Weird Problem (or not) I stop and car doesn't

[beau]

This is one that might be tough for ya'll to diagnose over the internet, but maybe someone has experienced this.

On my new (101K miles old) 1997 explorer sport that I just bought something weird happens when I stop. Its like the car stops and then it sort of rocks forward. At first I thought it was just a suspension thing and the front shocks were just kinda worn out and compressing weird, but now I feel like the engine or tranny (something big) is sort of lurching forward as I come to a stop. I know it can't be the engine mounts, but its almost like the engine is on a rocker that tips forward just a fraction of a second after you stop.

Has anyone experienced this? It's weird, I know. Truck doesn't appear to have been in any accidents. Runs and tranny shifts great. Only other problem is a rough idle that I'm trying to diagnose though a seperate thread and some trial and error fixes.

 

[hydroxy]

Just to be sure... you're not just experiencing the front end compressing down under brake pressure and then rising back up once at a stop are you?

 

[bbmoose]

sounds like either mounts like said above or bumpstop.
But bumpstop is well known in jeeps i can say.Its like the the driveshaft is taking up and releasing slack tension at a stop.
Its almost like when you stop then there is a little bump forward(like someone tapped you from behind).
Sounds like your problem?

 

[ravekid]

i have a similar problem...
i have a 98 sport, and when i stop the front end dips (as with any vehicle) and then after she comes to a complete stop, as the front end comes back up, there is a mild thump and it seems as though i am rocking backward slightly. at first i thought the spare was rocking a bit (imagine the thump of a tire bumping lightly under the rear of the truck) but i pulled the spare and it still makes the noise.

now this noise is only heard during quick brakeing... if i ease off the brake and coast to a stop the noise is not heard.

any ideas?

thanks

 

[Charlie's_93EB]

Its almost like when you stop then there is a little bump forward(like someone tapped you from behind).
Sounds like your problem?

that is me bbmoose to a T.
what is it drive shaft?
can "I" fix it?

 

[bbmoose]

This is what i found out about the jeeps problem.
By the way i not only have a 2000xls but also a 99 jeep grand cherokee(this ones my wifes daily).
"A condition may exist where the vehicles owner may feel an intermittent bump (stop-bump) once the vehicle is brought to a full stop. The repair technician may erroneously diagnose this condition as a delayed transmission down shift into first gear. This condition may occur 3 to 20 seconds following the stop or when the load on the rear driveline is reduced (e.g., when the applied brake pressure is decreased). The stop-bump condition may be the result of a binding between the splined surfaces of the rear propeller shaft slip yoke and the rear output shaft of either the transfer case or the transmission. As load on the driveline is reduced, the bound slip yoke will release suddenly causing a bump-like sensation. The condition may be intermittent. If the above condition has been experienced, then perform the Repair Procedure. The splined surfaces on the slip yoke section of the new propeller shaft are nickel coated to reduce the opportunity of binding."
Take it how you want but by my thoughts it might be worn or dry u- joints on your x or possible worn or dry cv/axle joints.Either of these might cause a binding when stopping and the bump you feel is the kenetic release of built up torque?
Just a thought.
Goodluck.
Hopefully it gives you something to go on

 

[beau]

Hmmm... the bumpstop thing could be it. But it doesn't happen unless I stop moderately quick. If I coast to a stop it or stop slowly it doesn't happen. I don't think its just general compression of the shocks rebounding. More like what Rave Kid is describing. I'm going to the dealership tomorrow and will take one of the service guys for a ride. I'll post what he tells me.

 

[mhn3773]

beau...read the post above urs again..explains totaly what is happening

says The stop-bump condition may be the result of a binding between the splined surfaces of the rear propeller shaft slip yoke and the rear output shaft of either the transfer case or the transmission. As load on the driveline is reduced, the bound slip yoke will release suddenly causing a bump-like sensation. The condition may be intermittent.

 

[ravekid]

The stop-bump condition may be the result of a binding between the splined surfaces of the rear propeller shaft slip yoke and the rear output shaft of either the transfer case or the transmission.

are both of these joints greeseable? if so are they open or inside of a bellhousing or dust sheild?

just go the x and havent had a chance to look under her, its been sort of wet lately@!

 

[Nam 67]

You need to lubricate your slip yoke.That's what makes it feel like someone has tapped your bumper when you stop.This is a real common problem and there are lots of threads here about this.There's a boot that covers the yoke.You need to grease inside of there.It washes away in time so use a type of grease that will last.Read through this post,it may help. http://www.explorerforum.com/forums/showthread.php?t=105261

 

[beau]

Hmm... thanks. I took it to the dealership for other stuff and told them about this problem too. I'm sure they'll just grease it and charge me $300.00 for it. Perhaps I'll call the service guy in the morning and tell him not to worry about it if I can find some instructions here somewhere about how to do it myself.

 

[beau]

Yea, dealer said the slip yoke was fine - from the notes the mech seemed to know it could be lubed - service guy told me it was sealed and does not need to be/can not be maintained.

The mech stated the following with regard to the problem in his notes:

TEST DROVE AND MADE SEVERAL STOPS. THIS IS A NORMAL REAR DISKS BRAKE NOISE. THE SLIP YOKE IS ONLY HEARD WHEN CHANGING DIRECTIONS AND IT IS SLIDING FINE. NO REPAIR REQUIRED AT THIS TIME.

Damn, not sure what to do now. I know this isn't right because my 97 mountaineer does not have this problem. However, I really don't want to dump more money into this. Perhaps if someone posts good photos on how to do do the slip yoke fix sometime (hint, hint) I'll just do it myself. Otherwise I guess I'll just be glad they say its fine.

 

[EBInterceptor]

After reading this, I've decided to grease my slip yoke up this weekend, I'll do my best to get some pictures out.

 

[beau]

WOOHOO! Pics on the way! (Seriously though, if you don't get to it right away no problem. It'll be ok for awhile methinks.)

 

[Nam 67]

When I first learned about this slip yoke problem I brought mine in to my local Ford dealership.I told them I wanted my slip yoke lubed.I left my vehicle there for four hours and when I went to pick it up they told me that it was a sealed unit and couldn't be lubricated.Finally I brought it to a garage up the road from me,told them my problem,and left the vehicle with them.When I went to pick it up the mechanic told me he was able to insert a small nozzle grease gun into the boot and greased it.It has been fine ever since.I live in a condo and I'm not able to get underneath and check the situation out so I can't describe the yoke to you .I do know that the joint is in a boot that holds grease and eventually the grease washes out.This causes the yoke to bind up when you stop,and then slips forward abruptly causing that bumper tapping sensation.You need to remove that boot or somehow get grease inside it.That boot is replaceable.Hopefully someone who has done this can be more help to you.

 

[EBInterceptor]

I found this which gives a description of the parts of the driveshaft and everything. It's off a 1998 Ranger, but since it was the first thing that came across and it's pretty generic I thought it was a good visual.

http://rockledge.home.comcast.net/RangerPictureGallery/Driveshaft_Slip_Yoke_Lube.pdf

I actually haven't done this before, but there are some other posts here about it if you search "slip yoke", that I'm going to use to do this job.

Didn't see any pictures along with the how-to's so I have to get some pics so if anyone else wants to see them.

 

[Nam 67]

That parts blow up shows it pretty well.That boot is where you need to insert the grease.I believe those clamps are for one time use only.I read somewhere that someone used hose clamps as an alternative.That does not sound like a good alternative since I think it may create an out of balance problem.My guy slit that boot somehow and shot the grease right in there without removing the boot.Please let us know how you make out on this.

 

[EBInterceptor]

It better not cause it to be unbalanced since I've just done it. The clips pop off real easily with a slotted screwdriver, you just have to lift up the one end and it pops right off. I didn't drop my driveshaft but just pulled back the boot and sprayed right in with some white lithium grease. I have pictures, just need to get them up. Without taking pictures, it's under a 10 min. job. I wouldn't cut the boot because it's suppose to be free from contaminants. Only tools that were needed were the grease, 2 hose clamps, and a slotted screwdriver. Don't even need to jack it up, so a creeper would be an important thing to have. My friend slid in and out with the creeper getting what I needed and took pictures while I hung out under the X doing the work.

 

[bbmoose]

wow i am happy to see i was on the right track.Glad it helped out.I know with my wifes grand cherokee it solved the problem(so far 2yrs and counting).
I agree with NOT cutting the boot.I know they sell a needle tip for grease guns to poke a very small hole into the rubber,and the grease will stay put because the total size of the hole made is as smaller than a pencil point.Most of the time the rubber will reseal the tiny hole too.I would use that rather than cutting.

 

[EBInterceptor]

Put up some pictures and a write up.

http://www.explorerforum.com/forums/showthread.php?t=106307