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Driveshaft Issues After Suspension Work

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Hey guys,

I just finished a small suspension overhaul, and I believe there is a problem with my OEM 2-piece driveshaft. First, the particulars:

2013 Boss 302
9,140 original miles
Stock shifter
Stock clutch
Stock driveshaft

This past Saturday, I upgraded some to the suspension components on my car. I used all FRPP parts, and kept it mild as far as changes go;

M-5300-T springs all around
M-5649-R1 rear lower control arms
M-5650-A lower control arm brackets
M-4264-A adj panhard bar.

Install was pretty straight forward, as these are all good parts that fell right into place. They look great under the car, and gave me the drop that I was after while also getting rid of the wheel-hop during "spirited acceleration".

Problem is... I heard a "clunking" noise now while driving. Mostly at low speeds while using the clutch. I've been listening intently for noises, as it's after a fresh round of work done, but I'm not sure if it was there before, or I just didn't notice it. It makes me nervous, because we all know the clutch/trans is made of glass, and it's in my head to be easy and careful with both of them. I put the rear of the car up on ramps in my driveway so I could roll under there with the suspension loaded and give things a good once over. I checked everything I could put my hands on, and especially everything I touched during the install. Nothing loose, missing, or seems to be stressed. I shook all the parts I installed, and even felt them up with a wrench to make sure.

Just because I was there, I grabbed the driveshaft. There's play in it. It definitely sounds like the "clunking" noise I believe I'm hearing. It moves front to back about 1/16" (1.5mm) and I can twist/rotate it side to side about 3/16" (4.5mm).

Now, I am no mechanic. I only have experience with full on race cars (worked in NASCAR for 15+ years) and the odd, mini-truck/tuner car now and then, so I know about pinion angle and such, but I'm more a fabricator than anything, so I feel a little out of my wheel house on this kind of stuff. I regretfully didn't check the pinion angle before I started, or after I finished. I bolted the shiznit up and set the LCA's in the most bottom hole of the brackets. I am planning on getting the car aligned this Wednesday at Ford and was gonna ask them to check the pinion while they were at it, but I like opinions from people more experienced than me so I figured y'all were the best to ask.

Any and all guidance or advice is greatly appreciated. I look forward to hearing from everyone. Here’s a link for some pics, if anyone wants to see the car.

https://imgur.com/gallery/vHBF9Rw
 
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My 3000 mile 2 piece shaft clunked mildly since day 1.

I believe the carrier bearing rubber is designed for the v6 secretary car, soft and allows all sorts of wind up.

I have similar mods on mine.

Anxious to see what you find.
 
My 3000 mile 2 piece shaft clunked mildly since day 1.

I believe the carrier bearing rubber is designed for the v6 secretary car, soft and allows all sorts of wind up.

I have similar mods on mine.

Anxious to see what you find.
Makes me feel a little better knowing it’s a common problem, I guess. I plan on the 1 piece driveshaft, but I’m waiting to do that with the clutch and shifter either this winter or next spring.

How many miles on your car?
 
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123
Makes me feel a little better knowing it’s a common problem, I guess. I plan on the 1 piece driveshaft, but I’m waiting to do that with the clutch and shifter either this winter or next spring.

How many miles on your car?

Only 8K.
I put spicer/Ford Performance aluminum one piece in, significantly more NVH, it transfers lots of noise but it’s perfectly acceptable in my opinion and the “thump” that was present with the stocker is gone.
 
I have an aluminum driveshaft too. Just be careful if you lower the car. Since it’s bigger in diameter it can get really close to the tunnel,especially in the rear.


Sent from my iPhone using Tapatalk
 
My 3000 mile 2 piece shaft clunked mildly since day 1.

I believe the carrier bearing rubber is designed for the v6 secretary car, soft and allows all sorts of wind up.

I have similar mods on mine.

Anxious to see what you find.


I went to Ford for an alignment, and the tech said the driveshaft was, in fact, out by 0.3 degrees (sitting at -0.2°; should be -0.5° according to the alignment tech). Honestly I’ll be astonished if this is enough to create the small clunk (or the mysterious whine over 65 mph) but I ordered a Steeda adj upper anyway and will fix it tomorrow. I’ll let you guys know what I figure out.

In all honesty, I’m thinking I may just take a reading with the car on the wheel stands, and then make adjustments until I lose the play in the driveshaft. Take another reading, and post the results here.
 
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I went to Ford for an alignment, and the tech said the driveshaft was, in fact, out by 0.3 degrees (sitting at -0.2°; should be -0.5° according to the alignment tech). Honestly I’ll be astonished if this is enough to create the small clunk (or the mysterious whine over 65 mph) but I ordered a Steeda adj upper anyway and will fix it tomorrow. I’ll let you guys know what I figure out.

In all honesty, I’m thinking I may just take a reading with the car on the wheel stands, and then make adjustments until I lose the play in the driveshaft. Take another reading, and post the results here.

This may make your work easier
I think your going after setting the correct pinion angle vs chasing a clunk away

https://spicerparts.com/calculators/driveline-operating-angle-calculator
 
This may make your work easier
I think your going after setting the correct pinion angle vs chasing a clunk away

https://spicerparts.com/calculators/driveline-operating-angle-calculator


Definitely want it correct. I just find the clunk and whine suspicious after using all Ford parts, and I’m kinda frustrated that I need to do this when I thought everything would work together.

I really appreciate your help, and I don’t want to seem ungrateful. I’m not. More just venting out of frustration.

Thank you again. I really appreciate it.
 
Welp...

Went to the shop today around lunch. Got the car on the lift, busted open the box that had my UCA from Steeda inside, and went at it. The Steeda control arm is NICE. Billet adjuster nut and billet spacers to take up the slack on the stock chassis mount. I know, I know, I should've changed the chassis mount as well, but I don't really drag race the car, and wasn't planning on removing it if I didn't have to.

For the record; you have to remove the chassis mount. The bolt that attaches the control arm in place of the mount is situated inside the driveshaft tunnel. you can't get it out without removing the mount.

Anyways, after a few online searches, sounds like the ideal pinion angle is -2°. I learned that on a two piece driveshaft, you take the angle of the rear driveshaft and subtract it from the angle of the rear end housing output flange, and that gives you the pinion angle. FYI: the stock upper control arm is 9 1/2" (241.3mm) center to center. after adjusting the Steeda arm to get the -2° angle I was after, It ended up being around 9 5/16" (236.5mm). I finished up, pulled the car off the lift, and went for a drive, hoping this would correct my clunk and whine.

It did not. The clunk and whine are still very much present. I called a friend, put him in the car while the car was on the lift, and asked him to put the car in gear while I got underneath and observed to try and figure out the origin of the noise. It's definitely the play in the driveshaft.

For whatever reason, the driveshaft has what I would call excessive play in it. The clunking noise is the slack being taken up whenever the drivetrain is put under load or the load is removed. I don't know how, or why it's so apparent now and it wasn't before, but this is where I'm at. It's incredibly frustrating to have spent the money on good parts and invested all this time only to have the car sound like it's coming apart every time I take off or come to a stop, and change gears. It really sucks. This is the first "new" car I've purchased in 19 years, and just as I get used to the quietness of the cabin, now this.

...

The only thing I can even think to check next is the rear gear. I don't know how in the hell it could be worn out or broken with 9,XXX miles on the car, but that's my next move. I was going to wait until next year to do the clutch and one piece driveshaft, but maybe all that will come sooner than expected. If anyone, anywhere has any other ideas or thoughts on what to do from here, I'd love to hear your opinions. Otherwise, I'll keep you guys posted. Thanks again for all the help so far.
 

TMSBOSS

Spending my pension on car parts and track fees.
7,530
5,247
Exp. Type
HPDE
Exp. Level
10-20 Years
Illinois
It appears you are experiencing the same noises I had when I installed P springs, LCAs and an adjustable panhard bar. The Poly bushings dont mask the sounds like the stock rubber pieces.
My solution was to remove the stock two piece shaft and install a one piece aluminum shaft.
 
It appears you are experiencing the same noises I had when I installed P springs, LCAs and an adjustable panhard bar. The Poly bushings dont mask the sounds like the stock rubber pieces.
My solution was to remove the stock two piece shaft and install a one piece aluminum shaft.
So the one piece fixed your clunking noise?

Maybe I’ll start there. I was gonna do that anyway, but was trying to stay out of the driveline until I could do the clutch and driveshaft all at once.
 
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You mentioned putting the car on the lift and looking at the drivetrain slack.

Was the angle measuring and adjusting done with the suspension unloaded?
 
Same here. When I replaced everything with Kenny Brown, the rear got noticeably louder and a one piece Spicer didn’t help. I think the Torsen is just noisier. Mine makes a clunk when you switch direction.


Sent from my iPhone using Tapatalk
 
You mentioned putting the car on the lift and looking at the drivetrain slack.

Was the angle measuring and adjusting done with the suspension unloaded?

No, it was under load at ride height. I work at a restoration shop, and for our high-end displays, we have wheel stands that sit under the tires and elevate the car. I used those so I could get under there and make adjustments while the suspension was loaded.

Like these.
https://raceramps.com/car-ramps/garage-and-service-ramps/12-wheel-cribs/
 
Same here. When I replaced everything with Kenny Brown, the rear got noticeably louder and a one piece Spicer didn’t help. I think the Torsen is just noisier. Mine makes a clunk when you switch direction.

Sent from my iPhone using Tapatalk

I do not have a Torsten rear end. My car was one of 89 in 2013 sold with zero options...
 
10-4 sounds like you got this figured out.

Man, like I said-I’ve been a straight fabricator for so long... it was a transition for me to start doing real mechanic work again. I mean, I went to tech school for it and all, but that was a looooong time ago!

The restoration shop has been good for me. It’s really made me a better all-around car guy, and I’m appreciative of that. I also really appreciate the help I’ve gotten from you and the other guys on the forum here.

We’ll get it figured out, I have no doubt. As aggravating as it is, I still Love working on cars!
 
How is the hunt for the driveshaft fix going?

I’ve got whiteline adjustable lca and Panhard / Steeda Boss Springs and I too have a vibration in my car above 75 or so. Curious if the one piece would fix it...
 
How is the hunt for the driveshaft fix going?

I’ve got whiteline adjustable lca and Panhard / Steeda Boss Springs and I too have a vibration in my car above 75 or so. Curious if the one piece would fix it...

I took the rear end apart, and upon doing so... figured out nothing. The lash was set at .007”, which smack dab where it should be. The fluid was clean (although about 1/2 a qt low... from the factory...) with no metal in it, and the gears themselves showed no signs of wear at all.

So... I’m gonna drive it until something breaks. The whine, after talking with several other shops more familiar with these cars, is just the harmonics of the rear suspension. Specifically the third link being attached to the sheetmetal under the passenger seat, not to mention the sound insulation being removed from the Boss 302.

They clunk? It’s still there. I can’t figure it out. It’s either the slack in the driveline being transferred through all those new, stiff poly bushings, or the clutch making its shortcomings known. It’s definitely noticeable more when it’s hot than cold, which is confusing.

Either way; I’m tired of f***ing with it. It still works just as it always has. Honestly better than before, IMO since it’s lower. I’ll be keeping a close eye on it and report if there’s any new changes.

As far as your vibration: I’ve had no issue with a vibration, but have had several people telling me that the driveshaft can be clocked at 90° intervals at the rear pumpkin, and that will somehow fix the vibration. It may take 2-3 tries, but it can be fixed by doing such.
 

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