PLEASE HELP! shaking bronco when taking off

[jbrown98604]

I bought this bronco about five years ago thinking it only needed a clutch, I have tried several clutches currently running a center force, with a newly resurfaced fly wheel, the bronco shakes when i try to take off. I have put new springs front and rear james duff 3.5", i installed a new motor, different transfer case, transmission, purchased new body mounts, clutch rod adjustable from wild horses, changed clutch push rod and all mounts / rods. I have changed the rear end to big bearing 31 spline and installed factory limited slip third member, bought new drivlines from wild horses. If i pull the front drive line and put it in 4wd it drives fine no shaking. I have also replaced the shackle bushings, motor mounts tranny mounts, is there anything i missed? or any ideas?

 

[Flash69]

What gears and size tires do you have? You may need a different gear.

 

[SaddleUp]

Do you live around Longview, Wa? (Your name rings a bell and it looks like part of it is the zip which would also be about right) If so we talked about this a little a year ago when you got the tranny and t-case from me. Have you checked the motor mounts? Is it driveable enough to get it down here? If so then some weekend or evening I could take a quick look at it to see if I can figure it out. It sounds like you've covered almost all of the obvious stuff.

 

[musetech]

"If i pull the front drive line and put it in 4wd it drives fine no shaking."

You are getting this in 2WD? This impacts the troubleshooting a bit.

You have replaced enough to eliminate the most common problems. Mounts (I assume you mean engine/trans/transfer case), oil on clutch/flywheel etc.

If this is a 4WD only problem then you have a differential gear mismatch. Sorry if this insults your intelligence as you've done enough work and I'm sure you know better.

As long as we are on the subject...did the pilot bearing get installed?...Sorry again.

If it is in 2WD then it could be an engine/trans misalignment. About the only thing left as you have changed your entire drivetrain. The shudder comes from the clutch slipping and engaging repeatedly under load in most cases. Usually reverse. Once your cruising it goes away right?

 

[SaddleUp]

As long as we are on the subject...did the pilot bearing get installed?...Sorry again.

If it is in 2WD then it could be an engine/trans misalignment. About the only thing left as you have changed your entire drivetrain. The shudder comes from the clutch slipping and engaging repeatedly under load in most cases. Usually reverse. Once your cruising it goes away right?

I think pretty much everything forward of the transfer case in the drivetrain is eliminated by driving on the front axle instead of the back one. The only items not would be ones that are effected by a shift of torque from one side to the other. (Which is why I mentioned engine mounts)

My first thought on this which I recall mentioning last year when we were talking about it is a bad rear driveline angle. (I'm pretty sure your the same person) Not necessarily a bad driveline but rather a bad angle on the u-joints. If you move along really slowly can you hear a thud underneath that seems to be in time with the revolutions of the driveline?

 

[72Sport]

Difference in tire diameter. Mine had 31" tires on one end and 32" on the other when I bought it. The limited slip didn't like it.

Front and rear gear ratios are different.

 

[idahobronc]

Motor mounts?
I had the same problem and did not realize it was my motor mounts until I used a jack to check them.


sorry Just read you replaced them.

 

[chuck]

My guess is that you are bending the clutch disc whe you install the trans. This is easy to do by just having the trans most of the way in then letting the weight hang for a sec to get a new hold. Could be wrong but that seems the most likely. To test a disc put it on the input shaft and turn the output shaft and watch the disc turn. Does it wobble?

 

[hackyrat]

You are suffering from axle wrap. Have someone watch the rear axle from a safe position while you take off. You need to stabilize the axle. Or just go with an automatic transmission and be done with it.

 

[bronco-uno]

My guess is that you are bending the clutch disc whe you install the trans.

Chuck How did you ever discover this problem/fix?

 

[SaddleUp]

It's pretty doubtful that it's a bent clutch disc. If it was then it wouldn't matter whether it was running on the front or rear axle.

 

[bronco-uno]

As Taken from the centerforce website:


--------------------------------------------------------------------------------

WHAT COULD BE THE CAUSES FOR CLUTCH CHATTER?


CHATTER PROBLEMS CAN BE CAUSED BY MANY PROBLEMS. POSSIBLE CAUSES MAY BE AS FOLLOWS:

FLYWHEEL HAS EXCESSIVE RUN-OUT.
FLY WHEEL WAS NOT RESURFACED BEFORE THE NEW CLUTCH WAS INSTALLED.
FLYWHEEL WAS RESURFACED IMPROPERLY OR HAS IMPROPER SURFACE FINISH.
FLYWHEEL HAS SEVERE HARD SPOTS OR HOT SPOTS.
FLYWHEEL RESURFACED IMPROPERLY (I.E. INCORRECT FLYWHEEL STEP).
DAMAGED OR EXCESSIVELY WORN CV JOINTS.
BAD U-JOINTS IN DRIVE SHAFT OR U-JOINTS MISALIGNED.
EXCESSIVE BACKLASH IN DIFFERENTIAL.
EXCESSIVE DRIVE-LINE ANGLE.
BAD LEAF SPRINGS, BUSHINGS OR MOUNTS.
IMPROPER GEAR RATIO VERSUS TIRE DIAMETER.
DEFECTIVE PRESSURE PLATE AND/OR DISC.
DISC HAS INADEQUATE OR NO MARCEL (NOT ENOUGH CUSHION BETWEEN THE FRICTION FACINGS).
OIL OR GREASE CONTAMINATION ON CLUTCH FACINGS.
WORN OR DAMAGED CLUTCH LINKAGE.
BENT COVER ASSEMBLY AND/OR DISC .
IMPROPERLY TUNED ENGINE.
WORN OR DAMAGED ENGINE MOUNTS OR TRANSMISSION MOUNTS.

 

[chuck]

Chuck How did you ever discover this problem/fix?

I used to a very long time ago, work on VWs for a living. It's a common problem with them. And I used to be a tuff guy that could put the trans/tcase in without a jack... o.k. or so I thought. It didn't go all the way in and I had to rest a little, just a little was enough to bend the disc. After messing around with it a lot I pulled it all back apart and found that the disc was warped. I ended up taking 2 more rebuilt disc back to the parts store before I gave up and paid for a new disc and rented a trans jack. The rebuilts were warped right out of the box. There are other things that cause that chatter like oil on the disc or loose t-case mounts or bad drive line parts like splines, balls and U-joints. Sometimes loose U bolts but if it happens shortly after you replace the clutch my money is on a warped disc.

 

[SaddleUp]

my money is on a warped disc.

Okay, now you have me wondering how you came to this conclusion. How would it even be possible for a warped disk to chatter "only" when the rear axle is connected but not when "only" the front one is?

Simple answer: It can't. It needs to either be related to the change of torque from one side to the other (Motor mounts or loose bolts between the components) or needs to be between the transfer case and rear tires.

 

[76Broncofromhell]

My guess is a funky rear driveline angle combined lots of slop in the drivetrain. Lifted Broncos have a lot of slop in the drivetrain and that exaggerates any clutch chatter.

I think he meant if he pulls the rear driveline and puts it in 4wd, the chatter goes away?

 

[Sac '68 sport]

Did the chatter go away at all when you put the new clutches in, or was it the same right from the very first time you drove it with the new clutches? A leaky rear main will put some oil on the clutch pretty fast and cause the chatter to come back.
How did the clutches you pulled look? Was there oil on them or any other hint of something wrong? IE did they look like they were chattering? Out of the two that I pulled, the first showed some pretty obvious signs, the other wasn't very old, but I could still tell it had a little oil on it and the disks were not smoothly/evenly worn. It just had some darker areas and a few shinny spots.

Although you said that you pulled the Front drive shaft and that seemed to stop the shaking? That's a strange one. Doesn't make sense that the front drive shaft could cause shaking if it's in 2wd.

 

[chuck]

I read the first post and it says "If i pull the front drive line and put it in 4wd it drives fine no shaking." If you pull the front drive shaft and put it in 4wd you still have the same thing, rear wheel drive so that can't be right, if he mint 4wd lo, the warped clutch chatter mostly goes away so that fits. Or assuming that he mint that he removed the rear drive shaft and put it in 4wd so had power to the front wheels only that fits also in my experance. It seems that he has already checked the other things. I could be wrong, it's only a guess. I am only trying to help by sharing my experance. He, you or anyone else can take it or leave it, it's free.

Okay, now you have me wondering how you came to this conclusion. How would it even be possible for a warped disk to chatter "only" when the rear axle is connected but not when "only" the front one is?

Simple answer: It can't. It needs to either be related to the change of torque from one side to the other (Motor mounts or loose bolts between the components) or needs to be between the transfer case and rear tires.

 

[SaddleUp]

I read the first post and it says "If i pull the front drive line and put it in 4wd it drives fine no shaking." If you pull the front drive shaft and put it in 4wd you still have the same thing, rear wheel drive so that can't be right, if he mint 4wd lo, the warped clutch chatter mostly goes away so that fits. Or assuming that he mint that he removed the rear drive shaft and put it in 4wd so had power to the front wheels only that fits also in my experance. It seems that he has already checked the other things. I could be wrong, it's only a guess. I am only trying to help by sharing my experance. He, you or anyone else can take it or leave it, it's free.

I went back and read it again. For some reason I thought he told me it was fine when he drove on the front driveline without the rear one. I know this problem has continued from before he changed to the NP435 and then back to the 3 speed and is still happening. He also has used at least 2 different clutches. Both of us know all too well though that the descriptions often don't give much to go on.

 

[chuck]

It is very tough to diagnose a problem over the internet. People just naturally leave parts of any story out, we all do it. I guess because we think it's not important or we don't know it's wrong or we don't notice it, whatever it makes it hard. My favorite ie. is "my turn signals don't work, anyone know why?"

 

[jbrown98604]

Thanks guy's for the ideas! I noticed while looking in the wild horses catalog that the transfer case mounts have a metal spacer in them the mounts I bought from woody's 4X4 did not could this be a problem? I think I will order new transfer case mounts and the extreme motor mounts from wild horses and install them if this dont take care of the problem I would really appreciate it saddleup if you could look at it. i live Battle Ground WA so Iam only a half hour from your house. I think I still have your number from when I bought the tranny and transfer case from you! Thanks again!