kingtaco

Good evening audi world friends. This is my first ever post here, so thank you very much for taking the time to read. Usually I just read the forums, but I am finally stumped and am seeking some input. Audiworld seemed more active than audizine for older models so here I am.

The car:
Recently acquired 1995 Audi 90 FWD
5sp manual
205k miles

Here are the key highlights of what is happening and where I stand to date. Each event is bulleted:

• First time jacking vehicle up I notice right (passenger) outer CV boot is torn. Noted so I add it to the parts list and plan to replace soon
• Shortly (30 or so miles) after, I begin to feel vibrations at speeds of around 40mph and up. Quickly jerking the steering wheel left makes the vibration go away. Diagnosis: bad right axle, replace entire unit
• New unit is a advance auto brand new carquest axle. I am aware aftermarket axles "suck" but it was the only one available at the local parts stores and I wanted it asap
•When removing the old unit I noticed the old axle was missing 2 out of the 6 total m10 triple square bolts that hold it to the flange on the transmission side. The remaining 4 were finger tight. I said hmmmmmm? but proceeded to do the job and got 2 new bolts to replace the missing bolts
•Initial test drive: total death wobble at all speeds above 20mph. Cannot begin to imagine what is wrong but start blaming myself for buying a parts store axle.
•Second test drive after changing out a wheel (thinking maybe that tire is just way out of balance) I hear BANG BANG BANG at about 20mph.
•Successfully limp the car home (2mph ish haha. Feathering the clutch) and realize the axle is totally snapped at the inner CV joint
•Stillllll thinking maybe the parts store axle was just ****, I put the old axle back in. Initial test drive indicated if I drove it any longer it would most likely snap this axle too.

SO. What is causing my axles to want to snap and total death wobble??? The only thing I can think is that I have a shot transmission mount. I included a pic of the passenger side mount. It looks a little beat but I was hoping for worse given the severity of the symptoms. This could possibly explain why the bolts loosened up on the original axle. It could also be explained by if the trans is bouncing around while the car is in motion, it is tugging on the axles and causing a death wobble.


Last notes:
•Death wobble is independent of gear or anything of that sort. Strictly speed related. Anything 20mph does not feel safe
•The issue came out of nowhere, so I do not suspect wheel balance. However I needed new tires anyway so they will be getting mounted and balanced tomorrow and I'll take it for a test drive after that
• I took out the axle by unbolting the strut to knuckle bolts. I allowed the knuckle to swing down and pulled the axle out that way. Since I didnt mess with any of the steering components, I do not suspect bad alignment. Alignment also rarely exhibits a condition of shaking wheels.

Thank you for taking your time to read. Please share with me any ideas you may have, or similar stories you may have heard or experienced.

-Mike

Rusty Spokes

Very weird..looks like the inner CV did not "snap" or break the axle..looks like the tripod pulled out of the CV cup...is that the case? Is the replacement axle the same length as the old one? Was the inner CV boot broken on the old axle or did it break when you re-installed it?

If so..something is moving around allowing the axle to move laterally, pulling the tripods out of the CV cup (which are supposed to be removed by taking an inside cover off the CV cup..not out towards the wheel..as I recall)

Could be the engine or transmission mounts or the sub-frame bushings or the lower "A" arm bushings..something is allowing the transmission to wheel distance to change. Is the right side transmission flange still secure in the transmission..and not floating around? It is held in with a "C" clip #7 in the image..very odd if it is loose.



The lower "A" arms are almost always shot on a used B4 unless the PO took care of the car. Sub-frame bushing need to looked at too...if the tripod pulled out..there is way too much lateral (side to side) movement going on.

kingtaco

Thank you so much for your reply.

To start, the old axle did not break at the inner CV boot. When I installed it back into the car, I got the sense that if I continuted to drive it, it would break in the same manner that the new axle broke in.

When I say the "axle broke" I didnt mean the axle itself literally snapped. I'm not entirely positive how the inner CV boot broke. There is so much fresh grease it's hard to tell exactly. If you say the cup pulled out I'm sure that's what happened. I can see a bunch of needle bearings and the u-joint looking piece is missing one of the round pieces. Sorry for the lack of technicality.

When I did reinstall the old axle, I checked the flange on the transmission side because I also suspected that component. It seemed to be regular, no issues, however didnt see the c clip you speak of.
No concrete knowledge of if it is the two axles were the same length. I did a rough measurement and it checked out. Regardless, both axles exhibit the same symptoms, and it began happening randomly so I think we can rule out axle length.

I 100% agree that there is too much lateral play. I can feel the wheels "shimmying" underneath me moving back and forth. Steering wheel not shaking very badly. As I said, I suspected the tranny mounts, but cant really visually determine if they are good or bad. Is there any way to do so? I hate to throw parts at the car and tranny mounts aren't cheap.
Speaking of, where can good mounts be bought?
I will also look into the A arm bushings and subframe mounts. But all those bushings could soley be the cause of significant lateral play?

Cannot thank you enough for your response.

Rusty Spokes

That "C" clip is inside the transmission..so long as the output flange is secure and not bent or wobbly..it should be fine.

Lateral movement could be bad sub-frame bushings or "A" arm bushings (a combination of both maybe) bad lower ball joints or even a wheel bearing.

You will have to get the car in the air and inspect. Pull on the right wheel and see if things are moving around. See if the sub-frame is loose or the bushings are gone.


There is a picture of the sub-frame. As you can see the transmission mounts on the sub-frame at the rear.




Here is a shot of the sub-frame with the "A" arms (your "A" arms are likely forged and not cast like the ones in the picture).

You have an unusual problem..inspect and post any solutions.

grillage

The two axles are NOT the same size.

You may notice one has a single indention in it and the other has two. With OEM axles, the drivers side has one indented ring, the passengers side has two.

When I did the manual swap on my cabriolet I took some pics:

kingtaco

I understand the driver side and passenger side are not the same length. I ordered and received the correct part for the application, and did a rough measurement before I installed, and then it broke. Additionally the axle shaft that was in the vehicle when I bought the car WAS fine before the vibration started. It is NOW too vibrating and I do not suspect it grew in length haha.

@Rusty Spokes thank you again for your detailed and thoughtful response. By A-arm I assume you mean control arm bushings?
Ill be pulling it into the garage this evening to check over all the bushings you mentioned. As it stands I'm preparing to replace the following parts and will do everything in Driver and Passenger side pairs:

•Ball Joints - Moog from Rock Auto
•A-arm bushings (control arm bushings?)
•Tranny mounts - Rock Auto unless someone can suggest a better supplier

I will probably hold off on the subframe mounts for now since it seems much more involved, and I suspect doing the above parts alone will make a drastic improvement.

Rusty Spokes

I would wait till you get the car in the air..the list you have is a good though.

The "A" arm bushings at part number 893407181 (for the forged A arms)..if you can find them try Lemforder. Moog would be okay too. Meyle is a crap shoot, although the HDs are supposed to be better.

They are fiddly to remove and replace..I use a press. There is a write up over at Cabrio-Info..I will try and find a link. You should replace the bolts/nuts too. You will need an off-set wrench to get to the nuts. Once done you will need to "load" the front wheels prior to tightening the A arm nuts..if you don't it will tear the rubber and destroy the new parts.

The RA tranny mounts are probably better than your old ones..Pelican has the mounts part number 8A0399151D..made by Meyle for $17 each.

kingtaco

So this is a bit of embarrassing news to share.

Earlier today I had some fresh rubber mounted on the stock wheels. The car came with 2 sets. The other set is Borbet 15 inch 5 spokes. I like the stock wheels more so the Borbets will be for sale locally in NY if anyone is interested.

Anyway, before changing over to the stock wheels and tires I went to check the play in the ball joints and bushings on both sides. The driver side the lug nuts were less than finger tight! Wow. Horrible mistake on my part. Not sure when exactly I forgot to torque them down but im sure that would have a lot to do with the start of my problems.

Could this explain why I broke that new axle? It was the passenger side axle I replaced and the driver side lug nuts that were loose most likely the entire time the axle was installed.


Results of checking for play in the wheels:
Absolutely zero radial or axial play. I can definitely move the wheel side to side, however. This movement is allowed by the tie rods. Not sure how much play is acceptable.


Good news also. Drove the car after throwing up the freshly mounted and balanced wheels (old axle with torn boot still in car) and it drove like butter. Did 60mph very smoothly but was not going to push it past that.

Rusty Spokes

I think you got a bum or incorrect axle..originally. That is why it failed.

That side-to-side play, being in the tie rods, is not normal. Take a look at the tie rod ends, are they loose? The other end of the tie rods is bolted to the steering rack..is the rack secure? Some slight internal back and forth movement in the steering rack assembly is normal..but the tie rods and rack should be firm.

kingtaco

I'm thinking exactly the same thing. Two sets of symptoms happening at once. Forgetting to torque lug nuts combined with a wrong-length axle producing some dramatic sensations.

Everything seems to be back in check right now. I will probably reboot the axle with the torn boot instead of replacing the entire assembly.