davehop Posted March 8, 2007 Report Share Posted March 8, 2007 Hi All There I was getting all pleased that the weather was letting me replace the driveshafts and hubs with shiny new ones bought during the Moss pre-Christmas sale. Upon very carefully tightening the hub fixing nuts to a paltry 20nm two of them just kept turning. thinking ahead, it occured to me that I'd like the wheels to remain on the car whilst in motion, so it looks like the studs are going to need replacing, and, from what I hear, the trailing arm will need re-threading or need helicoils fitting. Do any of you experienced gentlemen know what size taps and helicoils I'll need, or is there a simple kit available for the job? Many thanks Dave Quote Link to post Share on other sites
IanR Posted March 8, 2007 Report Share Posted March 8, 2007 Hi Dave, Not a big problem. You need a 5/16UNF helicoil kit and they are easily available. Revington TR do one part no RTR 5046 for which you will need an 8.3 mm drill. You get enough helicoils in the kit for 1 car and an inserting tool, correct tap, but dont forget to but new studs as well Cheers Quote Link to post Share on other sites
Guest ron Posted March 8, 2007 Report Share Posted March 8, 2007 (edited) Further to what Ian posted, if you can get UNF/UNC studs [Moss used to sell them] it is better to use UNC Helicoils in the soft alloy. You don't need a tapping drill, the stripped hole is near enough to take the tap, and shop about for the kit, the prices vary quite a bit. Ron Edited March 8, 2007 by ron Quote Link to post Share on other sites
davehop Posted March 8, 2007 Author Report Share Posted March 8, 2007 Thanks Guys Brilliant forum! Always a pleasure to discover the wealth of experience. I'll check out both options. Cheers Dave Quote Link to post Share on other sites
jonlar Posted March 8, 2007 Report Share Posted March 8, 2007 Hi Dave, as Ron says use UNC, it's the UNF thread in alloy causes them to strip in the first place. Quote Link to post Share on other sites
RobIsaacson Posted March 8, 2007 Report Share Posted March 8, 2007 Finally, I question where I can help others rather than continually asking myself. Due to the ally trailing arm, the studs should be UNC thread (although they are UNF) whilst the outer bit (the bit the hub bolts to) should remain UNF. Moss do a stud which is 5/16 UNC one end and 5/16 UNF the other - part number TE505121. I know this as I had to send the studs back twice before I received the correct items. When I bought them they were 89p each, December 2005. Have fun Rob Quote Link to post Share on other sites
davehop Posted March 8, 2007 Author Report Share Posted March 8, 2007 UNC/UNF studs it is then - may as well do them all whilst I'm at it. I'll give Moss a call tomorrow. The upside of all this time on axle stands seems to be that the doors are fitting a bit better than before! This car is going to be so over-engineered in the end that it'll probably outlast me thanks a lot all - a great help cheers Dave Quote Link to post Share on other sites
boxer Posted March 8, 2007 Report Share Posted March 8, 2007 hi dave had the same problem with my trailing arms.Helicoiled them but something always was nagging me what if what if .They are still on the car but i dont feel happy about them .found a chap who seems to have loads of tr stuff he sold me a pair for £60 inc post and blasting and all the studs are nice and solid.Give him a try if you change your mind about helicoiling hes at andrew@warrener.freeserve.co.uk remember those fast corners,Bob Quote Link to post Share on other sites
davehop Posted March 8, 2007 Author Report Share Posted March 8, 2007 Thanks Bob I'll Keep that one in mind - see how I get on with the Helicoils first. I had a good result with them on a Mini Cooper S engine block nearly 20 years ago (Head stud) but it's been a while since I did any tapping! Cheers Dave Quote Link to post Share on other sites
Richard Crawley Posted March 8, 2007 Report Share Posted March 8, 2007 (edited) Thanks Bob I'll Keep that one in mind - see how I get on with the Helicoils first. You won't have any problems with the Helicoil inserts, I've got on in my crank shaft! Edited March 8, 2007 by Richard Crawley Quote Link to post Share on other sites
JohnC Posted March 8, 2007 Report Share Posted March 8, 2007 I helicoiled (Recoiled actually, I don't know if Helicoil is available here in Oz) a T/A stud a few months ago, following Richard's advice to use UNC/UNF studs. Very easy (just keep the tap nice & straight). Question - Is it best to use a threadlocker on the stud when you put it into the T/A? Should a threadlocker be used on the helicoil itself? Cheers, John Quote Link to post Share on other sites
guzzitrike Posted March 8, 2007 Report Share Posted March 8, 2007 (edited) I helicoiled (Recoiled actually, I don't know if Helicoil is available here in Oz) a T/A stud a few months ago, following Richard's advice to use UNC/UNF studs. Very easy (just keep the tap nice & straight). Question - Is it best to use a threadlocker on the stud when you put it into the T/A? Should a threadlocker be used on the helicoil itself? Cheers, John Shouldn't need to John as the act of inserting the helicoil compresses the coil so that when it is in the correct position is "springs" into place locking itself, and, as generally it is made of tougher stuff than the origional should last better, and with no fears of going awol - as long as it done properly in the first place. I once had 3 out of the 4 mounting studs on a turbo charger on a suzuki M/Cycle once helicoiled and that was no problem even at constant naughty speeds and large amounts of waste gate pressure. Bryan Edited March 8, 2007 by guzzitrike Quote Link to post Share on other sites
jonlar Posted March 9, 2007 Report Share Posted March 9, 2007 I've never had problems with helicoiled threads, I had to have all the cylinder block threads done on a '59 Square 4, as that uses alloy block with steel liners and all had been overtightened and stripped (wish I still had it - at a moment of financial crisis, sold it to a chap in Denmark, who completely re-built it). Quote Link to post Share on other sites
Tom Fremont Posted March 9, 2007 Report Share Posted March 9, 2007 Happily, the trailing arm studs are subjected to tension loads when they are the inside wheel in a curve Quote Link to post Share on other sites
rpurchon Posted March 9, 2007 Report Share Posted March 9, 2007 i have replaced a few of mine by tapping the hole out with a m8 tap. buy a lenght of stainless m8 threaded bar and some nylon lock nuts.tis a course thread& no drilling or helicoils required. richard Quote Link to post Share on other sites
jonlar Posted March 9, 2007 Report Share Posted March 9, 2007 Hi Richard, good lateral thinking but if the threads are stripped in the TA, to cut a decent thread, you must go up in size and will the studding pass through the hub attachment piece, having to enlarge those holes, and there's also the element of the all threaded studding wearing as opposed to the blank parts of the studs? Quote Link to post Share on other sites
rpurchon Posted March 9, 2007 Report Share Posted March 9, 2007 Hi Richard, good lateral thinking but if the threads are stripped in the TA, to cut a decent thread, you must go up in size and will the studding pass through the hub attachment piece, having to enlarge those holes, and there's also the element of the all threaded studding wearing as opposed to the blank parts of the studs? all i can say is it works fine for me.tap the trailing arm with a tapered tap as far as you can .and even better if you have one use a bottom tap after. they tighten up fine . put some thread lock on as well. the 8 mm stud goes through the hub no problem. if you want to be even safer you can drill the bottom of the hole with the correct size pilot drill another 6mm [put the drill bit in a piece of tube so you dont cut into the side] 8mm taps are cheap and its easier than pissing about with helecoils richard Quote Link to post Share on other sites
davehop Posted March 10, 2007 Author Report Share Posted March 10, 2007 All Well the helicoil kit arrived today. I'll get to it over the weekend. Excellent service and price from A & R Sheldon in Stockport 0161 440 0821. Very friendly and helpful. £34 inc postage. this includes the tap, drill, special tool, and 3 sets of 12 inserts of varying lengths. A good £15 cheaper than a well known TR specialist - makes you wonder... UNC/UNF studs easily sourced from Moss with the appropriate part number - thanks for that info Rob. got a good feeling about this one - we'll see Cheers Dave Quote Link to post Share on other sites
Guest ron Posted March 10, 2007 Report Share Posted March 10, 2007 Dave, just make sure you start the tap square and you can't go wrong, good luck, you'll have the satisfaction of knowing the job's done right. Ron Quote Link to post Share on other sites
davehop Posted March 10, 2007 Author Report Share Posted March 10, 2007 Success! What an excellent product. I ran out of daylight so I ended up doing only the ones that needed it - 2 on one side, with a tap holder(?) or key(?) borrowed from a neighbour. A little thread-lock on the studs (Just in case!) and they are very solid (Very dificult to remove after just a couple of turns and then realising I had the wrong length!) and I'm sure will last indefinitely. Next time I'm mucking about with the back end the others will all get done - that fine UNF thread just doesn't seem right in such a soft metal. Thanks again all Dave Quote Link to post Share on other sites
Richard Crawley Posted March 10, 2007 Report Share Posted March 10, 2007 Success! What an excellent product. I ran out of daylight so I ended up doing only the ones that needed it - 2 on one side Easy init; do the lot tomorrow while you've still got the tap wrench, you won’t regret it! I’ve mentioned it before but to avoid any chance of stripping, I tighten these fixings by hand using just a socket on a ½” extension bar (no ratchet or lever); if you check the torque, it’s just about right; but I suppose it depends on how strong you are! Quote Link to post Share on other sites
davehop Posted March 12, 2007 Author Report Share Posted March 12, 2007 hi Richard Ended up having to work today, so for now I'll be going with the "If it ain't broke..." axium - neighbours tap wrench already returned - doh! All feels pretty solid and done up to a mild 20NM. Still have the kit for the next long winter! Cheers all Dave Quote Link to post Share on other sites
Richard Crawley Posted March 12, 2007 Report Share Posted March 12, 2007 for now I'll be going with the "If it ain't broke..." axium - neighbours tap wrench already returned I would normally agree with ‘if it ain’t broke’ etc. unnecessary tinkering can do more harm than good but theses studs are a renowned weak point & Helicoiling is a recognised cure; the threads get very tired with age & I think it would be a good idea to do the rest when you have a bit more time. Quote Link to post Share on other sites
davehop Posted March 12, 2007 Author Report Share Posted March 12, 2007 I would normally agree with ‘if it ain’t broke’ etc. unnecessary tinkering can do more harm than good but theses studs are a renowned weak point & Helicoiling is a recognised cure; the threads get very tired with age & I think it would be a good idea to do the rest when you have a bit more time. Was definitely feeling lazy! I take your point - if a job's worth doing... That, and then having to undo a hub centre nut tightened to a recommended 270NM! (posh new hubs). See if I get some time this week. Dave Quote Link to post Share on other sites
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