moorsd123 Posted April 13, 2023 Share Posted April 13, 2023 Hi All,Just fitting a Petty Strut to my R400D (Metric Chassis), and all seems to have gone well finding the boss etc, however....I was under the impression the thread size on the boss in the Chassis was 7/16 UNF regardless of Chassis type, but this doesn't appear to be the case as a 7/16 UNF bolt is too big?Does anyone know the correct thread side, the id of the boss is coming out at around 7.9mm give or take? Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted April 13, 2023 Member Share Posted April 13, 2023 The 2015 Assembly Guide has 7/16" bolt (fastener pack ZPS01 Item 2).I can''t find any note on changes from a quick search of the archives:https://duckduckgo.com/?q=site:caterhamlotus7.club+petty+boltJonathan Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted April 13, 2023 Member Share Posted April 13, 2023 So I'd start by having a look at that female thread... is it nice and clean or does it have paint or swarf up it?Jonathan Link to comment Share on other sites More sharing options...
moorsd123 Posted April 13, 2023 Author Share Posted April 13, 2023 Thanks Jonathan,I've called Arch as figured they'll know best...confirmed 7/16 UNF, so think I'll get a 7/16 tap and run it through to clean the thread out! Link to comment Share on other sites More sharing options...
Wrightpayne Posted April 13, 2023 Share Posted April 13, 2023 I dont think Arch make the metric chassis ?? Link to comment Share on other sites More sharing options...
moorsd123 Posted April 13, 2023 Author Share Posted April 13, 2023 That's probably why the boss turned out to be M10 thread then!! There was no way the 7/16 UNF tap was going in the hole, so tried metric and the M10 worked after cutting the first few threads (obviously damaged them trying to get the 7/16 in!).So for anyone doing this in future it appears the boss on the metric chassis is M10x1.5 thread (I'm going to use an M10x30 bolt. Mine is a 2008 R400D for reference.The next challenge will be lining up the Petty Strut to the mounting holes, as a "dry fit" looks like the chassis mounting hole is about 5mm off center, so guess I'll have to loosen the roll bar bolts to get some additional play...grrrr!!! Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted April 13, 2023 Member Share Posted April 13, 2023 Thanks for adding the answer.Jonathan Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted April 13, 2023 Member Share Posted April 13, 2023 "The next challenge will be lining up the Petty Strut to the mounting holes, as a "dry fit" looks like the chassis mounting hole is about 5mm off center, so guess I'll have to loosen the roll bar bolts to get some additional play...grrrr!!!"Is that lateral... if the roll bar is nicely positioned already could you pack the strut with washers?Jonathan Link to comment Share on other sites More sharing options...
moorsd123 Posted April 13, 2023 Author Share Posted April 13, 2023 Unfortunately not, it's as if the roll hoop needs to go back slightly (so the strut move back and up in the 10 oclock direction).... Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted April 13, 2023 Member Share Posted April 13, 2023 You're not alone:https://www.caterhamlotus7.club/forum/chitchat/petty-strut-againJonathan Link to comment Share on other sites More sharing options...
moorsd123 Posted April 13, 2023 Author Share Posted April 13, 2023 Yep...that's exactly the issue I have!! Obviously another case of great "British Engineering". I'll see how I get on with loosening the roll bar bolts, but may decide to open up the bottom mount hole in the strut a bit to make fitting easier in future! Link to comment Share on other sites More sharing options...
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