CV joint making noise?

[vanwyk4257]

I just bought a '66 912 with only 39,000 original miles on it. It has been converted over to Lobro axles from the original Nadella's, although I don't know when this was done or how many miles are on the Lobro's. There is no noise from the car driving down the road, but if I take a right-hand corner at a quick pace there is a groaning noise coming from the LH rear corner of the car. The noise seems to pulse with the rotation of the axles and stops as soon as the car is straightened out. I don't think it has anything to do with the brakes or wheel bearings as the car doesn't make the noise in a straight line or in a left-hand turn.
Am I on the right track thinking that it may be a bad CV joint, or perhaps it just needs to be repacked with grease? Any insight would be much appreciated. Thanks!

[Grady Clay]

Michael,

Congratulations! Good find.

First I would check the lug nuts.
Next I would check to make sure all the CV bolts are tight (M8 = 32 ft-lbs). Also check the big castle nut on the stub axle is tight (221 – 258 ft-lbs). You will need a new cotter pin.

That kind of noise can be the CV, the wheel bearings or the rotor rubbing on a pad from some deflection (possibly something loose). With the tire off the ground, grab the wheel and wiggle. Put a wrench on all the hardware.

With about 40 years, the grease in the rear bearings or CVs can be dry.

Check both sides, noises can fool you.

Best,
Grady

[Zeke]

The CVs can make a clicking noise, I don't know about a groan. But, I wouldn't rule out the bearing, even the front one as the noise does transfer thru the tub and it's sometimes hard to tell where it's coming from even when you think you know..

[Nine9six]

I'm with Grady on his diagnosis...

[Breeang]

I had a rear wheel bearing go bad,and it made a moaning/whining noise when driving in a straight line but stopped as soon as I changed the weight loading with a left turn,and it got worse with a right turn.When I got it out to change it,the grease was all dried out and there was a definate smell of overheating to it.

[vanwyk4257]

Thanks for the input guys. It was definitely coming from the rear LH corner of the car. I will be checking everything over anyway before I do a DE in April next year with the car. At least now I have a list of things to check!

[randywebb]

It might be smart to invest a bit more time, and just about a $1.50 to pull each CV bolt out -- one at a time -- and put a new Schnorr lock washer in - they are cheap and should not be re-used.

Also, on any car you buy - replace the rubber brakes hoses, fluid; the engine oil and filter; and the tranny oil.

Enjoy the new ride

[vanwyk4257]

Thanks Randy, I planned on replacing all of the CV Bolts and washers when I pull the CV's out. I also planned on draining the gearbox and putting in some fresh swepco. The brake hoses look like they were recently replaced, but I'll look the brake system over very carefully anyway as I'm upgrading to a dual circuit master cylinder, and the engine oil's gettting changed as soon as I receive my deep sump kit! My list of things to do keeps getting longer...

[Grady Clay]

FYI,

The CV bolts are M8x45 12.9 internal hex wrenching available commercially from our host. Same with the M8 Schnorr lock washers. Make sure you have the washer (“moon”) plates between the lock washer and the tin cover.

The Porsche OE part number for the bolt is: 900.067.073.01 and 999.332.102.02 for the lock washer.

When you convert to the dual master cylinder, you will need the dual brake fluid reservoir from ’68 and later. That is very noticeable to experienced Porsche types. An alternative is a second reservoir, next to the original, in the Smuggler’s Box. The reservoir is a very standard Alfred Teves (ATE) part from the period German cars. The mounting bracket can come from a donor chassis.

Some other things you will want to look at are:

The accelerator cushion probably needs replacing.

When you have the master cylinder out, disassemble and lube the pedal assembly. I prefer the OEM plastic bushings. Take your original accelerator pedal and get some oil to the hinge via the openings at the mounting bolts.

Check the steering damper for function. I’m sure the part is NLA but I have heard that shock rebuilders can make it new. It is very similar to a VW part.

The OE connection from the clutch cable to the TO bearing arm was white plastic. There is a steel replacement part that is “failure proof.”.

Cycling the brake caliper pistons with some silicon lube may extend their life before a rebuild. You should start collecting the rebuild parts now.

Remove the fuel level sender and inspect the bottom of the fuel tank. You will probably want to pull the outlet filter screen fitting for cleaning. Your 912 could benefit from the ’70 911T Bosch electric fuel pump that mounted on the front suspension cross member. You can “gut” the 616 engine mechanical pump so it appears original or use just the OE fuel pipe-tee assembly to the carburetors.

A nice cleaning and lube of all the throttle linkage from the pedal to the butterflies is in order. I would disassemble the shift lever assembly and inspect, clean and lube. It is then good for another 40 years.

I can think of a lot more. We should develop a check list for low mileage/low use early 911/912s.

The biggest issue is it has “No Rust” but has spent 40 years priming for the dreaded unseen oxidation of its steel. Needless to say it shouldn’t be exposed to any corrosive environment (even like water or humidity). You need to make sure all the little chassis drains are free of any rust debris (yes, it is there). The torsion bar tube is of particular concern as it isn’t vented and can retain moisture. A good preservation procedure is to take the torsion bars out, vacuum up the rust, drill a 12 mm drain/ventilation hole on each side (like the later 911s), coat the inside with a mixture of heavy oil, light solvent and Tectyl (a wax), re-coat the torsion bars with grease and reassemble.

The area of the chassis just rear of the door has a hat-shape reinforcement. That provides a vee-trap for road dirt and must be clean. The bottom rear of the front fenders has a drain for the double panel. That should be free of debris and allow you to insert a catheter to add protectant to that critical double panel. The rear window and windshield seals may have leaked and those areas need to be preserved.

When you are the current caretaker of a nice early Porsche, it is your responsibility to preserve it in the best condition possible. Not an insignificant task. Good for you.

Best,
Grady

[Superman]

Wheel bearing, probably. CV joints don't make the same noise. They click, and they can shudder and vibrate, but growling is a wheel bearing noise. Lift the rear, separate the brake pads so they are not touching the rotor, and spin the tire. if you hear ANY noise whatsoever, it is a bad wheel bearing.

[randywebb]

"insert a catheter"

- OK, I see we are picking up some terms from "life experience"... hope you are feeling well.

[Fishcop]

My "clunking" noise during turns ended up being wheel bearings...

[randywebb]

re shift lever - check out Sherwood Lee's web site for instructions on this

Inspect wheel bearings

Search up the Long Term and neglected Maintenance thread and review those items -- if ther eis no recept for something, inspect carefully & with a jaundiced eye... if any doubt, do the repair/maintenance/repair....

Generally, you want to think about what you are going to change/replace and what will be rebuilt/adjusted. e.g. if you are going to repalce the shift lever with a 1985 one then no need to adjust a moderately sloppy old one in the car.

[vanwyk4257]

Grady, wow, great list of things to check! I'm fortunate that this car appears to have spend most if not all of it's life in a garage and obviously being about 40 years old with 40K on the odometer it was probably never driven in rain or snow! Even though this is only a 912 I do plan on keeping it for many years if I can help it. The early SWB body is just sex on wheels to me, it is right up there with the 904 in terms of appearance. I will be doing some carefully planned mods for doing DE's including installing harnesses and a roll bar, but I will be removing the original carpet and interior panels so I don't have to cut any of it and I'm going to try to attach the harnesses to the seat brackets as much as possible. Everything that comes off of or out of the car will be carefully stored in my dry basement to be put back on the car some day. I don't plan to hot rod the original motor either, I'll probably source another motor to build in a couple years to preserve the original one. Thanks to everyone for all of the input. I definitely know where to start now! Cheers!