Could you expand on what the extra $200 got you in the clutch? Interested in the tech behind that and what your $$$ is actually paying for.
Photography by Tom Suddard
We were well on the way to having our dream two vehicle, especially after choosing the right differential for our F-250. Time for the hard part: actually working on the truck. Let’s get to it.
[Installing a limited slip differential | Project Ford F-250]
Pick Your Battles: The Realities of Working on a Big Truck
Save for fuel injection and ABS, our 2001 Ford F-250 isn’t a modern truck. There aren’t any fancy computers or trick suspension parts that make it a great tow vehicle. Instead, there’s a far simpler solution: size, and lots of it.
This F-250 is a first-generation Ford Super Duty, a model that pioneered the trend in building pickup trucks on a larger scale than anything that had come before. It’s not rocket surgery: A bigger truck has more room for people, frame, and drivetrain, and consequently hauls more stuff. What’s not to love?
Size, that’s what.
All this mass is a double-edged sword and means our F-250 will only barely fit in the shop. Our truck hits our ceiling when its wheels are just a few feet off the ground, and we can’t even walk to the opposite side of our shop without crawling over the bed. This isn’t a big deal when we’re doing simple projects–like those Hawk brakes or that bigger Addco anti-roll bar–but it’s a dealbreaker with something as major as a transmission replacement.
That’s why we farmed out this project, and paid our trusted local shop to handle the work for us. We dropped the F-250 off at the Auto Clinic of Ormond Beach with that new limited-slip differential in the bed and a transmission rebuild appointment across the street.
Lost in Transmission: Rebuild or Replace That Bum Transmmisison?
Transmission rebuild? Sadly, yes: Our F-250 had a few worn-out synchros when purchased, and fresh fluid had only been a Band-Aid for the problem.
Every shift was an exercise in patience and double-clutching technique. This was fine for highway drives, but torture around town–especially when pulling out into traffic.
There are a few ways to fix this: install a good used transmission, install a refurbished transmission, or have our own transmission rebuilt locally. We crossed used transmissions off the list instantly–our configuration is exceptionally rare, and we simply couldn’t find any manual, V10, 4x4 transmissions available on the used market. Plus, we were hesitant to roll the dice on something in unknown condition.
That left refurbished transmissions and the local rebuild, and we decided to have our transmission rebuilt by Precision Transmission Center in Ormond Beach, Florida. This wasn’t the least expensive option at about $1000 with parts and labor, but we figured our truck deserved the same premium experience as our race cars, not some filthy back-alley transmission shop that would build us a ticking time bomb. We’ve never regretted splurging on quality parts and maintenance for a vehicle we frequently drive through the middle of nowhere at midnight 1000 miles from home.
Since we didn’t want to do the job twice, we decided to have the entire transmission rebuilt, with all bearings/synchros/seals replaced while it was apart.
Speccing a Clutch: a Spec Clutch for our F-250
You don’t pull the transmission out of a 175,000-mile truck without replacing the clutch, and we decided to deviate from OEM spec here. Instead, we called Spec Clutch and explained our use: Driving around at maximum capacity at all times, with the potential for some bolt-on engine upgrades in the future. We were in search of a clutch with a slightly higher torque capacity, but similar drivability to the stock part.
Spec recommended their Stage 1 clutch kit, the SF451, with a street price of about $450. That’s about $200 extra compared to the stock clutch, which we figure is cheap insurance to make sure we don’t have to do this job twice. Spec’s kit included a new throw-out bearing, while we chose to resurface the OEM flywheel.
Everything’s in Sync: Rebuilding our F-250’s Transmission
Parts in hand, or at least in the truck bed, we headed over to the Auto Clinic of Ormond Beach to watch the magic unfold. Within a few hours, our truck’s transmission was on the bench across the street at Precision Transmission Center, where shop owner Keary tore it apart to show us what went wrong–and why.
In short, our transmission wasn’t the problem, at least not at first. Instead, it seemed that a seized pilot bearing caused our truck’s engine to never fully disengage from the transmission.
That howling sound we heard whenever we pushed in the clutch, which we assumed was just a trashed throw-out bearing, was actually the transmission’s input shaft screaming as it rubbed against the crankshaft.
This put far more wear onto the synchros than ever intended, which explains why they were all ruined. Keary said our synchros were some of the worst he’d ever seen, and every single one needed replacement.
Fortunately, we’d stopped driving in time: The damage didn’t progress beyond the parts we’d be replacing anyway, and even our transmission input shaft was fine after a quick spin on the shop’s lathe. Keary replaced every bearing, synchro and seal, and a few days and $1000 later, our transmission was ready to reinstall.
Differential Rebuild: Adding an Eaton Detroit TrueTrac to Our F-250
While the transmission was being rebuilt, the Auto Clinic was hard at work converting our open differential to a limited-slip by installing an Eaton Detroit Truetrac. As we discussed in our last update, this helical differential should be the perfect traction adder for our use case.
Installation was fairly straightforward, or at least it looked straightforward as we watched from the sidelines: Remove the factory third member, remove the OEM center section, transfer the ring gear to the Truetrac, then reinstall.
While the rear end was apart, we also had the Auto Clinic replace every bearing and seal in the rear axle, including those for the pinion gear.
Did we need to spend the extra money to do this? No, but we’ve skipped this step before and paid the price on the side of the road later.
Our math when doing preventative maintenance on the tow vehicle is simple: Would we rather do this in a parking lot at midnight? No? Then it probably makes sense to get it out of the way now.
Differential installed, the Auto Clinic popped the rebuilt transmission in place, filled all the fluids, and tossed us the keys. All told, we spent about $2500 refreshing our truck’s driveline.
If that sounds expensive, then you probably haven’t looked up what a monthly payment on a new pickup truck looks like. This amount would buy about two months in a new truck, so we were happy to pay it to keep our old F-250 on the road.
Finally Driving our Rejuvinated F-250
Was it worth it? Absolutely! We’ll put it this way: In one fell swoop, we crossed our truck’s last issues off the list. It’s officially done, and all we’ve done ever since is add gas, change the oil, and drive to the track.
Sure, it still shifts like a truck, but the grinding is gone, as is that 10-second delay whenever pulling out into traffic.
Our only complaint is a slightly chattering clutch, which may be a consequence of re-using our OEM flywheel. Overall, though, we’re in love: We bought a cheap used truck and transformed it into the ultimate tow vehicle.
Could you expand on what the extra $200 got you in the clutch? Interested in the tech behind that and what your $$$ is actually paying for.
Sure. In theory, for that extra $200 I got more torque capacity vs. the stock clutch. That means it's less likely to slip in high gear, high load, high throttle situations, which this truck sees tons of. I'm eventually planning on installing a Banks kit for more power, so figured a stronger clutch was a good idea.
How does the clutch actually accomplish the higher torque capacity? Magic voodoo, but mostly it's a combination of clamping force from the pressure plate, and material on the friction disc.
Awesome! Thanks for sharing!
I was going to say that the SD transmissions are pretty robust but you guys managed to buy a truck with a clutch 
Every cool truck has a manual trans!
Tom Suddard said:Every cool truck has a manual trans!
Doesn't sound fun at all when you are crawling in traffic with the trailer
I'd take a manual trans truck over an automatic any day of the week.
I've driven PS Fords with a stick in Chicago traffic with no issues.
When your used to using a clutch you don't really mind.
Every daily driver I've ever owned has been a stick.
Tom Suddard said:Sure. In theory, for that extra $200 I got more torque capacity vs. the stock clutch. That means it's less likely to slip in high gear, high load, high throttle situations, which this truck sees tons of. I'm eventually planning on installing a Banks kit for more power, so figured a stronger clutch was a good idea.
How does the clutch actually accomplish the higher torque capacity? Magic voodoo, but mostly it's a combination of clamping force from the pressure plate, and material on the friction disc.
Thanks Tom!!!
Have you ever thought of a more technical article on clutches? Something that explains the clamping force and the ways it is applied and friction material and how they interact with each other. Then there is the lever action of the clutch springs that generate the clamping force as well as the springs that reduce shock loads that are again tied into both the material type and the clamping strings. In your case, I am betting your needs were very different from say the GRM C5 Corvette that is a light vehicle (relatively speaking) that will want it clamping forces higher up in the up in the RPM range with an already engaged clutch and will have to deal ith the shock loading that high HP can also cause. I understand it in theory but never have had anyone actually break it down and show it physically or in diagrammatic detail of the actual design of clutches.
I have always done as you just did. I try and deal with a reputable manufacturer and describe my use case and then use whatever they sell me. I am just curious as to the tech behind it.
$1000 sounds like a fine bargain for a full rebuild on a ZF-5.
Hmm, could an F250 manual be swapped into a 2000-2005 Excursion?
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