andy987 Posted November 27, 2021 Report Share Posted November 27, 2021 Car is in the for brake lines next week and I’d like to get some spare undertray nuts. Are those unthread VW/Audi ones on eBay the same? I think they are a one time use? The original ones will screw back but new ones will be more secure 1 Quote Link to comment Share on other sites More sharing options...
Lennym1984 Posted November 27, 2021 Report Share Posted November 27, 2021 Short answer is... No, not quite. They are slightly too small but you can kind of pre-tap them with an appropriately sized screw. You don't really want to be forcing them on as the underbody studs are prone to snapping Quote Link to comment Share on other sites More sharing options...
andy987 Posted November 27, 2021 Author Report Share Posted November 27, 2021 👍 Quote Link to comment Share on other sites More sharing options...
iborguk Posted November 27, 2021 Report Share Posted November 27, 2021 (edited) 1 minute ago, andy987 said: 👍 Replacements will be the kind of thing which will the be the right fitment and cheaper if bought from an OPC. Edited November 27, 2021 by iborguk Quote Link to comment Share on other sites More sharing options...
andy987 Posted November 27, 2021 Author Report Share Posted November 27, 2021 Ok thanks! Quote Link to comment Share on other sites More sharing options...
Felipe Posted January 3, 2022 Report Share Posted January 3, 2022 for future reference, I think the plastic nuts are part number 99904900740 As for the tapping screws (wide head, torx T25) are: 99907323109 (16mm) 99907322709 (19mm) be extremely careful removing the plastic nuts, rust make them a bit stubborn to get out and studs might be quite corroded and brake. ... speaking of which.. any ideas on how to replace a broken stud? 😕 Quote Link to comment Share on other sites More sharing options...
T911UK Posted January 4, 2022 Report Share Posted January 4, 2022 Hot air gun the nuts before you try and undo them, then the stud wont break! 3 Quote Link to comment Share on other sites More sharing options...
deanmr2 Posted January 4, 2022 Report Share Posted January 4, 2022 13 hours ago, Felipe said: for future reference, I think the plastic nuts are part number 99904900740 As for the tapping screws (wide head, torx T25) are:99907323109 (16mm) 99907322709 (19mm) be extremely careful removing the plastic nuts, rust make them a bit stubborn to get out and studs might be quite corroded and brake. ... speaking of which.. any ideas on how to replace a broken stud? 😕 If you are going to replace the plastic nuts with new ones then just take a Stanley knife with a new blade and cut the old ones off, that way you will not break off any of the metal studs Quote Link to comment Share on other sites More sharing options...
Felipe Posted January 4, 2022 Report Share Posted January 4, 2022 thanks! I'll try that for the next ones I have to undo. unfortunately this is the case where all metals are exposed to water and salt, having a look at the remains of the stud there wasn't much metal left, I recon it would brake either the nut going out or in. Now, I need to resolve this as it might move dangerously while driving at high speed. Perhaps the only option now is to drill the remains out and install a rivnut, then a stud secured with loctite -- other ideas? Quote Link to comment Share on other sites More sharing options...
MikeT999 Posted January 4, 2022 Report Share Posted January 4, 2022 I was thinking of maybe using something like this...https://www.carbuilder.com/uk/big-head-fixing-m6-x-25-pack-of-5?gclid=Cj0KCQiA_c-OBhDFARIsAIFg3ez_fsCXsAMAPJvSijGDNrSFu-ICwnHm_c02X7Xffv1oGn6bw_YKLZ0aAsXTEALw_wcB For areas where you're not sure what's behind where you're drilling for a rivnut. Nut sure what you'd bond them with yet though... Mike. Quote Link to comment Share on other sites More sharing options...
½cwt Posted January 4, 2022 Report Share Posted January 4, 2022 (edited) 2 hours ago, MikeT999 said: I was thinking of maybe using something like this...https://www.carbuilder.com/uk/big-head-fixing-m6-x-25-pack-of-5?gclid=Cj0KCQiA_c-OBhDFARIsAIFg3ez_fsCXsAMAPJvSijGDNrSFu-ICwnHm_c02X7Xffv1oGn6bw_YKLZ0aAsXTEALw_wcB For areas where you're not sure what's behind where you're drilling for a rivnut. Nut sure what you'd bond them with yet though... Mike. A good quality industrial 2 part epoxy adhesive is what I used in the composites industry 8 or 9 years ago. It will need a good keyed surface to bond to, which is a problem as that technically means back to bare metal... Edited January 4, 2022 by ½cwt Quote Link to comment Share on other sites More sharing options...
Felipe Posted January 4, 2022 Report Share Posted January 4, 2022 Thanks Mike, that is actually a better solution, less intrusive. Yes, there are some good epoxy when well used could be as good as a weld. I will do a research on that. I'm afraid I can get another in similar situation at some point, so better to be prepared. The problem is not the nuts, but the studs. What is the thread size for the stud btw? 5mm 22 tpi? (from the code T5/22) Definitively coarser than a standard M5https://zuffenhausenparts.com/products/porsche-plastic-nut-t5-22-x-10-999-049-007-40 Quote Link to comment Share on other sites More sharing options...
andy987 Posted January 4, 2022 Author Report Share Posted January 4, 2022 The garage doing my brakes took all the trays off, must have been lucky as could only see one snapped stud. Someone handy with a welder could tack new ones on. Anyway I sprayed some bilt hamber dynax on them as there were a bit rusty. Quote Link to comment Share on other sites More sharing options...
Felipe Posted January 4, 2022 Report Share Posted January 4, 2022 ohh.. didn't know about Dynax ( https://bilthamber.com/product/dynax-s50/ ) I was looking for something like that, thanks! Glad no many issues for you. Quote Link to comment Share on other sites More sharing options...
½cwt Posted January 4, 2022 Report Share Posted January 4, 2022 46 minutes ago, andy987 said: The garage doing my brakes took all the trays off, must have been lucky as could only see one snapped stud. Someone handy with a welder could tack new ones on. Anyway I sprayed some bilt hamber dynax on them as there were a bit rusty. Based on my 986 (same studs...) you can live without one or two of the studs in the less critical places and have no problems. Quote Link to comment Share on other sites More sharing options...
Sword Posted January 5, 2022 Report Share Posted January 5, 2022 check this out for rivstuds 1 Quote Link to comment Share on other sites More sharing options...
MikeT999 Posted January 5, 2022 Report Share Posted January 5, 2022 Ooh, I like that idea! The trouble with my suggestion of the bonded studs above as ½cwt points out is the need to key back to bare metal, which I'm not keen on doing - unless someone knows of an adhesive more suitable. I have a Rivnut tool already, I might end up drilling them out and inserting Rivnuts yet, with a stainless bolt and penny washers. There's only 2 that have gone, so it's not a major issue at the moment. Cheers, Mike. Quote Link to comment Share on other sites More sharing options...
Greenman Posted January 5, 2022 Report Share Posted January 5, 2022 Anyone tried those double sided sticky pads for this type of job. They are sticky as hell and would easily hold the weight, but I guess it’s whether the heat will melt them off? Just yesterday I was reattaching a heat-shield on my wife’s car (not Porsche). I didn’t realise the plastic nuts were single use, got quite annoyed when I couldn’t get them to rethread. Eventually I managed it using brute force, but at one point I was going to try a sticky pad under one corner, what’s the worse that could happen? Quote Link to comment Share on other sites More sharing options...
½cwt Posted January 5, 2022 Report Share Posted January 5, 2022 4 hours ago, MikeT999 said: Ooh, I like that idea! The trouble with my suggestion of the bonded studs above as ½cwt points out is the need to key back to bare metal, which I'm not keen on doing - unless someone knows of an adhesive more suitable. I have a Rivnut tool already, I might end up drilling them out and inserting Rivnuts yet, with a stainless bolt and penny washers. There's only 2 that have gone, so it's not a major issue at the moment. Cheers, Mike. Drill out the old stud, fit a Rivnut, then with some thread lock on a short length of stainless studding leaving 12-15 mm projecting out of the Rivnut seems like a decent idea. Would leave a fine thread not a coarse thread but the plastic nut should still grip it. Quote Link to comment Share on other sites More sharing options...
Ninesomething Posted January 6, 2022 Report Share Posted January 6, 2022 In defence of the plastic undertrays they are not nuts. They are a useful feature of the car for many reasons. They just get in the way a bit occasionally. Quote Link to comment Share on other sites More sharing options...
½cwt Posted January 6, 2022 Report Share Posted January 6, 2022 Retaining nuts for the plastic under trays... 🙄 Quote Link to comment Share on other sites More sharing options...
Felipe Posted January 6, 2022 Report Share Posted January 6, 2022 thanks for the video, that was exactly what I was thinking to do and I'm glad that the original part confirm is a valid way to resolve it. For reference this is the part number for the studs: 99919034201 and for the tool.... https://www.ebay.co.uk/itm/254766868920 -- only cost effective for professional use. Perhaps the glued stud is not that bad idea after all Quote Link to comment Share on other sites More sharing options...
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