Whittie Posted October 29, 2008 Share Posted October 29, 2008 As the title says, last weekend I was out at the track for a regularity event when on the first lap of the first event for the day I was coming down the hill into the 90 degree right hander at about 180kph when I stood on the brakes and the radius rod snapped. Good thing it had been a while since id been at the track and I hadn’t had a good chance to get to know the new brakes at my 'home' track. I’m in Perth, Australia, so some ozies might know Wanneroo raceway that the v8's visit annually. The track is basically an over sized backwards L with a big hill in the middle of the top stroke. Coming back down the hill towards the right-hander onto pit straight, trying hard to stay ahead of another datsun 260, pushing the left hand edge of the track. I hit my 'old' braking marker and push HARD on the brakes to see how much better the new brakes are over the older 2 pots, when suddenly the wheel snaps right in my hand. I get off the brakes and JUST manage to keep the car on the track. So I’ve got this guy on my tail that I’m trying to stay ahead of and now I’m on the inside of the track approaching the corner WAY to fast. I grab the brakes again, more gently this time, and whilst it’s trying to pull hard right I manage to wash off enough speed to get around the corner, even if I did hit the outside curb hard. All the while I’m thinking something is SERIOUSLY wrong with the car. At first I think it might have been something like a brake failure, but they’re new brakes and I’ve just done 500k's around Bathurst and they were fine. Now it’s time to back off. I slow down and proceed slowly around the track whilst indicating with indicators and my hand out the window that I’m on a slow lap. I make my way round the track and head directly for the pits. I get back to the garage and without even waiting for the car to cool down I’ve got my gloves on to ensure I don’t burn my hands and I start to jack the car up and remove the right front wheel. I can’t put my finger on why the right, because if it was a brake failure and pulled right it would be a left brake failure, but it just felt like something was wrong the right hand side of the car. So I keep working and get the car up and the wheel off.... Now of all the things in the world to find I was NOT expecting this: They're standard radius rods with a thread cut into them allow for toe adjustment and they’ve failed right on the nut. Good thing that they didn’t break further back because without the nut to hold the rod in relative place then the front wheel would have collapsed, probably sending me pirouetting down the hill at a phenomenal rate into a nice soft concrete wall. The other scary thing is in the past few weeks I’ve done several hundred kilometers on the road. Imagin if I’d hit the brakes in an emergency on the road and this had happened... !!! Just counting my lucky stars at the moment that I’m ok! If it had been Bathurst earlier in the year it would have been a concrete wall at 230kph, a few weeks earlier on the road and it would have been a curb, car or some other unpleasant solid object. Needless to say, 2 new radius rods have just gone in, I WONT be threading them in the same way that I did last time and I’ll probably be looking for a manufactured alternative rather than a custom mod. All in all a scary adventure but a scary reminder of the dangers involved with the speeds and forces involved in racing. Tom. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted October 29, 2008 Share Posted October 29, 2008 Do you run a stock soft rubber bushing on the back of the radius rod bucket? The soft bushing on the back will keep the threaded portion from some of the bending stresses of suspension travel. I recently switched the back bushings from Poly to the original rubber. Keep the poly on the front only. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted October 29, 2008 Share Posted October 29, 2008 I would go even futher and say "don't use urethane bushings on the T/C assembly". This is a critical component and any time you restrict the movement of the entire suspension through this bushing, you're looking for trouble on the rod regardless if you've retreaded it or not. I see you don't have many posts, so in case you've not read them, there are a few strings about this very same situation happening to others. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 29, 2008 Share Posted October 29, 2008 Here is one of the threads Terry is referring to: http://forums.hybridz.org/showthread.php?t=87758 I prefer a rod end style joint here that doesn't rely on a bushing compressing and putting a bending load on the TC rod to allow movement of the suspension. I know that you guys have some pretty restrictive laws in Australia that may not allow for the modifications necessary to install a rod end, so that may not be an option. This is a technical post, so I'm going to move it to the brakes/wheels/suspension/chassis forum. Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 29, 2008 Share Posted October 29, 2008 There is a manufacturer in Europe (VA Motorsport Engineering) that makes these items with a BMW Inner Tie Rod End in the spot where yours broke. Allows for proper solid mounting, and gives a nice frictionless spherical ball joint that is very strong in compression. Adjustment fore/aft is done with a hexagonal piece in the middle of the rod and two jamb nuts like on a tie rod. I believe this has passed scrutineering in FIA Group 4, which should clear most any sanctioning body... Yours broke as someone said from a deflecting moment. If the rod was only in compression, the thread would not have had itself set up as a stress point from a movement of the A-Arm up and down. Hopefully my description was good enough you can visualize the component and go 'blimey, I can make that!' Failing that, contact Adrian (Ad) at VA Motorsport Engineering in Rotterdam and I'm sure he can ship you a set for an appropriate fee.... Muahahaha! Quote Link to comment Share on other sites More sharing options...
trwebb26 Posted October 29, 2008 Share Posted October 29, 2008 I've never seen a nut on the front side of the T/C rod bucket??? Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted October 29, 2008 Share Posted October 29, 2008 Well, yeah he modified it for adjustability and put the threads in the highest stressed area of the rod. Threads are serious stress risers. I have seen it done before but it should be frowned upon for now obvious reasons. Quote Link to comment Share on other sites More sharing options...
260DET Posted October 30, 2008 Share Posted October 30, 2008 Cutting threads into the rod there is an engineering nono, its seriously weakened the rod with a predictable result. You need to find the person who did that and deal with them, its a life threatening thing to do. Suggestions ^ re using a spherical ball joint are the go or else get and adapt some adjustable rods off another make of car. Early front strut suspension Falcon or Torana rings bells. Quote Link to comment Share on other sites More sharing options...
mjfawke Posted October 30, 2008 Share Posted October 30, 2008 Cutting threads into the rod there is an engineering nono, its seriously weakened the rod with a predictable result. You need to find the person who did that and deal with them, its a life threatening thing to do. Suggestions ^ re using a spherical ball joint are the go or else get and adapt some adjustable rods off another make of car. Early front strut suspension Falcon or Torana rings bells. XC Falcon. Haven't tried it myself. And I have a 260Z radius rod sitting in my shed that is bent 90 degree in the middle from a crash. Quote Link to comment Share on other sites More sharing options...
Whittie Posted October 30, 2008 Author Share Posted October 30, 2008 You need to find the person who did that and deal with them, its a life threatening thing to do. went to see the engineer today and when i showed him the broken rod he vehemently denied that he would ever do such a thing. So yeah no help there, im just glad that given what other circumstances it might have failed under that it wasnt worse and that no one was injured. Any more details on these ball joints? pics of other peoples or links on how to adapt it? Going to bathurst next year and the car will be gone from early Jan so i need to get on this pretty quick. Quote Link to comment Share on other sites More sharing options...
Flexicoker Posted October 30, 2008 Share Posted October 30, 2008 Has anyone had any problems with these? http://www.technotoytuning.com/productdetail.php?p=668 Quote Link to comment Share on other sites More sharing options...
Mike Mileski Posted October 30, 2008 Share Posted October 30, 2008 Whittie, look at the bottom of post 7 in this thread. http://forums.hybridz.org/showthread.php?t=116043&highlight=%22tc+rod%22 Mike Mileski Tucson, AZ Quote Link to comment Share on other sites More sharing options...
sickboy Posted October 30, 2008 Share Posted October 30, 2008 I've seen this happen twice, one was a modified 240z with urethane t/c bushings and the other was a bone stock 280z. The 240z t/c rod snapped while driving, the 280z snapped while backing out of a service bay. They both broke right in front of the bushing. Unpredictable and scary! I bought a set of front control arms from Mike Mileski and modified them slightly. They are very well made and easy to adjust IMO. Thanks Mike! Quote Link to comment Share on other sites More sharing options...
Cruez Posted October 31, 2008 Share Posted October 31, 2008 I agree with this also, the main reason I put new rubber ones on the wagon.. Some people have drilled holes in the urethane bushings to give the a little more "give" I would go even futher and say "don't use urethane bushings on the T/C assembly". This is a critical component and any time you restrict the movement of the entire suspension through this bushing, you're looking for trouble on the rod regardless if you've retreaded it or not. I see you don't have many posts, so in case you've not read them, there are a few strings about this very same situation happening to others. Quote Link to comment Share on other sites More sharing options...
Nigel Posted October 31, 2008 Share Posted October 31, 2008 I would go even futher and say "don't use urethane bushings on the T/C assembly". This is a critical component and any time you restrict the movement of the entire suspension through this bushing, you're looking for trouble on the rod regardless if you've retreaded it or not. I see you don't have many posts, so in case you've not read them, there are a few strings about this very same situation happening to others. I thought this was primarily an issue with poly bushings the ZX's. I've only heard of a very few failures with Z's. My recollection from other discussions of this issue was that the failure was due to the ZX rods being under tension, whereas the Z rods are under compression... Nigel '73 240ZT Quote Link to comment Share on other sites More sharing options...
blueovalz Posted October 31, 2008 Share Posted October 31, 2008 I've not measured this but assume the ZX rod is shorter than the Z? If so, this may explain some of the additional failure rates for the ZX verses the Z (same compliance means greater angle of movement at the bushing). Quote Link to comment Share on other sites More sharing options...
Whittie Posted November 2, 2008 Author Share Posted November 2, 2008 im looking at the techtoytuning ones at the moment as the best option. anyone had any experience with them? Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 2, 2008 Share Posted November 2, 2008 Hey, just a suggestion, but I've seen the bits firsthand, and they are nice! They won't do what happened to you. Check out the fabricator's CV from reading his website: http://www.va-motorsport.com/index.php?page=1 For a dedicated or part-time track car, bushings at that point add un-required compliance. The only reason they are there is with the existing design, bushings are required for up and down movement of the lower arm, and the OEM rubber deadens chassis resonance with an impact. Unfortunately they let the wheel deflect under braking (sometimes at different rates!), and are just a pain to get right. Solid is nice. But you hit a whack, and you will hear it. Quote Link to comment Share on other sites More sharing options...
Whittie Posted November 2, 2008 Author Share Posted November 2, 2008 do you mean to say that Va motorsport manufacture the techtoytuning arm or do they make their own? i dont read dutch so the site was a bit hard to navigate and i couldnt find anything that looked like an online parts section.... Probably put urethane bushes in regardless to reduce that noise and reduce impact on the chassis. that part of the chassis is original i believe and i dont want to go unneccesarily cracking fram rails Quote Link to comment Share on other sites More sharing options...
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