Welcome Visitor! Please take a few seconds and MikeG
Well-Known Member
- Joined
- Jul 15, 2020
- Messages
- 1,353
- Reaction score
- 752
- Points
- 113
- Location
- central Texas
- Vehicle Year
- 1997
- Make / Model
- B4000
- Engine Type
- 4.0 V6
- Transmission
- Automatic
- 2WD / 4WD
- 2WD
- Total Lift
- 2"
- Tire Size
- 235/75r15
Explorer spring swap
My 1997 B4000 was purchased as a daily driver, and not a serious work or off-road truck. However, after the 2001 dot-com bust, life changed and it went to work in ways that the manufacturer probably never intended. We’ve probably all stuffed the tires into the wheelwells a time or two, but this truck got a bit more of a workout than that. Just sayin’…..
Needless to say, it wasn’t long before the suspension needed attention. Wanting a bit of lift as well, the front was easily handled by 2” coil spacers. The rear springs would involve either some dumpster-diving at the junkyard, or new replacement springs. Reading that Explorer springs were the same length, a trip to the salvage yard was made.
Not knowing any better, the first convenient set of springs was purchased. These were (eventually) discovered to be 1250 LB springs, and exactly match the description on this page – three 0.360” leaves, with a 0.590” overload.
Not knowing much about springs at the time, but being mildly curious, I attempted to check the spring rates of both the old and “new” springs as while swapping them out. This was done in the *very* un-scientific manner of standing on the overturned spring pack, trying to balance and not fall off, while reading a tape measure (harder than it looks!!!). Dividing my bodyweight by the amount of travel, the Ranger springs were found to be “about” 150 pounds / inch, and the Explorer springs, roughly double that. No matter – they were going in the truck, one way or the other.
If the front of the truck had not been lifted, that probably would have been the end of it, but the Explorer springpack didn’t quite lift the back as much as the 2” spacers in the front. A friend had given me some leaves from his mid 90’s Cherokee when he lifted it, and eventually, I ended up with a pair of 12” leaves from the bottom of a Bronco II spring pack. The Cherokee springs had been pretty well used/abused, as my friend flogged it off-road like a rented mule. As I recall, the Cherokee springs were easily flattened by stepping on them. Being heavily tapered, and probably somewhat abused, they didn’t contribute much to the spring rate, but they lifted everything off of the Ranger overload, as did the Bronco II 12” leaf. Since the Ranger overload was longer and more tapered than the Explorer overload, I used it.
A grade 8 bolt from the local hardware store replaced the centerbolt from the Explorer springpack, after turning the head to fit the hole in the truck spring perch.
The truck rode pretty harshly, but for what I was using it for, not a big deal. Keeping a couple hundred pounds in the toolbox, plus all the crap behind the seat, plus the receiver hitch, etc.., helped the ride – a little. Still, 6 or 700 pounds in the bed did wonders for the ride quality.
Fast forward to the present day. Discovering the spring rate chart on TRS, out of curiosity, I tried to figure out exactly what had been the original springs. There wasn’t an exact match on the chart, but the top entry for Rangers seemed to be the closest match – roughly 6” of arch, two thicker leaves at 0.325”, and one thinner leaf at 0.280,” plus the overload of 0.585.” What struck me is that the Ranger springs seemed to be rated for exactly the same 1,250lbs as the Explorer springs, yet rode much nicer. How could this be?????
The answer seemed to come in two parts. First….. the Ranger springs had a much greater arch. Second, the Explorer springs seemed to not have any of their 1,250Lb. spring rating from the overload leaf. The Explorer overload leaf was completely flat, and in fact, tapered on both sides. So, to even engage the overload, the springs would have to be in a negative arch. Whereas the Ranger overload had at least an inch of arch, and with the shorter length, would engage about the last two inches of spring travel.
Finding a leaf spring rate calculator, I put in the length /thickness of the Explorer springs, and came up with s theoretical spring rate of 312lbs / inch. Which wasn’t too far off of my unscientific measurement. Also, dividing the travel (4 7/8”) by the spring rating of 1250 lbs, yielded an estimate of 260 lbs/inch, assuming max spring load was achieved when the springs were completely flat. Everything is at least in the ballpark.
The spring rate calculator seems to be a simple calculation based on Hook’s law for springs. It doesn’t take into consideration the length of the spring perch (which changes the fulcrum point of the spring), nor does it take into consideration that shorter leaves will travel less distance before flattening out. But, it is certainly a useful tool with some understanding of the limitations.
suspensionmaxx.com
The first attachment is a (blurry) picture of the original Ranger springs, but with the Explorer overload leaf. Note in particular, the difference in the total arch of the Ranger springs, as well as the Explorer overload being completely flat.
Second attachment is the spring rate calculator for the first three Explorer leaves.
Putting the (non overload) Ranger leaves in the spring rate calculator yielded an estimate of 169 lbs/inch, not too far off of my unscientific measurements of ~150 lbs/inch. It would seem to validate that the Ranger overload is part of the total spring rating, whereas the Explorer overload is not.
Is this important? Depends on the truck. For my B4000 (4.0L OHV, auto, extended cab), the Explorer spring pack (with a toolbox and other “stuff” in the truck), the ride quality was acceptable, but not exactly a Town Car. For a single-cab 4cyl…. Maybe not so much. Unless a (lighter) truck is routinely driven with pretty much maximum load in the bed, the next lower set of Explorer springs would likely be a much better choice. The second listing in the Explorer spring chart of 1,110 lbs. and a 6.5” arch would certainly yield a much better ride, and possibly more lift, than the 1,250lb springs with the 4 13/16” arch. The overload leaves could be swapped out as well, if desired. Right now my Ranger overload doesn’t engage till at least the first 2” of spring travel (roughly 1,200 lbs) and doesn’t seem to hurt the ride quality, although that would not be true without the Cherokee and Bronco II leaves.
Point being – It might well be worth the trouble to take a dial caliper to the junkyard, when shopping for a new set of springs.
My 1997 B4000 was purchased as a daily driver, and not a serious work or off-road truck. However, after the 2001 dot-com bust, life changed and it went to work in ways that the manufacturer probably never intended. We’ve probably all stuffed the tires into the wheelwells a time or two, but this truck got a bit more of a workout than that. Just sayin’…..
Needless to say, it wasn’t long before the suspension needed attention. Wanting a bit of lift as well, the front was easily handled by 2” coil spacers. The rear springs would involve either some dumpster-diving at the junkyard, or new replacement springs. Reading that Explorer springs were the same length, a trip to the salvage yard was made.
Not knowing any better, the first convenient set of springs was purchased. These were (eventually) discovered to be 1250 LB springs, and exactly match the description on this page – three 0.360” leaves, with a 0.590” overload.
Ford Ranger, Explorer & Bronco Rear Leaf Spring Specs - The Ranger Station
Rear Leaf Spring Specs: The chart below lists the leaf spring specs for the Ford Explorer, Ranger, Bronco, and Bronco II. Leaf Spring Eye Bolts: 9/16″ Grade 8 The 1991-2002 Ford Explorer and Explorer Sport uses 9/16″ x 4-1/2″ Grade … Continued
www.therangerstation.com
If the front of the truck had not been lifted, that probably would have been the end of it, but the Explorer springpack didn’t quite lift the back as much as the 2” spacers in the front. A friend had given me some leaves from his mid 90’s Cherokee when he lifted it, and eventually, I ended up with a pair of 12” leaves from the bottom of a Bronco II spring pack. The Cherokee springs had been pretty well used/abused, as my friend flogged it off-road like a rented mule. As I recall, the Cherokee springs were easily flattened by stepping on them. Being heavily tapered, and probably somewhat abused, they didn’t contribute much to the spring rate, but they lifted everything off of the Ranger overload, as did the Bronco II 12” leaf. Since the Ranger overload was longer and more tapered than the Explorer overload, I used it.
A grade 8 bolt from the local hardware store replaced the centerbolt from the Explorer springpack, after turning the head to fit the hole in the truck spring perch.
The truck rode pretty harshly, but for what I was using it for, not a big deal. Keeping a couple hundred pounds in the toolbox, plus all the crap behind the seat, plus the receiver hitch, etc.., helped the ride – a little. Still, 6 or 700 pounds in the bed did wonders for the ride quality.
Fast forward to the present day. Discovering the spring rate chart on TRS, out of curiosity, I tried to figure out exactly what had been the original springs. There wasn’t an exact match on the chart, but the top entry for Rangers seemed to be the closest match – roughly 6” of arch, two thicker leaves at 0.325”, and one thinner leaf at 0.280,” plus the overload of 0.585.” What struck me is that the Ranger springs seemed to be rated for exactly the same 1,250lbs as the Explorer springs, yet rode much nicer. How could this be?????
The answer seemed to come in two parts. First….. the Ranger springs had a much greater arch. Second, the Explorer springs seemed to not have any of their 1,250Lb. spring rating from the overload leaf. The Explorer overload leaf was completely flat, and in fact, tapered on both sides. So, to even engage the overload, the springs would have to be in a negative arch. Whereas the Ranger overload had at least an inch of arch, and with the shorter length, would engage about the last two inches of spring travel.
Finding a leaf spring rate calculator, I put in the length /thickness of the Explorer springs, and came up with s theoretical spring rate of 312lbs / inch. Which wasn’t too far off of my unscientific measurement. Also, dividing the travel (4 7/8”) by the spring rating of 1250 lbs, yielded an estimate of 260 lbs/inch, assuming max spring load was achieved when the springs were completely flat. Everything is at least in the ballpark.
The spring rate calculator seems to be a simple calculation based on Hook’s law for springs. It doesn’t take into consideration the length of the spring perch (which changes the fulcrum point of the spring), nor does it take into consideration that shorter leaves will travel less distance before flattening out. But, it is certainly a useful tool with some understanding of the limitations.
SuspensionMAXX Leaf Spring Rate Calculator :: SuspensionMAXX
SuspensionMAXX Adjustable Leveling Kits. Less expensive than lift kits. Adjustable torsion bar keys, extended sway bar links. Chevy, Ford, Dodge, Toyota, GMC, Hummer and more. Get the "Just Right" amount of leveling lift for your needs with a SuspensionMAXX adjustable leveling kit.
suspensionmaxx.com
Second attachment is the spring rate calculator for the first three Explorer leaves.
Putting the (non overload) Ranger leaves in the spring rate calculator yielded an estimate of 169 lbs/inch, not too far off of my unscientific measurements of ~150 lbs/inch. It would seem to validate that the Ranger overload is part of the total spring rating, whereas the Explorer overload is not.
Is this important? Depends on the truck. For my B4000 (4.0L OHV, auto, extended cab), the Explorer spring pack (with a toolbox and other “stuff” in the truck), the ride quality was acceptable, but not exactly a Town Car. For a single-cab 4cyl…. Maybe not so much. Unless a (lighter) truck is routinely driven with pretty much maximum load in the bed, the next lower set of Explorer springs would likely be a much better choice. The second listing in the Explorer spring chart of 1,110 lbs. and a 6.5” arch would certainly yield a much better ride, and possibly more lift, than the 1,250lb springs with the 4 13/16” arch. The overload leaves could be swapped out as well, if desired. Right now my Ranger overload doesn’t engage till at least the first 2” of spring travel (roughly 1,200 lbs) and doesn’t seem to hurt the ride quality, although that would not be true without the Cherokee and Bronco II leaves.
Point being – It might well be worth the trouble to take a dial caliper to the junkyard, when shopping for a new set of springs.
