Mike Bees Posted May 9, 2002 Share Posted May 9, 2002 Stock Caterham ali rad, 1997 vintage. I've stripped the thread for the bleed screw. It appears to be a fine pitch 10mm bolt. Any suggestions for a quick fix (like I need to fix it by 4pm tomorrow!)? There *might* be enough surface area to put in a 12mm tap (what size hole do I need for that?) and use a 12mm bolt. Any such thing as 11mm bolts? Or a non-metric size that would do the trick? It does need to be a fine pitch thread. Buying a new rad isn't an option. Help! Mike Link to comment Share on other sites More sharing options...
John Vine Posted May 9, 2002 Share Posted May 9, 2002 Mike, Ouch! I can't help with the tap sizes, but I do have a newly reconditioned steel/copper rad if you want it (from a 1999 1.8K SS). Yours for £65. (New £100+?) A lot cheaper than a new ali rad! JV Link to comment Share on other sites More sharing options...
scooby dooby doo Posted May 9, 2002 Share Posted May 9, 2002 mike - if you go to the railway tavern in great shelford (just south of cam) you'll find most of cam7 there. i expect one of them my have an answer. or at least they'll buy you a drink! Dave Hooper - North London dmch2@lineone.net Link to comment Share on other sites More sharing options...
Mike Bees Posted May 10, 2002 Author Share Posted May 10, 2002 Thanks for the offer John. I'll try to fix this one first. Hoop - yes I did go to the Railway last night, though sadly not in the 7. Only advice was to try a larger tap/bolt. Mike Link to comment Share on other sites More sharing options...
Mike Bees Posted May 10, 2002 Author Share Posted May 10, 2002 Another thought... In my haste & frustation last night I'd assumed that a helicoil was out of the question since it's not a blind hole so the insert could just wind all the way out the other side. This must be wrong 'cos I know they helicoil spark plug holes. An M10x1mm helicoil kit from Namrick is 47 quid! Ouch. Mike Link to comment Share on other sites More sharing options...
Lawrence_Z Posted May 10, 2002 Share Posted May 10, 2002 If you're going to tap for a bigger hole, You'll find the hole sizes here http://www.spiralock.com/docs/rec-drill-sizes.pdf You may however be able to secure the existing bolt by building up the thread with PTFE tape, after tightening the bolt, take it off and try taping a second time for best results be lucky smile.gif Lawrence Link to comment Share on other sites More sharing options...
R2D2 Posted May 10, 2002 Share Posted May 10, 2002 Mike, You can fit a helicoil or a timesert. I have some helicoil tools and wiil try to find a size. If the thread is a fine pitch then this is probably why you have had the problem. Aluminium really needs coarse threads such as UNC or metric coarse. Will check what I have and post it later. Link to comment Share on other sites More sharing options...
pie_boy69 Posted May 10, 2002 Share Posted May 10, 2002 Mike whip it of and pop down to your local tig welder he or she will be able to clean up the hole fill with new weld if needed and tap and supply a new bolt and should do while you wait. My local guy did this for me when my sump plug was rounded from repeated beating with tarmac. But before you say ah this is a rad not a sump my guy used to build all of our ali rads so it's no prob to weld the tanks. Keith Link to comment Share on other sites More sharing options...
Mike Bees Posted May 10, 2002 Author Share Posted May 10, 2002 Chris, Thks for the offer to post bits - I need to fix this today, so I'll have a go at tapping a bigger hole or putting in a helicoil. What pitch thread would you recommend? Mike Link to comment Share on other sites More sharing options...
Graham Perry Posted May 10, 2002 Share Posted May 10, 2002 Mike, I hope you make it to Debden this weekend, looks like the best class 7 in a while there. Its borderline if we will make it ourselves as we have starter troubles ! Edited by - Graham Perry on 10 May 2002 11:30:29 Link to comment Share on other sites More sharing options...
Mike Bees Posted May 10, 2002 Author Share Posted May 10, 2002 Graham - we can always push! Cheers, Mike Link to comment Share on other sites More sharing options...
R2D2 Posted May 10, 2002 Share Posted May 10, 2002 Mike, I do have an M10 helicoil set. The recommended drill size for an M10 helicoil is 10.3 mm dia. The helicoil tap I would use would then be for the standard 1.25mm pitch. The drill size for an M10 x 1.5mm pitch helicoil is also 10.3mm so you can use either size depending on which taps and inserts you can find. Once the thread is heicoiled there is no need to use the coarse thread that I would normally recommend in Aluminium. The M10 hole should still drill out to 10.3mm without problem I am in Northampton so if you can get to me I have the drill, taps, inserts and tools you need to do the job. It will only take a few minutes so if you are stuck let me know how I can help. Link to comment Share on other sites More sharing options...
John Howe Posted May 10, 2002 Share Posted May 10, 2002 Mike, for an instant fix... why not JB Weld the original bolt in place and effect a more professional repair after the week end. JH Link to comment Share on other sites More sharing options...
Graham Perry Posted May 10, 2002 Share Posted May 10, 2002 Mike, If it goes wrong at Debden, we have a spare 'standard' Crossflow Rad at my brothers 1 minute from the track, that we could probably bodge up to get you home. Link to comment Share on other sites More sharing options...
Mike Bees Posted May 13, 2002 Author Share Posted May 13, 2002 Thanks for all the advice & offers of help chaps. I bought a cheap 7/16" tap and suitable bolt which seems to have done the job. Mike Link to comment Share on other sites More sharing options...
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