'00 Taco 4x4 Shimmying When Cold

[mburdick]

Greetings all. I'm a new registered user, but have been reading and following along for a while. I'm impressed with just how much knowledge is out there, and I'm hoping to be able to leverage it.

I work as a consultant and am on the road three to four days per week on average. So, about a year ago, I bought a 2000 Tacoma 4x4 XTra Cab. I've owned two previous Toyoya trucks, so had a decent idea of what to expect - reliability.

I've run into a couple of problems lately that I need some help diagnosing. Here are my vehicle specifics:

V6, 5-Speed, SR5
The truck came with the 225/75/15 tires originally. When I bought it, there were 30x9.5's on it, and I upped them all the way to 31x10.5. That was about six months ago.
87,000 miles

Problem #1) I live in New Hampshire, so winter temperatures may be compounding the problem. I typically leave my house in the morning and drive one mile to the convenience store and buy a coffee. I leave the truck running. Then, I drive 1/4 mile and get on the highway to head out of town. Once I get the truck up to highway speed (about 70), it vibrates like it's coming apart for the next five miles. It gradually lessens, and then goes away all together. This happened to me for the first time about two weeks ago. I have manual hubs, and they're currently locked (it is, after all, winter!).

Problem #2) Again, when cold is when this one shows up. If the truck is rolling at 3 or 4 MPH (like when I roll through the highway toll) and I go to drive away in second gear, I will get a screech when the clutch engages for about half a second. I have yet to make it do this on purpose, and it has never happened twice in a row.

If anyone can point me in the right direction to begin troubleshooting to at least find the problems, that would be great.

I'm getting ready to tear the engine down for the timing belt, at which point I will also be doing the water pump, all of the belts, the plugs, and most likely the wires. I figure I might as well also do a full cooling system flush since I'll have most of it out anyhow. Any other things I should be doing at the same time? Thermostat? Hoses?



I have been driving with the hubs unlocked (winter *was* starting to go away) without incident - until earlier this week. After driving at highway speed for almost an hour, the truck started to vibrate so violently I thought I was losing a wheel. I immediately pulled over to see if a tie rod had fallen off or something. Nope.

I was an hour from home, and figured I'd at least see if it was something major from the local dealer (I still have powertrain coverage on the truck). It turned out to be that the pivot arm in the rear that operates the e-brake was corroded and not operating smoothly. This was causing the shoes to not completely release into the normal position. That, coupled with a drum that was slightly out of round (only determined by lathing it) was causing a harmonic vibration under specific conditions. The dealer completely cleaned the parts, re-adjusted the e-brake, did a quick turn on the drum to smooth it out, and put me back on the road.

Since my check engine light was on, they checked that out - the MAF needed a thorough cleaning and they replaced the air filter. $250 later, the truck's working like a champ again.

[2tacomas]

You might want to make sure that your front-end is properly aligned and rotate your tires- my 88 use to vibrate real bad, but only at certain speeds, so I had it checked and found that the front end had come out of alignment. Also, are you engaging your 4wd on every trip that you take the truck on? If not, I would unlock the hubs when you are not using 4wd- you are burining a lot of extra gas by driving around with them engaged all of the time.

[mburdick]

2tacomas - Thanks for the reply. I haven't been thinking alignment because this vibration goes away after the truck warms up. And, since my hubs are manual, they stay locked in the winter. You just don't know when you'll need to pull the stick back around here...

[mburdick]

Ok. Update. Today I unlocked my hubs, and there was no apparent vibration from the vehicle. I'm going to run it again tomorrow with the hubs unlocked again. If there is no vibration again, I will lock the hubs for my drive home.