This past weekend, I did my first track event of the year (have been doing them for the last 18 years).

I started hearing a clunking noise from the rear. It sounded like it was coming from the Left Rear (Driver side). I checked it out and the only thing I could find was that if you grab the axle shaft and vigerously shake it side to side, the axle shaft will bottom out and cause the clunking sound I am hearing out on the track.

What I believe has happened is that there is no grease left at the end between the stub shaft and the end of the axle to cusion the shaft movement.

Here is part of my problem. I bought the axle shafts from Patrick Motorsports 2-3 years ago when I did the 915/916 transmission, and they are different axle shafts. The stub shaft is connected to the CV joint and the other CV joint (tranny end) has a sealing cap crimped to it. I don't know if it is perminantly attached, or if it comes off.

Are the axle shafts worn out when you can move the axle shaft like this, or do they need grease. If they need grease, how do I get the grease in where I think they need it?

The only changes I made to the rear suspension this winter was to lower it about 3/4" (axle shafts are horizontal), increase the spring rate from 350# to 400#, and align it. I have checked everything out and nothing is loose.

Any ideas, suggestions, or wisecracks welcomed.

Hey glad to see somebody else from the area with a 914...

Not all 914's live in Calyfornya.

What part of MO are you in? I NEVER see any out driving around.


Anyone have any ideas about these axles? I ordered a new set from Patrick Motorsports just to be safe..... (I never wore out the 914/6 axles, just the 901 box)

I live just north of the airport but the 914 has been sitting for a few years. just got some new calipers from eric shea gonna try to get them on this week and rebuild the carb, and try to fix my wiring where the mice have been dining.

Were the CV's cleaned and packed before they were installed?
If you remove the springs and move the suspension through an arc, does the driveshaft bind?

If you are hearing noise then in my opinion the safest thing to do is take the axles off and inspect them. If you don't see obvious damage them repack with good lube, reinstall and check them out.

I hate working on axles - one of the worst jobs (mess) period. I went to an off-road business and the sand racers all have extreme axle lube needs so I figured I would use what they do. The guy behind the counter said to mix 50-50, a tube of Swepco 101 Moly and a tube of BelRay lube and repack the axles. The stuff is outrageously expensive though.

The axles shouldn't hit the stub axle.

What axles are they? My guess is they are too long. By lowering your car you are now in essence seeing the full length of the axle in their new horizontal stance and it is hitting the stub axle. No amount of grease will stop it. You may be able to remove some material from the inside of your stub axle but it sounds like the axle length is wrong. You'll also wear out your CV's much faster than normal. I recall this being a problem with 911 axles in 914 applications... don't know for sure.

Just a shot in the dark.

I thought the 911 axles were shorter, although Brad said it was not much of an issue. Perhaps if the axle was stretched too much too often it may have popped loose or something. However with stiff springs the suspension should not have much travel. Still waiting to hear how they were prepped on installation.

QUOTE

I thought the 911 axles were shorter

Could be... I just remember something being said about them. It does sound like his axles are too long, if they're hitting the stub axle when you rock them back and forth

These perticular axles came from Patrick Motorsports.

They were new 2-3 years ago.

They came sealed up and were lubed.

These have a 911 CV joints (to work with the converted 915 gearbox). The outer CV joint is also the stub axle.

When I installed these axles, they came with a spacer that went between the stub axle and the Rear Wheel Bearing. I believe the spacers were about 3/8" thick.

These same axles have been used for the last 2 or 3 seasons of DE events without this clunking issue.

I agree with the idea that now that the ride height is lower, the axles are now effectively longer.

Patrick Motorsports offered to sell me MORE spacers to put in there, but I'm thinking that I may need LESS....


To answer some of the questions...

While the car is up on the lift with the wheels off the ground, there seems to be no binding of the axles as I rotate the wheels. I can set the trailing arms up on blocks (to simulate sitting on the ground) and feel no binding of the CV joints. The only symptom is that the axle shafts can move toward and away from the transmission easier than I believe they should and can "bottom out". I think that when they "bottom out" on the track it is just touching or it would really make a hellofa knock.

This same car ran for years on the track with 914/6 axles and CV joints with no issues.

These are indeed 911 axles (per Patrick Motorsports).

Fuck it. I'm taking the spacers out to see what happens.

(I may have to limit the downward travel of the trailing arms somehow)

Any suggestions? I'll try pulling one out tonight and take a pic......

Yup they are 911 axles. I pulled them out tonight.

Another Pic. I took out the spacers and got the axles back in tonight.

I still need to torque the axle nuts when I put the car back down on the ground.

Did you find any dimples or dents on the caps?

No there were no dimples or dents in the caps. They looked good to me, so I put them back in.

We had another DE this weekend Fri, Sat, Sun.

The car still made some of the noises, but it was not as bad.

The clunking is not noticable under power, but under light power or coasting through a turn, the clunking returns. While at speed and pushing the car hard, no clunking noise is noticable.

This is a weird problem and even Patrick Motorsports does not have a clue as to what this might be caused by.

I guess that replacement of these 911 axles will be necessary, but it seems like these did not last long at all (these are only 3 years old).

When I know new ones have been ordered, I will probably figure out a way to remove the caps and rubber boots to try to inspect the actual CV joints themselves. It sure feels like the CV joints are very loose (especially on the stub axle side).

Any suggestions as to how I should try to get the caps or the rubber boots off of the CV joints?

As an update to the noisy CV joints. I replaced the axles with new (911 Carrera axle assemblies) from PMS.

Today at the track, there was NO clunking noises from the rear of the car.

It was indeed the axles.

In the many years of D.E. events, I have never worn out a CV joint and up until a few years ago, we were using the 914-6 axle shafts/CV joints.

Is there some problem with using the 911 axles in a 914 (too long/too short)???? Are these new axles going to wear out in a year or two like the old ones?

I just thought I would share my experiences with the PMS supplied 911 axle shafts.

most guys running track events repack the CV's AT LEAST once a season.
the hot setup these days seems to be Swepco Moly, although in the past i have always had excellent results with LubroMoly CV grease.

something that's also frequently done is to swap the axles side-to-side with each R&R to equalise wear.

the inner CV's have a very hard life - behind the engine, next to the transmission, above the exhaust.

QUOTE

most guys running track events repack the CV's AT LEAST once a season.

Yes this was the case when I ran 914 parts. When we went to 911 axles this seems no longer totally possible. (refer to pic above showing the sealed axle assemblies)

The inner CV joints on 911 axle shafts could be repacked as that half comes apart. (I think)

The outer CV joint (the one with the integral stub axle) is the one I don't have a clue as to how to get apart.

If you know how to dissassemble the outer portion, please enlighten us, as these axles are not cheap.

Thanks,

QUOTE (JOHNMAN @ Jul 9 2005, 08:00 PM)

If you know how to dissassemble the outer portion, please enlighten us, as these axles are not cheap.

some FWD cars used a similar CV, and had a circlip that could be used to release the joint from the axle. you might look for such a mechanism on those, but my understanding is that they are, indeed, not dis-assemblable. you'd hope there's some documented way of cleaning and relubricating them but i don't know what it is. i'd guess that hot-tanking it, with an ultrasonic cleaner to break up the dead grease, would do it, and grease re-introdued to the joint through a really thin tube.

it's possible that they're considered "lifetime" jints, in which case, you kinda hafta hope there's really good grease in there.

but the outers don't have nearly the issues the inners do. i'd guess that if you disassembled your axle joints, you'd find that the outer is still in pretty good shape but the grease in the inner is dead.

Well, since these axles are not going to be doing any good anymore, I will take them apart (one way or another) and figure out how to get them back together. This will be sometime when I have some spare time to kill on such a thing (not anytime soon).

I'll be sure to take pictures when they come apart. I'm expecting that they will be very "loose" when I go to get the balls out.

I am guessing that both ends are going to be too loose.

At the same time, I will be documenting the dimensions between my old 914-6 axles & CV Joints as opposed to these 911 axles & CV Joints, since I can't find anyone to verify that the 911 Axles & CV Joints are shorter or longer than 914 parts.

I will start with the Trans flange width and work toward the wheel hub. Look for more info this fall.