CrookedRacer

Coming home from my track weekend in March, I was about ten miles from home when I realized the rear end would make a pronounced TICK TICK TICK sound when the car was under acceleration. If I recall correctly, it made the same noise, but not quite as loud, when engine braking. When it was coasting it was silent. It was happening in all gears.

I've just replaced the rear bearings, so they are solid and they turn easily. So that leaves two diagnoses: bad CV joints, or a noisy transaxle.

Inspecting the rear end noise:

Tonight I took the axles off the car and I was disappointed that I didn't find any smoking gun there. They both feel really solid and tight in all the ranges of their motion. I'm going to go ahead and rebuild all the joints since I have them off, but what a pain they are going to be. It seemed like it took half a roll of paper towels just to clean off the transaxle and outer axle cups.

The transaxle itself may be the source of the noise. It's a little noisy as it turns (it feels/sounds like the feel/sound of gears meshing together, not terribly "grindy"), but I don't know what's normal. What could be the source of the TICK TICK TICK sound is the fact that I can move either of the transaxle cups in and out (towards and away from the wheels) about 1/16" on each side, and I can make a "tick" sound in both directions as it bottoms out at the end of its axial play. Again, however, I don't know if that's normal or how much axial play is normal.

With the car in gear, I can't find any play when turning both inner axles forward or backward. And there's not much play in the differential when turning just one axle forward or backward. So there's that.

Maybe it just needs an adjustment or a shim inside that transaxle? My next job will be to check the transaxle oil level, and then draining the gear oil out to see its condition. Then I'll filter it and put it right back in if it looks ok. I mean, that's $40 worth of gear oil that I just put in there four track weekends ago.

Please weigh in with your opinion or with any recommendations for next steps at this point. I have three weeks until my next track day, and I don't want to be hurried right up to the event. It's just too stressful.

Thanks in advance, again!

John

www.dogparkracing.com for the fun of it!

V2Rocket

I got the occasional clicking under load uphill and on corners, certain speeds, etc a while back...
it was my CV joints.

CrookedRacer

I take it everyone else agrees that it's probably a CV joint. I hope you are right.

The axles are off...

<img src="https://farm2.staticflickr.com/1506/26185404591_131dd2c37d_z.jpg" width="360" height="640" alt="2016-04-05_08-54-53">

<img src="https://farm2.staticflickr.com/1557/26225768366_810be34ae6_z.jpg" width="360" height="640" alt="2016-04-05_08-55-12">

And I began by preparing the surgery table...

<img src="https://farm2.staticflickr.com/1580/26170395442_105502a9e9_z.jpg" width="640" height="478" alt="image">

CrookedRacer

The first joint, the left hand outer one, was perfect. No play, not much wear to speak of...


<img src="https://farm2.staticflickr.com/1591/25658041854_1d5b9989d0_z.jpg" width="640" height="478" alt="image">

<img src="https://farm2.staticflickr.com/1489/25658040644_7452b7a348_z.jpg" width="640" height="478" alt="image">

And here it is assembled, ready for grease...

<img src="https://farm2.staticflickr.com/1448/26262833295_2409e69b9b_z.jpg" width="478" height="640" alt="image">

I understand you can put it back together in a way that will make the ***** press in new areas of the collar and hub races. How exactly is that accomplished? By swapping inner and outer joints? Flipping them in place?

Thanks!

CrookedRacer

In this case, it's fine, but in case one of the others could use swapping with this one in order to perform that trick, I'd like to do that one next.

Thanks again!

Tomorrow night I will probably be able to clean up all three of the remaining joints. Stay tuned!

CrookedRacer

More progress. They all seemed to be in good shape after cleaning. No smoking gun.

Some pictures. I have been pretty efficient in the paper towels department.

<img src="https://farm2.staticflickr.com/1465/26196999391_5b6215e184_z.jpg" width="640" height="480" alt="image">

<img src="https://farm2.staticflickr.com/1537/26256038766_b74538eeab_z.jpg" width="478" height="640" alt="image">

<img src="https://farm2.staticflickr.com/1576/26009107100_a897e0c7e7_z.jpg" width="478" height="640" alt="image">

<img src="https://farm2.staticflickr.com/1509/26215718771_151a94fc77_z.jpg" width="478" height="640" alt="image">

mrgreenjeans

If you don't find the ticking resolved by the C/V refurb, I would like to know if you have an open diff or if it's a code 220 - LSD.
IF a LSD unit, did you use SWEPCO 201 ? If something else was used, did you add a friction modifier additive to it ? ( SWEPCO doesn't need it, but most of the others do or premature wearing will occur within the unit )

I am guessing it isn't an LSD unit unless you added it, as most Jubilee/ Celebration cars didn't come so equipped from Porsche unless special ordered as such. I have never seen one yet, but the companion car, the 924 SE also made in conjunction with the Jubilee 911s and 944 normals, almost exclusively had them as part of that stripped down, lightened, and specially equipped model, built for a stillborn race series which didn't get off the ground.

CrookedRacer

Thanks, Mr. Jeans!

It is an open diff with fresh Red Line MTL (75W80 Gear Oil) in it.

The service records that came with the car don't indicate what lubricant was used prior to that.

CrookedRacer

Turns out the transaxle has to be making the noise. Tonight I finished rebuilding the CV joints and installed them, and took a test drive... No joy. I torqued all bolts to 30 ft-lbs.

Symptom review:
It makes a pronounced "TICK TICK TICK TICK" only when I am accelerating. It makes the same noise under acceleration, whether I'm turning left or right or going straight.

It does not make the noise when coasting. It doesn't make the noise when engine-braking, or not nearly as loudly as far as I can tell.

I leveled the car and checked the gear oil level with a clean pipe cleaner, and it was spot on. The fluid is the exact same color as when I put it in. It's pristine with no signs of excessive metal flake or metallic sparkle. So I don't think anything bombed in there.

Could axial play (in and out of the transaxle case) of the drive "cups" be the source of the noise? It sounded to me like it could. What to do next?

Thanks in advance for your help!