Surging vibration (this ended very badly) -new pics

Cougar72

Cougar72

Daily Driver
developed new issue. Car surges / lunges.

Can feel it in all gears when applying any level of torque. It's somewhat speed dependent but mostly torque dependent. As soon as clutched or coasting it's gone. Causes a rhythmic shake at a rate similar to how you would comfortably say the alphabet. It's more than just irritating, it's concerning.

Idles smooth, revs smooth, power feels normal, happens cold and hot, it's not the road surface. Worse when carrying 2 people as it takes a deeper pedal and more torque to move due to the extra weight. Mostly gone on down hills even if I stay on the pedal....conversely much worse when climbing hills

It's a very major shake, I have taken her off the road as this is something wrong that I can't yet figure out. Driving like this is NO fun and it feels like it's killing her.

Any ideas?

Dist advance freaking out and oscillating somehow?
Spark weak or improperly timed?
Drive axles CV's ?
Cylinder dying under torque?
Carb fluttering some how.?

1978 carby 1500 5spd.
 
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Likely drive shaft/CV related. Have you checked all the bolts on the CV joints?
 
When I installed a 34 DMTR the car was almost undriveable with major surging when applying throttle. Turns out the carb was jetted way too lean. If yout car was performing OK in the past with the carb you have on it then jetting for you won't be the issue but you could have a fuel flow problem causing insufficient gas. With problems like this you are apt to get all kinds of answers so just hang in there and check out each possible source of the problem.
 
Bump & Update

1. Checked all fuel related items, cleaned carb, jets are clear, nothing looks amiss.
2 Dizzy looks good vacuum and centripetal advance functions normal
3 Plugs look fine
4. all the bolts on the cv's are there and tight... I suspect VERY tight (frozen) as I have never removed them.
5. I don't think it is anything related to rotating mass, or wheel bearing as it goes away as soon as the throttle is released.

More test drives... Seems to be more of a lunging shake, than anything engine related. Still only aparrent under power. Keep in mind this whole issue is a newer symptom that has been getting more aparent. The car had run fine for thousands of miles.

Feels a lot like the lugging oscillation that some cars do after an early shift. Seems to be the same frequency regardless of gear selection, but it is speed related as (it increases its frequency with speed)

Question 1: how do I tell if my axles, (cv joints etc). Are the culprit? I jacked it up and looked and listened for axial play or binding or grumbling by manually rotating the wheels, and also did this under engine power...could not detect anything that seems abnormal. Should I shotgun it and pull and rebuild the axles (or install complete new axles) ? It also need some shaft seals on the tranny. Of note, I did notice a split in one cv boot, and I do live on a dirt road.... so possibly??? I just don't get how mechanically this could cause the symptom I have.

Question 2: is there any chance it is related to something inside the tranny? -if it could be, I think I will sell it.

Any and all help is much appreciated. Eric
 
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The lower engine mount might be the culprit. Is the passenger side transmission CV shiny near the mount where it might be dragging on the cross member?

Are all the wheels actually true? From your teeny tiny picture it looks like you are running non Fiat rims that are quite large, are they all properly hub centric still?

If you are running an adjustable camber bolt, are they all tight? Could it be oscillating from positive to negative camber under load?

Are the rear adjustable links on the lower A arm in good shape? Could one of ends be bad allowing the wheel on that side to drive forwards and back taking the wheel on that side from toe in to toe out?

I doubt it is related to a bad CV that just suddenly occurred, they die progressively.

Is it actually lunging, bucking forward and backwards as you drive or is it some other motion?

This is a thorny one.
 
Still no idea...

CV axles are out. Two broken boots, but still very well greased and they did not look too poluted, will be disassembling them and replacing all the boots...because-why not at this point, they all had surface cracks.

The passenger axle shaft does have a ring around it -but just from occasional contact with the hard rubber spray shield (covers the oil filter area) when the suspension is fully compressed. No contact with anything metallic

I Will look for wear as I clean them up - but I have no idea what I might be looking for. There is only a tiny bit of axial play.

I Will get appropriate grease for reassembly

QUESTION: do these 2 axles need to go back in in the same orientation?? Because I only know which way the long one was in... Oopsie.. I am actually thinking that shifting orientation might be a good trouble shooting step, as if it's some sort of torque wear, it will be opposite in the joints then when switched.

I looked at all the links, and ball joints - nothing seems amiss. Yes, the rubbers all look a little bit dry but all are tight, including adjustable trailing arms. I will be crowbaring on them some more to see if I can get movement

QUESTION: any thing I should look for in the outer stub axles - I don't have them out. I can't feel any lateral shifting or movement in the wheel bearings when I grab the wheels and push-pull on them.

Car has adjustable coil-overs -with camber. All fasteners seem to be solid and tight. Car has after market wheels with half inch spacers, I ran the engine thru a couple of gears while up on my jacks and stands, and there is a teeny tiny bit of out of true on the passenger wheel/tire. But even air spinning at 50mph no bump or hop -really smooth and balanced (I know that's pretty dangerous). Was careful that no one would get hurt if it left the jacks. I will put rear tires on front when I reassemble, but this can't be the problem as it only shows when under power.

Confused to say the least... The shake Only happens under power, it's quite bad, so much that anyone would say "park this thing" It's really not drivable.

I can't imagine that it's clutch related (gosh I hope not). As again it's only under power - and the clutch is not slipping.

Sigh....
 
Dumb question, but when you had it on jacks and running it were the jacks in a position to keep full weight of car on the wheel support as though it was sitting on the ground? That may change the way the axels are responding rather than if the jacks were supporting the car and the wheels just hanging.
Just a thought

Stoney
 
Very Good point... It was jacked on the center point under the engine and ramps under the front tires with Jack stands on the frame...so, yes the wheels were hanging / unloaded.... I will jack it after reassembly with the suspension loaded if I have no change with what I am already into.
 
Question... Is there a "special" quantity of grease to load these joints up with during reassembly? Or just pack em up within reason
 
Within reason. They used to come with a set amount of grease with the rubber bellows. You don't want to overpack them as they will pump the grease out in the course of suspension motion.
 
Cougar72 said:
Question... Is there a "special" quantity of grease to load these joints up with during reassembly? Or just pack em up within reason
Click to expand...
Shop manual sez no more than 3.2oz of grease.

Shop manual also sez to NOT re-use the 6 allen-head cap screws that hold each CV joint to its flange. These are of the higher strength 10.9 grade. Prior to assembling, ensure that the threaded portion of the allen head cap screw AND the threaded hole in the flange are free of grease, oil and dirt. Torque to 31 ft-lbs.
 
CV joints are inherently a high friction bearing due to their design. This is why they are lubricant sensitive, over heat when pushed at high torque transmitting levels, cook their lubricant (grease) into hard clay then fail with much drama.

In race cars, this means a CV joint failure. In road-street cars, this means clicking and wore out CV joints in short time. There are other tweaks to reduce heat in CV joints used in race cars like grinding out the ball retainer cage that prevents clacking in road-street applications, but cause excessive added friction under race conditions.

One of the best CV joint greases on the market would be Neo Oil HPCC-1, about $80 per pound.
http://shop.neosyntheticoil.com/HPCC-1-CV-joint-grease-HPCC-1-CV.htm

At much lower cost and proven good performance in CV joints, Swepco 101, about $12 per 14 oz. tube.
http://swepcolube.com/products/swepco-101-moly-grease

Similar would be Red Line CV-2, about $12 per 14 oz tube.
https://www.redlineoil.com/product.aspx?pid=82

Do not mix lubricants (grease), doing so runs the risk of unknown chemical interactions that can have very negative results. This means cleaning out the old lubricant before applying new lubricant.

Always install new CV joint screws when these are removed. The screws are M8x1.25, 45mm long, must be grade 12.9 torqued Fiat service manual spec and use a high quality 6mm hex bit or problems will be assured.


Bernice


Cougar72 said:
Question... Is there a "special" quantity of grease to load these joints up with during reassembly? Or just pack em up within reason
Click to expand...
 
Most all of the grease cleaned up.... It was still really soft, smooth and not cakey at all. Both axles are soaking in my parts bath now... Will be sparkly clean tomorrow. All 4 joints do feel a bit "binding". But I suspect that I am bending them beyond their normal travel angles and also the grease is now gone.

I see the "C clip" to slide them off of the axles, Do they just fall apart once they are off of the axles? What should I look for in the way of wear? I did see one hair of loose metal ... It was like a hair in thickness and about an inch long. No other shavings or pieces of anything as I searched all the grease I scraped out.

Sorry so many questions, I have never pulled a cv apart before...and I could not find any good threads searching here on X web

I use a lot of redline oils/lubes. So that will be what goes in. I get it at the local "WINE Country motorsports". Strange name but has good racing stuff.

If I see anything that looks strange, I will post a picture.

Fingers are crossed that something fixes my surge/jounce issue.
 
HOWDY ALL, I have an update... and its not a pleasant one.

1. I removed the axles and fully cleaned and disassembled the CV's I noted their original position (driver/passenger & Inboard/Outboard)
2. I fully cleaned and inspected them. There was only one spot on one of the races that had a very small wear dent
3. I reassembled all of them and switched them from inboard to outboard AND ALSO I switched them from driver to passenger - this completely switched up their rotation and pressure spots and angles when under torque as all 4 of them are the same part. I used proper CV grease and new boots and new proper hex bolts to attach the axles to all the stubs.
4. I went for some test drives ( total of 50 miles) and although it seemed that it made a difference ( 30-40% change for the better??) - the issue was not fully corrected.
5. I sadly parked the car for a few days and pondered my existence
6. After a week of pondering.... I decided that I would now adjust the car back up to its original height (or even higher as a test) - My car is what today they call "slammed" as I have adjustable coil overs and they are set with the car super low to the ground - to the point that there is almost zero clearance for wheels and like only 3 inches clearance from its belly to the asphault. My thought was that it would straighten out the axles a bit and reduce the acute angles on the CV's and thus reduce the movement and positions of the ball cages as the axle rotates.
7. My plan was to go on a short well known drive and carefully notate how much of the surge/shake was occurring and where and then come back and adjust my coil-overs... and do the exact drive again to see if there was any noticeable change.

This is where everything went very wrong - very very wrong.



While heading down the driveway for the pre-adjustment test drive - at 8 MPH coasting in 1st gear the tranny exploded - YEP, exploded!!!. the whole differential area blew out the case top and bottom. You can grab the speedo cable and pull it up into your hand and it has a 6inch piece of the case still attached to it. and 100 bucks worth of redline MTD painted my driveway with a 4 inch wide stripe as I coasted to a stop - I suspect this new "graffiti" on my driveway will continue to remind me of this unpleasantness (and worse remind my wife) for quite a long time.

I will start a thread related to the tranny with some pictures at some point here soon with additional descriptions and my plans to remediate.

I talked to Matt at MWB and he does not believe my work on the axles OR the jounce/shudder/surge was related to the tranny exploding - but it was not conclusive. He speculated that a bolt backed out of the differential ring gear- <shrug?>and bound up / blew up. Matt did mention that he too has experienced the shudder I describe, and that I was on the right path to solve and troubleshoot it. and the next steps would be to more closely inspect motor mounts

So in summary, I don't know yet what will resolve my shuddering issue noted in this thread - AS I NOW HAVE BIGGER PROBLEMS TO FRY..... (crying)
 
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I just took apart my '81 transmission that I am not going to do anything with. There is some wear on most of the gears (5th is trashed), but the case is intact (a bit greasy). The differential and shafts all look good. It is all apart and you are welcome to any or all of the parts that you want. Just pay for the shipping.
 
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