Ian C Posted March 26, 2007 Share Posted March 26, 2007 As mentioned here: http://www.mkivsupra.net/vbb/showpost.php?p=1313153&postcount=43 Our man in the know drops a hint about rear subframe probs and I was wondering if there was any more info on this, such as what the problem actually is for a start How it manifests and why we haven't heard much about it already - unless it is indeed the wobbly back end thang? -Ian APRIL FOOLS!!! Link to comment Share on other sites More sharing options...
Toy Motor Posted March 26, 2007 Share Posted March 26, 2007 Hi Ian, I was hoping no-one would want more info on this as it's likely to cause concern. From my experience in testing and in my ownership, we found that the Supra's rear subframe has a designed flaw in the rear subframe chassis support. After 15 to 16 years the rear shell will fail where the subframe bolts to it. Accelerated durability tests during the development phase showed that the rear subframe was marginal in supporting the rear wheel drive layout with the torsional forces put through it by a limited slip diff. Over time, this twisting action fatigues the supporting areas, fracturing them. Non limited slip diffs never put enough twisting action into the chassis mounts so didn't ever display this issue. If you have retrofitted a limited slip diff then the issue will manifest itself around 15 years after the installation. If you have modified your car to increase the power output, the lifespan may be shortened even further. This is theoretical however as Toyota saw no point in spending R&D money performing durability testing above the stock power output. As there have only been a couple of reported incidents 'in the wild' so far and none in owners' clubs that we know of yet, an increase in power probably doesn't accelerate the process that much. It was, after all, a twist action causing flex fatigue, and not a torque issue causing a bending force. If the failure occurs, it will be under acceleration, probably from a hard standing start as that induces the most shock loading. This is a good thing because the side that fails will collapse to the point that the rear wheel fouls on the wheel arch - not something you want happening at 80mph! This sudden twist can cause the other side of the frame to fail as well, causing the back to drop fully. At this stage in the car's life it's probably not economical to repair, a re-shelling would be required. Trying to re-weld and patch up the affected areas would be seriously inadequate and could fail at any point while driving, thus making it very dangerous. Please don't hate me for sharing this with you guys! I know it's NOT what people want to hear about their pride and joy - as I've already said the MKIV Supra is one of THE most durable and well engineered cars to come out of Japan, and that's saying something! Bob. APRIL FOOLS!!! Link to comment Share on other sites More sharing options...
michael Posted March 26, 2007 Share Posted March 26, 2007 Interesting stuff, I would have expected one of the mega power US chaps to have experienced this by now, unless driveshafts go first... Link to comment Share on other sites More sharing options...
Alex Posted March 26, 2007 Share Posted March 26, 2007 It's good to know about it...cause now people can think about preventing it... Would there be any specific points on the chassis that you could toughen things up to reduce the twisting fatigue? Link to comment Share on other sites More sharing options...
mikeyb10supra Posted March 26, 2007 Share Posted March 26, 2007 Well worth hearing though Bob, thanks for the heads up, are there a lot of reported cases of this that you have come across? Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted March 26, 2007 Share Posted March 26, 2007 :(Goes to Look for the weider and some heavy duty plate;) surly there must be a way of beefing up the area? has anyone actually got some pics or line drawring of the precise area? Link to comment Share on other sites More sharing options...
Thorin Posted March 26, 2007 Share Posted March 26, 2007 Toy Motor scares me, make him stop Link to comment Share on other sites More sharing options...
tDR Posted March 26, 2007 Share Posted March 26, 2007 Holy shit that's some clanger! Always thought the shell was particularly well made for a 90's sportscar. Well, mine's 10 yrs old now.... anyone wanna buy it in say....... 5 years time? Think I'll need to get under it and have a good look at the metal surrounding the subframe mounting points. Hopefully we can figure out a way to avoid the fatigue failures - extra bracing or something along those lines. Cheers, Brian. Link to comment Share on other sites More sharing options...
Tom Posted March 26, 2007 Share Posted March 26, 2007 I wonder if toyota did anything on the later models to rectify this? and if they did it could be another uk vs jspec difference Link to comment Share on other sites More sharing options...
SatSport Posted March 26, 2007 Share Posted March 26, 2007 This is very concerning, the subframe is attached by rubber bushings i assume. Found this which you may comment on....?? http://store.titanmotorsports.com/soresumofort.html Parts are CNC'ed out of Billet aluminum. Total of 4 pieces these help solidify the whole subframe assembly to the chassis. These are stock replacement parts. These press in with relative ease. Whether your a road racer or drag racer these will work for you. Help eliminate suspension flex/wear of your stock components, help eliminate wheel hop and tune the suspension of the vehicle. You can never tune a flex or bend you can tune your suspension. This replaces the front stock rubber bushings that mount from subframe assembly to the vehicle chassis. Regular price: $325.00Sale price: $299.95 Link to comment Share on other sites More sharing options...
AlanM Posted March 26, 2007 Share Posted March 26, 2007 I may be picking this up wrong but will these not make matters worse rather than better? Link to comment Share on other sites More sharing options...
Ian C Posted March 26, 2007 Author Share Posted March 26, 2007 Whoa jesus I way expecting some accelerated bushing wear, not the back of the car falling off? You sure about this? Have you got the EPC diagrams or anything of the affected area? You wouldn't happen to have piccies stashed from the time you spent testing? Which bit is it that goes? Surely a big name company wouldn't let a defect like that out the door if it let go in traffic you could get a hell of a lawsuit on your hands? Maybe indeed the UK/US spec ones are different in that respect, to avoid litigation - they are, after all, heavier in almost all other areas -Ian Link to comment Share on other sites More sharing options...
Ian C Posted March 26, 2007 Author Share Posted March 26, 2007 I wonder if toyota did anything on the later models to rectify this? and if they did it could be another uk vs jspec difference Ooh, mine is a facelift... *crosses fingers* -Ian Link to comment Share on other sites More sharing options...
colsoop Posted March 26, 2007 Share Posted March 26, 2007 Saves web page for possible litigation Link to comment Share on other sites More sharing options...
Mike M Posted March 26, 2007 Share Posted March 26, 2007 Hmmm, mine is knocking on 14 years. Interesting stuff but hopefully real life wear & tear will have been kinder. Link to comment Share on other sites More sharing options...
jaymdee Posted March 26, 2007 Share Posted March 26, 2007 I don't even know what a rear sub frame is ... Found this link to strengthening what may be the same thing on E36 BMWs: http://home.comcast.net/~matthew.c.smith/mods/rear_subframe/index.htm Link to comment Share on other sites More sharing options...
Ian C Posted March 26, 2007 Author Share Posted March 26, 2007 Hmmm, mine is knocking on 14 years. Interesting stuff but hopefully real life wear & tear will have been kinder. That's a good point actually, how did you accelerate 15 years+ of drivetrain wear in what, 6 months? Out of interest -Ian Link to comment Share on other sites More sharing options...
JustGav Posted March 26, 2007 Share Posted March 26, 2007 I'm lucky, DB's old aerotop which served as the donor shell didn't have an torsen diff.. Now with the new subframe I've 15 years to go...sweet... Link to comment Share on other sites More sharing options...
Ian C Posted March 26, 2007 Author Share Posted March 26, 2007 And another thing - if I prised off the LSD and fitted a non-LSD, which I won't do because that would be awful, but theoretically would it waylay the disaster? -Ian Link to comment Share on other sites More sharing options...
Chiefgroover Posted March 26, 2007 Share Posted March 26, 2007 Oddly enough, when Marc Ludemann of TTE techincs (Germany) looked my car over he reckoned I was taking a chance on the ring unless I seam welded the rear legs. He didnt go into why, however being a well experienced race car builder saw a problem. So this year when i leave the car with him he can do what he feel best with it. Link to comment Share on other sites More sharing options...
JustGav Posted March 26, 2007 Share Posted March 26, 2007 It might be worthwhile getting some pictures of the subframe mounting points on from various cars... listing age of car as well as diff type fitted (if changed to an LSD date as well)... I would hope the wear can be seen. Possible fixes can then be worked out. Bob - What happens on failure, bolt mouting pulls out or does it sheer the floor pan? Link to comment Share on other sites More sharing options...
Chris and Alana Posted March 26, 2007 Share Posted March 26, 2007 I wish I never read this thread, what a bummer my GZ is nearly 14 years old with under 50,000miles cost me a fortune and now im going to live in fear that its arse end is going to drop off Is it based on age? surely it should be based on milage? (I can hope) Link to comment Share on other sites More sharing options...
AlanM Posted March 26, 2007 Share Posted March 26, 2007 If it is fatigue failure it will be based on many things, including power and how it is applied, how often at high loading etc but it must be area that can be reinforced. Don't think making the "system" more rigid would help, in fact would prob make it worse. Hopefully CW will have a view on this Link to comment Share on other sites More sharing options...
Toy Motor Posted March 26, 2007 Share Posted March 26, 2007 I may be picking this up wrong but will these not make matters worse rather than better? I agree, such an item would only accelerate the fatigue by transferring a greater amount of the operational load to the floorpan. Bob. Link to comment Share on other sites More sharing options...
Toy Motor Posted March 26, 2007 Share Posted March 26, 2007 Ooh, mine is a facelift... *crosses fingers* -Ian I honestly don't know if there were any improvements made throughout the life of the model Sorry! I left in early '95 during which Supra sales were extremely strong. It was my favourite project from my time there. Bob. Link to comment Share on other sites More sharing options...
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