Outriggers/trailing arms

[Oddball]

Hi All

The problem of the internal plates found inside the outrigger chassis sections of the IRS cars has bothered me for many years. The external sections have probably been repaired , however the internal strengthening section that stops the sides of the chassis collapsing inward when the trailing arm brackets are tightened have long gone.

This has occurred on one side of my chassis and I am considering welding in steel tubes to add the required strength.

This must be a safety issue I can't help feeling that there are a lot of car on the road with weakened outriggers.

Any comments or observation on this subject would be appreciated

 

Thanks

Cameron

[Guest Neil Russell]

This area is critical in any IRS car, since all of the stresses are concentrated in this area. In my opinion, you have 2 options.

 

The first is a trip to a chassis specialist for new outriggers and T-shirt pressings.

 

The second is as follows.

if as you say your main sections seem ok, then I would effect a repair similar to the procedure used when strengthening the diff bridges.

 

1. remove arm and rear suspension

2 drill clearance holes through mounting holes

3 insert some thick walled steel tubing with an inner diameter the correct clearance size for the bolt

4 weld to the existing section leaving an 1/8" proud

5 fit square strengthening plates to each side of the section with clearance holes for the welded tube and welded end. Then seam weld all around and around your thick wall tubing.

6 take care with the thickness of the rearmost strengthener since it will effectively increase the length of your wheelbase. This shouldn't be too much of a problem however, since the brackets are often shimmed to correct dimensions anyway.

 

I wouldn't advocate cutting out the rear section and patching, since if you are doing this then you should really be stripping your body off and having the chassis restored.

 

Food for thought. if the inner strengthener has corroded away, what is the inner box section like???

 

Neil.

[Richard Crawley]

Cameron,

the outrigger internal spacing tubes are made from fairly thick steel & if these have gone, there is likely to be some serious corrosion all around this area. I would bet that the inner cruciform sections (underneath the breastplates where the outriggers meet the inner, longitudinal chassis sections), the outer chassis members where they meet the outriggers & the rear cross tube sections have also gone & you won’t see the extent of the corrosion on the cruciform unless you remove the plates to inspect the chassis sections underneath.

Problem is that the chassis tends to look OK from underneath; mine looked pretty good & even a few sharp pokes with a screwdriver failed to penetrate but once I had removed the body, it was a different story. The top faces were totally shot!

If the chassis has been previously “patched” without cutting out the rot, these patches are likely to be hiding some serious corrosion. You can make some temporary repairs but, for your own piece of mind, I would seriously start to consider removing the body to affect some proper repairs.