4x4Wire's TrailTalk Forums: Big concerns with my front suspension

My 4Runner has developed a very annoying symptom in the front end. When going over minor pavement irregularities or ripples, the front end will exhibit a significant ‘shudder’. Normal dips in the road will have no effect. It is actually alarming enough that I am taking the time to post this, rather than laying on my back under the truck theorizing on what may be amiss. I welcome any and all thoughts, and will attempt to explain the current state of the truck.

I purchased the truck new in 2001 and now have 125,XXX miles on it, mostly highway.

At around 70,000 miles (three years ago), I replaced the stock suspension with a set of Bilstein HD shocks and factory new ’99 4WD/auto/V6 coils. Shortly thereafter, I ditched the stock 265/70/16 Dunlop TG35 Grandtrek tires and installed a set of 275/70/16 Bridgestone Dueler A/T REVOs (standard load). This combination gave me a great ride, whether on the highway or during mild off-road usage. With fairly religious 5,000 mile rotations, I was able to get close to 50,000 miles on the REVOS – I loved the way the truck rode and how it looked with a slightly fatter tire. Tire wear was even for about 40,000 miles before the tires started getting loud. Before replacing the tires, I noticed quite a bit of lateral play in the steering rack, so I replaced the rack bushings with polyurethane pieces from Wheeler’s. I also replaced the completely-degraded sway bar bushings with polyurethane pieces at that time.

At 120,000 miles (January 2007), I replaced the worn tires with a set of 265/75/16 REVOs (standard load). I think this is where the symptoms became noticeable. At the time, the shop (Goss’s Garage) noticed that I had significant play in the steering rack, which would make an alignment difficult. Since I was there and witnessed the play, I decided to personally replace the rack with a factory new piece. Prior to this, I had noticed more and more play in the front end, as well as a distinct ‘clunking’ when going over uneven surfaces. I replaced the entire rack (plus tie rods) a few weeks ago (with a bad back) and then had the truck properly aligned (the front left camber bolt refused to budge, so the shop resorted to a torch and brute force to remove it. The threads were gone and I bit the bullet for a new bolt set from Toyota.) The next day I took it on a 1,000 trip. It was very smooth, but the ‘shuddering’ issue reared its head constantly.

So here I am. The truck drives very smoothly on the highway, but as soon as I drive over a fairly-small pavement irregularity or rough patch, the entire front end simply ‘shudders’ very noticeably. When this happens, I can see the hood shake, can feel the 'shudder' through the steering wheel, and can see the dashboad shake. It’s only for a second or two, but is so distinct that I am determined to find the cause. I know these are trucks, but I have enjoyed nearly 6 years of reliable, and smooth driving. The condition is annoying enough that I don’t even want to take the truck beyond normal around-town driving, and cringe when I see a rough patch in the road.

Here are some thoughts that have crossed my mind. Bear in mind that the truck is otherwise stock and has been overly maintained by myself. Even at 125,XXX miles, the truck looks new from 10 feet:

- Upper or lower control arm bushings. Has anyone experienced failures of these? Are they replaceable?
- Lower shock mount rubber bushings. I presume these are cast into the eye and are not replaceable?
- Worn front shocks. These are roughly three years old and have around 55,000 highway miles on them. Absolutely no off-road abuse.
- Excessive tire weight. The 265/75/16 REVOs weigh 45 lbs each. My former 275/70 REVOs weighed 43 lbs each. My original 265/70/16 Dunlops weighed 36 lbs each. That’s a nine-pound difference between the stock tires and what I have now, but only a two-pound difference between the REVOs.
- Failed lower control arm bushing. Excessive heat from the torch may have roasted the rubber bushing.

Please let me know your thoughts. I appreciate any and all responses, but am really looking for some real-world possibilities/solutions. Thanks in advance!

Andreas

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2001 4Runner SR5 4WD, Dorado Gold, 246,000 miles
2007 Volvo XC 90 AWD V6, Silver
1995 Porsche 993, Polar Silver

Edited by aowRS (04/24/07 12:36 AM)





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