F-code modifications-another way.

[boertje]

So far I am very satisfied with the spring changes I have made to my X. However one of the things that has bothered me is that the spring forward of the rear axle rests entirely on the variable weight leaf giving it little "spring." There are those that have used the bottom leaf of the original X spring pack but this too bothered me since it is much shorter than the thick variable bottom leaf. Towrig mentions that the 2nd leaf is perhaps a good choice. As I was looking at the F code and the original X spring pack I noticed that the 3rd leaf fits almost perfectly between the think variable leaf and the 4th leaf that normally sits on the variable leaf. So I gave it a try. All I had to do is trim about 1/4 inch off the forward end of the leaf to be added and also remove the retaining bracket from said leaf. Pics are here.
The mods are the pics dated 4-15-07. The pics show the unmodifed F-code and the modified F-code with the added leaf. It also shows that now there is space between the bottom leaf and the thick variable leaf giving me some "spring" and a litle bit of travel. Originally I had added .66 inches of shims in the form of a piece of the original anti wrap leaf and leaf spacer but these I removed since the added leaf and the additional shim plus a shim on the very bottom of the spring pack add up to the same as what I had removed.
Since I first installed the F-code the rear of the X had dropped by 0.25 inch from 40.75 to 40.5. Now with the newly modified F-code I am at 41.0 inch. The ride is good and there is a little more spring. Perhaps this mod might solve some issues on towing with the F-code and perhaps this applies to the B-code as well.

[JMFINLEY]

How does the ride differ since you have made the change? Notice any difference?

[ldmc]

Boertje,

You read my mind. This weekend I was also looking at the length of the springs. I was looking into the 2nd or like you the third spring.

Let me know how the 3rd spring is working out.

Thanks,

[towrig]

boertje,

I'm glad you tried this out. I have been holding off until warmer weather hits.

Like the others said, please let us know how the ride changed, both unloaded and loaded. You said it is good, but how is it different?

Thanks

[boertje]

Unloaded in the few miles I have driven it, the ride seems more cushioned in the rear. I purposefully drove rough roads too. Loaded, well in May I am driving from CA to TN and finally Iowa with the family and loaded with stuff...I shall report back.

Just drove 150 miles with the new spring mods. The handling is the same but the ride is softer on the rear. There is more give or "spring" than before. I find that a good thing.

[Bruce1954]

I like it!

The only question I have come up with is spring wrap, the way the original variable rate leaf sits it helps prevent spring wrap.

On the other hand I have always wondered if the X was so heavy it was always into the variable rate anyway and not able to give the softer ride we want in the back.

Looks like a great set up for springs only rear end.

You can sure see the difference in the arch in your pictures this will also help in high rebound situations since the lower leaf will disengage and lessen the rebound effect. Not sure it this will happen in normal driving but it can't hurt.

Now the only question is if stock Fs with a sleave type air bag set up would be better. Guess I will have to build it and see.

Bruce

[TxSam]

Bruce stated my thoughts exactly concerning axle wrap. I was wondering if the fact that the variable rate spring being engaged on the Excursion is what helped with the axle wrap/wander issues some of us have. I have the V and B codes to swap in, still trying to decide if I want to modify the B codes or not.

[boertje]

I too was thinking about that but so far I cannot tell if this is an issue. It drives fine with a little softer ride yet feels solid on bumps. I like the difference so far.

But wouldn't an air bag decrease the engagement of the bottom leaf from the variable leaf even further and thus increase the potential of spring wrap?

Jack

[Bruce1954]

[ QUOTE ]
I too was thinking about that but so far I cannot tell if this is an issue. It drives fine with a little softer ride yet feels solid on bumps. I like the difference so far.

But wouldn't an air bag decrease the engagement of the bottom leaf from the variable leaf even further and thus increase the potential of spring wrap?

Jack

[/ QUOTE ]

Yep

"Engineering" another word for Compromise [img]/ubbthreads/images/graemlins/rolleyes.gif[/img]

Bruce