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-   -   'Bump' at a stop? (https://www.toyota-4runner.org/general-discussions/49083-bump-stop.html)

iLLWiLL 04-01-2009 01:40 PM

'Bump' at a stop?
 
This has to be something that someone else here as experienced, as I have a friend that experiences it in her '04 Corolla...

Occassionally -- well, rather infrequently -- when I come to a full stop, and my foot is still holding down the brake, my 4Runner ('07) will suddenly lunge forward slightly, feeling as though I just got lightly 'tapped' from a car behind me or something.

Certainly doesn't seem like anything serious...but was just wondering if anyone else has experienced this, and knows what this is...

Thanks :)

Mirlen 04-01-2009 03:47 PM

Annoying isn't it? It's the driveshaft shifting on the splined portion suddenly. My dealer denies that it's a common problem and just shrugs at me.

G.I.G. 04-01-2009 04:12 PM

Ahhh, the infamous drive line "clunk". Do some searches on this board and you will find plenty of info around it.

I started noticing the "clunk" when my brand new runner had about 2k miles on it. After doing some research here, I've been greasing the drive shafts every 5k when I change my oil. Haven't had a problem since. :)

http://www.toyota-4runner.org/showth...threadid=28414

If it makes you and others feel any better about it, I had the same problem only worse on my old '00 Grand Cherokee with full-time 4x4. I'm not making excuses for Toyota, but other manufactures are not immune to this problem either.

ALLEGRO 04-02-2009 08:47 PM

Mine did it too, and after a trip to the dealer and no response, I fixed it myself thanks to the web.

You don't even need ramps or a lift. There are six zerks in the driveline. Four are for the U-Joints and the other two are the slop-yolks. Hit the Ujoints with about 2 - 3 hits from your grease gun. Hit the slips about 12 times.....but stop if you see the slip yolk expanding. Mine did NOT expand and after about two days of driving....NO MORE THUMP

Here are some pics of the zerks:

http://www.toyota-4runner.org/showth...threadid=28414

Good luck

RPC 04-07-2009 08:06 PM

Do you happen to have the AC on when you experience this lunging?

adventureman73 04-09-2009 11:22 AM

Same issue here; can't remember if it happened on my '03, but my '07 does it sometimes. I just ignore it...but a friend of mine freaked out once and thought we'd been hit from behind! :D I chalk this up to "known issue that I can't do much about" and live with it. I have neither the tools nor the knowledge to grease the required portions of the drivetrain, so...

Vizwar 04-09-2009 12:16 PM

Time for a "my dad says..." post.

My dad is a ASE master machinist and been building sprint car engines and hot rods his whole life. He explained that the slack in the drive line is required. The thump is part of life with a 4x4. Hitting all the zerks is the best way to cope with it. Allows the slack but also allows it to move smoothly.

4runr30 04-09-2009 01:34 PM

Im glad to finally find out the true cause of this. I always just assumed it was my brake pads sticking because it only happens when I have to brake suddenly.

adventureman73 04-09-2009 01:40 PM

Quote:

Originally posted by KD7SMX
Time for a "my dad says..." post.

My dad is a ASE master machinist and been building sprint car engines and hot rods his whole life. He explained that the slack in the drive line is required. The thump is part of life with a 4x4. Hitting all the zerks is the best way to cope with it. Allows the slack but also allows it to move smoothly.

Good to know, thanks!!

Ron Helmuth 04-11-2009 06:59 PM

auto trannys only?
 
I used to think I noticed something similar but was convinced it was brake related.

Would this driveline slack be on the manny trannys too?

Yes I do realize every car has a driveline...

ALLEGRO 04-11-2009 09:23 PM

Re: auto trannys only?
 
Quote:

Originally posted by Ron Helmuth
I used to think I noticed something similar but was convinced it was brake related.

Would this driveline slack be on the manny trannys too?

Yes I do realize every car has a driveline...

YES

I think that it is related to coming to a stop, weight transfer to the front, rear suspension slightly elevated...therefore the slip-joint is extended...held there by the brakes. When you leave, you release the stored energy and in that the slop-joint is storing the energy (not lubed well) it bumps as it moves back to normal.

This can happen whether an auto or manual.

Ron Helmuth 04-12-2009 12:34 AM

thanks allegro
 
appreciate that-it seems logical


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