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Noise in driveline after torque arm installation

9K views 29 replies 9 participants last post by  SilverGT1 
#1 ·
2003 GT
MM torque arm
MM PHB
Ford Racing Aluminum Drive Line

Finished installing my MM torque arm MMTA-1. I have set the pinion angle to match the angle at the crank pulley while at ride height. I also have fresh gear oil in the diff as I had to rework my cover.

I took the car out out for the first shake down drive. First few miles were fine. Made a few spirited starts, no issues. came to a point that I let it rip pretty good and all of a sudden I started getting bad noise in the drive line. I could swear it was coming from the front u-joint, almost like it was hitting the tunnel. It was so bad that I couldn't drive it back the three miles to my house. Once I got it towed back, I got it on the lift and did a visual. Nothing seems out of the ordinary and seems OK with hand rotation. I started the car and let it idle in 1st gear and its definitely still making noise. But I can not Isolate the problem. it is not hitting anywhere. I can't tell if I killed one of the u-joints (doesn't sound like the typical beginning of failure) or if they are binding under load with the new pinion angle. Most likely I think I killed one of the plenary gears? I just spun the rear tire by hand. They the opposite side spins in the opposite directions. I thought the LSD both spun in same direction?

Any thoughts on how to isolate / trouble shoot this?
 
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#2 ·
I always put a angle finder across the machined face areas of the yoke without the driveshaft attached, and matched the pinion like that.

As for the rear end with a limited slip... If you can turn the wheel by hand and the other side rotates, your clutches are toast. It is basically an open differential now.

Can you put it in neutral, on the lift, and turn the driveshaft by hand and feel for the issue? Probably the easiest thing would be to remove the driveshaft, and try turning the trans output shaft and the axle pinion yke by hand, see if you can feel it in either one. This would also let you manually manipulate the u-joints and feel for issues.
 
#3 ·
I’ll be able to spend more time troubleshooting after work today. I’ll be able to be more methodical now that I’ve calmed down. The more I think about it, it’s probably the spider gears. Not sure why they would give up now though. No previous warning signs (NVH). Who knows. Maybe the removal of all the rubber isolators and locking the axel in a fixed position was too much direct torque for it to handle.
 
#5 ·
Well, it's confirmed. My LSD is now an open diff. I went out at lunch and checked the driveline. Looks good. Made my way back the rear end. Spun the tires listening for noise. Then I realize that I had left it in gear and the driveline wasn't moving but I could make the wheels spin... uh oh.

So, I'll pop the cover off and assess the damage later. Hopefully, I can get away with just new clutch packs and spider gears. I am concerned about metal contaminating the carrier bearings though.

Since I am doing the work anyway, I'll upgrade to 31 spline gears and axles.

Option 1, just do a clutch pack / gear rebuild.
Spider gears 31 spline - Ford - AL32-4215-A ~$90.00
Clutch pack, Carbon Disc - Ford - M-4799-C ~107.00
Total: $197

Option 2, replace the whole center section.
Traction-LOK Limited Slip Differential w/ Carbon Discs - Ford - M-4204-F318C ~$227
Differential Bearings - TBD - ~40 / set
Total: $267


31 Spline axles - Moser - A883153 ~$288.00
ABS reluctor ring(s) - Ford - F4ZZ-2C189-A ~$32.00 (x2) $64.00
Axle Bearings - TBD - ~$40 / set
Total: $392
 
#25 ·
Just following up with something that I discussed in post # where I as talking about swapping my 28 spline Diff to a 31 spline. I suggested that I would just swap the spider gears. Well, I am an idiot. I did order the gears as noted in my quote. and the clutch pack rebuild kit,
Issue #1 - the gears i selected are for an F150 and similar trucks - WTF was I thinking?
Issue #2 - I found our the hard way that YOU CANNOT JUST SWAP THE SPIDER GEARS TO MAKE YOUR DIFF A 31 SPLINE!!!!!!

I am sort of comitted to this now that I have it all apart and purchased the Yukon axles. I just have to figure out what diff to go with now. Maybe I'll just buy a complete new 31 spline Trac-Loc. Pick-n-Pull probably has trucks (I dont know what other ford cars had 31 spline) that I can get a diff from. I just need to make sure what ever junk I buy is 100% compatible. Anyone already know the answer?

Since I am doing the work anyway, I'll upgrade to 31 spline gears and axles.

Option 1, just do a clutch pack / gear rebuild.
Spider gears 31 spline - Ford - AL32-4215-A ~$90.00
Clutch pack, Carbon Disc - Ford - M-4799-C ~107.00
Total: $197
 
#7 ·
Did you feel anything odd when turning the wheels?

Spiders are only doing their job in turns or lack of traction. Going straight down the road they are not turning, so they wouldn't be making any NVH. Only way I can see it is if a tooth broke off and damaged the ring/pinion or bearings.

Sent from my VS995 using Tapatalk
 
#9 ·
Not especially. However, when I rotate the wheel there is about 0.5” of free backlash.

I don’t think it’s the driveshaft. It was fine at speed. The clunk, vibration, knocking I am experiencing after that fateful launch is immediate at low speed under any load.

Manually manipulating the driveshaft, it feels nice and tight. No clunk, nothing loose.
 
#8 ·
After installing TA in my car I had a bad vibration as well, especially north of 65 mph. Took the driveshaft, had it balanced (was way out) and now silky smooth. Solid mounting the rear made a previously masked issue come to light.

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#10 ·
Pulled the diff cover. Looks ok. However, the backlash is horrendous. I will go ahead and do the spiders and clutch packs.

So, with the car on the lift, drop it into gear, I can definitely tell it is in the front. Especially when I engage the clutch. I have rotated the driveshaft by hand and inspected the yoke. I don't have any unusual movement in the u-joint and I don't see any signs of in binding. Clutch seems to engage and disengage fine.

I am wondering if it is in the transmission? I suppose I can drain the trans and see if there is any debris in there. But is seems to go through the gears ok.

Could it be bad trans mount? Again, I don't see signs of hitting or binding.

I don't know. I am really grasping at straws now...

I need a second set of eyes and ears too...
 
#11 ·
OK. I have to pull it all apart and get the driveshaft out. I know this is going to sound weird but I swear I hear the noise coming from almost dead center of it. Maybe a bad u-joint and the noise is traveling like on a tuning fork? I don't know. I am really perplexed by this one. At least its a good excuse to check out the u-joints and maybe upgrade while its out. The only other thing it can be is the output shaft of the TR3650 (or something else internal). Just wish I could nail down where the hell the noise is really coming from. Side note... clutch packs and spiders ordered...
 
#12 ·
The TA is bolted to the axle housing. The nose of the TA is connected to the TA crossmember through the polyurethane bushing. THe TA crossmember is bolted to the subframe connectors in the middle of the car. This means that any driveline noises are now going to come from the middle of the car, no matter where they are actually present in the driveline.

In the TA installation instructions, it says to jam the TA crossmember against the bottom of the floorpan. This is a mistake. You should leave a small (1/8") gap between the top of the crossmember and the bottom of the floorpan. You will need to look carefully to find the spot where the clearance is closest. This will minimize sound conduction from the TA to the floorpan of the car.

Because the TA conducts driveline noises into the chassis efficiently, any problems with the driveline will be much more obvious.

If you change axles, I would use Yukons. They have good spline forming, correct hardening and accurate dimensions.

With the TA, at low speeds, avoid on/off throttle transitions. This will minimize clunking in the driveline. Either be on the throttle slightly (possibly with some brakes) or completely off the brakes. The more lash your driveline has, the more this will help.

I would put jack stands under the rear axle housing. Block the front tires. Have someone drive the car, while you go over all of the fixed driveline parts with a mechanics stethoscope. This will make it easy to find the source of the noise.
 
#13 ·
In the TA installation instructions, it says to jam the TA crossmember against the bottom of the floorpan. This is a mistake. You should leave a small (1/8") gap between the top of the crossmember and the bottom of the floorpan. You will need to look carefully to find the spot where the clearance is closest. This will minimize sound conduction from the TA to the floorpan of the car.
Thanks for that tip. Fortunately, after much effort removing the interfering material from the seat belt anchors and beating the snot out of the tunnel, I ended up moving the crossmember down before welding in order to get the most weld area on the SFC's. Thus ended up with good crossmember to floor clearance.

I would put jack stands under the rear axle housing. Block the front tires. Have someone drive the car, while you go over all of the fixed driveline parts with a mechanics stethoscope. This will make it easy to find the source of the noise.
I have the car at ride height just barely off of the lift and sitting on four stands. I have been poking around with my stethoscope while it idles in gear. I just need to do this with someone on the throttle.

I'll continue troubleshooting and report back on the saga.
 
#14 ·
It appears to be in the transmission. Seems to be the forward side of the gearbox but can't really isolate it. I don't hear grinding in the trans with my stethoscope. Not sure what to think. I'll pull the driveshaft and see if that helps to isolate. Clutch operation is fine. I don't hear any tale tell signs from the throw out bearing. I'll dump the oil to see if there are any fragments. As far as I know, the transmission is original with ~160k on it. Had no warning signs of trouble before this.

Here is an audio clip (it's long). You can really hear it clunk and grind with the clutch out. You can also hear it as it idles in gear.
 
#19 ·
I know. I hear you.

But the transmission is toast. I know I could pick up a junkyard special for about $500. But I don't want to go that route. I'd just be buying the uncertainty that I had before. I did some pricing on a reputable good rebuild. It was going to end up costing me ~$1800 including the core shipping. It would be an extra $500 to get the 5th gear 0.81 ratio conversion. The T-56 I picked up has about 54k on it. Includes everything from the flywheel to driveshaft. I think it was an equitable decision.
 
#22 · (Edited)
T56 is in. It’s a slow process when working solo. Still have to adjust it. Couple of small things to button up. MGW shifter, tap the +12V for reverse lockout module. Exhaust... A whole other debacle with Magnaflow 4-cat 441114...

I replaced the rear main seal while I was at. Installed a Mcleod lightened flywheel along with the RXT twin disc that came with the transmission.

I opted to swap the rear u-joint rather than the pinion flange. The Cobra style with the larger yolk would be nice but I’m not doing crazy hard launches so the u-joint that adapts the cobra drive line to the GT flange will suffice and was fast and cheaper.

Ran into an issue with the pivot stud. I got a new pivot stud but when it arrived, it was for the GT. That is too long. Started looking for the shorter stud for the T56 Cobra. It is NLA from Ford. Then started looking where to find a replacement. Found a bunch of threads that said you need the McLeod adjustable (or an adjustable) because it wants to be even shorter for lower release when running the RXT or RST twin disc. It was about 50/50 on those that said release was too high with fixed stud and those that said it was just fine. Due to my time constraints, I bit the bullet and just cleaned up the stud that was in there and moved forward. Hopefully, I am one of those that likes the release height.

Modifying the harness for the back up light and the reverse lockout module took some extra time but it’s all done right with, soldered connections, marine heat shrink over that and finally nice tape wrapped looms.

Drive line is in, torque arm is in. So the car is still on the lift awaiting resolution to the Magnaflow fitment issue but at least everything is in the car and out of the rain we are gonna have here all this week and through the weekend and as far out as my iPhone will show. Once that breaks, I can button up the remaining items and then install the new spider gears, 31 spline axles and cobra spec rear brakes.
 
#23 ·
Are you doing the T56 install or is it being done at AED?

With a multidisc 10.5" clutch you really do need a shorter ball stud. You may also need to grind on the midplate for clutch fork clearance and shorten the quill. If some of these things are done correctly, you will damage the clutch and/or transmission.
 
#24 · (Edited)
Yes, installed myself. The RXT twin disc came with the T56. It did have some mileage on it but I called McLeod to find out what the clutch(es) thickness is new. Both measured out well. There had been no evidence of any clearance issues. Regarding the stud, it is too late now. It is all back together. If I really hate the release point, I'll tear all back apart. It will be faster now that I know how to deal with the TA as a complete unit. Also, I don't have to deal with the bellhousing now that I have the 2 piece. Working solo, it wont be fast but it will be faster than last time.

Funny you mentioned AED. They are only about 5 miles from my house. I had them do my tuning after installing my Kenne Bell 2.1. It was cool watching Shawn dial it in. Really a master at his craft.
 
#26 ·
The cross shaft pin in a 28 spline differential is 0.75". In the 31 spline units the shaft is 0.875" diameter. That means that the spider gears are farther apart and the pin hole in the differential is the wrong diameter. Not gonna fit. When Ford designed the 31 spline unit, they changed everything in the system which was a torque limitation. The ring and pinion aren't, so they weren't changed.
 
#27 ·
I tried to go cheap. But as soon as I started looking at this yesterday, i loads of threads saying it can’t be done. Not sure why I missed it before.

Now I have a spider gear set that apparently is for the wrong diff. I haven’t looked to see what the difference is between the 31 spline gear set that I have versus the recommended gear set for the cobra differential.
 
#28 ·
Well, I guess I need to correct myself yet again... Looking at American Muscle and their site show that the spider gears I have already purchased, AL3Z-4215-A, are a fit for the 03-04 Cobra 31 spline carrier. Looks like I am off to Pick-n-Pull to see if I can find a carrier.
 
#29 ·
Silver, do you have an update?
 
#30 ·
I did end up going to Pick-n-Pull and pulled out a 31 spline carrier from an Explorer. It was about $90 ($75 + $15 core). Tore it all down and rebuilt with new bearings, carbon fiber clutch packs and new gears. Had I not already purchased the gears and clutch packs, I would have been happy to just buy a complete new Ford Performance Trac-Lok M-4204-F318C. You can find these for <$250. Everything is back together and seems to be working OK. Working on brake caliper upgrades now.
 
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