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JeepEV: Electric Vehicle Conversion Project
Suspension Upgrade



The need for new suspension:

     It was apparent from the beginning of the project that my Jeep's old suspension had to go. The rear leaf springs and shocks were original, and with over 400,000 miles on them the springs were sagging badly and the shocks were worn. The front coil springs and shocks had been replaced after the Cherokee suffered a head-on collision some years ago, but still had several hundred thousand miles on them. For this reason I decided to buy and install new suspension parts for both the front and rear of my Jeep.

     I used the suspension upgrade as an excuse to lift the Jeep. This would provide some extra ground clearance (for the recessed rear battery boxes going in soon). Also, lift kits usually come with stiffer springs, which is a plus when you're hauling extra weight around. I chose the 3" Cherokee lift kit from Rusty's Offroad, which offers lift and (hopefully) better support for the added weight. Since the leaf springs were shot, I went with a kit that included completely new leaf springs rather than add-a-leafs.

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Here are the old front and rear suspensions. Also, the components of
Rusty's lift kit (Although it came with 4 shocks and 4 springs, of course!).



Rear suspension:

     I decided to begin with the rear of the Jeep cause I thought it would be easiest. Ha! yeah right. I began by supporting the rear of the Jeep's frame with jackstands. I then placed a jack in the center of the axle and removed the tires. Next I removed the shock absorbers and u-bolts that hold the leaf springs to the axle. Then, using the jack, I lowered the axle until there was no tension on the leaf springs. I should mention that I had also removed the bolt that holds the brake line to the axle and the differential breather tube.

     Now the hard part, removing the springs. The leaf springs are held to the frame by two long bolts through the eyes of the spring. The front attaches directly to the frame and the rear attaches to a shackle then the frame. These eye bolts were a real pain in the a$$ to remove. What made it most difficult was the fact that the fenders blocked the bolts and left no room for my impact wrench. So I had to use my long breaker bar to loosen them by hand. Finally after a day and an entire can of PB Blaster, the bolts came out. I would have liked to replaced all the bolts with new ones but I was dumb and did this on a weekend when none of the specialty bolt and screw places were opened. So the new equipment went on with reused bolts.

     Basically the new parts were installed opposite of how they were removed. The one problem I encountered was trying to get the new leafsprings to line up with the axle. There are little stubs that have to line up with holes at the axle, and it took some time and effort to get them to line up just right again.

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Here you see the spring-to-axle U-bolts, and the new vs
old Leaf springs and shock absorbers.



Front suspension:

     With the rear suspension done and the Jeep's butt sticking up in the air, I began working on the front. The front suspension proved to be just as tricky, scratch that, trickier than the rear. My first big problem was that I had to track down some coil spring compressors so I would be able to insert the new, larger springs without having to completely drop the front axle.

     After placing the front frame of the Jeep on jackstands and a jack under the differential, I removed the shock absorbers. I was shocked to find out that one of the shock absorbers had been missing its top mounting hardware. Hmmm so that's what that clunking noise was! Next I lightly compressed the old coil springs, removed the Upper control arms, unbolted the brake line holders, and slowly lowered the axle. When there was enough room, I pulled out the old coil springs.

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Here are the new and old coil springs compared to each
other, and a new spring loaded on the spring compressor.

     Installing the new springs was a bit tricky. They had to be compressed a lot in order to be able to slip on. Once I got the new coils in place (each on a spring compressor), I had to reattach the Upper control arms before unloading them. I was under the impression the UCAs would fit after the lift was installed, but the holes just wouldn't line up. So what I did was using a drill and file, enlarged the holes about 1/8" and re-inserted the bolts using washers. Now the Upper control arms would reattach to the axle. I was also told it may have been a good idea to get new Lower control arms, but I think it will be fine the way it is.

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The Upper control arms had to be modified to reach the axle.
Also, a picture of the new spring and shock installed.



Update (2/26/2005): Leaf spring helpers:

     I have noticed for some time now that the Jeep's rear end had begun sagging a bit lower than it should be resting. Also, the suspension got too soft in the rear. It seems that the Rusty's offroad leaf springs, though tougher than stock, just haven't been happy being loaded with so much weight for the last year+ now. In order to bring my Cherokee's rear end back up a little bit, and to help save the Rusty's leaf springs, I decided that I needed to do something. I ended up purchasing some leaf spring helpers from JCWhitney. These are the type which you bolt on to the bottom of the leaf springs, rear of the axle. They are about 20" long (roughly half the length of the Jeep's leaf springs), and are rated to assist up to 1500 lbs. I spent time today installing them on the rear leafs. This consisted of jacking up the rear axle enough to remove the rear tires. I then placed a jack under the rear battery box, and used it to lift the body of the Jeep. Once most of the load was off of the leaf springs, I bolted on the helper springs. It was a very easy process. Once the springs were installed, I reinstalled the tires and removed the jacks. After a 15 mile drive today, I could tell that the springs helped a lot. The rear suspension is firmer now. Also, the Jeep no longer has a sagging rear, which is good. :-)

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The new helper springs are bolted onto the bottom of the existing leaf springs.



Update (5/05/2005): Front anti-sway bar link modification:

     One minor annoyance that I'd yet to solve with the Jeep was that the front Anti-sway bar links were too short. The Anti-sway bar is a suspension component that connects the axle to the body of the vehicle through a non-ridgid connection at the anti-sway bar links. Its purpose is to help keep the axle centered properly and keep it from moving around excessively as the suspension travels. Ever since I installed the lift kit on my Jeep, the sway bar links were too short, causing the rubber bushings to not fit on properly. At the time I was lazy and bolted the sway bar to its links without using any bushings, knowing that I'd fix the situation later. Well, I never got around to doing so for some time, and as a result my Jeep didn't handle as well as it should. That is, my Jeep experienced things like "bump-steer" way more than it should have. Also, because the sway bar was at an incorrect angle, it would rest against the passenger side coil spring, and would collide with it when the suspension traveled too much, making an annoying "thunk" sound.

     Today, I finally got around to fixing this problem. I had thought about buying "adjustable" sway bar liks from a 4x4 store, but I didn't think they were worth the $100+ for a set. So I instead got out my jig saw and welding machine to lengthen my Jeep's existing sway bar links instead. Luckily, the main part of the Jeep sway bar links is a standard-sized 1/2" steel rod. This made the job of lengthening the rods pretty easy. After I ground the paint off of the top part of the links, I used a jigsaw to cut them in half. I then cut some 2" long pieces out of a section of 1/2" steel rod I bought. I then clamped the new 2" sections of steel rod in between the halves of the old sway bar links. I then welded everything together. Lastly, once the steel had cooled off (welding is hot!), I painted my newly lengthened sway bar links a flat black. I reinstalled the lengthened links with new poly (red) bushings to replace the old, worn rubber bushings. The results are good! The bump-steer and annoying thunking sounds are now gone!

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The old Anti-sway bar links are lengthened and reinstalled.


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