flatback90 Posted November 13, 2011 Share Posted November 13, 2011 lads i'm looking at a custom 3/4 link set up on our new build and was wondering about the difference between rose and johnny joints, how do you size them? grp4 fabrications show up to 5/8" rose for rally cars but devon show 2.5" johnny joints! is it the pin size or outside dia? anyone using them instead of bushes at the axle end, as i figure that you could get some more flex that end? Quote Link to comment Share on other sites More sharing options...
moose Posted November 14, 2011 Share Posted November 14, 2011 I have used both rose joints and Johnny joints. I would defiantly not use rose joints on both ends on a link, any wear in the joint will be exaggerated a rubber bush will help take some to the impact when your axle hits some thing. also every rose joint i have used wears, how quickly depends on the quality on the joint and the loading placed on them. For that reason i would try and keep them out of the muck as much as possible and not put them on the axle end. I have been running on my own trailing arms with Jonny Joints in the form of "trail gear creeper joints" for the last three years. I imported and used their middle of the range 5/8 (or 16mm through hole) joint at the time this was the cheapest way to get hold of them, but now lots of people stock these or like joints. Most people seem to use the 9/16 (or 14mm through hole) joint (like the gigglepin arms) with out problems. I used to use a ( m24 ) rose joint as A-frame joint in the same way as the qt joint but these used to wear very quickly and on one occasion I riped the center of the joint out while on a flat out hill climb. I was basically pushing the joint passed its max movement, so i switched its plane of movement making an axle truss for it and so far so good infact i have not need to replace it this year due to wear. Just my views hope it helps Paul Quote Link to comment Share on other sites More sharing options...
simonr Posted November 14, 2011 Share Posted November 14, 2011 Johnny Joints (or creeper joints) have much better wear characteristics than rose joints - though they have relatively little offset (flex). If you have one on either end of the bar, it's enough for most purposes but in many of the applications (trailing arms) they rely on the screw thread to provide some of the apparent flexibility. In applications like steering links where you do not want any give (which the rubber / PU internal bushings provide) then Rose joints are better. You can buy very good rubber boots for rose joints (McGill Motorsport supply them). They are a very tight fit around the shaft / bolt and if you fill the boot with grease, the joint will last as long as the rubber the boot is made from. I've used this combo on steering links very successfully. Si Quote Link to comment Share on other sites More sharing options...
moose Posted November 14, 2011 Share Posted November 14, 2011 Johnny Joints (or creeper joints) have much better wear characteristics than rose joints - though they have relatively little offset (flex). If you have one on either end of the bar, it's enough for most purposes but in many of the applications (trailing arms) they rely on the screw thread to provide some of the apparent flexibility. This is true I defiantly would not use one to replace the A-joint for example but.... On my setup (200ish mm longer than standard arms) the creep joints don't bind movement of these joints could be also improved by machining up some spacers. Quote Link to comment Share on other sites More sharing options...
Range Rover Blues Posted November 14, 2011 Share Posted November 14, 2011 Moose, I like you A frame set-up. Did you deliberatley move the centre of the joint up from the diff (that's how it looks) and did you notice any effects? Quote Link to comment Share on other sites More sharing options...
moose Posted November 15, 2011 Share Posted November 15, 2011 Moose, I like you A frame set-up. Did you deliberatley move the centre of the joint up from the diff (that's how it looks) and did you notice any effects? yes its deliberate. the lower hole on the truss is the standard landrover link postion. Wont do a massive post about link geometry. It all about how to you use your truck, i was looking to make mine more stable at speed and when climbing by reducing the anti-squat. The way I under stand it (iam by no way and expert )Land rovers have a huge amount of anti-squat, you see trucks with a big lift and the links are at a massive angle to the chassis and ground. By making the links longer and flatter and with greater separation you reduce the load on the mounts and lower the anti-squat. This means more weight shift over the back wheels for better traction and less bounce, but to much and the front will kick up. There is of course a lot more to it than this, including center of gravity and roll center etc.. I have also just started playing with shock and spring setup when i get round to I will be redoing the standard front setup and going to a 3 link in order to create a more balanced setup.... Quote Link to comment Share on other sites More sharing options...
simonr Posted November 15, 2011 Share Posted November 15, 2011 Additionally, you reduce the tensile and compressive force going through the links by increasing the separation. 3 link front setups often fail because the force is just too much for the third link. The force can be in excess of 30 tons with the separation often used on the front. Si Quote Link to comment Share on other sites More sharing options...
flatback90 Posted November 15, 2011 Author Share Posted November 15, 2011 hmmm thats got me thinking...... reason i asked is because the new build is a t***** cough, and the rear suspension arragnment is carp! what i was thinking was if i replace the rear trailing arms with landrover type but with a johnny joint axle end and rubber bush the chassis end and then a similar A frame type arrangement it would give us similar travel to a landrover... Quote Link to comment Share on other sites More sharing options...
simonr Posted November 16, 2011 Share Posted November 16, 2011 It's unlikely to improve it much! Si Quote Link to comment Share on other sites More sharing options...
flatback90 Posted November 16, 2011 Author Share Posted November 16, 2011 well its gotta be better than the ****e thats already on it!! what are your thoughts on improving it then? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.