BritishV8 Forum

Hi All,

Although the early Jaguar IRS offers attractive features, it can have some shortcomings when used in high performance applications.

Jaguar used 3 different inner fulcrum bracket designs to account for pinion angles of 0, 3 and 6 degrees. Opinions/information on these two topics can be found at the links below,

Ed

http://www.jcna.com/library/tech/tech0009.html
http://members.boardhost.com/IRS/msg/1276106025.html

Hi All,

Although the early Jaguar IRS offers attractive features, it can have some shortcomings when used in high performance applications.

Jaguar used 3 different inner fulcrum bracket designs to account for pinion angles of 0, 3 and 6 degrees. Opinions/information on these two topics can be found at the links below,

Ed

http://www.jcna.com/library/tech/tech0009.html
http://members.boardhost.com/IRS/msg/1276106025.html

Feel strongly about that, eh Ed?

He should I suppose, that's some pretty good info.

JB

I pulled off one shock/coil on each side and it resulted in almost 2" difference in ride height.  It's still a little higher than I would like but it's about stock rubber bumper height.  I'll see if that results in satisfactory suspension performance when I get the car running - if not I'll buy two adjustable shocks with appropriate springs at that time.

The next step is to install the transmission mount, weld in the underbody reinforcements to attach the two bolts for the front of the cage, and fabricate the mounts for the front of  the cage as suggested by Jim S.  And, of course, decide where to attach the front trailing arms.

Thanks for all the comments and ideas,

Bill

If you do decide to use the front leaf spring hangar brackets for the trailing arms, do yourself a favor and make up a temporary arm out of a 2x2 and bolt it in place on one side. Then take out the coilovers and try to move the hub up and down and see what kind of binding you get. That way you won't have the time and expense of making the short arms before you have to remake them so they pivot at the axis of the inner pickup points of the LCA.

If you make mounts for the front of the cage that bolt into the shock mounting holes in the frame, you don't need the front bolts on the top of the cage. Just mount it at the back through the trunk and at the front using the shock holes.

I've been convinced from earlier posts that using the spring hangers for the trailing arms is not a good idea.  I'll attach them on the pivot axis of the LCA, I just don't know exactly how yet. Is it a good idea to use "rose" joints on the front attachment point?

Bill

PS Can I make the longer trailing arm out of a 2x4?  Might save some time  

2x4 trailing arms might work so long as you keep them far enough away from the exhaust and you get a Terminex inspection once a year.

I'm not familiar with the term "rose joint" but whatever you use needs some compliance if the attachment bolt axis is not in line with the axis of the LCA pivots. A self lubricated heim would work or a rubber insulator similar to what Jag used in their trailing arms would work as well. If you use a heim you should get the shields that seal out the dirt because of all the junk that gets stirred up under the car - Speedway Motors sells them. http://www.speedwaymotors.com/Seals-It-Heim-Seals,1528.html

Jim Blackwood's design may give you some ideas. Front crossbar connects to spring hangers, heims prevent bind:

"Rose joint" is British-English for "Heim joint". I think both terms originally referred to specific manufacturers, but have become generic through common usage. Some catalogs list the same parts as "spherical rod end bearings" or even just "rod ends".

Thanks Curtis. 66 years and I'm still learning - or did I already know it and forgot???