Independent Rear Suspension, OEM, aftermarket, stock configuration or heavily modified, all makes and models, everyone is welcome here!!!

You are not logged in. Would you like to login?



10/20/2011 6:19 pm  #1


Finally!!!!! I got to work on the IRS project today.

on June 23, 2010, 9:28 pm, Daze wrote:

Today was the big day I started fitting the actual Jag parts to the crossbar. I started by making a two hole template and then used it to drill two holes in a piece of 1.5" X 2" rectangular tubing (same stuff I used for the cross bars) I like using templates because you can check your accuracy before you actually drill in to the final piece and it can be used to reproduce identical hole spacing on both cross bars. With the holes drilled I set it on the differential, and freehanded the approximate area that I needed to cut out to notch the cross bars to clear the parking brake calipers, Then I cut them out and bolted the test piece on to the diff. Looks good except the notch I made was about 1" to long and needed to be moved toward the differential about 1/8" 

As I was messing with it I looked in to using some 1/8" plate to box in the notch. the only stuff I had was 2" and wouldn't you know it was almost a perfect fit!!! So much so that that is what I am going to use. I decided to use an 18" long piece and drill holes in the middle (was glad I made a template, by the time it was all said and done I drilled 4 sets of holes) that way I could slide it in, use one piece to box in both notches and reinforce the entire middle section of the crossbar. By doing it this way I am thinking I may be able to use an 18" X 6" piece of 1/8" plate on top of the two crossbars, rater than using a piece of 1/4" plate of similar dimensions as I had originally planned, or run a diagonal piece of 2" plate the full length of both crossbars and then not use the top plate at all, what do you guys think???

I was pleased with the results and then used my template to drill out the actual back and front cross bares. I bolted the back one up to the differential, with the test bar still bolted up just to make sure that the caliper cleared it. All looks good.

From there I was able to get the front bar marked for cutting but I ran out of time before I got it notched. When I write it down it doesn't sound like much got done, BUT I am very pleased with what I got done in 6 hours


post


If it isn't broken..... modify it anyway!!!!
 

10/20/2011 6:28 pm  #2


Re: Finally!!!!! I got to work on the IRS project today.

on June 24, 2010, 8:58 pm, Daze wrote:

no one has an opinion of me using a piece of 2" bar stock diagonally... inside the side bars rather than using a plate on the top???


If it isn't broken..... modify it anyway!!!!
     Thread Starter
 

10/20/2011 6:35 pm  #3


Re: Finally!!!!! I got to work on the IRS project today.

on June 24, 2010, 9:10 pm, cecil671 wrote:

In my opinion the 2" plate diagonally welded into the tubing would be much stronger than a flat plate welded on top or bottom.
It would triangulate the boxed tubing and stiffen it, making it stronger than it was before you notched a piece out of it.
Great thinking.


If it isn't broken..... modify it anyway!!!!
     Thread Starter
 

10/20/2011 6:36 pm  #4


Re: Finally!!!!! I got to work on the IRS project today.

on June 25, 2010, 11:37 am, Daze wrote:

I decided to do both... well sort of I too really like the idea of triangulating by crossbars so I am going to do that. I did a little math and the original 6 X 18 X 1/4" plate I was going to use is 27 cubic inches of material. The triangulating bars are only 20 cubic inches. the only down side to not having the plate on top is I wanted it there to tie the two bars together AND I wanted it to spread the load over the entire cross bar as the bolts were torqued down. So I am going to do both. I will put a 5" X 5" piece of plate on the top which will only add 6.25 cubic inches of material. basically I will be at the same weight, but have a much stronger set up. Thoughts???


If it isn't broken..... modify it anyway!!!!
     Thread Starter
 

10/20/2011 6:37 pm  #5


Re: Finally!!!!! I got to work on the IRS project today.

on June 25, 2010, 6:48 pm, Joe wrote:

For what it's worth I like the idea of tieing in the cross bars with the 5x5 plate. The only question is whether the plate is stronger on the top side or the bottom side. The load / torsion is being addressed by the bolts, and cross bars, holding on to the third member. The taller the bolts the less strength. The closer you can get the bolts to the third member the more strength you should get.


If it isn't broken..... modify it anyway!!!!
     Thread Starter
 

10/20/2011 6:38 pm  #6


Re: Finally!!!!! I got to work on the IRS project today.

on June 25, 2010, 10:15 pm, Daze wrote:

No matter what I do the bolts will be going down through the cross bar The main purpose for the plate is so that I do not have to sleeve the cross bar where the bolts go. With out the plate or a sleeve I am worried that the .120 wall tubing would bend when I torque the mounting bolts down. the bolts are only 2.5" long total so I think I will be OK especially sense there are 4 of them and they are in double shear.


If it isn't broken..... modify it anyway!!!!
     Thread Starter
 

10/20/2011 6:40 pm  #7


Re: Finally!!!!! I got to work on the IRS project today.

on July 3, 2010, 2:56 am, tyrellracing wrote:

I only see a few serious problems with this type of mounting. The original set up used a counter sunk bolt for an important reason. These four 1/2 inch bolts control how square most of the suspension is to the thrust line of vehicle. The taper provides a wedge type locating devise that when done correctly allows the taper to extend from the mount in to the Diff. removing the threads from the shear plane. The plain bolt holes will have more free play radially and since you are using thin wall tube with out support tubes welded in there will be a distortion problem or at the least stretching issue with the hole. Most professional type mounts use flat plate for all serious hard point mounts. By doing this they gain a non crush able mount that will be less likely to distort under spike loads. Very rarely is tube steel used in applications where a bolt passes through with out at least a support tube. Let alone one that should be torqued further than the tube can tolerate even with support tube. Once you start using this type mount the next failure will be the tubing collapse due to the torque load on such a small surface area on the tube. This will be far less obvious but the corner loading of the small rectangular pad on the diff. against the tube will cause small dents where contact is made. This in turn will reduce the pre-load on the four 1/2 inch bolts and allow the diff to rock under acceleration and braking. My over all opinion of this mounting system is to scrap it and try again. The tube steel that is used to replace the the leaf springs is redundant from an engineering point of view. Look at the image of a reproduced Klaus Arnings design that you posted at the IRS forum, he used a simple bolt on hydra-formed plate steel cross member that went from frame rail to rail for the top support and spring mounts. Two diagonal supports were used for the bottom. This is all that's required to control the torque couple associated with differentials.


If it isn't broken..... modify it anyway!!!!
     Thread Starter
 

10/20/2011 6:41 pm  #8


Re: Finally!!!!! I got to work on the IRS project today.

on July 3, 2010, 6:42 pm, Daze wrote:

I see your point, I will keep the design and...... sleeve the bolt holes. I have some heavy duty mechanical tubing... 1/4" wall I believe that will make good sleeving.


If it isn't broken..... modify it anyway!!!!
     Thread Starter
 

10/20/2011 6:42 pm  #9


Re: Finally!!!!! I got to work on the IRS project today.

on July 4, 2010, 3:19 am, tyrellracing wrote:

Yes, a support tube will improve your .120 wall tube cross member. I would use 1 inch mild round bar stock, cut it to length and chuck it up in a small lathe and drill .005 bigger than the bolt on center. The lathe will make it much easier to keep the hole accurately centered and face both ends perpendicular to the bore. But this is just my opinion.


If it isn't broken..... modify it anyway!!!!
     Thread Starter
 

10/20/2011 6:43 pm  #10


Re: Finally!!!!! I got to work on the IRS project today.

on July 4, 2010, 9:42 pm, Daze wrote:

That's almost exactly what I had in mind I have some 1" DOM tubing with a .49" hole. I will cut it and then chuck it up in the lathe. I was planning on making the sleeves .005" to tall and insert them from the top and weld it in place. Then bolt on my top plate and torque it down prior to welding the plate in place then clamp the plate to the rectangular tubing before welding it in, that way there is a load built in to the sleeve.


If it isn't broken..... modify it anyway!!!!
     Thread Starter
 

Board footera

 

Powered by Boardhost. Create a Free Forum