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Bump pad on Radius Arm

Posted: Sun Apr 29, 2012 9:33 am
by brooksy
On current build I am struggling for room to mount Fox bumps on the front. The solution I have come up with is mounting the cans inside the coilover tower & have the bump pad roughly 50mm behind top bush on the radius arm. What is opinions about loading bushes ??
The build is the Lux winch truck I am doing with custom bisalloy RA's. Using GU front bushes & 80 series rear bush.

http://www.outerlimits4x4.com/viewtopic ... 3&start=90" onclick="window.open(this.href);return false;



brooksy

Re: Bump pad on Radius Arm

Posted: Sun Apr 29, 2012 10:58 am
by toughnut
What about mounting them on the inside of your chassis rails? I'm going to look at doing this on my truck because of the suspension setup that I'm going to run. I'm going to recess them into the chassis rails like I've done on the rear.

I don't know the technical reasons for not doing what you're suggesting but I know that if you're using bushes it isn't recommended because it loads up your bushes and not only flogs them out earlier but creates variations in your steering geometry when hitting the bumps that may make your truck more unstable than it already is.

Re: Bump pad on Radius Arm

Posted: Sun Apr 29, 2012 12:33 pm
by brooksy
Can't mount inside of chassis rails as IronJock centre & 24V alternator is the issue on drivers side. Recessing into chassis won't work either unfortunately :bad-words:
If having to replace bushes after each season is the downside, it may have to be the sacrifice. Steering & Geometry shouldn't come into play as bumps will be so close to front upper mount I would have thought :?



brooksy

Re: Bump pad on Radius Arm

Posted: Sun Apr 29, 2012 3:22 pm
by toughnut
I was being lazy before but I've just had a look at your setup. I see what you mean about space. The lower radius bush will be behind the bump stop so you shouldn't get too much deflection or rotation of the diff if you land on the stops. Like I said though. I'm not an engineer. Just working through it in my head.

Re: Bump pad on Radius Arm

Posted: Mon May 14, 2012 5:27 pm
by stool
In the You tube video ive posted below you will see a Hilux with what looks like what your after

Have a look around the 7 mins into the vid

http://www.youtube.com/watch?v=aye0Ch19fZY" onclick="window.open(this.href);return false;

Re: Bump pad on Radius Arm

Posted: Tue May 15, 2012 10:25 pm
by Struth
On initial thoughts I would think you will cause premature wear of the RA bushes, especially the front two.

Cheers

Re: Bump pad on Radius Arm

Posted: Wed May 16, 2012 5:51 am
by brooksy
Cool vid.....

Always going to be the case with premature wear on front bushes due to extra stresses but I am sure they will last within the maintenance schedule that would be in place (change bushes every season).



brooksy

Re: Bump pad on Radius Arm

Posted: Wed May 16, 2012 7:49 am
by rustys
Can you box the top of the radius arm mounts and bounce the bumps of them then the cans can be mounted behind the coil over and on the out side of the rail.I have been thinking of putting my bumps on top of my sway bars and running 1 1/2 sway bar links with 7/8 heims that way I don't need I large pad for the diff to roll on as the bumps will only be getting vertical load.
Always hard in the front you should of just gone leaves .

Re: Bump pad on Radius Arm

Posted: Wed May 16, 2012 8:21 am
by brooksy
Hahahahaaaa funny bastard Garth !!
Leaves are too hardcore ....
But yeah, was originally thinking flush with top of arms & box in a pad slightly to the inside of arm. This placement has the bump hitting in between the 2 front bushes & should clear coilover at full droop with mounting just behind but inside tower bracket.
I'll get Twisty to post a couple pics to show better.



brooksy

Re: Bump pad on Radius Arm

Posted: Fri May 18, 2012 9:57 am
by Guy
I could not think of good way to describe what i was thinking ... remembered reading about Light racings "jounce shocks"

http://www.lightracing.com/images/stori ... heeler.pdf" onclick="window.open(this.href);return false;
Using the bump can remote and using a lever ... ? may not suit your needs but might give you some idea's ..

Re: Bump pad on Radius Arm

Posted: Fri May 18, 2012 10:32 am
by brooksy
Yeah the LR's are nice & I have dealt directly with them over the years with good service. They are what I have planned for my build but unfortunately not for this one.


brooksy

Re: Bump pad on Radius Arm

Posted: Fri May 18, 2012 2:00 pm
by toughnut
Hey Brooksy, have you thought about just extending the diff brackets to include a cap over the top of the radius arm and use that as a pad for the bump stops? That way you transfer the force directly to the diff instead of the radius arms. That way you could also move the bump stops forward to hit directly above the axle instead of behind it. It wouldn't take much to do. You could even have it as a bolt on kind of like castor plates. Just goes over your existing mounts and uses the bolts that you already have.

Re: Bump pad on Radius Arm

Posted: Fri May 18, 2012 8:21 pm
by rustys
Tough nuts idea sounds like a good one if I do say so my self ,have you thought of mounting the bump up side down on the inside of the radius arm with a pad on the out side of the chassis it would look wrong but work the same and when you roll it it will look like you put the cab on up side down.
Have you thought about putting leaves back in if you are worried about flex you could go buggy leaf ?

Re: Bump pad on Radius Arm

Posted: Mon May 21, 2012 11:47 am
by gudge
Wouldnt mounting a pad off the Diff above the radius arm cause the housing to rotate backwards everytime they hit? Wouldn't do your bushes any favours, I think right on top of the housing is the only place they should be. And I believe it says somewhere on the bumps not to be mounted upside down.

Re: Bump pad on Radius Arm

Posted: Mon May 21, 2012 11:56 am
by brooksy
It's alright gudge .... Garth is a joker with a splash of serious. You unfortunately took the bait :finger:

I do like toughnuts idea, might see if it will work for me.




brooksy

Re: Bump pad on Radius Arm

Posted: Mon May 21, 2012 12:14 pm
by gu town
gudge wrote:Wouldnt mounting a pad off the Diff above the radius arm cause the housing to rotate backwards everytime they hit? .
My thoughts too.

Re: Bump pad on Radius Arm

Posted: Mon May 21, 2012 2:08 pm
by brooksy
Nope, but will cause extra forces on bushes which I agree will happen but maintenance schedule makes it negligible.
Bump stop locations are not always directly mounted over axle although only in comp & recreational style vehicles. Factory style is over axle due to bump stops not being regarded as a periodic servicing item.



brooksy

Re: Bump pad on Radius Arm

Posted: Mon May 21, 2012 2:40 pm
by rockcrawler31
I think that the rotation it would incur on the bushes would cause a bump steer situation due to the change in castor during rotation. Right when you don't want it.......

Re: Bump pad on Radius Arm

Posted: Mon May 21, 2012 6:53 pm
by toughnut
rockcrawler31 wrote:I think that the rotation it would incur on the bushes would cause a bump steer situation due to the change in castor during rotation. Right when you don't want it.......
Thats why I suggested a mounting that sits directly above the diff and even easier if you just bolt or weld it above the upper radius bush.