Halfshaft shudder?

PaulProe · #1 (**permalink**) 04-29-2012, 08:50 AM

I am chasing a shudder in the rear end of my car that uses TurboCoupe IRS.

The shudder comes from the backend and shows up mainly when the axles articulate. I first thougth it was tire rub but wasn't getting any marks in the wheel wells. The more I drive it, I wonder if maybe it isn't the half shafts.

Do the ends or internal rollers/carriers need to be indexed or aligned a specific way?

When I am driving down the highway normally - no issues. When I get into some body roll, aggressive cornering or suspension loading/unloading, it shows up.

The differential is a 3.55 TrakLoc and I don't get any chatter as it corners. I am using Lucas 85W140 lube that supposedly doesn't need any additional friction modifier in it.

Open to any ideas or suggestions.

Thanks for any help

Paul

FWB · #2 (**permalink**) 04-29-2012, 10:18 AM

diagnose a shudder over the internet? honestly, if i was in your shoes with the setup you have i would seek out a ford dealer i could deal with and let them have a go with it.....that rear was used extensively in many ford lincoln and mercury models.

PurpleVenom · #3 (**permalink**) 04-29-2012, 07:02 PM

Paul, check out this link - Driveline phasing

LMH · #4 (**permalink**) 04-29-2012, 07:36 PM

My first thought was the T-Bird knuckle bushings. Not sure how yours are but mine are very tight and make a lot of noise when the suspension is moved up and down. Mine are poly.
I don't know of any indexing marks on the CV splines. My axles were put together by The Driveshaft Shop and shipped to me as ready to install units. No reference marks on the joints though.
Larry

joyridin' · #5 (**permalink**) 04-30-2012, 04:41 AM

Sounds like you need LSD lube or synthetic gear lube..

PaulProe · #6 (**permalink**) 04-30-2012, 04:52 PM

Larry,
I converted my car from the Poly bushings that came with the IRS (Hurricane) to the spherical bushing mod that Dave Borden/Whitby supplies.

The sound is a "rotating" sound. I fought the poly bushings to get rid of the squeaking sound (and won) but this sounds like something rubbing.

My next guess is to try a bottle of Ford friction modifier. I switched to Lucas gearlube which is supposed to have modifier in it.

The sound seems to be worse in a hard right turn than in a left turn or when the suspension loads/unloads to its extremes. Maybe it is the differential clutches.

I noticed the tightness of the halfshafts and was chasing down the customer support number of the DriveShaft Shop but haven't called them yet. They seemed like they were binding slightly but I can't imagine how that could be.

Paul

LMH · #7 (**permalink**) 04-30-2012, 05:30 PM

Do you have the lower A-arms adjusted in as far as they will go? (With the correct camber of course)
Thought maybe that might load the axle during compression/extension.

Another thought is that when I pressed in the new bearings to the knuckle, I found that the inner race seperated slightly. I had to repress it a second time pressing on the inner race to seat it correctly. Could that be an issue here? Have you tried to tighten the CV shaft nut to make sure its torqued?
Larry

cab · #8 (**permalink**) 04-30-2012, 05:51 PM

larry nice chatten with u at the pier,i got best paint scheme,sorry to hijack now carry on.....

LMH · #9 (**permalink**) 04-30-2012, 06:32 PM

It was nice chatting with you too! I saw your award...congrats!
Larry

PaulProe · #10 (**permalink**) 05-01-2012, 05:26 PM

Quote:

Originally Posted by LMH

Do you have the lower A-arms adjusted in as far as they will go? (With the correct camber of course)
Thought maybe that might load the axle during compression/extension.

Another thought is that when I pressed in the new bearings to the knuckle, I found that the inner race seperated slightly. I had to repress it a second time pressing on the inner race to seat it correctly. Could that be an issue here? Have you tried to tighten the CV shaft nut to make sure its torqued?
Larry

Car has 4,800 miles on it. The issue began after I converted the bushings/shock mount issues. Before, it would bottom out and I don't recall it doing this "shudder" Lower control arms are in as much as the "camber" setting will allow. Running .5 degrees. Didn't take the bearings out of the hubs and I torqued the half shaft nuts to 250 ft.lb.

I am hoping the friction modifier is the issue. I did change fluids while the diff was out. While I am adding fluid, I'll remove shock and move wheel thru its range to look for issues.

Paul

elmariachi · #11 (**permalink**) 05-01-2012, 07:07 PM

Quote:

Originally Posted by PaulProe

Car has 4,800 miles on it. Paul

There's your problem. Car is worn out.

LMH · #12 (**permalink**) 05-01-2012, 07:30 PM

Quote:

Originally Posted by elmariachi

There's your problem. Car is worn out.

LMAO!

Hopefully it is the gear oil. That's probably the easiest to fix.
Let us know what you find.
Larry

PaulProe · #13 (**permalink**) 05-03-2012, 06:15 PM

Whaaaa,
Thought this thing came with a 5yr/100,000 mile unlimited - bumper to bumper warranty.

Paul

MFE III · #14 (**permalink**) 05-03-2012, 10:23 PM

Paul, could the problem be more upstream, like the front mounts for the pumpkin? Many have switched the rubber/poly mounts for solid alum versions.
Did you check out the T'bird SC forum? I found the answer to a question I had on our IRS.
Keep us posted.
Matt

PaulProe · #15 (**permalink**) 05-04-2012, 06:11 PM

Matt
Converted to aluminum mounts for the pumpkin - I don't think that's it.

The noise/vibration/sensation seems to be rotational in nature - that's why I first thought it was tire scrub. But there aren't any marks in the wells or undercarriage.

Paul