Shuddering/Bucking when clutching in, loose engine bell housing bolts
 

This is 3rd or 4th time have had this issue, open to suggestions on solution, and want to alert others to issue. I have a 96 XJ with 5spd and 4.0L, 10 years ago at stop signs it would shudder and buck starting in first gear from a stop. Suspected engine mounts and trans mount but could not find. Then it got hellous and pulled the trans (big job) thinking bad clutch or pilot bearing, they were perfect even though 120K miles on them, but the bell housing bolts were loose, that was the issue. Had it apart so put in new clutch and pilot bearing and put in a TeraLow (which I had invented 5 years before them just did not have means to manufacture them).

Then problem came back, this time so bad the flywheel started scraping that sheet metal thing between engine and bellhousing. If you hear that, means engine and bell housing separating.

Anyone else having this problem?

The bigger lower bolt on Pssng side that goes blind into block seems stripped, it keeps turning. I have put two nuts on pass through lower bolt on drv side, it seems quite tight was only able to get a half turn more on it. So guessing upper bolts loose or out.

Funny thing on this is that it can go away for a month then come back. This time its been on and off for a year, I would check that one bolt (drv lower) and see it was tight and the upper bolts seemed fine. This time think upper bolts are missing.

Oh well wanted to pass this on if anyone has shuddering when clutching from a stop.

Have heard you can use 3/8 x 16 hex head to replace 2 top ebolt. Is that true and if so how long a bolt?

And are there just 4 bolts that hold on the bellhousing, it is so tight in there having trouble finding the bolt heads.

It's just the 4 bolts that are supporting. There are some smaller bolts that hold the spacer plate (the sheet metal thing) on that have to be accessed from the engine compartment and of course the 3 bolts on the bottom that secure the spacer to the bell housing and the 2 CPS bolts.

I've never had an issue with the engine/tranny connection on either my current 95 or my previous 00 TJ. My Dad had a 94 XJ and never had an issue either. (All in all that's about 710k of manual transmission Jeep I6's).

Are you certain you're torquing the bolts to spec?
Are the bolts in good condition?
Do you have both the alignment pins in place?
(Note - my 95 was missing one when I did the clutch a few months ago, I replaced it but didn't have any issues without it.)
Are the flywheel bolts torqued correctly?
(They need to be replaced if the flywheel is removed per the FSM.)
How are your engine mounts and tranny mount?

Yes you can replace the inverse Torx (E12 IIRC) bolts with standard hex head bolts. I can't recall the size, but if you take one of the old bolts down to the hardware store you should be able to find the correct size. I replaced mine when I did the clutch.

If you're having trouble seeing the bolts, lower the jack under the transfer case and look from behind the transfer case (or tranny if you've removed the xfer case or have 2wd). You'll need a good 2.5-3ft of socket extensions to get enough leverage on the suckers to loosen them up (or tighten them in). If you have the luxury of time - spray the heck out of the bolts with PB blaster or liquid wrench and let it sit overnight before removing them. I mangled one of those E-bolts on the TJ and it was a beast to try to drill it out.

Pat thanks for your answers. About 1 min ago got the worst possible news. Could not hand push in the replacement 3/8" x 1/3/4 " coarse bolt with hex head. Then got a mirror in there (upper Passng) and the bolt did not fall out is snapped off in block!

Yes the aligning pins were in. Its such a bad job pulling the tranny/clutch out, but how can I get snapped off bolt out now without doing that. $1 bolt, $500 labor to replace it.

So situation now is
1. Drv bottom have a 3/8" pass thru bolt and nut, seems tight.
2. Bottom Psng have original 7/16" screw into block bolt was tight, but turned it maybe 2/3s turn more using helper bar. This bolt has always been a mystery, It takes maybe 100 pounds torque to turn, but seems to never bottom.
3. Upper psng snapped off in block,
4. Upper Drv think see it, appears to be hex head, but so so hard to see it, not 100% positive it is the Bell to bolt bolt, maybe 90%. My bellhousing looks different than others have seen pics of,, that have two ribs on either side of bolt head (uppers) Mine seems to have just one rib .

And the weird symptom of can drive just fine for a couple of months, then bucks and shudders just trying to leave a stop sign. Then drives just fine for months. I do have about 240k on it now and have done a lot of extreme 4wd with near stock XJ 9 (3" LIFT) Just about everything underneath is dented/scraped..

A bit puzzled.

Yeah, broken bolts are always a PITA.

You'll have to pull the tranny - you can do it yourself, just get a transmission jack (about $130 at Harbor Freight) and once it's off you'll have plenty of room to get a drill in there.

I think the main connection of transmission to engine is the two big bolts. They won't bottom out since the threaded part of the block is open.

I wonder if you have the wrong bellhousing. I don't remember what mine looked like, so I don't know about the ridges.

When it shudders, does it feel like just the tranny is moving or does it feel like the whole engine is moving? If you've done a lot of off-roading, I'd suspect that the motor or tranny mount is bad - have you checked the mounts carefully?
I'd use a long prybar or Big Daddy screwdriver to see if the tranny mount is bad and a floor jack with a block of wood under the oil pan to see if the motor mounts are solid. On my 95 with a new Mopar tranny mount there is the slightest of movement (rubber flexing) when prying and if I lift the floor jack with good motor mounts the whole front end will lift with no play in the mount to engine connection.

I would suspect that if the mounts are all sound then it could be a worn pressure plate or loose flywheel rather than the mating of the tranny to the engine.

You might try removing the tranny mount nuts and putting a jack with a block of wood under the tranny and seeing if the engine and tranny rotate in sync when raising and lowering the jack. If the engine and tranny don't move as if they were a single unit, then the mating is incorrect.

Good idea Pat on prybar, I always suspected the tranny mount first. I bot it in 2001 with 63k miles in like new condition from first owner, so BH is factory.

On big right bottom bolt, the no bottoming mean it will never stop turning, so it is somewhat stripped even though it takes about 120 pounds to turn. On Drv side it fell out so did 3/8" passthrough with nut on other side.

This has always been a mystery and I worked in auto parts industry for 10 years, grew up in it. My best guess now is it hinging on bottom, top coming back. Eng mounts are polyurethane I put in so no issue there (ah maybe the bolts there loosened?). Back to guess. Most of the time the top is naturally compressed, then something makes it hump up and gap the top of BH, that allows ring gear to scrape the sheet metal cover, and or shuddering.

Thinking of putting spacer on trans mount to lift real more and put more compression in top of BH so it does not gap.

It clutches normal 99% of time then shudders so bad it hard to get it going 1% of time. I have had friends watch from underneath(to side) trying to figure this out, we never do on shuddering. Another thought, it sheared off a 3/8" bolt at upper Psg location, that takes a lot of force.

Next step now trying to tighten the upper drv bolt, if possible.

maybe some progress. I bought 2 Motor mounts (poly) but it was so hard getting them in as so stiff, only got the drv side in (most important side). The other is orig rubber, it does look loose(rubber).

This explains the shuddering. It's the down side (less force, under compression) Hopefully the poly mount that is in has loosened some after 5 years and it will be easier to get the other one in. On XJ most things are shoehorn.

I was able by blind feel to get box end wrench on remaining upper bolt. It seems tight and looks tight.

Have a feeling if get the poly motor mount in on psg side the shuddering goes away. Memory coming back, going poly was to attack the shuddering problem and worked for a while just doing the drv side. So do have BH issues and one missing bolt, but if can get the 2nd poly mount in think will cure it.

This video shows exactly the problem I had, he had to come along pull the engine forward to get it to fit.

Re: Motor mounts --
Some patience with raising and lowering the jack under the oil pan and the bolt slid right in when I did my pass side motor mount recently. I used a regular rubber mount, but the flexibility of the material shouldn't make much of a difference when trying to get the bolt through - I couldn't move the rubber on the mount at all. I used anti-seize on the bolt to lubricate it, but once I got the engine in the correct position the bolt just slid right in.
I had a lot more trouble getting the bolt out than I did getting it back in.

Re: Transmission mounting
I think that the 3/8 pass through bolt is a concern, despite it being tight. In theory, it's hard to see how the transmission could shift when that alignment sleeve/pin is between the block and bell housing, but I'd still worry about having a smaller than acceptable bolt in there.
If the motor mounts don't resolve the issue, I'd consider figuring out how to get a snug bolt in there. (In other words, tap the original threads if they're restorable or drill up to next bigger size, etc.)

I still can't fathom how the flywheel could be interfering with the spacer plate without there being a major looseness in the mating or the flywheel mounting being off somehow.

The whole saga has been a mystery. Yes the first and only other time ring gear hit inspection plate, it was very loose (eng/BH), that is when first discovered the problem 10 years ago. And at that point trans had never been pulled out.
I can not explain with 3 bolts in and seemingly tight, how that can be, nor why 4th bolt snapped off.

On mount It is much harder to get a urethane mount in, trying to drive thru bolt it would not budge, so put back in rubber (think bot new one as so cheap).

Here is more mystery, that rubber mount looks just fine on close inspection/comparison to new part pics online. It has a gap on upper 180 degrees, but that is the way they are new. Some people make their own poly mounts, with caulk guns. Am thinking of sealing off both ends then put hole in both, insert gun and fill the gap with polyU and let it set up, maybe half way between polyU, and rubber. Nothing to lose, see if it helps.

on 7/16th bottom bolt, thinking same thing, it case torsion is issue. Will try that plus a nut on other side.

I'm a fan of the rubber mounts - unless you're doing really hardcore wheeling, I like the extra cushion of the rubber.

The only way that that upper bolt could have broken off is if someone attempted to remove it and snapped the head off or the shifting of the mating between the tranny and block sheared it off.

If the snug lower bolt doesn't correct the issue - I'd pull the tranny off and put a new clutch set in it. It's possible that the pressure plate was installed without cross-torquing and it's warped a bit, or the pilot or TOB is not right. Yes it's a PITA, but certainly is doable with normal DIY tools plus a transmission jack and a good day of wrenching.

If you live anywhere near north central MA I'll be happy to help or let you borrow my jack if you do want to pull the tranny. Edit - Just saw NV.

Extremely kind of you Pat, thanks! I am out west, Reno. Well drove the XJ to get the polyU roofing caulk, and had zero problems, even clutched it from sign in 3rd gear, no problem. Get home, drive into driveway to back up so hitting a dip then going to reverse and it shuddered backing up, Somethings it forward sometimes it reverse. The clue may be stopping shifts eng forward of something. Always a mystery. I have put two new clutches in it, made no difference. I have managed auto parts stores, it is the rare and unpredictable occurrence that is so mysterious. Most things when they go bad do not act right years later which is the case for this issue.

Cheers

Oh well next step

I can see 2 things that haven't been addressed.

#1, are you sure the transmission input shaft is not bent? This would cause vibration and tend to loosen the bolts. Add to this wear out the pilot bearing.

#2, if it's an aftermarket bellhousing, is the transmission mounting bore perfectly aligned with the center of the engine mounting bolt pattern.

Hi Dave, Thanks for your thoughts. When I first found out bell housing had loosened up, assumed that pilot bushing would be bad, hence pulled tranny out. The pilot bushing was fine, but replaced it and clutch. Flywheel was fine, no hard spots or signs of overheating.

Symptoms wise, never any issues at speed shifting up under power, never. But very rarely decelerating and putting into a lower gear down a hill have felt some shudders. 99.9% it is from a stop. Bent shaft would cause vibration all the time and less when jeep is at a stop. I have never had a clutch go bad in this XJ even though 240K on it, but in other vehicles have and shuddering is similar. I will jack up on trans that is a good test. 10 years ago that was my first guess a bad trans mount but looked at them today, not only look good, style is such very tough to break.

U-Joints are original, never gave had a car go so far without any problems with u joints, my old 53 Willys 4x4 Wagon would go thru them in 50K miles.

This has been to hell and back, just about everything underneath is dented scraped etc, had mechanic tell me in 20 years he "had never seen a car that was so torn up underneath , where has this been?" and that was 10 years ago. It will buzz down a freeway at 75mph smooth as silk and 99% of time pull away from a stop smoothly. Maybe some weird binding forward and back when engine shifts, and engines do shift a fair amount on braking.

Factory bellhousing, I bot in 2000 with 63k and it was like new, no mechanical problems for another 60K, so hard to see how tranny had ever been out.

Thanks

Doing a bit of looking around the consensus seems to be motor mounts, flywheel or oil on the disc are usual causes.

If it were me, I'd get the motor mounts squared away, get the pass through bolt tight and snug and see if adjusting the clutching helps (in other words, more/less gas etc). If it gets worse or you get ambitious, then pull the tranny and replace everything including flywheel.

I do not think oil on the disc is happening - the P.O. of my 95 used an automatic's spacer plate top half (leaving the bottom totally exposed) for 2 years/30k. The entire inside of the bellhousing was coated with oil and I never had any issue with shaking/chattering..
Premature TOB failure on the othert hand... :) :)

The mounts can look fine, but what often happens is that they separate, so you really have to pry on them to determine if they're intact. With the weight of the tranny on them they will look really nice visually, not so much when you lift the tranny up and only half the mount goes with it.. lol.

Thinking of the tranny mount - I definitely loosened mine when doing the motor mount - if you didn't do this it may have contributed to your difficulty getting the bolt aligned.

I disconnected the tranny mount, and used a wrecker 6 foot crowbar on it just to get as close as I did. On the PolyU mounts forget the brand but was bright red, they are like 5 times stiffer than a rubber mount. On that Youtube others commented they has same problem. And he had to hand winch the engine to get his to fit. Some aftermarket parts just do not fit and in this case you can not grind it to fit.

That's definitely a good idea - post up any video that you get, even if it's obvious what's wrong so we can see the results.

Good luck brother!

Ok Do have good video from many angles, but not sure still what is causing the shuddering??/ Any thoughts?

I see considerable forward and back movement, and upward movement, not just rotational.

Loose bell housing bolts just do not seem apparent here as cause.

Did jack up on both trans and oil pan since, see no issues.

My action cam, died, returned it, have order for new one, Walmart has 720 Vivitar ones for $22 closeout, get it tomorrow, will try more video tests. I am getting the big shuttering as video shows, just hard to pinpoint why.

Mounts look sloppy, also the two #12 e-torx bolts can be replaced with 3/8 x 16 x 1 3/4 in grade 5 or 8 hex heads.

The drv side is polyurethane, pretty much indestructible. There is big shudder as video shows, but do not see any defect in the mounts. Next step is close up in slomo of each mount, waiting for new action cam to do that.

The front of transfer case seems to be especially shuddering, will slomo that.

Thanks

If the mounts are good it could possibly be a warped pressure plate /clutch setup .
P.S after I used a cut-off tool om my e-torx bolts and pulled my engine I was able to take out the remaining pieces with just my fingers no tools needed, Hopefully you have a little to grab onto. If not it shouldn't be too much trouble with an easy out. I would also put a dab of anti seize on the new bolts. I'm putting it on every thing that touches aluminum .

You got me thinking, maybe I can get that broken piece with a rare earth super magnet (1/4) cylinder or superglue a rod to it to remove the bolt, it looks clean in hole.

Thanks