Motorsport Mickey Posted July 17, 2014 Report Share Posted July 17, 2014 PCD I think from memory 4.250 inches. Mick Richards Quote Link to post Share on other sites
Motorsport Mickey Posted July 17, 2014 Report Share Posted July 17, 2014 Harry how many times do you plan to drill your Trailing arms ? Mick Richards Quote Link to post Share on other sites
harrytr5 Posted July 17, 2014 Report Share Posted July 17, 2014 Hi Roger, Your PM is full.Andy(coco) wants a pair of s/s folded plates for the rear of his surrey backlite. We will be in the Uxbridge car show this Sunday and if you are going... Regards Harry Quote Link to post Share on other sites
stuart Posted July 17, 2014 Report Share Posted July 17, 2014 An old hub can be useful to make up a jig. Stuart. Quote Link to post Share on other sites
bob Posted July 17, 2014 Report Share Posted July 17, 2014 It seems to me that things are getting a bit over complicated. Unless we're talking about drilling completely new holes then there are already very decent "pilot" holes (albeit approx 5/16 diameter) in the hub to start with. Putting the correct drill for a 5/16 heli-coil (other inserts are probably available) through the existing holes should be straight forward if necessary. I'd hazard a guess that if the thread were already stripped then the insert tap could probably be used without any further drilling as long as care, and plenty of cutting compound, is used. In my (humble) opinion a jig shouldn't be necessary. Quote Link to post Share on other sites
harrytr5 Posted July 17, 2014 Report Share Posted July 17, 2014 It seems to me that things are getting a bit over complicated. Unless we're talking about drilling completely new holes then there are already very decent "pilot" holes (albeit approx 5/16 diameter) in the hub to start with. Putting the correct drill for a 5/16 heli-coil (other inserts are probably available) through the existing holes should be straight forward if necessary. I'd hazard a guess that if the thread were already stripped then the insert tap could probably be used without any further drilling as long as care, and plenty of cutting compound, is used. In my (humble) opinion a jig shouldn't be necessary. I beg to differ Bob.I have tried it without and it is far,far more accurate with a jig. Only once Mick and used on others of course. Quote Link to post Share on other sites
AlanT Posted July 17, 2014 Report Share Posted July 17, 2014 This is all down to the "feel" of the hand behind the tool. I did two of mine and never thought about making a jig for it. But then I can hacksaw square to 10 thou and file flat to 5 thou. In a soft material the insensitive hand can put the drill in 10-15 degrees off axis. Then the studs will get bent when the hub goes on. Having said that the USA jig shown above is a super thing. Steel inserts pushed into alloy. Two big bushes, don't loose 'em. One piece 5/8 in thick, with 6 holes of various sizes, might do the whole job. Quote Link to post Share on other sites
Motorsport Mickey Posted July 17, 2014 Report Share Posted July 17, 2014 Bob, I have an engineering background and have no compunction in drilling cylinder head bolts out enlarging etc by hand using a pistol grip drill. But when you have 6 close fit 5/16th studs which need all to be square in two planes at 90 deg and into soft material which is almost the correct size and "grabs" the drill before you have a chance to straighten it it's asking for trouble. The slightest lean in any plane may point studs in opposite directions causing the hubs to foul the studs when you try and slide them on, leading to having to drill out the hub holes in ever bigger sizes until the studs will enter all the 6 holes. Then although the hub will fit when tightened the studs will be in a bending motion as Alan says and are possible candidates for future fatigue and failing...whose wheel is that ? oh bugger ! No chance of correction, one shot only, do it right. Mick Richards Quote Link to post Share on other sites
Peter Cobbold Posted July 17, 2014 Report Share Posted July 17, 2014 (edited) As back-up, belt and braces, what about using an epoxy resin to supplement the bolts? Epoxy bond strength around 10,000 psi should help. What's the area of contact between the hub and t/a? If not, why not? -does the area get hot? Peter Edited July 17, 2014 by Peter Cobbold Quote Link to post Share on other sites
Motorsport Mickey Posted July 17, 2014 Report Share Posted July 17, 2014 The 16 lb ft torque applied to each stud and nut although weedy because of the number of fixings (6) seem to be ok and provides reasonable clamping force. The weak point is the thread into the trailing arm which because of the age now of these components and a spectacularly weird choice by Triumph of UNF fine thread into the soft alloy castings has a propensity to easily strip. Then botched running repairs eventually cause high stressing of the studs as outlined above and possibility of exciting failures on the studs when in use. Just engineering a reasonable fixing repair will sort the problem, the hubs in use will suffer a reasonable heat loading with transference of braking and bearing temperatures into the hub, I've never measured the temps there but certainly much too hot to touch and maybe enough to degrade any Epoxy adhesive over a period. Mick Richards Quote Link to post Share on other sites
RogerH Posted July 18, 2014 Report Share Posted July 18, 2014 Once upon a time there was an engineer, a professor, and a ludite and they each had their own idea of keeping the wheel on the cart. Who would you believe? Do it once, do it right and forget it. Roger PS - if you bond anything you have to consider how to take it apart next time. Quote Link to post Share on other sites
TR NIALL Posted July 18, 2014 Report Share Posted July 18, 2014 (edited) I wish we could finally decide what is best to use and where these Parts can be got,a Link or 2 might be useful. So we need, 1 Jig ??? 2 Drill Bit,what Size. 3 Tap,what Size. 4 Inserts ??? so many Choices. Edited July 18, 2014 by TR NIALL Quote Link to post Share on other sites
Steves_TR6 Posted July 18, 2014 Report Share Posted July 18, 2014 Think you are confusing fitting a 5/16th UNC helicoil with tapping a 5/16th hole in the parent metal. There's only 15 thou difference in material for parent metal hole size between UNF and UNC at 5/16th size, so not enough to hold a thread if you are fitting it to a damaged hole. Refer back to Rogers post if you wish to fit a UNC Helicoil but beware some of the trailing arms are a bit problematical on material around the stud holes, the casting blocks that carry the studs are not all centrally positioned accurately and the holes are closeish to the edge on some castings. You may well find that the holes break through on the inner edge, the Helicoil tapping size is .328 for the hole (carrying a 5/16th UNC inner tapped hole) that's why I prefer a 3/8th UNC stud. The drilling size for 3/8th UNC is only .312 and that 16thou less on dia may be all that you have before breaking through, so a 3/8th UNC stud with a longer length than standard (about 8mm) into the casting with a 5/16th UNF standard length stud on the other end is my choice when I can get round to fitting them into my Stag (same rear trailing arm casting) and after making/begging a jig to drill it. You'll only get one chance to achieve a workmanlike improvement on this and I don't want to risk hand drilling and keeping it bang on 90 deg in two planes at once, not into alloy where the drill will get snatched or want to wander if the original hole is damaged. Mick Richards Thanks Mick, that explains it nicely! Quote Link to post Share on other sites
RogerH Posted July 18, 2014 Report Share Posted July 18, 2014 Hi Niall, I wish we could finally decide what is best to use and where these Parts can be got,a Link or 2 might be useful. So we need,1 Jig ??? Harry has one but he may need to do his T/A again (just for fun) 2 Drill Bit,what Size. This comes with the helicoil set3 Tap,what Size. This comes with the helicoil set4 Inserts ??? so many Choices. These come with the set 5/16" UNC is the general upgrade. Roger Quote Link to post Share on other sites
TR NIALL Posted July 18, 2014 Report Share Posted July 18, 2014 (edited) And a Link where these can be Purchased from Roger,Cheers. Edited July 18, 2014 by TR NIALL Quote Link to post Share on other sites
AlanT Posted July 18, 2014 Report Share Posted July 18, 2014 (edited) Roger, I have all the UNC Helicoil tools from 1/4in to 1/2in and also the 5/16in UNF. I probably have enough inserts but these are easily available. The Recoil brand is interchangeable. These are cheap but work OK. http://www.chronos.ltd.uk/acatalog/INDIVIDUAL_SIZE_THREAD_REPAIR_KITS.html Edited July 18, 2014 by AlanT Quote Link to post Share on other sites
stuart Posted July 18, 2014 Report Share Posted July 18, 2014 Or if you do a fair bit of garage work then buy their complete kits which are very good value. http://www.chronos.ltd.uk/acatalog/Master_Thread_Repair_Sets.html Stuart. Quote Link to post Share on other sites
TR NIALL Posted July 18, 2014 Report Share Posted July 18, 2014 Right,so it's a 5/16th UNC Helicoil Kit.........On Order. Now where do I Buy the Studs and what Size should I Order. Many Thanks for the Suggestions. Quote Link to post Share on other sites
RogerH Posted July 18, 2014 Report Share Posted July 18, 2014 Hi Neil, have a look in the back of the Moss Cat. They do various lengths P/No. is TE505161 = 2" overall http://www.moss-europe.co.uk/Pdfs/TR253-67/TR2-4A%20RESTORATION%20SECTION.pdf Roger Quote Link to post Share on other sites
AlanT Posted July 18, 2014 Report Share Posted July 18, 2014 Its the full Chronos kit that I have. They are carbon-steel taps not High-speed steel. This will make no difference at all in Alloy and no real difference for occasional hand use in Steel. This also a good supplier of inserts and taps: http://www.ebay.co.uk/itm/V-Coil-Thread-Repair-Inserts-M10-x-1-5-2-5D-10-Compatible-With-Helicoil-/231283946114?pt=UK_Hand_Tools_Equipment&hash=item35d998f282 Quote Link to post Share on other sites
simonjrwinter Posted July 25, 2014 Author Report Share Posted July 25, 2014 Ok What I need to do is get a steel plate made up with six holes in it. every other hole needs to be the size of the hole in the hub for a 5/16 stud to pass through, while the remaining three holes need to be the size of the drill bit for whatever helicoils I use. Remove every other stud and line up and bolt down the jig, drill three holes, remove jig, tap holes, insert three studs Remove remaining studs, index the jig around one position, drill tap and install studs..... Anyone see any problems with that? Just need someone to make me up a jig! Quote Link to post Share on other sites
RogerH Posted July 25, 2014 Report Share Posted July 25, 2014 Hi Simon, I may not have read your process exactly but I think you are missing a step. Plate with six holes. 3 holes fit the original 5/16 studs - to hold it down. The alternate 3 holes need to be able to accept the helicoil tapping drill and the tap (which is bigger than the drill). So if it were me I would have the 3 alternate holes big enough to take a 1" deep plug that has a hole for the tapping drill and another 1" plug to take the helicoil tap. This will ensure that both the drill AND tap are held square. Don;t try to tap free hand - you need a guide Good luck Roger Quote Link to post Share on other sites
Motorsport Mickey Posted July 25, 2014 Report Share Posted July 25, 2014 Rogers on the money. Or if you didn't want the complexity of removable plugs or inserts to drill through you could just have 2x 5/16th stud holes holding the jig as long as you pick studs which are not directly adjacent to one another, this would then locate the jig in two axis which is what you need and then have 2 holes at drilling dia for tapping and 2 holes at tapping outer dia size. Then with a bit of judicious bolting up, drilling and tapping and rebolting on the various stud holes complete all the holes. You do need to use a plate thick enough to guide the drills and taps 6mm won't do the job. I'd suggest 15mm as a minimum and preferably thicker, if you don't decide to use plugs or inserts to drill and tap through (presumably in steel) you will need a steel plate to avoid the drills or taps opening up the holes. PS: You will need to make the jig on a milling machine or drill with a digital readout unless you are completely happy with drilling centre popped holes marked out by hand on the jig. Unless you feel you can achieve the necessary accuracy by doing this (and I think you need each hole centre to be out by a maximum of 5 thou each if you do) stick with machine accuracy. Mick Richards Quote Link to post Share on other sites
AlanT Posted July 25, 2014 Report Share Posted July 25, 2014 I can't hand centre-pop, locate and drill and come out to within 5-thou centres. i'd do well to get 10 thou. The work is in cutting and preparing the circular blank. First off you got to find the material. In a small quantity. Then part it off and face it. Or start from sheet and do a lot of sawing. This is at least a £50 job in a pro shop. Quote Link to post Share on other sites
Motorsport Mickey Posted July 26, 2014 Report Share Posted July 26, 2014 To mark out by hand the PCD centres you would have to bring your A game. I'd use a vertical Vernier guage with a chisel edge tool steel stylus on a face plate with the blank fixed to vertical angle frame set on it after facing up the blank (both sides ) on a lathe and drilling a hole in the middle (for securing). Engineers marking blue on the face of the blank and mark out the hole centres in one axis to the PCD dimensions available from tables, rotate the blank and set at 90 degrees and remark the hole centres (from tables) in the other axis. Then a gentle centre pop mark with a very sharp centre pop and set up on a drill press (if no miller available) and centre exactly over each centre pop individually by using eccentric needle in plastercine that's centred. Then drill as required. Mick Richards Quote Link to post Share on other sites
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