LSD Help

[crouse]

Last summer I purchased a used carrier from MustangEddie, because my spider gears were shot, and had a local shop install new carbon fiber clutches along with new axles, and axle seals. I provided all of the parts and soaked the clutches in friction modifier.

Shortly after I got the car back, I jacked up the left rear and was able to turn the left rear wheel/tire with a little bit of effort. I thought I read that it should take about 200 ft/lbs of torque to break the LSD loose?

I run several auto cross events each year and I'm still spinning the unloaded wheel around corners.

Is it possible to install wider discs or a stronger spring to tighten up the LSD?

[RubberCtyRauder]

I think justbob put in a F150 S spring. He should confirm or deny.

[justbob]

In my opinion the more both wheels grab also increases your chance of whipping a 180.

I NEVER give my MM throttle around a wet or even damp curve/turn until straight, it would not end well, and never more than 1/4 throttle at most on warm dry pavement powering out of even he slightest curve. My F150 has open diffs and never once has the rear end broke loose unless the weight of the truck pushes me sideways from aggressive driving. With 4WD I have plenty of traction when needed and I would never want limited slip on it as we get decent snows here. It’s a great feeling of safety and nerves when I’m good and used to the unpredictable car.

With the old Trilogy and only 461 HP I had and plenty of loonngg burnouts along the way the carbon clutch packs never failed to last 40,000 miles. You could pretty much set the clock on the next embarrassing one tire fire.. I honestly can’t recall how much force it took to spin one wheel lifted. The concern is really more how much it takes to stop it from turning when the pinion is spinning it.

There really is nothing else you can do besides a diff upgrade. A new standard size spring will work wonders. No matter how hard an old spring is to install, obviously springs wear. I’m not at all a fan of crushing an F150 spring to fit like I’ve read over the years, plenty have done it, but I never saw the purpose. You completely change the characteristics of the spring’s design the second you alter it and every tiny fraction will yield it’s effectiveness of design, to me it’s common sense physics, but that’s just my opinion.

Like I said, never an issue lasting a good amount of time on decent power, decent street tread, rarely on stickies, regular old Motorcraft fluid with modifier, cobra clutches, and a new stock spring. Honestly I got the same mileage out of the stock clutches before boost even.

But who am I besides another internet opinion? Go with your gut.


Sent from my iPhone using Tapatalk Pro

[Prospect62]

I would think that slightly thicker clutch pack washers (for example .040 vs .030 thickness) and a new spring (not an F-150 one, I have no idea how people get those to fit) would help you quite a bit.

I'm rebuilding mine now with factory style clutches but I got a new S-spring and I'm using .30 shims where the ones I am taking out were around .25 or less. It should tighten things up nicely.

[crouse]

Thanks for the help. Where is a good place to buy the thicker washers and spring?

Here's a video where when making the wide sweeping turn, I'm typically spinning the unloaded wheel.

https://crouse.smugmug.com/DCTC-5-23-2021/i-HpRZLpT/A

Thanks,
Curt

[mustangeddie]

Where is a good place to buy the thicker washers and spring?
Thanks,
CurtA trick I learned in my fox body Mustang days is you can remove one of the steel plates from the clutch kit & add an extra clutch plate on each side which ends up giving it a bit more grip. The different thickness shims used to come with the new clutch kit. Have plenty of extra shims here if you need lmk.

[crouse]

I just remembered that I still have the clutch set from the differential I bought from you. I'll check to see if I can find two plates that are still ok.

[Prospect62]

I referred to them as washers but the actual name for what I’m talking about are shims, specifically Trac Loc shims. I looked in the usual places like eBay and Amazon and couldn’t find any. The Ford M-4700-B Trac Loc rebuild kit that I bought came with a nice assortment but outside of buying that whole kit, this is the only place I could find that sold just the shims…

https://www.diffsonly.com/FORF880730--0030-Trac-Loc-shim-for-88-Ford_p_10847.html

[Prospect62]

The part number for the S-spring is EOAZ-4214-A. They’re going for around $28 on eBay.

[crouse]

Thanks again for the help.

[BLACKMARAUDER04]

That's one reason I decided to go with a Eaton Detroit Tru-Track when my Right Axel Seal blew for the third time and took out the gears.
I upgraded to 31 spline axels at the time.

[daniel.drives]

That set of videos is verrry cool, that might just convince me to go run an autocross, and also to get around to making a legit camera setup. You can definitely hear a lot of inside wheelspin though.

One other trick I've heard is to not run the friction modifier, that stuff reduces the friction between the clutches and steels. This increases the "lock" of trac-loc at the expense (presumably) of clutch life and noise. If you're going to add another clutch or run thicker shims, make sure you check your axle endplay once you get the c clips in and the pinion shaft installed (but before you tighten that little single use bolt). If there's 0 end play to the axles at all, you're looking at a quick failure

On thing I learned the hard way is that the fluid will get hot, it will degrade, and the clutches will die. I replaced mine back in April, 8 months and about as many track weekends later I noticed I wasn't getting much grab from side to side, so I figured I'd replace them again before an event over thanksgiving weekend. I learned that much of the clutch material had disintegrated, the steels were wearing the clutch metals, some loose metal had cracked the teeth of my spider gears, and metal shavings in the fluid for long enough have worn down the faces of the ring and pinion and the axles at the wheel bearings. Oops. Suddenly two qts of fluid and that goddawful smell doesn't seem too bad. I'm 98% sure the damage started after a hot track day at willow springs back in september, the car hasn't spent that much time above 100mph or on power through corners (big sweepers) before or since. That's on me for leaving gear oil off my maintenance sheet. Anyways, currently looking at Torsen units, I think with my stock power that will be the best solution for what I need. If anyone is about to say detroit locker, don't, I want progressive torque split engagement, not on/off engagement lockers.

Crouse, out of curiousity, what make/model tire are you running in the video? With those wider wheels I'd guess it's a 275 width, no? Just for kicks and giggles before opening your diff, try unhooking the rear swaybar for a session, that should keep the weight more even between your rear tires, less difference in traction, less work for the trac-loc. If you can tolerate the changes in handling (it'll get understeery) the additional on-throttle traction will probably make up for it in lap times. If you do try that I'd love to hear how it feels/responds.

Edit to add: that was the day my trans hit 280F and went into limp mode. If you're not running that hard for that long, you probably wont have an issue with the diff clutches like that. Amazingly, once the transmission cooled down it drove back from socal to phoenix just fine.

[blazen71]

"One other trick I've heard is to not run the friction modifier, that stuff reduces the friction between the clutches and steels. This increases the "lock" of trac-loc at the expense (presumably) of clutch life and noise. If you're going to add another clutch or run thicker shims, make sure you check your axle endplay once you get the c clips in and the pinion shaft installed (but before you tighten that little single use bolt). If there's 0 end play to the axles at all, you're looking at a quick failure"

Have you ever actually done this? This is horrible advise. As far as the clutch-steel reordering, it's just that, reordering. You still end up with appox. the same overall thickness. And if you choose to leave the modifier out you will get chatter. A limited slip is what it's called. It's supposed to have some slip. If someone needs less slip, get a different diff.

[crouse]

I was running a Falken Azenis RT615K in 265/35-18. It was all I could find last spring.

https://www.tirerack.com/tires/tires.jsp?tireMake=Falken&tireModel=Azenis+RT615K%2B&frontTire=735WR8RT615KP&rearTire=94WR8RT615KP&vehicleSearch=false&fromCompare1=yes

I'm either going to 275/35 front and 295/40 rear or 275/35 on all four corners next year. I'd love to run a 295/40 on all four corners. but I'm not sure if I'll rub. I might go to the RT660 if my budget (aka wife) allows.

I run Shelby GT500 wheels that are 18x9.5.

[Agent2006]

Wait: spinning the unloaded wheel in corners? That's what LSD Is supposed

To do , are we trying to solve the right problem here...

[offroadkarter]

Last summer I purchased a used carrier from MustangEddie, because my spider gears were shot, and had a local shop install new carbon fiber clutches along with new axles, and axle seals. I provided all of the parts and soaked the clutches in friction modifier.

Shortly after I got the car back, I jacked up the left rear and was able to turn the left rear wheel/tire with a little bit of effort. I thought I read that it should take about 200 ft/lbs of torque to break the LSD loose?

I run several auto cross events each year and I'm still spinning the unloaded wheel around corners.

Is it possible to install wider discs or a stronger spring to tighten up the LSD?


When I did the carbon clutch pack and F150 S spring in my 03 Marauder, it was dramatically grippier going around turns compared to my 04 which kept the factory spring. the F150 S spring does put more preload on the clutch packs.

Honestly though, you're better off stepping up to something like a Torsen. Mustang guys have also noticed that after a bit of track time the factory clutch pack limited slip starts to get weak.

[daniel.drives]

Blazen: No I have not. I have a friend with an LS swapped f100 with the 8.8 axle that he road races, he's planning on doing that next time he has the axle apart, along with swapping to 4.10s. We'll see how that goes, I guess.

Crouse: Those are good tires, I was thinking if you were on less grippy tires, then the unloaded traction would be so little that no LSD could hold the axles together, but that's a pretty good setup. I've been running the rt660s up front this year, and I really like them. Grippy, communicative, consistent grip through a session. 275/35 should be plenty, especially when learning. I've found that too much grip can cover for poor driving technique, when less grip will let you know when you've made a mistake

Agent2006: Since Crouse is more or less at stock HP, if the torque is properly distributed between the wheels there should be no spinning, just faster times.

[crouse]

I just had the rear end rebuilt this summer and really don't want to spend the money on a a new Torsen differential. I have 28 spline axles, so it would probably take new 31 spline axles. I'd really like to buy Falken 660's next spring.

I just can't help think that the shop that rebuilt the rear end didn't install the clutch packs correctly. Since I have a leaking RR axle seal, I think I'll try and see about a stiffer spring or wider washers.

[crouse]

From what I read in this article, I believe the T-2R is what would benefit me when running auto cross events.

https://torsen.com/ask-torsen-type-2-vs-t-2r/

But a smaller, more technical course – especially in autocross – may force you into a more aggressive differential due to tight corners and high weight transfer. There is a much greater potential to lift an inside tire off the pavement. Frankly, the T-2R owes its existence to autocross. It was due to the complaints of wheelspin and Type-2 not being aggressive enough in that environment that we created the T-2R product line.

[crouse]

I searched M-4700-B and found this on Amazon.

https://www.amazon.com/Ford-Racing-M-4700-B-Differential-Rebuild/dp/B003TPEQ9E

The clutch discs look different than I've seen in the past. These look like they have more material versus what I've seen before with three clutch patches spaced around the disc. Is this a better clutch disc?

[offroadkarter]

I searched M-4700-B and found this on Amazon.

https://www.amazon.com/Ford-Racing-M-4700-B-Differential-Rebuild/dp/B003TPEQ9E

The clutch discs look different than I've seen in the past. These look like they have more material versus what I've seen before with three clutch patches spaced around the disc. Is this a better clutch disc?


This kit has existed for ages, I helped a friend put these in his marauder like a decade ago. Ford made this revised set for chatter/NVH reasons. They are not intended to be higher performance/grippier over factory, just a updated factory replacement.

if you want the grippiest set for a factory diff, you need the carbon clutch pack kit.

https://www.amazon.com/Ford-Racing-M4700C-Rebuild-Carbon/dp/B009XRPK1A

Anything past this you'll need a mechanical LSD like a torsen.

[crouse]

Ahhh. The C stands for Carbon Fiber. That's what I have now. Thanks.