mcgrison Posted June 17, 2017 Report Share Posted June 17, 2017 Hi everyone the dampers on my SU carburettors are prone to unscrew. No way to eliminate the problem: you can screw them as tight as you can ...they unscrew! I even tried to block them with tape: better but not reliable, as tape gets soft with engine heat and after a while it becomes uneffective. I am thinking of making a little hole in the black plastic top of the two dampers and to connect them with a small rod. Any suggestion? Thanks Alberto Quote Link to post Share on other sites
boxofbits Posted June 17, 2017 Report Share Posted June 17, 2017 Thats an unusual issue. First are you sure you are using a light or appropriate oil, and are the breather holes unblocked? The only other problem might be worn threads, incorrect dampers or the small plastic sealing washers missing? Kevin Quote Link to post Share on other sites
mcgrison Posted June 17, 2017 Author Report Share Posted June 17, 2017 Thanks Kevin, probably worn plastic threads is the answer, even if they do not look bad. I am reluctant to change the dampers but I am afraid their end has arrived... Quote Link to post Share on other sites
monty Posted June 17, 2017 Report Share Posted June 17, 2017 Some race cars running SU's wire lock the damper tops but that is assuming the older brass caps rather than the plastic probably. Having said that I believe I have seen a racing Cooper S with plastic caps wire locked. I have the older brass caps which I tighten by hand & then give a tiny tweak with a spanner to 'lock on'. Seems to keep them tight. Cheers. Quote Link to post Share on other sites
boxofbits Posted June 17, 2017 Report Share Posted June 17, 2017 Some race cars running SU's wire lock the damper tops but that is assuming the older brass caps rather than the plastic probably. Having said that I believe I have seen a racing Cooper S with plastic caps wire locked. I have the older brass caps which I tighten by hand & then give a tiny tweak with a spanner to 'lock on'. Seems to keep them tight. Cheers. Yes you can probably get a bit more bite on the brass type Monty. I've never seen them wired, but don't doubt some racing Cooper S's for example might want to do that. I worked at a BL dealer for quite a few years but don't remember any coming undone, let alone both. Kevin Quote Link to post Share on other sites
AndyR100 Posted June 17, 2017 Report Share Posted June 17, 2017 I've never really given this much thought.... I have always just nipped them to ensure they are tight each week along with usual checks - the only set of SU's that havn't moved much are the current ones on my 4..... took the same approach with stroms as well. ..... Andy Quote Link to post Share on other sites
mcgrison Posted June 17, 2017 Author Report Share Posted June 17, 2017 (edited) I think that to wire lock the tops is an interesting option. I have run my TR4A for 100.000 miles without experiencing this but once they started to unscrew, the problem got worse and worse. Edited June 17, 2017 by mcgrison Quote Link to post Share on other sites
BlueTR3A-5EKT Posted June 17, 2017 Report Share Posted June 17, 2017 Metro Turbo had this issue. The clamp they fitted stopped the damper falling out did not lock it from unscrewing. http://ebayapi.loc8apartltd.netdna-cdn.com/00/s/MTA5M1g3NjU=/z/F7EAAOSwe7BWx2lz/$_1.JPG Peter W Quote Link to post Share on other sites
ron88 Posted June 18, 2017 Report Share Posted June 18, 2017 Just make sure you haven't put a chrome sleeve over your carbs to make them look better - I did that on my Morris once; it seemed fine but consistent slight pressure from the sleeve on the cap always saw it unscrewed after a week. Quote Link to post Share on other sites
mcgrison Posted June 18, 2017 Author Report Share Posted June 18, 2017 Thanks Ron. You are right. I put the chrome sleeves over the carbs many years ago. I had to shorten their neck with the file , to prevent what you say and untill last month they did not cause any trouble. I just checked them right now and they do not touch the damper top but are very near. I will shorten them a bit more and let you know. Quote Link to post Share on other sites
TR NIALL Posted June 18, 2017 Report Share Posted June 18, 2017 Alberto I also have the same problem but with only 1 of them I switched them around and the problem followed,I had a good look at the Threads and they look good but obviously one isn't,they are available New fron Burlen Carbs. Quote Link to post Share on other sites
mcgrison Posted June 18, 2017 Author Report Share Posted June 18, 2017 Very interesting Niall! As I wrote above, this afternoon I filed the necks of the chrome sleeves, in order to reduce their high of 5 mm. and to be sure they do not interfere with the plastic top of the dampers. After that, I drove the car for 40 miles and they did'nt unscrew. Cross fingers! One question: do you have the chrome sleeves as well? Quote Link to post Share on other sites
TR NIALL Posted June 19, 2017 Report Share Posted June 19, 2017 (edited) On 6/18/2017 at 10:47 PM, mcgrison said: Very interesting Niall! As I wrote above, this afternoon I filed the necks of the chrome sleeves, in order to reduce their high of 5 mm. and to be sure they do not interfere with the plastic top of the dampers. After that, I drove the car for 40 miles and they did'nt unscrew. Cross fingers! One question: do you have the chrome sleeves as well? No Chrome Sleeves,what I do at the moment to keep it in place is wrap it with Insulating Tape and don't block the Breather Hole. Edited October 26, 2019 by TR NIALL Quote Link to post Share on other sites
Charlie D Posted June 19, 2017 Report Share Posted June 19, 2017 Hi Alberto, You could try “Heat shrink” tubing to fit over the SU neck and up a bit over the screw cap. You can get it in quite large diameters, and probably not go soft with the engine heat, which tape will probably do. I see you are in Maggiore. Can't think of a more perfect place to drive a TR. (Lucky B.) Charlie D Quote Link to post Share on other sites
mcgrison Posted June 19, 2017 Author Report Share Posted June 19, 2017 (edited) Hi Charlie, heat shrink tube could be a good solution! For the moment , after I shortened the chrome sleeves necks they are not unscrewing any more but I must try on a longer distance. Next week I'll go with my wife to Isola d' Elba on the TR ( a journey of 600/700 miles) and we'll see. Anyway, to be sure, I prepared the two plastic caps to be connected with a small rod ( see the attached pic). And yes....Lago Maggiore is a good place to drive a TR but Herefordshire as well !! Edited June 19, 2017 by mcgrison Quote Link to post Share on other sites
BlueTR3A-5EKT Posted June 19, 2017 Report Share Posted June 19, 2017 legamento carburatori TR4.JPGHi Charlie, heat shrink tube could be a good solution! For the moment , after I shortened the chrome sleeves necks they are not unscrewing any more but I must try on a longer distance. Next week I'll go with my wife to Isola d' Elba on the TR ( a journey of 600/700 miles) and we'll see. Anyway, to be sure, I prepared the two plastic caps to be connected with a small rod ( see the attached pic). And yes....Lago Maggiore is a good place to drive a TR but Herefordshire as well !! Don't block the breather holes in the damper plastic caps. They are required to make the carb work correctly. Peter W Quote Link to post Share on other sites
TR NIALL Posted June 19, 2017 Report Share Posted June 19, 2017 Don't block the breather holes in the damper plastic caps. They are required to make the carb work correctly. Peter W Looks like Alberto Drilled 2 other Holes inline with each other. Quote Link to post Share on other sites
mcgrison Posted June 19, 2017 Author Report Share Posted June 19, 2017 (edited) exactly: two new holes 2,5 mm of diameter...but for the moment I keep the rod in the glovebox. The day the caps unscrew again....I 'm ready! Edited June 19, 2017 by mcgrison Quote Link to post Share on other sites
stuartmac Posted June 20, 2017 Report Share Posted June 20, 2017 I have the opposite problem with the brass tops. Screw then in finger tight then need a spanner to release them Quote Link to post Share on other sites
mcgrison Posted June 20, 2017 Author Report Share Posted June 20, 2017 Stuartmac...at this point I imagine SU carburettors live a life of them own! Quote Link to post Share on other sites
mcgrison Posted July 9, 2017 Author Report Share Posted July 9, 2017 (edited) Hello everyone, the friends of dampers! I am just back from a 850 miles journey to Isola d'Elba-Tuscany on my TR4A. Fantastic sea, hotel, sun, food, ecc. Here is un update to this topic. I discovered that my dampers do not unscrew: they pop up directly, as thread is worn. For this reason, the device I had invented ( the little rod I had fitted to the black plastic screw) does not work. To block them I returned to the insulating tape : until now this is the only real solution ( not very elegant but effective). At this point...I will buy new dampers! Edited July 10, 2017 by mcgrison Quote Link to post Share on other sites
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