Maru-So Posted January 10, 2008 Share Posted January 10, 2008 My other hobbie is mountain biking and though rebuilding my bike suspension ive learnt a bit about how suspension works. How they shorten mountain bike shocks is with a topout spacer. since i replaced the shocks in my car i have the old ones to play with. I wanted to see if the stroke of the shocks could be reduced in the same way. I just looking to see people opinion and if its safe or not. This method would only be used for lowness and not really preformance. Firstly cut the shock like so... I was scared it was going to blow up so i had all the safety gear on and periced the shock first to let any pressure off. There was no pressure to speak of really. no bang no big hiss nothing. Take care to only cut the outer part of the shock then this inner piece just pulls out. This is full with oil so hold it right way up over a cup or bucket and cycle the shock through to get most of the oil out Give the shaft a few sharp tugs and the shaft and the piston/shim stack comes out These are shims replacing these with thicker ones or different id holes will change rebound and compression characteristics of the shock. they can just be left alone tho. this bit is the factory top out spacer this is what the assembly looks like when the shock is at full extension this is the stroke of the shock with factory assembly add a spacer between the seal and the top out spacer. this can be any size and dictates how much the stroke of the shock is reduced Excuse the red spacer its just temorary until i get some proper pvc spacer. increasing the distance between the red lines decreases the stroke of the shock. reassembled with the spacer inplace you can see the shock has been shortened. fill the inershock with 300mls of shock oil 10wt or so im not sure what the oem oil weight is so it might take some experimenting. but by changing the oil weights you can adjust the rebound speed of the shock. slide the iner inside the outer and weld up along the red line and it should be golden. advantages over just getting the threads machined. Cost, more overlap as the shaft is permantly half in the shock(stiffer). and the ability to change oil. any comments on how safe it is or if it would even work would be apreciated. Quote Link to comment Share on other sites More sharing options...
sentra Posted January 10, 2008 Share Posted January 10, 2008 i did this when i was at school and broke as (not long ago), asking the same thing at the time someone said the only thing to watch out for was to put exactly exactly the same amount of oil back in. so yeah i did and put thicker oil back in, spaced the inner stop out with garden hose and i thought they were just the bees knees/worked fine. if you wanted to be a full pro you could get a very fine pitch turned in the 2 cut ends of the outer body, and a internally threaded sleeve to join it all back together. Quote Link to comment Share on other sites More sharing options...
twosmoke Posted January 10, 2008 Share Posted January 10, 2008 . Quote Link to comment Share on other sites More sharing options...
Gaz Posted January 10, 2008 Share Posted January 10, 2008 ^^ Yup BUT.. both times ive needed my shopcks shortened I have found a machinist to do em for $40-45 each. Is it worth the effort and possiable dogyness for $80?? Quote Link to comment Share on other sites More sharing options...
fuel Posted January 10, 2008 Share Posted January 10, 2008 what about nitrogen filled shocks? obviously wont work for them eh? Quote Link to comment Share on other sites More sharing options...
twosmoke Posted January 10, 2008 Share Posted January 10, 2008 . Quote Link to comment Share on other sites More sharing options...
Gaz Posted January 10, 2008 Share Posted January 10, 2008 When they do it they machine the top shaft of the shock down and put a new thread on it. Quote Link to comment Share on other sites More sharing options...
twosmoke Posted January 10, 2008 Share Posted January 10, 2008 . Quote Link to comment Share on other sites More sharing options...
sentra Posted January 10, 2008 Share Posted January 10, 2008 if your broke and have free time why not, if theres a glandnut on the top you can do it ultra easy, but that shock looks like its not macpherson style suspension/even if it broke in half it wouldnt matter really. 1 Quote Link to comment Share on other sites More sharing options...
Gaz Posted January 10, 2008 Share Posted January 10, 2008 I have a lathe and some taps could I do the same?Or is it more complicated than that? If your lathe has a large enough hole through the back of it (Dunno what this is technaically called) to fit the shock AND you have tungsten tools then you can. The shaft of the shock will be hard as hell so dont use a std tool. Also I think youd prob be better of using the thread cutting feature of the lathe if its got one. Quote Link to comment Share on other sites More sharing options...
twosmoke Posted January 10, 2008 Share Posted January 10, 2008 . Quote Link to comment Share on other sites More sharing options...
Maru-So Posted January 10, 2008 Author Share Posted January 10, 2008 sweet those were the responses i was looking for. The way this parrticular shock goes even if the welds didnt hold its still inside the strut so cant really catostrofically fail. To me this method is easier than getting them machined and you get the added bonus of making them stiffer. Is there a way to shorrten rear gas shocks? Quote Link to comment Share on other sites More sharing options...
kpr Posted January 10, 2008 Share Posted January 10, 2008 lathe doesnt really need to fit the shock thru the hole. when i did mine i had them setup around the other way. clamp current thread in chuck. machine the shaft down to correct size. the cut thread, cut excess thread off last. hardest bit is cutting the thread if you havent done it before. need special thread cutting tip to do it as well. Quote Link to comment Share on other sites More sharing options...
Ke36 Posted January 10, 2008 Share Posted January 10, 2008 sweet those were the responses i was looking for. The way this parrticular shock goes even if the welds didnt hold its still inside the strut so cant really catostrofically fail. To me this method is easier than getting them machined and you get the added bonus of making them stiffer. Is there a way to shorrten rear gas shocks? i have had some done, by a suspension place believe they were just cut then re gassed Quote Link to comment Share on other sites More sharing options...
Spencer Posted January 10, 2008 Share Posted January 10, 2008 for any decent drop that wouln't be anywhere near short enough Quote Link to comment Share on other sites More sharing options...
Ned Posted January 11, 2008 Share Posted January 11, 2008 i just took mine to the autoline in henderson for $50 each. seems simpler to me.... and safer... just my 2c Quote Link to comment Share on other sites More sharing options...
Yowzer Posted January 11, 2008 Share Posted January 11, 2008 for any decent drop that wouln't be anywhere near short enough Thats coz the OS definition of a decent drop removes at least 3 inches from the ride height Just use more spacers haha Quote Link to comment Share on other sites More sharing options...
RUNAMUCK Posted January 11, 2008 Share Posted January 11, 2008 The limiting factor with this method is if you fully slam your car, the shock still had the potential to bottom out internally. Where as with a shrtened shock that can't happen. I was hsown this trick originally by my warrant man. I remember riding in rx2's with cutties. They used to bottom out the shocks, and ride super rough. In time this fucks the shocks beyond repair. But it's fat that with sum pipe and and angle grinder you can slam your car and still have captive springs. Quote Link to comment Share on other sites More sharing options...
Maru-So Posted January 11, 2008 Author Share Posted January 11, 2008 in theory it shouldnt bottom out the shock more than normal. But if you add thicker oil it would help that. Cutting springs they become stiffer but standard springs are still too soft for extreme lowness. Quote Link to comment Share on other sites More sharing options...
lowlancer Posted January 12, 2008 Share Posted January 12, 2008 in theory it shouldnt bottom out the shock more than normal. But if you add thicker oil it would help that. Cutting springs they become stiffer but standard springs are still too soft for extreme lowness. How? Isn't it making the part of the shaft inside the shock itself longer? Thus making it closer to the bottom? Quote Link to comment Share on other sites More sharing options...
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