S550 Driveshaft Coupler

Shadow_Black_GT · Jun 2, 2018

So I recently purchased my 2016 GT with the MT82 & the performance pack and I love all aspects of it except the sloppy drivetrain. I drove a coworkers of mine that has a the same car but a 2017 and his feels much better. I'm assuming a lot was changed between the 2016 and 2017 or I just bought a car made on Monday lol. Anyway when I press in the clutch in (under power) I can feel and hear the drive train "unload" which does not inspire confidence in the car. Has anyone looked into replacing the stock rubber driveshaft coupler or had one fail? The way the car behaves it feels like that may be the issue. I don't want to upgrade to a one-piece since I've read those cause a significant increase in NVH and i want to say away from that. I ordered some poly rear diff bushing and transmount bushing from steeda as well and I'm going to inspect the coupler when i get under the car. Let me know what you guys think of my coupler idea I might be totally wrong in assuming that may be the cause of the sloppy feel.

Thanks all!

Mustg3 · Jun 2, 2018

Those poly diff mount may be to stiff for everyday drive. I experienced a lot of popping sounds with them.

tripp · Jun 2, 2018

There have been instances of the bolts going through the guibo getting ruined on power adder cars. See this thread for reference: https://www.mustang6g.com/forums/showthread.php?t=94257&highlight=driveshaft
Is your friend's car also a PP?

Shadow_Black_GT · Jun 3, 2018

tripp said:
There have been instances of the bolts going through the guibo getting ruined on power adder cars. See this thread for reference: https://www.mustang6g.com/forums/showthread.php?t=94257&highlight=driveshaft
Is your friend's car also a PP?

Thanks for that thread man! It’s crazy those bolts didn’t break. N yes the other car also had the performance pack. I looked under his car swearing that he had poly bushings but no, it was all stock.

It doesn’t look like anyone makes a poly version of that coupler. There are a few billet aluminum pieces that look like they would fit but aren’t advertised to. I’ll see what that piece looks like when I get under the car later in the week.

baazooka · Oct 7, 2022

Did you ever find a solution?

Porsche_Manny · Oct 10, 2022

baazooka said:
Did you ever find a solution?

If you have an S550 with a discernable "clunk" or sensation of "unloading/loading-up" at throttle-tip in or tip-off — some of this is unavoidable as a result of the drive-line's design. That being said — the "Guibo" flex-coupler between the transmission and differential is a European-esque solution to some refinement-concerns Ford may have had with its first officially-global Mustang.

S197-Coyotes do -NOT- have the flex-coupler that s550s do. I recently had a vibration at highway speeds that mimicked when two-of-the-four clutch-center hub springs went out on my factory, Turkey-made clutch.

-Fortunately- — it did not appear to be the clutch this time, but the flex-coupler. Get under your car and take a look at it.

If it looks like -this-

— replace it

(either through a Ford parts supplier, or you can get the Dorman-OE unit through AutoZone) (I got the Dorman, says "Made in Germany" on it

but it was better than what was on the car).

You'll be surprised what a difference that donut

makes — mine had 103K on it.

baazooka · Oct 10, 2022

Nice I appreciate the info, I kinda figured a 2 piece shaft would have some play but I would imagine there's stacked tolerances in the getrag and the diff as well, the slop is kind of ridiculous for such a powerful and heavy car makes it hard to control, any improvement counts, has anyone tried a machined replacement for the rubber donut? I considered diff bushings but some day the noise isn't worth it

Porsche_Manny · Oct 10, 2022

baazooka said:
Nice I appreciate the info, I kinda figured a 2 piece shaft would have some play but I would imagine there's stacked tolerances in the getrag and the diff as well, the slop is kind of ridiculous for such a powerful and heavy car makes it hard to control, any improvement counts, has anyone tried a machined replacement for the rubber donut? I considered diff bushings but some day the noise isn't worth it

Other brands have Polyurethane replacements for their "Guibos" (like BMW) — but nobody's made one for ours. Hell, the Dorman Guibo was the only non-Ford one I could readily find.

A -solid- replacement would have to be made at least reasonably-carefully — because if you're going to replace the Guibo-link for a solid, metal coupling, I'd imagine it would have to be a pretty balanced "disk" (since it would be taking the place of a u-joint or rubber flex coupling).

And even when the Guibo gets old and softer/degrades — it begins to allow quite a surprising amount of oscillation at the driveshaft (where it meets the transmission-flange). A solid coupling, if not tested at high-revolution — could cause more oscillation and vibration.

There's just a character to the S550/MT-82 combination that is (as a technician myself) — "operating as per manufacturer design". We get 911 GT3 customers that complain about "gearbox whine" and "excessive vibration" or "loud/rattly exhaust or engine sound" at cold-start.

They bought the rawest, track-ready 911 we make — likely as a status symbol

. The customers with tire-debris on the body (and a helmet in the back) never complain about that though.

The two-piece drive shaft and the gear-lash of the diffs (especially 3.73 Torsen diffs) give the cars clanks and clunks that (after being on here for a while, and being under the car myself) — appear to be normal.

BUT — a healthy "Guibo" and a healthy transmission mount (the actual mount, not an insert) can make a difference you'll certainly feel — if you've been driving around with one or both worn out.

baazooka · Oct 11, 2022

Porsche_Manny said:
Other brands have Polyurethane replacements for their "Guibos" (like BMW) — but nobody's made one for ours. Hell, the Dorman Guibo was the only non-Ford one I could readily find.

A -solid- replacement would have to be made at least reasonably-carefully — because if you're going to replace the Guibo-link for a solid, metal coupling, I'd imagine it would have to be a pretty balanced "disk" (since it would be taking the place of a u-joint or rubber flex coupling).

And even when the Guibo gets old and softer/degrades — it begins to allow quite a surprising amount of oscillation at the driveshaft (where it meets the transmission-flange). A solid coupling, if not tested at high-revolution — could cause more oscillation and vibration.

There's just a character to the S550/MT-82 combination that is (as a technician myself) — "operating as per manufacturer design". We get 911 GT3 customers that complain about "gearbox whine" and "excessive vibration" or "loud/rattly exhaust or engine sound" at cold-start.

They bought the rawest, track-ready 911 we make — likely as a status symbol . The customers with tire-debris on the body (and a helmet in the back) never complain about that though.

The two-piece drive shaft and the gear-lash of the diffs (especially 3.73 Torsen diffs) give the cars clanks and clunks that (after being on here for a while, and being under the car myself) — appear to be normal.

BUT — a healthy "Guibo" and a healthy transmission mount (the actual mount, not an insert) can make a difference you'll certainly feel — if you've been driving around with one or both worn out.

I'm only at around 50k miles, I'll check the guibo. Trans mount looked fine when I put the insert in

DANA44 · Oct 15, 2022

The flex coupler is most likely made by SGF both oem and aftermarket.
SGF is also a BMW supplier.
My experience on the industrial side with coupling failures in the short term is related to miss alignment issues.

Cobra Jet · Oct 20, 2022

@Porsche_Manny

That is great tech you have provided regarding the S550 driveshaft guibo flex coupler..

It's nice to know there is a repair part available; thanks for sharing!

HoosierDaddy · Nov 9, 2022

Porsche_Manny said:
If it looks like -this- — replace it

Side question but one anyone who replaces the part will run up on: anyone know the torque value for those bolts (In the drawn circle)? I recall trying to find it a few years ago and the Ford shop manual didn't list any.

Porsche_Manny · Nov 13, 2022

HoosierDaddy said:
Side question but one anyone who replaces the part will run up on: anyone know the torque value for those bolts (In the drawn circle)? I recall trying to find it a few years ago and the Ford shop manual didn't list any.

Apologies for not replying sooner, I was out of town. I just did a quick check and didn't find them right away either — but I'll tell you this: I replaced my Guibo at work with a Dorman unit — which didn't include new bolts. But I've been turning wrenches

to not-be-homeless for a bit now, and I just re-tightened the originals (-with- loctite) to 'that's not going anywhere' (have to actually say it aloud, that's part of the witch-craft) and it's been continuing to make me proud for a few 1,000 miles now.

"That's not going anywhere" vs. *SNAP* "GodDAMMIT" is a judicious application of "how hard was it to come-off?" — it shouldn't be tightened -THAT- much, just below the removing-effort — and loctite.

Prodigal · Nov 13, 2022

Porsche_Manny said:
Apologies for not replying sooner, I was out of town. I just did a quick check and didn't find them right away either — but I'll tell you this: I replaced my Guibo at work with a Dorman unit — which didn't include new bolts. But I've been turning wrenches to not-be-homeless for a bit now, and I just re-tightened the originals (-with- loctite) to 'that's not going anywhere' (have to actually say it aloud, that's part of the witch-craft) and it's been continuing to make me proud for a few 1,000 miles now.

"That's not going anywhere" vs. *SNAP* "GodDAMMIT" is a judicious application of "how hard was it to come-off?" — it shouldn't be tightened -THAT- much, just below the removing-effort — and loctite.

Estimated precision. Love it! I’ve Been known to employ similar process from time to time.

Prodigal · Nov 13, 2022

Shadow_Black_GT said:
So I recently purchased my 2016 GT with the MT82 & the performance pack and I love all aspects of it except the sloppy drivetrain. I drove a coworkers of mine that has a the same car but a 2017 and his feels much better. I'm assuming a lot was changed between the 2016 and 2017 or I just bought a car made on Monday lol. Anyway when I press in the clutch in (under power) I can feel and hear the drive train "unload" which does not inspire confidence in the car. Has anyone looked into replacing the stock rubber driveshaft coupler or had one fail? The way the car behaves it feels like that may be the issue. I don't want to upgrade to a one-piece since I've read those cause a significant increase in NVH and i want to say away from that. I ordered some poly rear diff bushing and transmount bushing from steeda as well and I'm going to inspect the coupler when i get under the car. Let me know what you guys think of my coupler idea I might be totally wrong in assuming that may be the cause of the sloppy feel.

Thanks all!

I believe a quality 1 piece shaft such a Steeda or Q carbon fiber will not have any increased NVH and will remove that added bearing and the slop of a 2 piece shaft.
I have not heard good things regarding the DSS products however.

S550 Driveshaft Coupler

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