TomB Posted February 16, 2018 Share Posted February 16, 2018 I’ve done a School boy error and stripped a thread on my front hub while fitting a new brake disc, despite using a torque wrench! I’m so cross - probably serves me right for rushing while toddler was sleeping! Aside from replacing it, is there anything I can do? I’m thinking tapping and fitting a bigger bolt isn’t the answer as it’s rotating and will be out of balance, plays I’d have to drill the disc too. Has anyone upgraded and got one or a pair knocking around? The ones I have are alloy, the felt seal and fairly light weight, but not the later uprated one with thicker stub axle. See wanted advert, thanks https://www.lotus7.club/forum/wanted/front-hub-0 Link to comment Share on other sites More sharing options...
TomB Posted February 16, 2018 Author Share Posted February 16, 2018 Where has the formatting gone! Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted February 16, 2018 Member Share Posted February 16, 2018 There's a problem with formatting in the first post of new threads. It appeared with the recent changes to the website, and Shaun knows about it.The best workaround is to reply to your own post and put the formatted stuff in that reply.Jonathan Link to comment Share on other sites More sharing options...
TomB Posted February 16, 2018 Author Share Posted February 16, 2018 Hellicoil has been suggested. Has anyone used one of these and know what imperial thread I need for the brake disc hub. Would you recommend using one in this application? Link to comment Share on other sites More sharing options...
Paul Deslandes Posted February 16, 2018 Share Posted February 16, 2018 You need to helicoil, or equivalent. Very easy to do although better still if you have access to a pillar drill. Where in the country are you?Paul Link to comment Share on other sites More sharing options...
Paul Deslandes Posted February 16, 2018 Share Posted February 16, 2018 Re you the Tom in Guildford/ If so Margnor in Jacobs Well do the re thread kits. They're open until 5 or 5.30. Take the bolt with you. Link to comment Share on other sites More sharing options...
TomB Posted February 16, 2018 Author Share Posted February 16, 2018 Manchester. I know a member with a pillar drill I think. Do you know what thread I need? Link to comment Share on other sites More sharing options...
Paul Deslandes Posted February 16, 2018 Share Posted February 16, 2018 And, yes, definitely okay for this job. Link to comment Share on other sites More sharing options...
Paul Deslandes Posted February 16, 2018 Share Posted February 16, 2018 3/8 X 1 1/2" UNF. 22-27 lbft Link to comment Share on other sites More sharing options...
Paul Deslandes Posted February 16, 2018 Share Posted February 16, 2018 The pillar drill makes it much easier to get the drilled out hole vertical and similarly the tap for the helicoil. Without it it's very easy for the thread to deviate from the vwertical. Once it's drilled put the tap in the pillar drill and turn it by hand with lots of cutting lube. Don't switch it on for goodness sake! Link to comment Share on other sites More sharing options...
Paul Deslandes Posted February 16, 2018 Share Posted February 16, 2018 BTW, that bolt size is taken from the '95 assembly manual and relates to the old style hubs. Before ordering the helicoil you might want to check the bolt thread unless you're certain. Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted February 16, 2018 Leadership Team Share Posted February 16, 2018 Tom, to get round the balance issue you could drill out all 4 and use larger bolts.Stu. Link to comment Share on other sites More sharing options...
TomB Posted February 16, 2018 Author Share Posted February 16, 2018 It's probably right as mine is the old triumph spitfire upright and my cat is early 1996. Thanks for your help I'm worrying less now. Kits on eBay for ~£20. Link to comment Share on other sites More sharing options...
Paul Deslandes Posted February 16, 2018 Share Posted February 16, 2018 Sounds about right. Make sure you order the correct length to suit the hole depth. Link to comment Share on other sites More sharing options...
Domus Posted February 16, 2018 Share Posted February 16, 2018 On Amazon Prime https://www.amazon.co.uk/V-Coil-8-inch-UNF-Thread-Repair/dp/B00EO4NYMEWhen you get a kit feel free to come over Link to comment Share on other sites More sharing options...
TomB Posted February 16, 2018 Author Share Posted February 16, 2018 Is helicoiling a brake disc safe/ sensible? Link to comment Share on other sites More sharing options...
Paul Deslandes Posted February 16, 2018 Share Posted February 16, 2018 It's been a long time since I had one apart but isn't the thread in the hub and the bolt passes through a hole in the disk? The helicoil is often stronger than the original thread, especially when use with an aluminium 'parent' body. When you see one you'll realise why that might be the case. Paul Link to comment Share on other sites More sharing options...
Wrightpayne Posted February 16, 2018 Share Posted February 16, 2018 Its only 1 of 4 bolts. I’d be happy doing it tiil a new hub becomes available.some would see this as an opportunity to upgrade the hubs/stub axles to the later type. Not an expensive upgrade!Ian Link to comment Share on other sites More sharing options...
TomB Posted February 16, 2018 Author Share Posted February 16, 2018 Yes Paul, it’s the hub that has the thread. Got to the conclusion I think it will be ok to coil.I could upgrade, but I haven’t a spare £300 for something that for a road car is probably over kill. The bearings are new in the last couple of year since I fitted wide track, so they’ve probably only done 5-6000 miles. Ive been offered a used one, but I don’t know it’s history so I think I’ll coil and may look to replace with new ones when/if I manage to get round to a rebuild. Link to comment Share on other sites More sharing options...
TomB Posted February 19, 2018 Author Share Posted February 19, 2018 Further to this, I haven't placed an order yet for a coil kit, but I was wondering whether to use thread lock after the coil has been inserted. Threadlock is recommended and a torque of 20-28lb/ft for the standard bolt into the ali hub. Would you threadlock the helicoil in place then put the bolt in, or put threadlock on the bolt? Or not at all? Could I risk gluing the hub/coil/bolt together and having problems if I wanted to change the discs in the future? Link to comment Share on other sites More sharing options...
Paul Deslandes Posted February 19, 2018 Share Posted February 19, 2018 TomYou shouldn't need to thread lock the helicoil in place but you can treat the bolt thread as you would any other. In fact the hardened steel thread insert will be hugely stronger than the original. Generally it's not recommended to use fine threads in castings as they are inclined to strip out, as you have discovered, so the helicoil will make the disk fixing better not worse. In light of the above you could increase the tightening torque but I'd stick with the original spec and use thread lock.The thread lock won't be strong enough to glue them together but make sure you don't get any between the two mating surfaces as this can prevent them from being flush as the liquid can act like a thin spacer. You only need a drop of thread lock on the bolt thread, not lashings of it everywhere.As said before, drilling and tapping vertically can be quite tricky unless you use a pillar drill so I hope you can find one to use as it's all too easy or them to drift off the perpendicular when doing it by hand.Best of luckPaul Link to comment Share on other sites More sharing options...
ECR Posted February 19, 2018 Share Posted February 19, 2018 Helicoils don't need threadlock to hold themselves in place but it won't hurt if you put some on. If threadlock is recommended for the bolt into the hub then use it when you fit the bolt into the helicoiled thread. Use a "normal" (not high strength) threadlock and disassembly won't be a problem in the future. I sense your trepidation in working this way on your brakes, but rest assured it's a well proven method. Link to comment Share on other sites More sharing options...
TomB Posted February 19, 2018 Author Share Posted February 19, 2018 Thanks for your help, and you're right Im a bit nervous! Would it be prudent to do all four at the same time? But it would be simpler to just change the hub I suppose, but I know the history of mine and a used one could easily have tired threads. Link to comment Share on other sites More sharing options...
Paul Deslandes Posted February 19, 2018 Share Posted February 19, 2018 I personally wouldn't change the hub unless it's cheaper that helicoiling, or you want to upgrade to the later hub (both sides). Paul Link to comment Share on other sites More sharing options...
ECR Posted February 19, 2018 Share Posted February 19, 2018 Do the Helicoil on the stripped thread and leave the others alone (If it ain't broke ......etc) Link to comment Share on other sites More sharing options...
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