Terry K Posted October 28, 2023 Share Posted October 28, 2023 Hi, I have recently purchased a 2019 360S, 8k miles, which has standard suspension at the rear, i.e. no Watts Linkage. I am experiencing a knocking noise coming from somewhere at the rear of my car when driving over bumpy roads. I have checked under the rear to look for witness marks and cannot see anywhere that could be causing the noise. I have secured the brake cables as best I can and secured the wooden boot floor, which I thought could be jumping up when hitting bumps, but I am still getting a knock on the most severe bumps or dips in the road. I have had a few Caterhams' over the years and the suspension on this model does seem a lot softer than I am used to. Has anyone experienced similar issues? Thanks Terry K Link to comment Share on other sites More sharing options...
nickh7 Posted October 28, 2023 Share Posted October 28, 2023 Do you have a rear anti roll bar fitted? If yes check the linkage isn't broken Link to comment Share on other sites More sharing options...
Chris SSR400 Posted October 28, 2023 Share Posted October 28, 2023 (edited) Worth checking the nylon washers in the centre of the A frame below the fuel tank. They don’t last too long. Edited October 30, 2023 by Chris SSR400 Link to comment Share on other sites More sharing options...
Glynh Posted October 28, 2023 Share Posted October 28, 2023 56 minutes ago, Chris SSR400 said: Worth chick the nylon washers in the centre of the A frame below the fuel tank. They don’t last too long. My 2022 factory built 360S had the same problem and I found that these washers were missing. After fitting them the noise went away. Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted October 28, 2023 Share Posted October 28, 2023 If the car has been frequently cornered enthusiastically, besides the washers not being in place (due to not being fitted, or they just disintegrated and fell off), the centre bush rubber could also have separated from the metal housing, giving no sideways resistance to movement, other than the A-arm and deDion tube banging together after moving a couple of mm either way. Link to comment Share on other sites More sharing options...
Ralph45 Posted October 29, 2023 Share Posted October 29, 2023 (edited) Just my thoughts reading this as I had a similar noise from my car a few years ago and on the advise of another club member checked the security off the fuel tank by trying to lift it of the rear most chassis rails where it sits.Sure enough there was some movement which was easily fixed by tightening the nut on the securing rods either side of the fuel tank and I’ve had no issues since.May be of some help? Edited October 29, 2023 by Ralph45 Spelling Link to comment Share on other sites More sharing options...
Terry K Posted October 29, 2023 Author Share Posted October 29, 2023 Hi All, thank you for your feedback. Definitely not the fuel tank moving or broken linkage on the ant roll bar but the A frame mounting to the De-dion tube could be suspect. Looking at it, the previous owner who built the car, has fitted black, cut round, plastic shim in the positions where the nylon shim washers should be. Presumably he had trouble getting the supplied washers in and instead decided to make his own. One of the shim pieces can be moved by my finger and so is not therefore under compression but not sure if it should be as the joint has to be able to pivot slightly. Presumably the correct washers should be fitted and if so would these be the nylon racing washer shim with I/d 17.5 mm fro Caterham parts? Thanks Terry Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted October 29, 2023 Share Posted October 29, 2023 1 hour ago, Terry K said: Hi All, thank you for your feedback. Definitely not the fuel tank moving or broken linkage on the ant roll bar but the A frame mounting to the De-dion tube could be suspect. Looking at it, the previous owner who built the car, has fitted black, cut round, plastic shim in the positions where the nylon shim washers should be. Presumably he had trouble getting the supplied washers in and instead decided to make his own. One of the shim pieces can be moved by my finger and so is not therefore under compression but not sure if it should be as the joint has to be able to pivot slightly. Presumably the correct washers should be fitted and if so would these be the nylon racing washer shim with I/d 17.5 mm fro Caterham parts? Thanks Terry If it is a black nylon washer with a flat cut on it it could be a PowerFlex bush in there. Their kit had a washer with a larger diameter than Caterham provided, so depending on the weld size on the deDion tube, some material has to be cut off the washer for it to fit flush. As they get worn out they start to look tatty until they break and fall off. If it is the PowerFlex bush, it provides little lateral resistance, so the washers have to be a tight fit. It also can become dry and noisy or wear if not covered with the special silicone lubricant. The central stainless steel core of those bushes can be removed with finger pressure. Link to comment Share on other sites More sharing options...
Peter G Posted October 30, 2023 Share Posted October 30, 2023 Just another option, if you have adjustable platforms on the rear, they can foul the De Dion tube, the lower mounting bolts need an extra washer or 2 so the shocks clear the tube,. Link to comment Share on other sites More sharing options...
Terry K Posted October 31, 2023 Author Share Posted October 31, 2023 Thanks everyone for your help. Terry K Link to comment Share on other sites More sharing options...
simon metcalfe Posted October 31, 2023 Share Posted October 31, 2023 Hi Terry, just a thought, after a rebuild I had a tapping noise with mine when going over bumps etc - took ages to diagnose as I thought it was suspension / bushes etc - but it was the fuel line from the tank, sometimes the bumps were just enough to cause it to hit the inside of the transmission tunnel. Additional P clip sorted it. Regards Simon. Link to comment Share on other sites More sharing options...
ChrisC Posted November 1, 2023 Share Posted November 1, 2023 (edited) Have you got ventilated front disc. If you have then you will have Delphi rear pads, these rattle in the new Caterham branded rear caliper, supplied since 2018 (ish). It didn’t happen with the refurbished Ford originals. You can tell if this is your problem, the noise will go away under braking. Edited November 1, 2023 by ChrisC Link to comment Share on other sites More sharing options...
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