carboy0 Posted March 15, 2019 Share Posted March 15, 2019 I started to replace the offside drive shaft and in the process of removal managed to strip two of the studs. I can helicoil the holes quite easily. I plan to go for 5/16” UNC studs in the aluminium trailing arm with 5/16” unf stud ends for the hub. This is rather than the standard 5/16” unf at both ends on the standard TD 812 Triumph studs. Does anyone have a part number and source for a suitable stud with combined unc/unf 5/16” studs, that are the right length? Thanks in advance. Quote Link to comment Share on other sites More sharing options...
nang Posted March 15, 2019 Share Posted March 15, 2019 If you're going to helecoil them why not keep them standard. You've already fixed the weak bits with the helecoils. Tony. Quote Link to comment Share on other sites More sharing options...
carboy0 Posted March 15, 2019 Author Share Posted March 15, 2019 Tony not really, UNF thread is too fine for aluminium, it’s always likely to pull through the body of the suspension arm. UNC or Metric coarse are the normally the preferred engineering option for aluminium thread holes. Helicoiling in UNF, will just mean pulling a bigger hole in the aluminium next time. Quote Link to comment Share on other sites More sharing options...
carboy0 Posted March 16, 2019 Author Share Posted March 16, 2019 I posted the same question on the Stag Owners Club forum and using the following studs was suggested. Rather than drill out the trailing arm for 5/16 unf helicoil, this company has made HT steel studs with 3/8 UNC on one end 5/16 on the other end. It bypasses the need for the helicoil,you just drill and tap for 3/8 UNC and screw in direct. https://www.classicdrivingdevelopment.co.uk/cats.asp?cID=3&carID=4&page=STAG+3%2F8+UNC+HUB+STUD Not cheap but a good solution. Quote Link to comment Share on other sites More sharing options...
Hogie Posted March 16, 2019 Share Posted March 16, 2019 Quoted from carboy0- Tony not really, UNF thread is too fine for aluminium, it’s always likely to pull through the body of the suspension arm. UNC or Metric coarse are the normally the preferred engineering option for aluminium thread holes. Helicoiling in UNF, will just mean pulling a bigger hole in the aluminium next time. Hi Chris, TRiumph got it right when they used UNF as the thread form. UNF is used to stop vibration loosening the stud/nut. Low torque figure is fine as the 6 studs do a good job. I think 50 years is a good life for a stud in Ali. If you go the 5/16UNF helicoil route you will have a greater locking system as the Helicoil actually moves outwards (into the Ali) and grips better. The logic behind UNC for this application is flawed. Stick with the 5/16UNF. Roger Quote Link to comment Share on other sites More sharing options...
Paul64 Posted March 22, 2019 Share Posted March 22, 2019 Quoted from carboy0- I posted the same question on the Stag Owners Club forum and using the following studs was suggested. Rather than drill out the trailing arm for 5/16 unf helicoil, this company has made HT steel studs with 3/8 UNC on one end 5/16 on the other end. It bypasses the need for the helicoil,you just drill and tap for 3/8 UNC and screw in direct. https://www.classicdrivingdevelopment.co.uk/cats.asp?cID=3&carID=4&page=STAG+3%2F8+UNC+HUB+STUD Not cheap but a good solution. I did this last year when I changed my driveshafts on the MK1 - easy to fit with the kit provided and will be there forever. Paul Quote Link to comment Share on other sites More sharing options...
carboy0 Posted March 23, 2019 Author Share Posted March 23, 2019 Thanks Paul Quote Link to comment Share on other sites More sharing options...
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