ISmall Posted October 19, 2000 Share Posted October 19, 2000 My message earlier this week regarding my disagreement with the rear end of my 7 has been solved. Red Line have established that the problem was the right radius bolt has sheered off completely leaving the rear end to effectively float free on that side. Small wonder that it felt like the car had uncontrollable rear-wheel steering! What concerns me is that it seems to be nothing more than a design fault on the car and it surprises me that Caterham have not been forced to recall cars to get the assembly upgraded, which I believe is the case on newer cars? Mine isn't exactly old (mid 1996) and this sort of failure astounds me, especially because it's potentially life threatening. I'd imagine that Lotus would recall Elises if something like this happened. Any thoughts? I'd argue that every car sold by Caterham Cars should have this particular problem rectified before resale to avoid the kind of situation I found myself in last weekend. If I had been killed, and we could prove that the accident was as a result of a basic well documented structural / design failure, surely Caterham Cars would have a case to answer? Link to comment Share on other sites More sharing options...
StewartG Posted October 19, 2000 Share Posted October 19, 2000 What's the difference between the unmodded and the modded version? How can we tell if we've got the dangerous one. Link to comment Share on other sites More sharing options...
Mike Bees Posted October 19, 2000 Share Posted October 19, 2000 Shome confushion here me thinks. In the old days the bolt attaching the forward end of the radius arm had a nut on it (inside the cockpit). At some point this changed to using a threaded bush, and then recently changed back to using a nut. I have heard of the threaded bush variety coming loose and falling out. I put the torque wrench on mine from time-to-time and they show no sign of loosening at all. Iain says "the right radius bolt has sheered off completely" which implies a faulty or wrong-spec bolt, not a design fault. Mike Link to comment Share on other sites More sharing options...
EFA Posted October 19, 2000 Share Posted October 19, 2000 Caterham have no recall policy. This is not a satisfactory matter. When rear anti-roll bars used to snap and puncture fuel tanks as they did on mine and Nick Dinsmore's car, Caterham did nothing to alert other owners. (Not to paint an unfair picture is was the case that most often the bar would just snap and not puncture the tank, but 1 small spark from a shorted wiring harnesss could have spelt the end of Nick or I) On some post '96 chassis. the front upright to wishbone lower sperical joint can work loose, especially when its been torqued to check its tight and the corrosion lock is broken. - this happenned to a car at Le Mans this year, only 2 miles driving after a 100mph+ hack down from Le HAvre. If this had let go then, driver and pasenger would have suffered considerable risk of considerable injury, or worse.... Worse than that I was in 1 on 3 other Sevens behind this car most of the way. Caterham I think have a mentality that because these mechanical failures do not kill people on the race track (where they mostly occur) the risk is no greater on the public highway. I guess they consider that if you ended up in the path of a 38 ton truck that would be incidental damages and not liability. These are two things I can think of without thinking very hard. How many more faults like this exist?? Arnie Link to comment Share on other sites More sharing options...
Peter Carmichael Posted October 19, 2000 Share Posted October 19, 2000 You can't rule out that a sheared bolt on a radius arm might have been associated with a previous ding. The radius arm bolts are in single shear, which isn't ideal. You could either over specify these to a *Mercedes quality engineered* (inappropriately heavy) specification or when buying a second hand car with uncertain history you could replace £50 worth of fasteners and eliminate all possibility of problems not created by your own driving. Self-destructing antiroll bars are a different matter. Link to comment Share on other sites More sharing options...
ISmall Posted October 19, 2000 Author Share Posted October 19, 2000 It's fair to say that many Caterham customers nowadays are probably the same people who buy Elise and MR2s. In years gone by the car was bought almost exclusively by die-hard enthusiasts who would probably build the car with engineering know-how. The problem arises when the popularity of the car outstretches the resources of Caterham Cars to deal with the average punter enthusiat who may not know what technical aspects to look for before purchasing it. Let's face it, most second-hand buyers are sold on their first blast upi the by-pass, and not on the owners manual. My argument is that if Caterham knew about the potential weakness of some radius bolts, they ought to have replaced them FOC when they were sold as part-ex for example. The car is well beyond the snug family atmosphere of Caterham on the Hill and the network is expanding further. I just don't believe that the aftersales abilities are good enough for the typical buyer, and they will need to improve as the network expands. Link to comment Share on other sites More sharing options...
Graham Sewell Posted October 19, 2000 Share Posted October 19, 2000 Check on the specification of the bolt that sheared. It could be that some 'wise' person substituted stainless steel for the usual bolts. S/S does not have the strength for critical components and should not be used. I nearly fell into this trap until I read the Namrick catalogue a second time. Also, if this has happened on one side, make sure that the bolts are replaced on both sides. Cheers, Graham Edited by - Graham Sewell on 19 Oct 2000 16:35:46 Link to comment Share on other sites More sharing options...
ISmall Posted October 19, 2000 Author Share Posted October 19, 2000 Yes, it makes sense to replace on both sides and also consider possible stress on the other end of the radius. I've no idea what kind of activity happened under the wheel arch as the car swerved around. Should I consider damage to suspension units and shocks as well? Link to comment Share on other sites More sharing options...
Pierre Gillet Posted October 19, 2000 Share Posted October 19, 2000 As I said lately, exactly the same accident happened to me except that the bolt in the threaded bush did go loose ( not sheared) and this caused the brutal 90 degree "spin" which sent me in the brown stuff. At this time, being in the ridiculous role of trying to extract the car and myself from this muddy spot while two hunters with shot guns and dogs ( exactly the ones that I had cleared of my way few seconds before using my horn..) where progressing toward me with a strange smile on their faces,I did not realize that the problem was caused by this loose bolt. Later, in a straight, I needed full lock to continue in the right direction. This time I discovered that the bolt was missing. I asked for two new ones to the French importer FOC, blue loctited them and torqued them as specified by Caterham. I check these two bolts every week... Pierre Link to comment Share on other sites More sharing options...
CHRIS CLARK Posted October 19, 2000 Share Posted October 19, 2000 This problem with 'Riv-nut' fixings is not un-common and at best is a pain to remove 'blind' fixing and at worst can cause hell as already documented. It is important to totque these bolts to the correct settings and not just 'wind 'em up'. What's the correct figure? Up to shear and then back half a turn!!!!!!!!! Link to comment Share on other sites More sharing options...
jamesm Posted October 20, 2000 Share Posted October 20, 2000 this whole episode does seem extremely worrying for a new caterham owner i think i will do a careful check of bolts, etc over the winter. i did notice a lot of grade 12.9 bolts when assembling my car, i know that ford stopped using these a while ago because they exhibit hydrogen embrittlement, so any of this type of bolt should be changed periodically. Link to comment Share on other sites More sharing options...
Graham Sewell Posted October 20, 2000 Share Posted October 20, 2000 So what should they be replaced with? Cheers, Graham Link to comment Share on other sites More sharing options...
Peter Carmichael Posted October 20, 2000 Share Posted October 20, 2000 They are not Rivnut fittings. They are threaded bushes brazed into the chassis structure. No bolt can be presumed to stay still in a vibration rich environment unless it has appropriate spring washers, nylocs or loctite securing it and torqued appropriately. Link to comment Share on other sites More sharing options...
jamesm Posted October 20, 2000 Share Posted October 20, 2000 On the bolt theme i think replacing highly stressed bolts every so often is a good way of avoiding fatigue failures. on the grade 12.9 issue all i know is that ford stopped using them and presumably went to a larger 10.9, as for the caterham ones if they are of a good quality then sufficient measures should have been taken to avoid embrittlement. if anyone wants anymore info i can email them some. Link to comment Share on other sites More sharing options...
Graham Sewell Posted October 20, 2000 Share Posted October 20, 2000 I assumed that 12.9 was an alloy rating for tensile strength - so any 12.9 would behave the same way. 10.9 would be a different alloy. Ready to be corrected. Cheers, Graham Link to comment Share on other sites More sharing options...
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