Zimmerman Rear Suspension Mod

[Rick]

I just did the "Zimmerman" mod to my rear suspension. Many of you have probably already seen the awesome rear (and front) wheel travel on the Zimmermans page www.4x4central.com/zims.htm

I went to the boneyard and picked up a set of leaf springs from an 89' Ranger for $90.00. I pulled apart the spring packs and tossed everything except the main leafs. Next I removed the spring packs from my Explorer and brought them to FST so they could hack off the spring eyes from the Explorers main leafs. They cut the spring so that the cut off end would fully support the new main leaf from the Ranger. The spring packs were then reassembled using Trailmaster centerpins which were cut to size.

After the springs were installed the back of the truck came up about an inch. When we checked the driveshaft slip yoke we found that the shaft was now to short when the suspension was maxed out.

I brought the driveshaft into Dicks Driveline in Phoenix. Bernie told me that the splines were shot and showed me how much play there was. I hadn't even bothered to check and never noticed a problem.

Anyway, I had a new driveshaft built with a heavier yoke larger diameter tube and coarse splines in the slip yoke. Overall much stronger and it only cost $200.00 with new U-joints and everything.

When the driveshaft was finished I drove back over to FST where Torrey cycled the rear suspension. After the mod my rear shocks were 3" to short. So he fabricated new lower shock mounts. I now get maximum droop and compression.

I tested out the setup on there 24deg. ramp where it scored 788 with the tires at street pressure. My previous best was 703 with aired down tires. I bet it's really close to 800 now with the tires aired down.

Anyway the mod really helps get more droop out of the rear suspension. I will hopefully have some photos of the suspension at work during the upcoming Arch Canyon run.

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Rick Horwitz
explorer@4x4central.com
Editor
www.4x4central.com

 

[Scott Bosso]

Rick,

Does the new, longer main leaf spring limit your upward travel at all? Or, was your upward travel limited by tire/fender contact?


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Scott
sjbosso@mindspring.com

 

[Rick]

Compression travel looks to be the same. I can still stuff a tire into the wheel well while the other is drooped down.

The leaf springs themselves seem to limit the travel as I don't contact the fender with the tire. The leaf spring on the compression side is bent past flat bowing back on itself while the droop side is flexed to the max.

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Rick Horwitz
explorer@4x4central.com
Editor
www.4x4central.com

 

[Todd]

Rick,
I have a couple of questions concerning this particular modification. I am unfamiliar with Ranger setups, so you may have to be patient and bear with me.
First of all, what is the span of model years that I can/could take the rear springs from a Ranger? Also, what type of Ranger 4x2,4x4, xlt, etc. or is there no difference?
Finally, will the added drop be too much for my stock brake lines to handle? (BTW, I only have stock displacement Bilsteins). Any help would be greatly appreciated. Thanks.


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Todd Metzger
'Off-Road and More!'
93 "Ford X 4" XLT

 

[Rick]

Todd, I'mk not sure of the exact range of years, but I believe '85-94 would work. I think that's what Lee Z. told me. I used the main leaf from an '89 2wd.

What you need to look for is the thickness of the Rangers main leaf. If it's thinner it will work.

You probably would need longer brake lines and definately will need longer shocks or reworked shock mounts.

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Rick Horwitz
explorer@4x4central.com
Editor
www.4x4central.com

 

[Todd]

Rick,
I went and picked myself up a set of rear leafs from a 90 2wd Ranger. However, after pulling the pack apart and comparing it to the main leaf already on my explorer, they look to be the exact same length. Is this correct or did I goof up and get the wrong set of springs? It seems that the Ranger spring has a little more arch than the stockers that I have but not much. Does the droop come from a different spring rate or what? I am at a loss on this one and really need some help please. Thanks in advance for any help you can provide.



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Todd Metzger
'Off-Road and More!'
93 "Ford X 4" XLT

 

[Rick]

The length is the same. The Ranger spring should be thinner than the Explorer spring.

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Rick Horwitz
explorer@4x4central.com
Editor
www.4x4central.com

 

[Todd]

Rick,
Thanks, I see what you are talking about now! Dead Link Removed



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Todd Metzger
'Off-Road and More!'
93 "Ford X 4" XLT

 

[Todd]

Well, I just finished the Zimmerman Rear Suspension Mod. I am very pleased with the change and its results. I did my mod just a tad different from Rick's and the Zimmerman's explorer.
First of all, I went to the local junk yard and picked up a set of leaf springs from a 2wd 90 Ranger for $50. (Not too bad.) Well, I took the original springs off of the truck and replaced the main leaf with the Ranger main leaf. I then, discarded my main leafs all together. Instead, I used a set of full length, 1.5" rise Rough Country Add-a-Leafs, that I already had, in place of the cut main leaf. I then removed the stock, flat overload spring.
The end result is wonderful. The ride has improved a tremendous amount and the ride height has also increased by .25 to .5 inches. The droop also increased by about 1.5 inches. However, my "stock length" Bilsteins still have another .5 inches of travel left beyond what the springs can provide. Regardless, it was an improvement over stock.
I would recommend this mod to anyone that is willing to undertake the six hour ordeal. It wasn't very difficult, but if you have never taken your leaf springs off before, prepare to use the entire dictionary of dirty words. Dead Link Removed Also, if you have a hitch installed, as I do, prepare to curse just a little more. Some of the bolts are extremely hard to take off and try your patience beyond any other task ever undertaken.
It was definitely a learning experience. Anyway, the mod was an ingenious one and works as said it would. Great job Rick and everyone!!


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Todd Metzger
'Off-Road and More!'
93 "Ford X 4" XLT

 

[dmeis]

Rick,

I am looking to level out my rear with the taller front springs.

Could you comment on using all of the Ranger leafs mixed in with the Explorer leaves to gain added lift?

I am thinking of trimming the extra leafs from the Zimm. mod to fill in between the existing leafs and provide the extra lift.

I am willing to experiment with the ride and travel but welcome your comments that may save me some time in the long run.

Also, does your drivers rear E-brake cable bind up now that you have more height and droop?

Thanks for the info,
David

 

[Extreme4x4]

Well, Zimmermann here, Gloria at least. Yes you can customize the height with a combination of springs. This is how I have the 7" of lift even with the added rear fuel tank full. The only mod to the e-brake line was to change the hanger..... basically get rid of it. This provides plenty of length. If you have any other questions feel free to ask.

 

[dmeis]

Gloria,
How many leafs did you add in to get the lift?

Also, have you been able to keep up with the higher end jeeps rock crawling? By this I mean taking the same lines as they do and not tipping over?

I have taken my explorer off camber pretty far but tend to avoid the larger rock lines that the high end jeeps take. I guess it may all come down to experience and knowing the breakover point. I would just feel better knowing how far I can go.

 

[Extreme4x4]

The amount of extra leafs that I added would not apply in most instances. The rear of my truck is much heavier than most due to an extra 14 gallon fuel tank and an 80 lb rear bumper. You pretty much need to play hit and miss with that one till you are happy with the results. As far as following the Jeeps, yes, I can go anywhere they go and am much more stable under most conditions. Occasionally they will be more stable on a certain obstacle, just as I am on some. If you want to see how far you can go and not tip, get the Rick Russel off road video, AZ Adventures. The Explorer is in that. The squeeze on Woodpecker shows just how ridiculously far you can lean and not go over.