El Gringo Posted September 6, 2013 Report Share Posted September 6, 2013 Alrite all A quick initial question I'm building a special, Bandit 400 with a GSXR600 K4 Swingarm with an 06 R6 Shock. I've got it fitted at the main pivot but the linkage as really wrong. I could really do with having quite a high rear to the back of the bike but when its all connected the suspension won't even compress. Heres a quick pic, you can just about see the problem, the dogbones are nigh on horizontal. The suspension linkage on the swingarm is on the bottom rather than the top like the standard arm. I've had a look on ebay, a K5 1000 linkage looks like it would extend the angle to the linkage but i'm not convinced Any ideas? Cheers Chris Link to comment Share on other sites More sharing options...
phildawson8270 Posted September 6, 2013 Report Share Posted September 6, 2013 Looks like the problem is the geometry between the lower shock linkage mount on the frame and the linkage on the swingarm. With the links at that angle you're not going to get much travel in relation to the wheel. Do you have any pics of a GSXR 600 K4 with no bodywork where I can see the actual linkage as it should be on the original bike? On my frame (GSXR400 73 swingarm on a 71F frame) I had to get new mounts welded to the frame in a place that gave me the correct geometry, but I am still to test properly yet. Link to comment Share on other sites More sharing options...
jezz Posted September 6, 2013 Report Share Posted September 6, 2013 Calling Kayla to the red phone. . . . Link to comment Share on other sites More sharing options...
garage19 Posted September 7, 2013 Report Share Posted September 7, 2013 You really want to replicate the R6 linkage as then you will have the right ratio for the spring rate, damping and stroke of the shock. Where are you based? If local I'd be happy to take a look. Link to comment Share on other sites More sharing options...
El Gringo Posted September 7, 2013 Author Report Share Posted September 7, 2013 Thanks guys,and thanks for the offer Doug but i'm a bit far from you i think, i'm in Stratford on Avon. I've only had a quick look at it, needs a bit more thinking about. The R6 linkage appears to be the opposite way round to the GSXR/Bandit, eg the dogbones connect to the frame from the linkage rather than to the swingarm from the linkage. Good call on Kayla Jezz, i had already thought about making the shock longer using one of her extenders, it would help bring the shock into the middle of the hole in the swingarm. I'll do a bit more investigation when i get it up on the ramp Cheers Link to comment Share on other sites More sharing options...
El Gringo Posted September 7, 2013 Author Report Share Posted September 7, 2013 Actually i reckon if i ran a late R6 linkage back to front it would move the dogbones into a more upright position http://www.ebay.co.uk/itm/YAMAHA-R6-2008-suspension-linkage-2C0-/141055206852?pt=UK_Motorcycle_Parts_13&hash=item20d78ba5c4 (I realise this is fairly pointless as no one has seen the bike close up, i'm thinking/typing out loud as it were) Link to comment Share on other sites More sharing options...
Kayla Posted September 7, 2013 Report Share Posted September 7, 2013 Wotcher It looks like you need a longer shock (if possible) and longer dogbones. As it is now, the swingarm is acting through the dogbones and just trying to pull the bell crank out of the frame because the loading through the shock is nearly at 90 degrees to the shock's action. The longer shock & dogbones will change the angle the shock is loaded and make it feel 'softer' (although not actually softer, you need to change the spring to do that) How long is the standard Bandit 400 shock? I'm guessing around 330mm... Link to comment Share on other sites More sharing options...
El Gringo Posted September 7, 2013 Author Report Share Posted September 7, 2013 My concern with increasing the shock length is that while the dogbones could be longer they'll still be roughly in the same orientation as they are now, as the bottom link point won't be too much lower even though the linkage is rotated further down (i hope that makes sense), having the link point on the swingarm below the level of the spars rather than above in the standard arm makes them really short. I think the Bandit shock is about 330mm, i'll double check Edit to add. in the top picture its just bodged together, in reality i need the rear wheel to be almost touching the floor rather than where it is now, this straightens the dogbones out even more. Link to comment Share on other sites More sharing options...
Kayla Posted September 7, 2013 Report Share Posted September 7, 2013 My concern with increasing the shock length is that while the dogbones could be longer they'll still be roughly in the same orientation as they are now, as the bottom link point won't be too much lower even though the linkage is rotated further down (i hope that makes sense), having the link point on the swingarm below the level of the spars rather than above in the standard arm makes them really short. I think the Bandit shock is about 330mm, i'll double check Edit to add. in the top picture its just bodged together, in reality i need the rear wheel to be almost touching the floor rather than where it is now, this straightens the dogbones out even more. The dogbone mounting point on the bell crank will also be positioned slightly further forward as well though, which in turn will pull the swingarm and wheel further down. The change in angle of the bell crank will also affect how the load is transmitted through the shock (up into the shock body rather than just pulling at the bell crank/frame mount- the bell crank will rotate about the frame mount if it can and is more likely to be able to if the shock mounting point on the bell crank is further out of line with the dogbones. I hope all of that makes sense, it's difficult to explain it without drawing it. Link to comment Share on other sites More sharing options...
El Gringo Posted September 7, 2013 Author Report Share Posted September 7, 2013 Thanks Kayla, it does make sense, i'll get some better pictures and take some measurements, i may well be on the phone for a shock extender soon, Could you do one with a 10mm bottom hole rather than the 12mm Yamaha hole to match the Suzuki linkage? Link to comment Share on other sites More sharing options...
Kayla Posted September 7, 2013 Report Share Posted September 7, 2013 Yep, we machine them in batches with the bottoms undrilled for just such an occasion Link to comment Share on other sites More sharing options...
El Gringo Posted September 9, 2013 Author Report Share Posted September 9, 2013 Had a bit more of a measure, This is how it currently looks This is where the rear end could really do with being This is roughly what i'd need to make it fit at this, 35mm longer shock and 115mm dog bones I can't drop the back anymore and the linkage can't go any lower without the shock hitting the inside of the swingarm, it's pretty tight as it is I've been looking at K5/6 1000 linkages again, this would put the lower dog bone link much lower than the link to the frame and make the dogbones longer - the K4750 link that matches the arm is also very similar in design Link to comment Share on other sites More sharing options...
Kayla Posted September 9, 2013 Report Share Posted September 9, 2013 Have a look at 3TJ and 4JH linkages as well, and possibly SRAD 600. They might do the job. Link to comment Share on other sites More sharing options...
El Gringo Posted September 9, 2013 Author Report Share Posted September 9, 2013 Just bought a K5 1000 link but I shall have a look at those too Kayla. Can you do the extender as short as 35mm? Link to comment Share on other sites More sharing options...
Kayla Posted September 10, 2013 Report Share Posted September 10, 2013 Yes, or we can send it out blank at the bottom if you want to drill it yourself. Link to comment Share on other sites More sharing options...
El Gringo Posted September 19, 2013 Author Report Share Posted September 19, 2013 Right bit of an update, got the K5 1000 linkage, no chance i reckon. I think i'm going to have to move the mount on the frame. Some piccys What do we reckon? Move the mount, different dog bones and a shock extension? Link to comment Share on other sites More sharing options...
drunkn munky Posted September 19, 2013 Report Share Posted September 19, 2013 Ive nothing constructive to add but ive always wondered when doing swingarm/shock swaps how do you know the linkage you end up fitting works out the right ratio for the spring rate, shock length, bike weight etc etc etc? Link to comment Share on other sites More sharing options...
El Gringo Posted September 19, 2013 Author Report Share Posted September 19, 2013 I'm not sure you do Tony, i certainly won't in this case. As long as it compresses a bit i'm not too fussed. I've gone too far down the route of fitting this swingarm not to make it work now Link to comment Share on other sites More sharing options...
El Gringo Posted September 19, 2013 Author Report Share Posted September 19, 2013 As an aside, i found this link on the bandit forum http://www.banditforum.co.uk/forum/index.php?topic=26029.0 It uses the centre stand mounts for the linkage, and the angle of the dogbones looks pretty similar to mine. Link to comment Share on other sites More sharing options...
Marb Posted September 21, 2013 Report Share Posted September 21, 2013 Looks like all you need is a shock lengtherner. Link to comment Share on other sites More sharing options...
Superdunc Posted September 22, 2013 Report Share Posted September 22, 2013 What do we reckon? Move the mount, different dog bones and a shock extension? If you can extended the shock, the geometry looks pretty good in that shot. Link to comment Share on other sites More sharing options...
El Gringo Posted September 22, 2013 Author Report Share Posted September 22, 2013 It does look pretty good, i finally got the centre stand off this afternoon, took 4 hours and eventually the use of the angle grinder to remove it. Have some spacer tube and a long bolt to go the full length of the stand brackets. Incidentally, i know you're not supposed to use stainless for suspension bolts, so i've ordered a 12.9 tensile bolt, does that sound about right? Hopefully once this is sorted i can get on with the fun stuff on this project Link to comment Share on other sites More sharing options...
El Gringo Posted September 26, 2013 Author Report Share Posted September 26, 2013 I think i'm getting somewhere now with it, should hopefully know what i need to finish the set up over the weekend. Going back to the bolt question, i had an idea in the back of my head i asked about this once before during my Z4 AMA build and sure enough i started a thread about suspension bolt pbmagforum.co.uk/index.php?showtopic=25054&st=0&p=487825 The general consensus was inconclusive, 8.8 should be ok but 12.9 and 10.9 bolts whilst being high enough tensile strength were too brittle. Theo also mentioned that BZP could (maybe) cause hydrogen embrittlement of the bolts. I've been doing a bit of research into the bolt types etc, and had a look at some linkage and shock bolts on a couple of different Suzooks - they have a "p" or "d" marking depending on which way up it is viewed. I'm buggered if i can find any reference to this on the T'interweb to draw a comparison on the grade etc The search continues, quite an interesting topic I'm inclined toward 8.8s but the self coloured ones will surely rusty like f**k, especially in a suspension type use? Cheers Chris Link to comment Share on other sites More sharing options...
Superdunc Posted September 26, 2013 Report Share Posted September 26, 2013 10.9 or 12.9 will not be too brittle. Link to comment Share on other sites More sharing options...
El Gringo Posted September 26, 2013 Author Report Share Posted September 26, 2013 Cool, i'll use the bolts i've bought then Dunc. I found a thing that says shear strength is approx 60% of tensile strength, so surely the higher the initial tensile strength the higher the shear strength? Which would make a 12.9 the highest shear strength as it has the highest tensile strength (of the "norma"l bolts i could find on eGay) Link to comment Share on other sites More sharing options...
Superdunc Posted September 26, 2013 Report Share Posted September 26, 2013 Ermm... you're getting a little confuddled there chap. An 8.8 bolt means that it's Ultimate tensile strength (uts), the point at which it will break, is 8 x 10 kg/mm2 So an m10 bolt which has a cross sectional area of 78.5mm2 so it will carry a load in tension 80 x 78.5 = 6280kg before it will break. If load the bolt correctly in twin shear the force is spread over the bolt in 2 areas so it will carry 2x the load so 12560kg. the .8 refrers to the yield point where the material will deform and not return to it's original dimensions, you don't want to exceed this, so 80x 0.8 = 64kg/mm2 sofor our M10 bolt in twin shear should not exceed a load of 10048kg. Then there are factors of safety, fatigue and other factors to consider. That's a simplified explaination, but hopefully you get the idea. Link to comment Share on other sites More sharing options...
El Gringo Posted September 26, 2013 Author Report Share Posted September 26, 2013 Thanks Dunc, useful info. I wasn't sure about the 60% bit, I wonder if i'm thinking about it too much Link to comment Share on other sites More sharing options...
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