New Owner looking to improve towing
#46
06-08-2018, 02:04 PM
Lead Driver
Hold on..... what weight did you use to arrive at your figures ?
before you go adding your trailer run the numbers using the 1280 pounds shown in the graph that was used.
that 1280 pounds would be the sprung weight per side of your Ex or 2560 total. Remember that sprung and unsprung weight is, Sprung = everything your springs hold up, Unsprung = everything under the springs ( including the spring itself )
by my figure the 1280 would compress the unmodified f250 spring 4 inches
before you go adding your trailer run the numbers using the 1280 pounds shown in the graph that was used.
that 1280 pounds would be the sprung weight per side of your Ex or 2560 total. Remember that sprung and unsprung weight is, Sprung = everything your springs hold up, Unsprung = everything under the springs ( including the spring itself )
by my figure the 1280 would compress the unmodified f250 spring 4 inches
#47
06-08-2018, 05:39 PM
I didnt check your numbers ( yet ) but it sounds like you get the jist of it.
but remember, when people do the f250mod springs, they remove the very bottom auxiliary spring which is what gives the f250 a secondary spring rate, Then they add the bottom 2 leafs from the Ex which then gives your modified f250 spring about the same spring rate as the stock excursion spring.
i say about because i calculated the figures off individual springs but you have to keep in mind that the Ex and the f250 have diffrent arc’s so there is going to be some funky binding going on. You would need to put them in a test jig and measure to get actual.
I have never ever seen ATS springs in person so I can not say how they build theirs.
but remember, when people do the f250mod springs, they remove the very bottom auxiliary spring which is what gives the f250 a secondary spring rate, Then they add the bottom 2 leafs from the Ex which then gives your modified f250 spring about the same spring rate as the stock excursion spring.
i say about because i calculated the figures off individual springs but you have to keep in mind that the Ex and the f250 have diffrent arc’s so there is going to be some funky binding going on. You would need to put them in a test jig and measure to get actual.
I have never ever seen ATS springs in person so I can not say how they build theirs.
#48
06-08-2018, 07:01 PM
Lead Driver
Pirate, I've seen you mention this a few times when discussing the B/C rear spring mods and am confused by exactly what you are referring to as the "bottom auxiliary spring ". All of the F-250/350 rear springs that I've seen modded and swapped under EXs have kept the bottom thick heavy leaf (or plate as I've referred to it in the past), the only part of the pickup truck spring pack that needs to be removed is the TOP 'overload" or Aux single leaf as the EX doesn't have the frame mounted landing pads for them and if left in the pack they can hit and damage the rear HVAC lines. Not all of the B/C truck packs have that single (thin) top leaf so it isn't a universal item on all the packs being modified for use under an EX. Which leaf exactly are you talking about as the "bottom aux spring", Is it the actual bottom heavy leaf/plate or the optional top "over load" leaf that typically has a 1" spacer between it and the main pack.
you are correct, I see quite a few people on FTE who have kept the bottom spring #5 and yes for sure the Top Auxiliary spring #1a would need to be removed if present. ( both marked in red on top drawing )
My reasoning for not keeping the Bottom or #5 spring is if you run the numbers of the modded pack without it,
420 pounds inch x 7' you get 2940 lbs.
2940 x 2 = 5880 exceeds the rear axle weight rating of 5250 by 630 lbs or 315 lbs per spring but the whole 7' of travel is usable.
Going to a modded F250 spring without the bottom #5 spring you have accomplished the goal of adding a Longer travel suspension and even added some payload capacity
if you keep the bottom #5 spring and run the numbers you will see that the first 5.5' of travel have a stock spring rate but when the Bottom #5 spring kicks in for the last 1.5" the rate is so high that it is basically unusable.
first 5.5" of travel is 5.5 x 420 = 2310
last 1.5" of travel is 1.5 x 420 = 630 and 1.5 x 737 =1105 for a total spring rate of 1735 pounds in the last 1.5" of travel
Total capacity of the F250 mod spring is now 2310 + 1735 = 4045 lbs per spring or 8090 pounds combined.
Keeping the Bottom # 5 spring effectively makes the new hybrid pack effectively a 5.5' travel spring, sort of defeating the purpose of building a longer travel pack. just use a lift block on the stock springs if all you wanted was an increase in ride height.
Essentially by keeping the bottom #5 spring you are using it as a shim to dial in ride height on a stock travel spring pack . in my opinion that makes it a silly work around when you could have easily had a better long travel spring or avoided the hassle of building a spring pack and just used a block.
Edit.... thanks for asking for clarity and don’t take the silly comment personal, I am not saying you or anybody is silly or wrong, that’s just not my style.
#49
06-08-2018, 08:22 PM
Interesting, and thanks for the clarification and added info. My modded B codes still have that #5 leaf on the very bottom, but my rear axle weight tends to run a little high 
(but still under the Sterling's rating) with the large TT hitched as it almost is when the EX is moving. It handles the load pretty well now (better than the stock setup did with a slightly lighter trailer and tongue weight), if I were to ever redo the suspension I would most likely go with a coil front conversion and a lighter spring in the rear with airbags. For now I'm a happy camper and the cobbled together setup I run has performed well on our tow rig EX for over 35K towing miles, but like anything else, there is always room for improvement with different options and more info as well as feedback from other users.
And don't worry, "silly" is one of the kindest (and most accurate) things that I've been called.
(but still under the Sterling's rating) with the large TT hitched as it almost is when the EX is moving. It handles the load pretty well now (better than the stock setup did with a slightly lighter trailer and tongue weight), if I were to ever redo the suspension I would most likely go with a coil front conversion and a lighter spring in the rear with airbags. For now I'm a happy camper and the cobbled together setup I run has performed well on our tow rig EX for over 35K towing miles, but like anything else, there is always room for improvement with different options and more info as well as feedback from other users.And don't worry, "silly" is one of the kindest (and most accurate) things that I've been called.
#50
06-08-2018, 09:00 PM
Lead Driver
Fwiw,
I know Cary who came up with the original f250 swap on the excursion and for the time it was a clever and easy way to accomplishment not only getting some additional ride height but the main point was to get rid of sagged front springs which are the main cause of aging Excursions having wander issues. By using the f250 spring which has a positive arch to it as opposed to the stock springs that when sagged sit flat and deflect to a nevitive arc which reduces caster to the point of white knuckle wandering.
By going to a slightly lower then stock spring rate you can make the unladen ride quality just a bit better then it is stock, the addition of air bags then handle any additional payload needs giving you the best of both world.
In the past past I have used the single rate pro comp 2” 4”and 6” springs but I don’t have the current data on them so it makes it difficult for me to recommend them. But essentially I built my excursions in the manner Carli advocates ( at substantial less cost then he sells his badass setup for )
If you have not not seen this it is a great read. Fwiw, Carli is consider one of the best street truck suspension tuners in the country. He is legit.
https://www.carlisuspension.com/prod...system-00.html
truth be told the 2 ex I did that way rode better then my current tricked out 4 link coil over setup but that is mostly because of the shock choice I used. ( working on fixing the shock situation but damn....they are spendy )
I know Cary who came up with the original f250 swap on the excursion and for the time it was a clever and easy way to accomplishment not only getting some additional ride height but the main point was to get rid of sagged front springs which are the main cause of aging Excursions having wander issues. By using the f250 spring which has a positive arch to it as opposed to the stock springs that when sagged sit flat and deflect to a nevitive arc which reduces caster to the point of white knuckle wandering.
By going to a slightly lower then stock spring rate you can make the unladen ride quality just a bit better then it is stock, the addition of air bags then handle any additional payload needs giving you the best of both world.
In the past past I have used the single rate pro comp 2” 4”and 6” springs but I don’t have the current data on them so it makes it difficult for me to recommend them. But essentially I built my excursions in the manner Carli advocates ( at substantial less cost then he sells his badass setup for )
If you have not not seen this it is a great read. Fwiw, Carli is consider one of the best street truck suspension tuners in the country. He is legit.
https://www.carlisuspension.com/prod...system-00.html
truth be told the 2 ex I did that way rode better then my current tricked out 4 link coil over setup but that is mostly because of the shock choice I used. ( working on fixing the shock situation but damn....they are spendy )
#51
06-08-2018, 09:32 PM
Lead Driver
OMG ...... I have never seen Carli’s blog on tire pressure and size but here he is saying what I try to convey here on FTE ( often to the point of people becoming combative because it goes against what they are doing )
Carli Blog: Tires and Wheels: How Do They Affect My Ride??
Carli Blog: Tires and Wheels: How Do They Affect My Ride??
#52
06-08-2018, 11:09 PM
Cary made it popular, but he is not the originator of the idea. Someone else came up with the idea and talked about it over at TDS back in '04 or '05. IIRC Cary had tried a couple different lifts before trying the F250 springs. Him conversing with others on the board about the mod made me research it and I ended up doing it shortly after he did.
Stewart
#53
06-08-2018, 11:48 PM
Lead Driver
#54
06-09-2018, 12:31 AM
Cary doing it before me, and him being sold on how much it improved the ride and steering is what pushed me over the edge to do the mod, instead of a lift. Glad I did too, in hindsight. But credit where credit is due, without Cary making this part of his business, I don't think it would have taken off like wildfire. He gets all the credit for making it the most popular mod for these badboys.
Stewart
#55
06-09-2018, 01:45 AM
Rcarpen -
This is a old thread where we worked on what hitches had what and loads for different years. If you are interested in what your Ex hardware is like, take a read.
https://www.ford-trucks.com/forums/9...-hardware.html
This is a old thread where we worked on what hitches had what and loads for different years. If you are interested in what your Ex hardware is like, take a read.
https://www.ford-trucks.com/forums/9...-hardware.html
#56
06-11-2018, 09:03 AM
I didn't get a chance to mess with the truck at all this weekend. Regarding the calcs above, I wasn't trying to figure the total deflection of a spring, only the change between curb load (assumes the weight of the vehicle already) and the additional load of my trailer. So I added half the assumed tongue weight and just looked at the corresponding point on the chart as compared to the curb load. I see I have a lot of homework to do now, as a LOT of excellent info has been added since I last looked at this thread. I will check it all out. I have noticed that since I set tire pressures to the recommended settings, the Ex drives better with less wander. My theory is evolving as I learn more, but currently think that shocks are shot, caster is too low, and stock springs are a little worn. This coupled with the rear being too stiff and high from the maxed out RAS are contributing to the floaty front end.
#57
07-13-2018, 09:18 AM
Ok, been a while, but I figured I would report back. I took the Ex into a truck alignment shop. They looked over everything and set the alignment. They also retorqued the ball joints, as they determined that the front end was "too tight." I asked for 5 degrees of + caster. They put 2 degree bushings on, which took it from +2 to +4. Bottom line, that solved the bulk of my problems. I took it (plus 6 other people) on a road trip and cruised easy at 75 with no issues. The steering still isn't great by normal car standards, but it no longer feels terrifying at high speeds. I'm going to install some new Bilsteins and tires and call it a day. Any tire recommendations for towing? I want a stiff sidewall, so thinking maybe BFG A/Ts. They are E load rated and have mega stiff sidewalls.
Thanks
Thanks
#58
07-13-2018, 10:45 AM
Cargo Master
I just bought a 2001 Excursion 7.3 expecting it to tow significantly better. I really like a lot of aspects of the Excursion, but it is terrifying to drive at highway speeds, especially when towing. The previous owner installed the RAS system, Hellwig rear sway bar, steering damper and the redhead steering gear. Despite these modifications, it is still very difficult to keep it pointed in a straight line, and hitting bumps makes it feel like I'm about to completely lose control. It's not a pleasant experience.
Read all that I could on the wander issue.
Swapped in V code front springs and did the modified B code rear spring setup.
On the drive home from my buddy's place, I could get on the freeway and let go of the wheel and she didn't budge for around .2 of a mile until I had a tiny adjustment...drove like it was on rails. With a trailer now my biggest worry is on windy days - bumps I don't even think about now.
I will say I added air lift springs to the rear, but that was just to level out when towing. We run 16' dual axle box trailers filled with around 5000lbs of search and rescue gear...the trailers weigh in just under 7500lbs total weight, with between 12% and 13% of the weight on the tongue. I also run E range tires at 80psi...so if it truly were anything to do with caster, 80lb tires would magnify any issues - and I have no issues now that I swapped the springs.
So before screwing with caster and all that, (which doesn't really cure the sag issue nor the bottoming out issue)...consider springs. For me at least, it completely removed steering wander, got me good ride height (that setup raised the front maybe 3/4" and the rear about 1.25"), and took out most of the sag when towing.
I am NOT a suspension or steering expert, but for me at least, springs cured all my ails. I have a sticky somewhere on my spring swap...did it in about 8 hours with floor jacks and jack stands while BSing with a buddy one Saturday.
#59
07-13-2018, 10:49 AM
Cargo Master
#60
07-13-2018, 11:05 AM
Fleet Mechanic
The Ex did not come with one, even though the F250s, Explorers, Expeditions, etc. all did.
A rear anti-roll bar helps keep the rear end under control when cornering and cross winds, especially when towing.
Our 8k TH tows great in winds.