jackb_ms Posted April 28, 2015 Share Posted April 28, 2015 Hello AllOn my 21, the Dedion tube has two fixing for the suspension, one under, and one in the middle of the tubeThe suspension is currently fitted to the "under the tube" fixing.With regards to the handling, what consequence would it have to the handling if I move the suspension to the "in the middle" fixing?Jack Link to comment Share on other sites More sharing options...
ECR Posted April 28, 2015 Share Posted April 28, 2015 If you did nothing elses, it would move the rear of the car up by 50mm(?). This would encourage oversteer. The centre hole is a stronger mounting position and is the one I would use if you can drop your spring platforms 50mm(?)Subject to nothing fouling on a 21 .... Link to comment Share on other sites More sharing options...
jackb_ms Posted April 28, 2015 Author Share Posted April 28, 2015 OK cool thanks for that I can drop the plat form by 50mm easy.Do you know the size of the nuts and bolts required?CheersJack Link to comment Share on other sites More sharing options...
Paul McKenzie Posted April 29, 2015 Share Posted April 29, 2015 0.5" UNF x 5" with large washer each side of the damper bush Link to comment Share on other sites More sharing options...
6speedmanual Posted April 29, 2015 Share Posted April 29, 2015 In all likelihood as you are currently fitted in the undertube bracket you have the longer rear shocks. These were introduced to allow longer rear suspension bump to rebound travel. If you fit these through the "through the tube" hole, the de Dion tube will hit the lo gditudinal chassis tube that runs below it. adjusting the spring seat does not influence the full bump and full rebound position of the strut. Peter Link to comment Share on other sites More sharing options...
Area Representative Paul Richards Posted April 29, 2015 Area Representative Share Posted April 29, 2015 What Peter says is correct. You need shorter shocks for the through de dion mountings. Link to comment Share on other sites More sharing options...
jackb_ms Posted April 30, 2015 Author Share Posted April 30, 2015 Hi PeterDo you have a picture which would show what you mean?I don't recall seeing those tube you are talking aboutI think there is maybe some differences at the back between a 21 and a 7 chassis.Jack Link to comment Share on other sites More sharing options...
6speedmanual Posted April 30, 2015 Share Posted April 30, 2015 https://www.google.co.uk/search?q=caterham+21+chassis&client=ms-android-orange-gb&hl=en-GB&source=lnms&tbm=isch&sa=X&ei=KLZCVY3lL8XnUv3qgfgI&ved=0CAcQ_AUoAWoVChMIjZmfgJOfxQIVxbMUCh19dQCP&biw=360&bih=567&dpr=2#imgrc=-gr66FCAG2JKAM%253A%3BEDbF5I0tuErhtM%3Bhttp%253A%252F%252Fthumbsnap.com%252Fs%252FjwhhS9E1.jpg%3Bhttp%253A%252F%252Fmobile.pistonheads.com%252Fgassing%252Ftopic.asp%253Fh%253D0%2526f%253D101%2526t%253D1457118%2526nmt%253Dchassis%252Bcompare%3B720%3B540 AND. https://www.google.co.uk/search?q=caterham+21+chassis&client=ms-android-orange-gb&hl=en-GB&source=lnms&tbm=isch&sa=X&ei=KLZCVY3lL8XnUv3qgfgI&ved=0CAcQ_AUoAWoVChMIjZmfgJOfxQIVxbMUCh19dQCP&biw=360&bih=567&dpr=2#hl=en-GB&tbm=isch&q=caterham+7+chassis&imgrc=qz71CLoNHRf4LM%253A%3BQE73yCc67aR8GM%3Bhttp%253A%252F%252Fgwellwood.com%252Fwordpress%252Fwp-content%252Fuploads%252F2011%252F03%252FProE-10.jpg%3Bhttp%253A%252F%252Fwww.gwellwood.com%252Fprogress-in-proengineer-lotuscaterham%252F%3B1437%3B865 The small longditudinal tube between the back end of the main cockpit runni g backwards. Present on 21 and 7. Rear beam sits above this member. Link to comment Share on other sites More sharing options...
MereCat Posted May 1, 2015 Share Posted May 1, 2015 This opens up a can of older worms around the lengthy debate on variances of dedion tubes as from memory some with lower mountings ( later variants ) were stronger than the older versions.what I would like to understand is why the centre mount was removed if this was the case and how many owners with the option for centre mounting actually opted for a shorter rear shock when retro fitting?The next question (and this will require someone with some expertise...Simon) is does running a shorter rear shock show any major difference given that there would be less travel? I guess this is compensated with dampening etc?It's relevant to your post but also helps me understand the best option to minimise the risk of the dedion tearing as I am also looking to fit new shocks. I guess the other option and perhaps the best is to strengthen the lower dedion mounts?food for thought. Link to comment Share on other sites More sharing options...
jackb_ms Posted May 1, 2015 Author Share Posted May 1, 2015 Do we have a defenitive answer on how long the damper should be for both versions?Jack Link to comment Share on other sites More sharing options...
revilla Posted May 1, 2015 Share Posted May 1, 2015 440mm and 470mm ... see here. Link to comment Share on other sites More sharing options...
6speedmanual Posted May 1, 2015 Share Posted May 1, 2015 The longer shock allows about 20mm of extra travel. Significant in keeping rear suspension from going to full bump, especially when using a multi-rate spring when the higher rate part can made shorter to interfere less with ride at normal ride level. Link to comment Share on other sites More sharing options...
6speedmanual Posted May 1, 2015 Share Posted May 1, 2015 Oops, double post. Link to comment Share on other sites More sharing options...
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