Icarus60 Posted April 4, 2012 Report Share Posted April 4, 2012 I am putting together a DIY front spring compressor making reference to the many previous forum posts on this subject. I hope to use a length of 12mm screwed rod. Can anybody please tell me if the upper shock absorber mounting hole is large enough to accept a 12mm rod passing through it. I want to make the compressor before taking the shocker out at the weekend and if anybody can let me know the size of this hole it will be greatly appreciated. Thanks in anticipation Gerry Quote Link to post Share on other sites
RogerH Posted April 4, 2012 Report Share Posted April 4, 2012 Hi Gerry, The 12mm studding should go through (it does on the 4A). Roger Quote Link to post Share on other sites
Andrew Smith Posted April 4, 2012 Report Share Posted April 4, 2012 Gerry, Yes, I use this little chap and the rod is 15mm. Cheers Andrew Quote Link to post Share on other sites
Fireman049 Posted April 4, 2012 Report Share Posted April 4, 2012 Gerry ~ It's VERY IMPORTANT that you use HIGH TENSILE STEEL for both the rod and the threaded part. When you compress a coiled spring this puts very high stress on the compressor and should the threads 'strip' under load it can cause severe injuries and damage! Tom. Quote Link to post Share on other sites
Icarus60 Posted April 4, 2012 Author Report Share Posted April 4, 2012 Thanks Roger, Thanks Andrew - that's a manly bit of kit you've got there! I give the 12mm studding a go. Best Regards Gerry Quote Link to post Share on other sites
Icarus60 Posted April 4, 2012 Author Report Share Posted April 4, 2012 Thanks Tom - we just crossed in the post. Point noted and will be undertaking a full risk assessment before use. Many Thanks Gerry Quote Link to post Share on other sites
Andrew Smith Posted April 4, 2012 Report Share Posted April 4, 2012 Thanks Andrew - that's a manly bit of kit you've got there! Yes it sure is Gerry, and makes light work of those springs! - it's a few years old now and not too dissimilar to the original Churchill tool (M50), or maybe it is? Cheers Andrew Quote Link to post Share on other sites
Guest ntc Posted April 4, 2012 Report Share Posted April 4, 2012 It is not to far away Andrew but not the same Quote Link to post Share on other sites
vivdownunder Posted April 5, 2012 Report Share Posted April 5, 2012 Yes Gerry, the upper hole in the tower is much larger than the shocker thread. The cushioning rubbers go through the hole so the shocker thread can't hit the tower. Please don't use 12mm threaded rod. If it fails, the spring might be found 3 suburbs away, along with whatever body parts it takes in the process. Not a recommendation, but I used 15mm threaded rod for my spring compressor, double nutted at each end. Regards, Viv. Quote Link to post Share on other sites
foster461 Posted April 5, 2012 Report Share Posted April 5, 2012 Yes it sure is Gerry, and makes light work of those springs! - it's a few years old now and not too dissimilar to the original Churchill tool (M50), or maybe it is? Cheers Andrew That is a formidable looking spring compressor Andrew. Can you get enough leverage to compress the spring by hand using those handles or do you need to put a wrench on the bottom ? Stan Quote Link to post Share on other sites
cliveinfrance Posted April 5, 2012 Report Share Posted April 5, 2012 With Andrews kit, same as mine, it is easy to get the leverage purely by hand, no probs. Clive Quote Link to post Share on other sites
Icarus60 Posted April 5, 2012 Author Report Share Posted April 5, 2012 Thanks for your input Viv. I can see the logic in using 15mm if the tower hole is big enough to accept it. I have asked a friendly stress man to look at the numbers to see what safety factor we have with 10, 12 and 15mm in a range of available materials. I am also mindful that a good thread form and adequate lubrication are also important factors. If I dont get back to you, you will know I got it wrong!!!! Best Regards Gerry Quote Link to post Share on other sites
Ian Vincent Posted April 5, 2012 Report Share Posted April 5, 2012 Just for the record, the ultimate tensile strength of a 12mm grade 8.8 bolt is approximately 7 tonne. with a load factor of 2 that gives an allowable load of 3.5 Te. That should be enough to compress a TR spring. Rgds Ian Quote Link to post Share on other sites
mike3md Posted April 5, 2012 Report Share Posted April 5, 2012 Andrew, On your tool (ooohhh), the LH end welded on to the screwed (ooohhh) rod looks weeny, is it all high tensile material? Mike Quote Link to post Share on other sites
BrianC Posted April 6, 2012 Report Share Posted April 6, 2012 With all this concern over strength and size, does that mean that all those who have just used studding from the DIY sheds are dicing with death? I recently acquired an ancient home-made device made of unknown materials. I haven't needed to use it yet but I know it has been used by many LVG members in the past and certainly would be safer then the pair of side-mount spring compressors I used to use before I realised how dangerous this type is. I lent these to someone years ago and they never came back - I hope whoever had them didn't fall victim to them. I guess, on H&S grounds, my antique should be condemned? Quote Link to post Share on other sites
Ian Vincent Posted April 6, 2012 Report Share Posted April 6, 2012 I used a length of mild steel 12mm studding with double nuts - greased the thread and kept a close eye on it - no problem. I don't know what the compressive load in a spring is but I can't imagine its much more than a tonne. If anyone wants to work it out its a function of the distance from the lower wishbone mount to the centre of the wheel, the distance from lower wishbone mount to the centre of the spring and the load on the front wheel. Rgds Ian Quote Link to post Share on other sites
Kiwifrog Posted April 6, 2012 Report Share Posted April 6, 2012 Andrew, On your tool (ooohhh), the LH end welded on to the screwed (ooohhh) rod looks weeny, is it all high tensile material? Mike It looks like Andrews tool has been modified at some point looking at the welds on the bottom. So now he has a modified tool with welds on the bottom which works a treat Alan Quote Link to post Share on other sites
RogerH Posted April 6, 2012 Report Share Posted April 6, 2012 (edited) Hi Folks, I appreciate your H&S concerns over whether an 8, 10,12 or 15mm is adequate. However I think that one is being overcautious. Anybody buying studding from B&Q etc will be getting some run-of-the-mill steel but is it good enough to use. The spring pan at the bottom of the spring is held by six 5/16 (8mm) bolts. Are they all required? They are there to hold the spring pan in place and to keep the arms aligned together - NOT because the spring is strong. One of those bolts would be strong enough to wind the spring in and out. 10mm would be more than adequate, 12mm more so. Andrews tool unwittingly shows this. A 15mm screw thread with a beautiful handle at one end but a significantly smaller thread and thin nut at the other. To improve things, the studding does not need to be big (8mm is fine) but the nuts need to be deep to pick up on as many threads as possible. A double or triple thickness nut would be nice. In my view 10mm or 12mm studding with deep nuts will work fine - you can guess what I have!!. Roger Edited April 6, 2012 by RogerH Quote Link to post Share on other sites
Motorsport Mickey Posted April 6, 2012 Report Share Posted April 6, 2012 I'm with Roger. Used B&Q 12mm studding for last 20 years, in a fit of psuedo H&E I use a lock nut on either extreme end of the bar so if the worst happens it will stop the collar of my compressor and arrest any material that has escaped and is being projected either up or down the stud at warp speed ! Mick Richards Quote Link to post Share on other sites
Andrew Smith Posted April 6, 2012 Report Share Posted April 6, 2012 I've got two of this type of spring compressor (although I can't find the one in the other photo?), but this one is the better of the two and has been made from a single piece of 15mm steel (turned down to 12mm at the top) and the bottom cup assembly is fitted with needle rollers, a nicely made piece of kit: Cheers Andrew Quote Link to post Share on other sites
Guest ntc Posted April 6, 2012 Report Share Posted April 6, 2012 The Daddy and how it should be Quote Link to post Share on other sites
BrianC Posted April 6, 2012 Report Share Posted April 6, 2012 ...in a fit of psuedo H&E... Is that schoolboy porno favourite still around? Quote Link to post Share on other sites
BlueTR3A-5EKT Posted April 11, 2012 Report Share Posted April 11, 2012 I've got two of this type of spring compressor (although I can't find the one in the other photo?), but this one is the better of the two and has been made from a single piece of 15mm steel (turned down to 12mm at the top) and the bottom cup assembly is fitted with needle rollers, a nicely made piece of kit: Cheers Andrew Coo that'll put your cam and diff bearings in OK too! Peter W Quote Link to post Share on other sites
MikeTR-6 Posted April 12, 2012 Report Share Posted April 12, 2012 Standard 15mm studding and greece the thread 100% OK an safe . The pressure is not that great . Two 5.16" bolt's say 6" long to guide the lower pan as you compress the spring . Each Pan has 2 studs in the arm 3 shouldered bolts and your bump stop Mike Quote Link to post Share on other sites
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