jbc3 Posted October 23, 2005 Share Posted October 23, 2005 Well a couple of weeks ago I mentioned in one of Jamie T's threads (below after the pictures is the thread and my response that I am referring to) that the R230 may need an additional IRS brace similar to the ones that are being made for the 03 and 04 Cobras. I should have taken my own advice before I went back to the track! I took the car to the track today and on my first run the rear cover split at the mustache bar mount bolts, twisted and the drivers side CV was grinding on the lower control arm. I "think" that the rear is OK. The under side and rear of the car was totally covered in rear fluid It may have been stressed from previous launches and today was the final straw. I was able to drive the car onto the trailer and under light load there is no noise. The clunking I was hearing seems to be just the CV hitting the lower control arm (seen in picture 3) I'll need a new rear cover and I will be making a rear girdle to support the diff housing as well as the cover. Unfortunately the pics don't show the cover damage, but it can be felt if you feel behind the mustache bar. It will be a couple of weeks before I have time to pull it apart and look more closely. I'll post the whole damage then. Yes the rear is hanging a little low on the driver side. http://forums.hybridz.org/showthread.php?t=104649 Another comment on the high HP launch problem with the R230, maybe something to add to your rear brace. Something that I have noticed after racing the car both times, I was leaking a little rear end fluid. When I drive the car normally there are no rear leaks at all. This weekend I had the car out and had an opportinity to really hit it hard, no tire slip in first, second and third and damn if I didn't have another few drops of fluid leaking out the cover of the rear. I know that some of the late model Mustang Cobras with IRS rears had similar problems and if not corrected with an IRS brace, the rear supports were breaking off. Take a look at this page... http://www.billetflow.com/irs_brace.htm or look at this page http://www.steeda.com/store/-catalog/555-8118.htm Their rear brace is shaped differently, but the brace is actually part of the cover also. We had to put one of these on my neighbor's Cobra to keep him from tearing up his rear. As soon as the brace was installed, there are no more leakage issues from the high launch stresses. I am thinking that I may try and do something like this brace. At least try and get a couple of the rear perimeter bolts on each side into a brace to help the rear from distorting the cover and causing a potential problem. Quote Link to comment Share on other sites More sharing options...
jaime240z Posted October 24, 2005 Share Posted October 24, 2005 I haven't completed my install yet but I would imagine the design of your front diff mount would have alot to do with what happened...? Do you have a pic of your front diff mount? Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted October 24, 2005 Share Posted October 24, 2005 Do you have any rubber bushings anymore? I'm mounting my diff ridged. No rubber or poly bushings. Not even in the front. I don't want mine to move at all. No movey, no breaky. I haven't had time to work on it in a week or more. I'm gonna try to get to it this week. But, my dad's buying a '50 Ford and I'm gonna be doing so frenching and other custom touches to it. So, I will put the Z on hold for a month or so until that car is in epoxy primer, so I can get it out of the shop. Quote Link to comment Share on other sites More sharing options...
rudypoochris Posted October 24, 2005 Share Posted October 24, 2005 HOw much hp/tq are you running just for curiosity? Also, is the actually diff broken or just the case (i hope just the case!) Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted October 24, 2005 Share Posted October 24, 2005 Just the rear cover... Quote Link to comment Share on other sites More sharing options...
Synlubes Posted October 24, 2005 Share Posted October 24, 2005 Is the fuild coming from the top vent or some where around the cover? Install a hose on the top vent and carry it up and mount it higher. You must be hooking pretty good. Quote Link to comment Share on other sites More sharing options...
jbc3 Posted October 24, 2005 Author Share Posted October 24, 2005 My front mount is poly bushings and the mount for the bushings is a brace that is both mounted to a bar that runs from the front crossmember mount to the rear as well as to the stock strap mounts on either side of the tunnel. I won't defend my design since I have not pulled it apart yet. Who knows, it may be a contributor. The front mounts still seem straight and solid. The rear is being held If I had not seen the problems the Cobras have been having personally, I would not have figured it into the picture. A rear girdle would likely have prevented the rear cover from breaking. The rear cover is not the strongest thing The fluid is coming from a break/tear in the rear cover just around the rear mount studs for the mustache bar. There could be more damage, but I "think" the cover is the only place it is coming from. I did get under it and feel for any other obvious problems, but it all seemed fine. I have not had the car on a dyno yet but the motor should be making at least in the 500hp/450tq range. One thing that may be contributing to the problem is I am running the McLeod steel flywheel street twin clutch. The clutch drop is bruital. One more thing, I think the back of the rear is being held down on the driver side by the cover. It is still attached to the mustache bar and the cover sort of tore but did not break off. By putting a jack under the rear it seemed to move up and stay. I don't want to force it around until I get it apart and see what the deal is. Quote Link to comment Share on other sites More sharing options...
jbc3 Posted October 24, 2005 Author Share Posted October 24, 2005 You must be hooking pretty good. A friend of mine took a short vid of the launch and e-mailed the link to me. http://para.noid.org/~wayne/280-launch.mpg Jody Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted October 24, 2005 Share Posted October 24, 2005 IMO you may be overdiagnosing the problem. Cracking at the mounting bolts doesn't necessarily imply the diff casing itself is flexing. All it means is the mounting bolts connected to the aluminum cover were not strong enough. If the cover had cracked from a lower corner or one on the cover to diff bolts (like the Cobra pictures you posted) then I would say the cover is warping. Cracking at the mounting bolts only means the bolt took a heavy jolt. When was the last time you retorqued those mounting bolts? If they were even slightly loose, the diff count have moved a bit before slamming the bolt into the other side of the hole. Have to agree with some of the comments above about the front diff mount. If the front mount flexes where the rear is solid, then it is the two mustache bar bolts that are handling all the torque. Quote Link to comment Share on other sites More sharing options...
jbc3 Posted November 6, 2005 Author Share Posted November 6, 2005 I pulled the cover off the R230 today and here are the pictures of the broken cover. The stud was also slightly bent. There was no other damage to the rear at all. Everything else is in great shape. I am planning on welding the cover back together and sealing the stud hole. Then I am working on making a mount that will use the cover bolts. The stud bolts were still tight so I am still not sure why the cover broke the way it did. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted November 6, 2005 Share Posted November 6, 2005 WOW I'm taking notes, since I have two of those diffs sitting in my floor. A custom craddle is a must. What about suspending the differential weight from the bottom, kinda like Jamie's setup? Mike Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted November 6, 2005 Share Posted November 6, 2005 IMHO, the front diff mount is what caused that failure. I don't know exactly what your mount looks like, but I suspect it has allowed the front of the diff to move. You said earlier(replying to my thread) that you had to rework your brace since it had bent. Your rear cover could have likely cracked at that time. Quote Link to comment Share on other sites More sharing options...
jbc3 Posted November 6, 2005 Author Share Posted November 6, 2005 Now that I dropped the rear I can see that the poly bushing on the passenger side of the front mount was crushed. It looked like it had 50K miles instead of a couple of hundred. I think that it was moving. The washer that capped the top of the bushing was bent. I will be replacing the bushings and I'll be using much larger heavier washers to sandwich the bushing. (Mustache bar washers look like they will be perfect) I also found another problem. The slip yoke in the transmission took a beating too. The inner splines twisted in the yoke. It was a MoFo to get it out! The transmission output shaft is fine. I will be replacing the slip yoke with a billet yoke. I thought that since the 280z is so much lighter than the Z28 I would be able to get away with a standard slip yoke... I was wrong. I trashed a slip yoke in my Z28 and replaced it with a billet yoke. Here are a couple of pictures of the inside of the slip yoke. Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted November 6, 2005 Share Posted November 6, 2005 YEAH BUDDY! That's putting the power to the pavement! Who says you can't make an IRS car hook?!!!! Way to go, and I am impressed by the carnaige of broken car parts you are leaving behind. Whittle down all the weak points and there will be no more. You are my new idle. Joel((J. Solieau), will have to be my second. You have proven two things, first, you CAN make an IRS car hook up, and second, the R230 is not indestructable. I want my car to hook as hard as yours, but hopefully I will be able to do it with the breakage first. I'm sorry your diff has had issues, but I'm glad you are figuring it out and posting the results here. You're the man! Quote Link to comment Share on other sites More sharing options...
jbc3 Posted November 6, 2005 Author Share Posted November 6, 2005 I'm glad someone is happy about my broken parts Quote Link to comment Share on other sites More sharing options...
fastzcars Posted November 6, 2005 Share Posted November 6, 2005 Yep I agree with jamiet. All the broken parts posted here will help other guys in ther quest to lay down the power. By the way, impressive dispaly of carnage, way to go. Quote Link to comment Share on other sites More sharing options...
jbc3 Posted November 6, 2005 Author Share Posted November 6, 2005 OK, I'll admit I also get a little pleasure seeing someone elses destruction. I usually think... that must have been one hell of a noise at XXX speed! Cool! Anyway, I am sure that I'll be breaking a few other parts in short order... as you all probably figured out, I'm not gentle on my car Jody Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted November 9, 2005 Share Posted November 9, 2005 OK' date='Anyway, I am sure that I'll be breaking a few other parts in short order... as you all probably figured out, I'm not gentle on my car Jody[/quote'] LOL, and for that... We are greatful! You inspire me! Quote Link to comment Share on other sites More sharing options...
jack46 Posted November 9, 2005 Share Posted November 9, 2005 What were your 60 foot times and ET's? Sounds sweet on launch. What cam are you running in your LT1? I have a 224/232 .508/524 @113 Quote Link to comment Share on other sites More sharing options...
jbc3 Posted November 9, 2005 Author Share Posted November 9, 2005 11.4 AT 120MPH W/ 1.6 60' NA I am running stock ported heads and a GM 847 cam which is I believe a 234/242 at 112 LS. I have yet to put the car on a dyno and give it a proper tune, it has been tuned by some street diagnostics only. I am running a McLeod street twin with the steel flywheel. I think it is too much for the little car. Too much torque when the clutch dumps on the line. I wish I had gotten the aluminum flywheel, but it is what I had in my Camaro that I transplanted the motor and transmission from. Jody Quote Link to comment Share on other sites More sharing options...
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