Possible Transmission Failure

lucasdw63 · 12-14-2013, 08:31 AM

Tried to take my 1981 911SC out for a drive this morning and pulled out of my driveway and all of a sudden I heard a clunk clunk then none of the gears worked. When I try to engage the gears I hear a metallic rattling coming from the rear of the car. How bad is this?

Trackrash · Trackrash's Garage

Today is your lucky day. Sounds like a CV let loose. Good thing it was in your driveway and not on the freeway.

lucasdw63 · 12-14-2013, 08:49 AM

So what now? I sounds more ominous that a CV joint!?!?

pete3799 · pete3799's Garage

Sure sounds like a CV to me too.

pete3799 · pete3799's Garage

Jack the back end up and see if one of the axles is disconnected.

aquazulu2 · 12-14-2013, 08:57 AM

Metallic rattling noise associated to transmission could be very bad news. Did you launch out of the driveway, did you miss a gear.

kodioneill · kodioneill's Garage

Axle C/v joint.

lucasdw63 · 12-14-2013, 09:19 AM

I backed out of the garage as I normally do; all gears were functioning, then when I went to drive down the road from reverse to first there was no response. I cycled through the rest of the gears to see f I could get a response and all I heard was this rattling sound!

I will put her back in the garage and check put the CVs as recommended. Thanks

lucasdw63 · 12-14-2013, 11:19 AM

You guys are geniuses. I got the car back into the garage and sure enough the left rear CV bolts have backed out. is it as simple as screwing them back in to fix the problem?

Bob Kontak · Bob Kontak's Garage

For now, I would think so. Re-tighten the bolts on the other flanges also.

The bolts that became separated have been beat up a bit so best replace them in the fairly short term depending on how much you plan on driving this winter. If a bolt is not straight, don't force it in.

That's just thoughts from a drive train layman.

lucasdw63 · 12-14-2013, 01:12 PM

I had a chance to take a closer look at the situation and what I found is all flange bolts on the wheel side have backed out completely so that the entire assembly is detached from the wheel. As I go in to re-attach the joint to the wheel is there some kind of way to get the joint aligned to the wheel so that I can screw the bolts in?

RWebb · RWebb's Garage

not sure what you mean, as you just turn the wheel/axle and line them up

but, first STOP

take each bolt out and inspect it carefully - use a magnifier if you have to

look at the threads to make sure they are in good shape & the wrenching fixture in the head

then go buy some brake cleaner and clean the threads on each cap screw of all oil, grease etc.

also clean the female threads inside the thing the cap screws go into - use Q-tips with brake cleaner on them & clean until the Q-tips shows NO grease after cleaning

you will do this while you are waiting for new Schnorr washers to arrive as they must be replaced each time

search on Schnorr for more info

use a good torque wrench whose calibration you have checked

hcoles · 12-14-2013, 04:10 PM

you might also look at the surfaces that come together and stone down any burrs that got kicked up as things came apart, this will help get things solidly reattached

lucasdw63 · 12-15-2013, 12:26 PM

Looks like things wont be quite as simple as cleaning thigs up and replacing washers before re-assembling.

I took all of the bolts out and inspected them and discovered one has been broken off so I am going to have to remove the broken piece from the part that it is screwed into.

Does anyone have any ideas on how to go about doing this and does anyone have a exploded diagram of the assembly so I can see what I am working with. I looked at the parts diagram online but don't see the piece that the broken bolt is screwed into.

Thanks in advance!

porwolf · 12-15-2013, 08:15 PM

Here are some links I collected just in case, that might help...........

CV Joint Failure Carnage

CV joint bolts/screws

CV Boot replacement rebuild part 1

Reconstructing Constant Velocity (CV) Joints

CV Torx Bolt sources?

Removing Half Shaft

CV Replacement Question

kodioneill · kodioneill's Garage

If the bolt is broken off then the tension is gone it should just back out with your fingers or pliers if necessary.

OsoMoore · OsoMoore's Garage

It will be a messy job but shouldn't be that difficult. I had a bolt break off (over-torqued) and was able to back it out with pliers.
You will probably want to clean the joint that is open and re-pack it with grease. If any grit got in the grease, you will have a CV joint failure before long and then you will have to take the whole thing out, which is an even bigger and messy job. That was last summer for me!

Bob Kontak · Bob Kontak's Garage

The "Reconstructing...." thread porwolf posted is a good one.

The 81 (non-turbo) has 8mm bolts, no washers, no moonplates from factory. I don't believe you can buy these parts (washers/plates) from Pelican so you have to source outside. The threads will give you direction.

Take your time. On the bright side, your trans is ok, right?

lucasdw63 · 12-16-2013, 11:29 AM

I suspect the trans is OK. The Joint on the trans side is intact. There is nothing for me to grab onto with pliers on the bolt-head side, is it possible that I could have something to grab onto on the wheel side?

HawgRyder · HawgRyder's Garage

Aren't you glad this happened a car length away from home?
This makes the idea of checking the car on a regular basis a good idea.
If you find something loose or broken...it's always cheaper and faster to repair it at home (your tools and sweat) than it is to have the car towed to some place that will probably over-charge you for a less than superior job.
No ill feeling towards repair facilities...but I like to rely on my eyes, hands, and brain for repairs (I'm cheap...LOL).
Bob