The Start/Stop Clunking Saga

(Sorry for the long post)

I have been fighting the clunking at start and stop for literally years and I’m suggesting that it’s just what a Tacoma does. This is the clunking/hesitation at the moment of stop moving and again at the moment of start moving forward. For reference my truck is pure stock with no oversized tires or suspension modification. Here are all the things I’ve done and checked.

Center Support Bearing: I replaced that about 2 years ago and it seemed to reduce the clunking at first but it slowly came back strong. Again last month the AutoZone one I put in went crap and I put in an OEM one. It has little to no play right now. It rides a little smoother but the clunking didn’t change.

Slip Yoke: I greased it heavily on the first carrier bearing replacement and again last month on the second one. I see no signs of wear and it slides back and forth just fine. There is rotation zero play on this yoke.

U joints: I religiously grease these every oil change pushing Lucas tacky red grease in until the crackling stops then wide it down. I see or feel no play in the joints and each one moves direction with no resistance. I’ve taken a crowbar to each joint and there is no movement. One thought on this. U joints usually manifest being worn out with moving from forward to reverse and back again. Not at a stop where forward pressure from the AT is still being applied.

Transmission Mount: I replace that 6 months ago with an OEM one. There is very little play with the new one compared to the old. This seems to reduce the clunking a little but after a few weeks it’s back. The old one had much more wear and so it was a good thing to do even if didn’t solve the clunking.

Shocks: These were replaced about 3 years ago. I’ve check the torque setting on the mounting bolt and they are to spec. The bushings are new. There is no play at all.

Brakes: The rear brake have all been replaced. I clean and lubricated all moving parts to a tee. I’ve inspected them for fluid leaks and they are dry as a bone. All the contact points and star gear move freely. The wheels spin just fine while on the jack with the brakes off. There is no binding or sticking.

Motor mounts: I have not replaced but having someone romp on the brakes and rev the engine in both forward and reverse does not twist the engine that much. It doesn’t jump to the left or right like I’ve seen other worn mounts do. I shoved a crowbar in the mounts and they seem tight with little play.

Axle and leaf springs: Now it gets a little interesting. The truck was involved in a wreck 4 years ago where I got a brand new OEM rear axle. The old one was bent. I’ve also had the TSB done with new 4 pack springs. As mentioned many times in other threads there are questions to how much to torque down the U bolts around the axle and leaf springs. The service manual calls for 37 lbs. Mine was on 37 lbs. Researching 3rd party leaf spring specs on torque per U bolt size (We have 1/2 inch bolts with, I want to say, 17 TPI threads), every manufacture will say those size bolts should be 80-90ft/lbs. I went with what some say are inverted numbers in the service manual and horsed them down to 73ft/lbs. I’m so pissed at this clunking I was going to fix it or break the U bolts trying. This sucked the bolt down a good 3/32” on each nut. The axle can handle it because so many of you have installed beefier aftermarket leafs with up to 120ft/lbs on the OEM axle and never mentioned swishing the axle. I’ve been driving for a week with the tightened U bolts and I have to say it’s WAY better. No clunking at all on the stop and just a little hesitation and looseness feel at start. I’m hyper focused on it so others may not notice or care.

What is really an improvement is the smoothness of the ride. It’s not my imagination like when someone says “I changed the oil and my car has more power”. My wife who notices nothing even said without asked, “are your tires going flat”. I thought my tire(s) were losing air since it felt so much softer. They are right on 35lbs as they always are. Also, all you can hear is the “clopping” of the tire over expansion joints and nothing else. The ride is noticeable better.

While the forward clunking isn’t totally gone, it’s the best it’s been in years. All this from tightening the U bolts down to 73ft/lbs. I still believe that Tacomas, at least 2nd generations, suffer from the clunking at start and stop to some degree. It’s just what they do.

 

Well written.

Search on the term 'axle wrap' and I think you'll find what you made better, and possibly some ways to eliminate it altogether. If it's worth the effort to you.