JulesMaximus
No Lifer
- Jul 3, 2003
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Quotes from Tundrasolutions.com:
had the driveline clunk problem with a 2002 tacoma prerunner. Dealer removed, inspected and lubed the drive shaft. Problem remained. Said it was the design of the vehicle due to the combination of driveline length, torque and suspension of the prerunner. They said it had to do with the spline when the driveline lengthens and contracts when coming to a stop. Also mentioned that happens to some 95 and up 4runners, TUNDRAS and tacomas with auto trans. The problem I had with the tacoma was on the extreme end. Clunk would be felt almost every time I came to a stop. First few times, had to check the rear view mirror to see if someone had rear ended the truck. Turned in the tacoma and got a tundra manual trans.
I have a 2001 Tundra 4X4 Limited with the 4.7 liter V-8. Often, but not always, when I stop at a light or stop sign it feels like someone just rear-ended me. The truck sort of lurches forward. I think it's the transmission shifting down after it sits for a few seconds but the Toyota dealer insists it's the front shocks "unloading." The only problem with that theory is that if I coast to a gradual stop so there is no dipping in the front end - in other words no loading on the shocks - it still happens. Has anyone else out there experienced this problem? I think Toyota is blowing smoke up my you know what.
I'm the one that wrote the original solution to the "thump in the rear" (at one time is was called the arkie6 fix) which was caused by binding in the driveshaft slip yoke being relieved when the transmission downshifted immediately after a stop which allowed the driveshaft to compress and the rear springs to un-wrap. The fix involved liberal application of grease to the driveshaft splines. What you have described here sounds like something different. If you get the bump feeling when you ease into a stop, this likely isn't the result of driveshaft slip yoke binding. What you have described sounds like the air conditioning compressor kicking in which also raises engine speed 200-300 RPMs to compensate for the increased engine load. When this happens at a stop light, the increased RPMs will result in increased torque on the torque converter output shaft and it will cause you to creep/lurch forward if you don't have the brake depressed firmly and aren't anticipating it. Next time it happens, look at your tachometer and see if it jumps up a couple hundred RPM at the same time. If this is what is causing the lurch forward, I don't know of any "fix" for this.
If you get the bump when you do this in gear, but don't get it when in neutral, then it is very likely that the driveshaft slip yoke is binding. The only cure that I have found for this is to THOROUGHLY grease the slip yoke - 5 or 6 shots of grease in the slip joint zerk fitting with a grease gun will do nothing to improve this condition because of the large void under the zerk fitting. You will either have to put like 20-40 shots of grease in the zerk fitting (at least until you see the joint begin expanding from the grease and then a few extra for good measure) and drive it through a half dozen or so abrupt stops (or just bounce on the rear bumper real good a few times) and then remove the zerk fitting to relieve any excess grease (you don't want the slip joint completely full of grease or it will restrict compression of the joint). Don't forget to put the zerk fitting back in when you are done.
An alternative is to drop the driveshaft at the rear end and pull the slip yoke apart (match mark both halves of the slip yoke and where the driveshaft bolts to the pinion flange for reassembly). You can then thoroughly hand lubricate the slip yoke splines. I recommend a good quality moly fortified chassis grease for this application (Toyota only recommends the moly grease in the double cardan joint).
Part of the problem with these binding slip yokes is inadequate lubrication from the factory. Another factor, at least on my truck, is the poor machining of the slip yoke splines. I pulled mine apart and believe that I could have done a better job of machining the splines with a Dremel tool - the splines were wavy and irregular, and this was not from wear or galling, this was the way they were manufactured. Fortunately, with the thorough hand lubrication of the slip yoke with moly grease I haven't had any more "bumps" or "thumps" in the rear end in I don't know how long.
