bill van snorkle Posted March 8, 2013 Share Posted March 8, 2013 What are peoples thoughts on replacing the A frame ball joint with a large (say 30mm) rose joint, would allow unlimited articulation. Not sure a metal to metal rose joint would last very long unless you encased it in a grease filled bag to prevent mud and dust from grinding it all sloppy like. Maybe the teflon lined Jonny Joint would be better. Teunico, I thought patents were only good for 12 years. The most popular camping toilet in Australia I think is the Thetford brand, which sounds more British than German, so it's not always the inventor that gains the most benefit. Quote Link to comment Share on other sites More sharing options...
discomark10 Posted March 8, 2013 Share Posted March 8, 2013 Not sure a metal to metal rose joint would last very long unless you encased it in a grease filled bag to prevent mud and dust from grinding it all sloppy like. Maybe the teflon lined Jonny Joint would be better. I know you can get boots for small rose joints, not sure about the 30mm ones, but that can be worked on. Main thing is to make sure it wont snap under strain. Quote Link to comment Share on other sites More sharing options...
bill van snorkle Posted March 8, 2013 Share Posted March 8, 2013 I know you can get boots for small rose joints, not sure about the 30mm ones, but that can be worked on.Main thing is to make sure it wont snap under strain. Do the Rose joint makers give tensile strength specifications? With a disco in low 1st gear you'd be unlikely to be able to generate more than 4000ft lbs of torque at the back axles before a diff or halfshaft gives in. If the rose joint was mounted 8'' above axle centre line it would be subjected to about 6000 lbs tensile force. Add another 50% safety factor. Quote Link to comment Share on other sites More sharing options...
dirtyninety Posted March 8, 2013 Share Posted March 8, 2013 A lot of compliance in the axle end bushings of a 3 link arrangement is neither needed nor desirable for good articulation. To run modified D2 radius arms would require a lot of vertical separation between the upper link and the 2 lowers. I haven't got a D2 to look at but if the leading radius arm bush on the rear axle is above the axle centreline then you would require even more vertical separation to control torque reaction. best to sleeve the modified radius arms down to accept less compliant bushings.Vertical separation of the links at the chassis would depend on how much antisquat geometry works best in the challenge conditions. The current mountings are roughly an inch below the axle centre line, however fabricating new mounts isn't a problem and would have to be changed if i was to use a radius arm set up. How much is "a lot" of vertical separation? 10 inchs? Ive been thinking all morning, squat and dive could potentially be very dangerous. Ideally you'd have no dive at all, and only a small amount of squat. Im not sure how easy that is to achieve tho, hence me asking! Why are large bushings undesirable? If i were to use radius arms, what angle should i set my diff pinion at? I have some people point at almost 35 degrees, whereas I was always under the impression that the diff flange and transfer box outputs should be parallel. (i haven't even started asking about panhards yet! Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted March 8, 2013 Share Posted March 8, 2013 I think I have this right, but shoot me if not. A lot of compliance at the axle end would allow axle hop as it gains/loses traction, the point of having the third link it to keep the axle rotation contains in a large part, so having compliant bushes would muck this up. The chassis end bushes are similar in a way, having too much fore-aft compliance would allow the axle to rotate and hop again, they do of course have to twist, especially the upper link, and rotate up and down through a few degrees, so jonny joint or similar is ideal for this situation, if you want rubber then a bush designed to flex rotationally and not longitudinally would be best, if you think about bushes you have seen about, you can probably work out which would be best. A bush like this would probably be ideal: http://www.brookwell.co.uk/wp-content/themes/brookwell/getimg.php?p=RBX101680&q=pi Disco 2 radius arm bush I think this is what DD is using on the wrangle build Quote Link to comment Share on other sites More sharing options...
Team Idris Posted March 8, 2013 Share Posted March 8, 2013 I had thought of that, and it would have good soak up on shock loads, but the top link is where the sump is. So I was thinking that the third link would be under the axel with both its bushes. And with a replica clevis like the ones on the standard radious arms. It would be a single central torque reaction arm. Quote Link to comment Share on other sites More sharing options...
o_teunico Posted March 8, 2013 Author Share Posted March 8, 2013 Apparently there will be no problems if the 3rd link is mounted offset to clear diff/sump. This is a sliding A frame I found in pirate. Some say that it could build up too much heat if used in bumpy tracks at speed. Bill, did you have heating problems with your hodraulic ram sliding A frame? Quote Link to comment Share on other sites More sharing options...
dirtydiesel Posted March 8, 2013 Share Posted March 8, 2013 Any pic showing how much flex can be obtained with this bushes? Quote Link to comment Share on other sites More sharing options...
dirtydiesel Posted March 8, 2013 Share Posted March 8, 2013 Apparently there will be no problems if the 3rd link is mounted offset to clear diff/sump. This is a sliding A frame I found in pirate. [img=http://www.pirate4x4.com/forum/attachments/suzuki/429265d1237325655-1-link-unilink-3-9-08-pics-249.jpg] Some say that it could build up too much heat if used in bumpy tracks at speed. Bill, did you have heating problems with your hodraulic ram sliding A frame? Offsetting the top arm will alter the torque reaction of the link setup. That sliding A frame looks quite crude, I imagine I makes a hideous amount of noise, not sure the back of the frame is robust enough for the side loadings from the A frame either. Quote Link to comment Share on other sites More sharing options...
o_teunico Posted March 8, 2013 Author Share Posted March 8, 2013 Very good articulation with those bushes! (OEM, Polibush?) Bill explained how offset 3rd link should be located Propshaft torque tends to roll the vehicles sprung mass to the right hand side.if the upper link on a rear 3 link for example is offset to the right side of the axle, it should angle down from the axle attachment to the chassis attachment point so that axle roll will apply a lifting force to the right hand side of the chassis, thereby counteracting torque roll.If for packaging reasons, the upper link is offset to the left, then it should angle upwards from axle to chassis to have a similar effect by pulling the left hand side of the chassis down. More "sliding" homemade devices, again, from pirate. Quote Link to comment Share on other sites More sharing options...
dirtydiesel Posted March 8, 2013 Share Posted March 8, 2013 Just looks like a square tube propshaft?? There's a guy on pirate that retails square tube props with hdpe sheet on each of the flats of the inner box. Quote Link to comment Share on other sites More sharing options...
bill van snorkle Posted March 8, 2013 Share Posted March 8, 2013 Square tube inside square tube for an A frame slider will just limit articulation. A ram doesn't, and greased up will not get hot enough to be a concern Quote Link to comment Share on other sites More sharing options...
mick the digger! Posted March 8, 2013 Share Posted March 8, 2013 . A bush like this would probably be ideal:http://www.brookwell.co.uk/wp-content/themes/brookwell/getimg.php?p=RBX101680&q=pi Disco 2 radius arm bush I think this is what DD is using on the wrangle build Id give that a miss for anything really....I used twelve to do a front an rear 3 link on a g wagen....they lasted a few hours. what killed them so fast was as the suspension flexed the bush needs to rotate far more than it would on a standard car, and as the center sleeve is bonded, and then in turn clamped to the bracket its bolted to it gets ripped free very quick with 14" shocks front and rear....once the center sleeve is no longer bonded the bushes are toast! MKII was to use poloy bushes....the center sleeve is free to rotate...but even with nearly 9" of separtion between top and bottom links there just too soft as theres to much 'meat' in them alowing the axles tramp. Mk III is these Quote Link to comment Share on other sites More sharing options...
mick the digger! Posted March 8, 2013 Share Posted March 8, 2013 here is one at the rear lower link at the axle end, this is it flexed out on 14" shocks with the springs re moved....the bush, actually a ball joint isnt maxed out here....they will mis aline more than a jonny joint....cost 6 pounds gbp from island 4x4!! Quote Link to comment Share on other sites More sharing options...
dirtydiesel Posted March 8, 2013 Share Posted March 8, 2013 Do you have any kind of center check strap Mick? Or can your axle droop the full 14" of the shocks? I Always center check strap my axles to limit droop saves prop issues and prevents endo's Were your bushes genuine or pattern? I bought some of each with the idea to use the Brit part ones just for the build and then fit the genuine ones after i'd finished welding, but they were nothing like each other in dimension or quality. I actually ended up reaming the center tubes in the genuine bushes out to 17mm from the oval 16mm-ish holes they came with. Quote Link to comment Share on other sites More sharing options...
bill van snorkle Posted March 8, 2013 Share Posted March 8, 2013 The current mountings are roughly an inch below the axle centre line, however fabricating new mounts isn't a problem and would have to be changed if i was to use a radius arm set up.How much is "a lot" of vertical separation? 10 inchs? Ive been thinking all morning, squat and dive could potentially be very dangerous. Ideally you'd have no dive at all, and only a small amount of squat. Im not sure how easy that is to achieve tho, hence me asking! Why are large bushings undesirable? If i were to use radius arms, what angle should i set my diff pinion at? I have some people point at almost 35 degrees, whereas I was always under the impression that the diff flange and transfer box outputs should be parallel. (i haven't even started asking about panhards yet! I think Bowie covered most points. The vertical separation between the upper and lower links of a RRC or defender axle, with much more rigid bushings is around 8.5'', so you would require at least 10'' if retaining D2 bushings, probably more. For antisquat/antidive geometry, If we use the Disco 2 vehicle as a guide. To replicate the D2's AS/AD geometry, assuming equal length links, you should have no vertical separation of the links at the chassis mountings.As you increase the vertical separation you decrease the AS/AD effect. Ideally the propshaft flanges at both diff and transfercase should be parrallel in order to give equal and opposite U joint angles,and with a 110'' wheelbase the propshaft would be long enough to retain that principal. On vehicles with very short propshafts you can gain constant velocity by tilting the pinion up till the universal joint angles are equal but parrallel. Just like the front prop on RRC's etc you may have to experiment with U joint phasing at the sliding joint to get the best compromise with regards vibration between drive and overun. Quote Link to comment Share on other sites More sharing options...
mick the digger! Posted March 8, 2013 Share Posted March 8, 2013 Do you have any kind of center check strap Mick? Or can your axle droop the full 14" of the shocks? I Always center check strap my axles to limit droop saves prop issues and prevents endo's Were your bushes genuine or pattern? I bought some of each with the idea to use the Brit part ones just for the build and then fit the genuine ones after i'd finished welding, but they were nothing like each other in dimension or quality. I actually ended up reaming the center tubes in the genuine bushes out to 17mm from the oval 16mm-ish holes they came with. havent fitted a center check yet dan and it doesnt feel like it needs one as it doesnt seem to unload when climbing or desents but it is on oil shocks too though as makes its way more stable on side slopes as unlike the standard G gas shocks they dont extend under pressure. but this does in turn make the stadard springs a liitle to soft in rate.. the first bushes were brit part, as was done on the cheap...did buy one gen one from the local dealer before ordering the 12 from island, definatly far better quality...but I say it would have killed them the same way eventualy. Your not going to see the same amount rotational force with a one link and especailly not with a center limit strap. Quote Link to comment Share on other sites More sharing options...
mick the digger! Posted March 9, 2013 Share Posted March 9, 2013 heres a link with the p38 range rover axle end front radius arm bushes Quote Link to comment Share on other sites More sharing options...
dirtydiesel Posted March 9, 2013 Share Posted March 9, 2013 I think we might be talking about different bushes Mick, the bushes I'm using are Disco 2 chassis end of radius form bushes they are lot more voided than those in your pic. Quote Link to comment Share on other sites More sharing options...
mick the digger! Posted March 9, 2013 Share Posted March 9, 2013 I think we might be talking about different bushes Mick, the bushes I'm using are Disco 2 chassis end of radius form bushes they are lot more voided than those in your pic. That we are, looked at them first, from memory there about 80mm in dia far too much rubber to stop axle rotation on a three link or simialr ...fine for a one link though as you know. the ones I went with were 60mm. Quote Link to comment Share on other sites More sharing options...
dirtydiesel Posted March 9, 2013 Share Posted March 9, 2013 I've found that the gwagon axle end of radius arm bush is perfect for 3 link, 70mm od, multiple steel tubes laminated into the bush, they're just a little pricey the last ones I bought were £30 a bush. These are the front upper links I built for my gwagons front 3 link The bush is the gwagon one and the other end is a ballistic fabrications 3" joint. Quote Link to comment Share on other sites More sharing options...
bill van snorkle Posted March 9, 2013 Share Posted March 9, 2013 here is one at the rear lower link at the axle end, this is it flexed out on 14" shocks with the springs re moved....the bush, actually a ball joint isnt maxed out here....they will mis aline more than a jonny joint....cost 6 pounds gbp from island 4x4!! The last time I had my truck from post 1 on my articulation ramp to check what various link bushings were doing, I noted that the axle end bushings of the front 3 link (RRC rear trailing arm bushes) hardly distorted at all.All the flex was in the chassis bushings. I never chop out axle bushings, but due to my coil springs being mounted behind the axle, the 2 piece rubber bushings (standard Ra bushings) did have a relatively short life due to high compression loadings. I've since replaced them with A frame ball joints. It would seem to me that Defender/RRC trailing arm bushings,with the mounting angles correctly set up would provide the best compromise between flex, torque reaction control, and bushing life. Quote Link to comment Share on other sites More sharing options...
mick the digger! Posted March 9, 2013 Share Posted March 9, 2013 Well spotted bill, but that photo doesn't give a true representation as there still is a poly bush in the other (chassis) end of that link. As the ball joint moves reasonably free it with deflect on that end first. Quote Link to comment Share on other sites More sharing options...
dirtydiesel Posted March 9, 2013 Share Posted March 9, 2013 What are the balljoints Mick? Lm rangerover upper control arm? Quote Link to comment Share on other sites More sharing options...
mick the digger! Posted March 9, 2013 Share Posted March 9, 2013 Rear lower wishbone to knuckle on a l322 RR...or 5 series bm of similar vintage. I chucked them in the lathe and took the lip of them, there around 54mm OD so I used a bit of 60mm OD blue band 3.2 wall opened out a fraction for a press fit, tacked the 60mm pipe into the ends of the existing links as the p38 bushes were 60mm then pressed the new joints in. I've had two Brit part ones on my daily driver l322 for two years 30+k and there still fine. Bear in mind the side loads they will see on RR will be massive as the wheel his a pot hole, where in this application they are only really going to be in tension so I'm confident they will last....other than the rubber boots getting torn Which would kill them fairly quick. But they are only 5 odd quid from island 4x4 Quote Link to comment Share on other sites More sharing options...
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