Smithy77 Posted January 26, 2015 Share Posted January 26, 2015 Hi all,I need to get round to the daunting task drilling and fitting my front exhaust mount through the side skin. When the car was rebuilt in 2012 this was missed off for whatever reason.I looked into this last year and found some good posts on here decribing exactly where to drill etc etc, but since we've had the new forum I haven't been able to search the archieves with anywhere near the ease of the old site. Just been searching through 8 pages of results without a sniff of what I was after!I would be grateful if anyone could point me in the direction of, or provide the info for, exactly where to drill my hole. If anyone else has any further wise words of wisdom for completing the job, that would also be great! Aside from where to drill the hole, some questions I have:- Is there a way to check if my chassis actually has the required captive nut on the otherside of the side skin? Would hate to drill the hole only to discover the reason why the mount wasn't done was because the fixing wasn't there!- What is the best way, if required, to treat the cut edges of unpainted aluminium?- I don't forsee the need for any special tools, would this be a correct assumption? Perhaps maybe a Dremel for enlarging the hole?Thanks Link to comment Share on other sites More sharing options...
revilla Posted January 26, 2015 Share Posted January 26, 2015 Now I know why you were wondering what I did to the edges of my hole (answer: nothing!) - also interested to hear suggestions so tagging myself in here. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted January 26, 2015 Member Share Posted January 26, 2015 I haven't seen anything on finding the location.Most experiences with cutting the sideskin are positive. At least those that are reported...Most common method involves a Dremel or similar or a flap wheel to finish, but some have nibbled. Practice on a bit of scrap first, of course.Jonathan Link to comment Share on other sites More sharing options...
SM25T Posted January 26, 2015 Share Posted January 26, 2015 Between 800-805 mm from the centre of the rear mount hole. Link to comment Share on other sites More sharing options...
ECR Posted January 26, 2015 Share Posted January 26, 2015 From Arch:Rear chassis exhaust mount centre to front chassis exhaust mount centre on a standard chassis is 803 mmSo this agrees nicely with SM25T above. Get drilling ! (start with a small drill to find the bush .....) Link to comment Share on other sites More sharing options...
revilla Posted January 26, 2015 Share Posted January 26, 2015 Presumably you need to be careful not to drill out the thread when you've found it and go in with a bigger drill? How deeply inset is the threaded section / captive nut? Link to comment Share on other sites More sharing options...
CharlesElliott Posted January 26, 2015 Share Posted January 26, 2015 it is right behind the sideskin, but because the sideskin is not attached to the chassis at that point, you get a bit of a gap. It's a worry I had, but having done it a few times, it isn't a problem. Link to comment Share on other sites More sharing options...
Smithy77 Posted January 27, 2015 Author Share Posted January 27, 2015 Now I know why you were wondering what I did to the edges of my hole (answer: nothing!) Ah, you got me! it is right behind the sideskin, but because the sideskin is not attached to the chassis at that point, you get a bit of a gap. It's a worry I had, but having done it a few times, it isn't a problem. If there is a bit of a gap between side skin and chassis, does that not distort the side skin as you tighten the exhaust mount?Thanks for all the measurements and other comments. So 803mm from rear mount it is - presumably that is at the same height from u/side chassis as the rear mount. Is the 803mm measured around the 'kink' in the side skin, or straight?What size hole should I start with, and is there a particular technique to finding the threaded section once a small hole is drilled? Or are tolerances so good that if you measure accurately you should find it pretty easilly? Last question, anything I need to do between the mount and side skin / around the drilled hole to prevent corrosion?Thanks Link to comment Share on other sites More sharing options...
CharlesElliott Posted January 27, 2015 Share Posted January 27, 2015 Well, when you bolt in the exhaust bracket you pull the sideskin tight against the boss so no, there isn't any distortion. But before you do that, when you are drilling the hole, there is nothing holding the sideskin tight against the boss.If you take it to Bruce, he'll get a drill, look at the side of the car and then drill straight into the centre of the boss hole!I would recommend something like 3mm - you need it to be big enough that you can see whether you are in the right place....Personally, I would touch up the edges with some touch up paint if you have some. Link to comment Share on other sites More sharing options...
Smithy77 Posted January 27, 2015 Author Share Posted January 27, 2015 Thanks, Charles! Link to comment Share on other sites More sharing options...
ECR Posted January 27, 2015 Share Posted January 27, 2015 You measure round the kink not straight i.e. your tape stays on the skin and bends round the kink. When you find the boss with your 3mm drill, open up the hole with a drill that will not touch the thread. I would then use a round file to finish off the hole. A dab of paint won't hurt but the hole is covered by the bracket and won't be seen. A dremel can be used to open up the hole but I wouldn't, a slip with the Dremel and your painted sideskin is buggered Link to comment Share on other sites More sharing options...
Smithy77 Posted January 27, 2015 Author Share Posted January 27, 2015 Thanks, ECR. I don't have a Dremel but I do have a round file so I'll try that first Link to comment Share on other sites More sharing options...
Smithy77 Posted March 1, 2015 Author Share Posted March 1, 2015 Please help folks! I've started drilling for this exhaust mount and as I've gone through the aluminium skin, I've hit something considerably harder - the chassis rail I presume! No sign of any captive thread. Not wanting to drill through the chassis I've stopped, but I'm worried that I could make a mess of it and don't know where to drill next. Can someone please advise what to do?Pic Link to comment Share on other sites More sharing options...
SM25T Posted March 1, 2015 Share Posted March 1, 2015 What dimension have you gone for from centreline of rear mount ? Link to comment Share on other sites More sharing options...
Smithy77 Posted March 1, 2015 Author Share Posted March 1, 2015 Exactly 803mm forward of the rear mount and the same distance up from the underside of chassis... Link to comment Share on other sites More sharing options...
SM25T Posted March 1, 2015 Share Posted March 1, 2015 Should be good Link to comment Share on other sites More sharing options...
revilla Posted March 1, 2015 Share Posted March 1, 2015 @SM25T - Did you spot the little "Pic" link that Pete posted?https://www.dropbox.com/s/ohvrklhjqxbrye2/20150301_124856.jpg?dl=0Whilst it "Should be good" ... it clearly isn't good in that picture. Looks like solid metal behind the skin there and no hint of a hole or captive nut. Pete the only thing I can suggest, and sorry if this sounds really patronising but I don't know what else to suggest, is ... double check your tape measure and make sure the line under the number corresponds to the number of centimeters shown, not the one over it? Long shot I know, but you never know!Unless anyone has some really good info, might it be worth phoning Bruce at Arch Motors on Monday morning to see if he knows of any reasons why it might be in a different place or missing - after all, if any were built differently, he built them. When I phoned him with a query on my read suspension geometry he was most helpful. Link to comment Share on other sites More sharing options...
Smithy77 Posted March 1, 2015 Author Share Posted March 1, 2015 But there is no sign of any thread, just solid steel chassis, which is the reason for asking what to do next? Up, down, left, right, something else...? Link to comment Share on other sites More sharing options...
Smithy77 Posted March 1, 2015 Author Share Posted March 1, 2015 Andrew, thanks for the tip (no offence taken, I'm sure it's been done before!). I've double checked the measurements and also verified with a tape measure just incase the tape was lying Link to comment Share on other sites More sharing options...
revilla Posted March 1, 2015 Share Posted March 1, 2015 Just been out and measured mine. Remember it's an SV so things might different, however as best I can measure it with the exhaust still in place, it is 805mm. Drilling a pilot hole at 803mm would expost the edge of the hole I'm sure. Sorry, out of ideas for now. Link to comment Share on other sites More sharing options...
Smithy77 Posted March 1, 2015 Author Share Posted March 1, 2015 Thanks for that Andrew. I'm going to try and offer the exhaust back up and see where the hole position compares to the exhaust bracket. Probably won't tell me much as I'm sure the mount/bracket allows for some tolerance and adjustment, but at least the car will be road worthy again to take advantage of the weather Link to comment Share on other sites More sharing options...
revilla Posted March 1, 2015 Share Posted March 1, 2015 If I were you I think I might try very gently tapping around the edge of the hole just to see if it sounded or felt like it had any "give" at any point adjacent to the current hole. Not sure you would pick anything up but might be worth a try? Link to comment Share on other sites More sharing options...
Smithy77 Posted March 1, 2015 Author Share Posted March 1, 2015 Well with the exhaust and mount offered up to the side panel it would suggest the hole needs to be a bit further forward, between 805-810 from the rear mount. Shall I also try and drill a bit further forward? Link to comment Share on other sites More sharing options...
revilla Posted March 1, 2015 Share Posted March 1, 2015 Pete,I wouldn't like to advise you to go drilling more holes looking for it.I have one idea ...<MadPhysicistMode>The chassis is magnetic, the skin isn't. Iron filings in the end of a bar magnet (both dirt cheap on eBay) will form a big "bush" radiating out along the field lines. If you can get a reasonably strong bar magnet with a good clump of filings on it and hold it a little distance from the skin, so that the bush of iron filings brushes against the skin, the field lines will be pulled towards the edges of the hole. If you're lucky, with a bit of waving around of the magent, you will be able to see a spot on the skin somewhere close to your existing hole that the iron filings are consistently pulled away from. Where there's a hole in the pattern of iron filings, there's a hole in the chassis underneath!OK I haven't tried it ... but in theory it should work right through an alloy skin. Got to be worth a try as a less destructive way of probing around than with a drill!</MadPhysicistMode>It's the best I've come up with so far! I'll keep thinking. If it works anywhere near as well as in my diagram it'll be a miracle. If it fails, you've lost nothing.Andrew Link to comment Share on other sites More sharing options...
TomB Posted March 1, 2015 Share Posted March 1, 2015 Can the other side of the bush be accessed through the inside skin? Might be easier to hide miss drillings.? Link to comment Share on other sites More sharing options...
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