken, but I'm just trying to point out the next weakest link, the stub axles, something a solid axle eliminates by definition. Quote Link to comment Share on other sites More sharing options...
SUNNY Z Posted October 2, 2012 Author Share Posted October 2, 2012 Point taken, but I'm just trying to point out the next weakest link, the stub axles, something a solid axle eliminates by definition. This is true. I'd hate to break one of those billet stub axles.... that would be really expensive. I only really have one more drag strip event to go to this year where I'll have the slicks on. I'll probably just put another input stub on that half shaft, put it all back together, and start sourcing parts for this winter. Luckily I have 2 spare drivers side stubs, and one passenger. So I can go to the track with one of each . Hopefully It can survive another 20 or so passes this year. Quote Link to comment Share on other sites More sharing options...
SUNNY Z Posted October 2, 2012 Author Share Posted October 2, 2012 Well I just took the first step and ordered the explorer diff cover. It was like $75 to my door. Worst case I can find an open diff for ~$100, weld it, and I'd be right back where I am now, only with stronger input stubs. Granted I'd have a little added cost of a new driveshaft, and CV mods. Quote Link to comment Share on other sites More sharing options...
SUNNY Z Posted October 3, 2012 Author Share Posted October 3, 2012 Spoke with the DSS today. They FOR SURE have the CV joint and internals to convert the 36 spline bar to the ford CV. I'm looking very hard at the 31 spline explorer units. Im hearing that the posi units arent the best, but there are others out there for a reasonable figure that are (tru trac). These are surviving in 1000+ hp cobra's (tanks) that have over 1000# on my go-kart. Quote Link to comment Share on other sites More sharing options...
rsicard Posted October 4, 2012 Share Posted October 4, 2012 SUNNY Z: Is that the 300ZXT half shaft stub that goes into the center section that SNAPPED? Which stub axles were in the car when the stub let loose? Was that a R200 center section/differential that the stub was inside? What do you figure was the amount of torque applied to the stub? Which engine and trans are being used? Please advise. Thanks. Quote Link to comment Share on other sites More sharing options...
SUNNY Z Posted October 4, 2012 Author Share Posted October 4, 2012 (edited) SUNNY Z: Is that the 300ZXT half shaft stub that goes into the center section that SNAPPED? Which stub axles were in the car when the stub let loose? Was that a R200 center section/differential that the stub was inside? What do you figure was the amount of torque applied to the stub? Which engine and trans are being used? Please advise. Thanks. Yes, it was the Z31 input stub in a welded 3.54 R200 Long nose. I have the chequered flag racing 39 spline stub axles in the car. I'd guess 450 lbft* 2.66 first gear* 3.54 final gear = 4237 lbft/ 2 = 2119 lbft/ axle This is an LS1 and T56. I might also add that I was on a 26 x 8.5 x 15 MT ET drag slick Edited October 4, 2012 by SUNNY Z Quote Link to comment Share on other sites More sharing options...
SUNNY Z Posted October 4, 2012 Author Share Posted October 4, 2012 (edited) Ideas for mounts from the LS miata crowd http://ls1tech.com/forums/12511950-post13.html Another mounting solution, as the stock cobra covers are known to crack. http://www.lpwracing.com/Instruction/LPW_ULTRA_IRS_Installation.pdf Kinda pricey though. About $200-250 Edited October 4, 2012 by SUNNY Z Quote Link to comment Share on other sites More sharing options...
rsicard Posted October 4, 2012 Share Posted October 4, 2012 SUNNY Z: What makes the Ford 8.8 IRS -31 Spline axle shafts with a 1.32" diameter, stronger than the Z31 Long Nose IRS differential? I have beefed up a 240Z with the Z31 Long Nose and beefy stub axles. Up till now was going to go to DSS to get the BEST CV half shafts with the best materials available for same. I have built a SBC 383 stroker with the absolutely best components and looking for 500+ HP/TQ. Really do not want to snap any rear end components. Looks best that I get tires that give/smoke under extreme torque. Quote Link to comment Share on other sites More sharing options...
SUNNY Z Posted October 4, 2012 Author Share Posted October 4, 2012 (edited) I already covered this in THIS thread. The diff is plenty strong, but the stub shafts going into the diff are are simply smaller. Smaller = weaker. If the input stubs were offered in a different material, then it might be sufficient for now. However, they aren't. The ford stubs ARE. It is a possibility that the stub that broke wasn't as good as others. However, I'm ready for a limited slip, and if I'm going to pay upwards of $1000, I want something I know won't break. Edited October 4, 2012 by SUNNY Z Quote Link to comment Share on other sites More sharing options...
rsicard Posted October 5, 2012 Share Posted October 5, 2012 SUNNY Z: Looks like the best bet is the later year Cobra differentials. Research first then invest if they spec out OK. Quote Link to comment Share on other sites More sharing options...
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