Rythmic right wheel knocking sound :-(

[CamB]

Hi all

New problem for me. Driving home last night after a busy afternoon accelerating unnecessarily up to the speed limit in second gear all over town (important to, ah, clean the plugs...), I now have a new, worrying noise.

It started as a quiet tapping sound when accelerating, from the right side of the car. After about 1 mile it became more of a knocking sound (like someone rapping their knuckle on the underside). It is now pretty loud (and concerning).

The noise is:

- dependent on road speed
- not dependent on engine speed (phew)
- pretty much goes away when clutch in or in neutral
- much worse when going uphill (ie greater load on engine)

I jacked up the car when I got home but nothing seems out of the ordinary when I turn the rear wheels. Maybe the RHS has the odd click a little more than the LHS?

I am surmising it is a CV, but this doesn't explain the incredibly rapid deterioration (over the course of about 1-2 miles) and it is more knocking than clicking. Can they suddenly fail????? Car still drives ok, just sounds bad...

Can anyone help? I will need to take it into the shop and want to give them a lead and make sure I keep them honest. I also need to try and figure out how many $$$ I am up for

Thanks!

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Cameron Baudinet
1975 911S (in bits)
1969 911T

[89911]

My CV joint went and it sounded like someone was underneath my car knocking on it with a rubber mallet. It was dependant on the rolling speed of the car and not the engine. I noticed this after a full weekend of DE's and only on the ride home so they do happen rather quickly if this is the problem. I replaced both of them while I was at, cost is about $225/side, excluding labor.

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8 9 9 1 1, The last of the line.

[Early_S_Man]

Cam,

Sure sounds like a CV-joint has lost its' grease, which can happen rather rapidly at road speed ... makes a big mess, too! Look for a black spray pattern on the underside ... not more than 100 mm wide. The boot will be visibly torn or cracked, and will be noticeable with one wheel off the ground, if you turn the wheel with transaxle in neutral.

Here are some tech. articles of interest, with very good pics:

http://www.type2.com/bartnik/cvjoints.htm

http://volksweb.relitech.com/cvjoints.htm


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Warren Hall
1973 911S Targa
1992 Dodge Dakota 5.2 4X4 parts hauler

[CamB]

Thanks guys. I will try and have a look tonight. It is pretty muhc like the rubber mallet sound (a pretty small mallet at the moment).

If I am going to have to take it to the shop (too much work on - weekends for a couple of weeks as well), can I safely drive it there or will I wear out something important other than the CV to be replaced.

The mechanic is about 2-3 miles away.

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Cameron Baudinet
1975 911S (in bits)
1969 911T

[Superman]

You won't hurt anything but the CV joint. the biggest danger is if the joint comes apart altogether, then the car will need towing. But I doubt that will happen.

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'83 SC

[critter]

You have probably already checked this but I would make sure that your wheel nuts are Tight.This exact thing same thing happened to a friend and it turns out that his lugnuts were loose.

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Grant 75 911s targa

[Bill Douglas]

Cam, it sounds a bit like a parking warden wrapped around your CV.

[CamB]

Nah Bill, that is more of a whumpawhumpawhumpa sound...

(Bad taste, I apologise)

[expat]

For my 2 cents I reckon its the clutch. I Had exactly the conditions you suggested and thought it was the CV's but no. I have a 87 so I'm not sure whether yours is similar but the clutch on mine has the rubber dampening clutch disc and it was this that started to break up after a few 'spirited' runs and caused the thump thump. This eventually got worse and hence the change of disc, release bearing, flywheel machining etc.
Good luck
Mark

[CamB]

Just to update:

It was the CV joints (well, one of them anyway). The shop pulled all 4 drive shafts, cleaned and repacked the CVs and reinstalled (plus one new boot). Cost was NZ$260 (which is only about US$105, but was pretty much all labour at NZ$60 an hour).

The CV's "all showed a fair bit of pitting", but since they are NZ$275 each, I am not keen to replace until I have no choice.

Either way, it is quiet now (well the CVs are). The mechanic said they were very very dry and hadn't had attention in a very long time. I'll see how they go.

Cam

[lsolon]

Wow, "that's cheap"!

[CamB]

Not if you earn NZ$ too

[Fishcop]

I feel your pain Cam, Aussie is not much better (.48 of US$)

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John Forcier
69 911T

[89911]

Could my correct answer qualify for Wayne's book?

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8 9 9 1 1, The last of the line.