Odd Bump When Letting Off the Brakes?

[gamefreakgc]

Hi all,

So starting to get at fixing things on the 4Runner and I've got most of the shakes/vibrations hammered down except for one. Here's the scenario:

When at a complete stop (either when first shifting to drive or letting off the brake after a complete stop at a light), there will be a "bump" that I can feel. Note this isn't while pressing the brakes, but rather while depressing them and no gas has been applied yet. Sometimes it does it, sometimes not. More often after it sits for 60 sec or more, or while parked for a long duration.

Any ideas? Maybe a bad caliper or sticking brakes causing it the suspension to ride up, kind of like if you've got the e-brake on and give it a little gas? I've never had this sort of problem though.

I will say that in the coming months (currently amassing parts and supplies) I will be doing the Tundra brake upgrade as well as all new coils, shocks, struts, LBJ's, and possible tie rods if needed. Just want to see if anyone has experience and if I should plan on fixing something else as well.

 

[NCrunner2012]

Most likely your drive shaft needs to be lubed. There are several zerks spread around the shaft.

Mine did the same thing and lubing the driveshaft fixed my issue.

 

[gamefreakgc]

I bet that's it! I kept my truck's drive chassis lubed well so I never found out what happens if you don't.

That makes me think maybe some of the vibration/pulsation might be related to the drive shaft and not the steering/suspension... since if it hasn't been lubed maybe parts are failing.

 

[sterbenlicht]

Good chance it's that drive shaft like he said. Classic "bump from behind" sensation usually caused by the slip yoke at the rear of the shaft. Lube all the joints, but also make sure you get the fitting back at the rear of the drive shaft for that slip yoke. It can hold a lot of grease, but isn't supposed to, so don't overfill it. Just a few squeezes. If too much is in there, it can blow out the seal on the rear of the shaft the next time you hit a bump and the rear suspension compresses. I actually marked the shaft position on mine, unbolted the rear of it and took the slip yoke out of the end and cleaned it out and then put it back together to fill it with fresh grease.

 

[AZ4Running]

Could be the drive shafts and u joints needing a lube. Also check your front upper and lower control arm bushing. My runner clunks or bumps in the front end when letting off the brake and its from bad control arm bushing letting the front end move just a little.

 

[gamefreakgc]

Bringing this one back from the dead :sadwave:

Greasing the drive line solved a couple of issues for me. Until now. The vibration that was gone is back again. New suspension parts and an alignment took out 1/2 and after I greased the drive line it was completely gone. Now I'm back to the 1/2 again.

I greased every zerk on the drive line and used this diagram to help me find them all. From what I remember, #1 and #3 on the first section listed were fine (grease came out after 1-2 pumps) as well as #5. I don't want to overload it and just hit all of them again... especially since some of them are sealed. Does anyone know which one(s) is for the slip yoke at the rear like what [MENTION=111469]sterbenlicht[/MENTION] mentioned?

 

[mtbtim]

Based off the picture you attached, it would be the No. 2 for the front propeller shaft and the No. 4 for the rear propeller shaft. The others grease the u-joints. It's pretty easy to tell which zerk fitting lubricates what by just looking what it's connected to. The zerk fittings for the u-joints will be connected directly to the u-joint. The slip joint zerk will be connected to the shaft.

I've had a clunk rolling from a stop and sometimes coming to a stop since I bought my used 2000 4runner 4x4 last September. I've greased all my u-jonits and slip yokes really well and I still have the clunk. My shift lever moves forward in conjunction with the clunk making me believe it's just the transmission finally dropping into 1st gear. Most people say it's a slip yoke issue so I'm just going to remove the propeller shaft from the differential, pull the slip yoke apart, clean it up, re-grease it really well and hope that does something.

Good luck!