I have an 05 x that I am going to be towing a Travel Trailer that is almost 11K pounds. Should I get B codes or C codes?


I am going to be putting on Bilstein 5100s.


If I use C codes would dual shocks on the rear help with the harsh ride unloaded or use 5160s?

 

I have the B code in the rear and while I haven't towed that much weight yet I did just do a trip with about 1300# in the rear and have towed about 6000# with the rear empty.


From this limited experience unless you are planning on have a large load in the rear of the vehicle while towing the B springs should be fine but I would consider a rear anti-sway bar a necessity.


The ride will feel harsher no matter what you do. But it isn't that bad - about the same as a F250 unloaded. You will gripe about it for the first two weeks then afterwards you won't even notice it. I have the Rancho 9000 shocks installed and keep them dialed at the lightest setting for daily driving.


Things like proper adjustment of the load leveling hitch, rear anti-sway bar, and proper maintenance of the front end will affect your towing, not going to C codes instead of B codes IMO.

 

On my truck I went with SRW C codes, reason being is here https://www.ford-trucks.com/forums/1...ring-swap.html

Unloaded the C has a better chance to ride better because the secondary rate is later than the B.

 

In that case I may be missing something. I had assumed the B springs were the "normal" rear (3000#) and the C were the slightly heavier (3300#) ones. This was from a chart from an aftermarket supplier but the searching became a bit confusing as what a "C" is depends on which model year.


If the only difference is the point that the additional leafs engage then Rob is correct and the C should give a smoother ride without a payload.

 

All of my research was part number based, I found the drawings and studied them. The rate/load I mention is from those drawings. I have no way to tell exactly which part number went with which spring code. If someone had a vin from truck with C codes (singe and dual wheel) I might be able to confirm the code(s) to the part number(s). From reading here I applied the codes to my spreadsheet of part numbers.

I think there are two C code versions, single rear wheel and dual

SRW - 330 lbs/in primary, 651 lb/in secondary, 1781 lbs transition, 2780 lbs max load

DRW - 350 lbs/in primary, 730 lb/in secondary, 1800 lbs transition, 3626 lbs max load

B Code - 320 lbs/in primary, 670 lb/in secondary, 1650 lbs transition, 2999 lbs max load

I looked at my spreadsheet and I don't see anything in my findings with a max load of ~3300 lbs.

I had sent my spreadsheet to one of the moderators but never heard back...

Does that help?

 

That right there is most likely where your issues are coming from. Aftermarket supplied springs are rarely up to the same specs as Ford OEM springs. A large number of the aftermarket "X" springs are barely better, if at all, than the OEM "V" code's. Same for the rear aftermarket springs as well.

Tom (WE3ZS) actually just sent me the chart that floats around here every now and then as I am looking at potentially revamping my suspension from V's and B-mod's to X's and C's.

I'd also recommend getting in touch with Junior from ATS (username ATS Junior) and see what he can do for you. Here's a blurb from the conversations he and I have been having via PM. I requested a rear spring similar to the C-codes but with some extra weight handling capacity for towing and here's what he suggested:
Hopefully some of that helps you out. I can say from personal experience that with the B-mod rear's the ride is not harsh, it's definitely more "trucky" than stock but nowhere near what I'd call harsh. Single Bilstein 5100's on all corners for me as well, duals out back is just asking to get pummeled to death (unless Cary has some trick rear setup up his sleeve). Not to mention I don't know where the heck you'd mount them, not exactly a lot of room to work with back there especially with the tank and exhaust.
I recently towed a friend's Duramax crewcab 4x4 on a 20' flatbed, I'd say the combined weight was smack dab between 10,200-11,500 lbs. With the B-mods out back and nothing else (no airbags, no RAS, no WD hitch) it made my truck squat so hard it was untowable. However, my rear bumpstops deteriorated long ago and I haven't replaced them yet. But the tires were rubbing on the fender flares. We had to load the truck on backwards (biiiiig no-no, I know) and take backroads at slow speeds to tow it safely.

I have no idea with you have a WD hitch, if not - get one. Tons of members here tow large trailers and they swear by them.

 

Keep in mind the load ratings in the above chart are GAWR and not max spring capacity. The #'s I quoted are max for each spring on a bench test.

 

Good catch, I was in a rush when I posted all that and meant to include what you mentioned. Thanks dude.

 

Krazee Matt,
Is there similar chart like that for the rear springs?

 

That chart includes the rear springs, B & C codes are at the top. Does not include the F codes (08-12 IIRC) that are the same as C's I think.

 

No, the B and C codes on the chart are the stock fronts, Ford used the same letter codes for fronts and rears to avoid any confusion, see how well that is working out!
Rob Ross has done some great detective work on these EX/SD springs and has some very good spring info! Dig into his posts about these springs.

 

WTaF Ford... Had me fooled forever with that damn thing. Im just full of useless misguided information tonight.

 

Thanks Tom!

If you're buying new, my spreadsheet may help, if you looking for used then I think any SD springs (B, C-SRW, C-DRW, F, etc) would such an upgrade that you would be happy.

You may want to consider an adjustable shock, in general, if you have less spring rate you will need more damping and vice versa. The SD springs do have less primary where the Ex springs is more or less a fixed rate. In my case the adjustable shocks helped me dial in my ride and helped me balance the front to the rear. Adjustable shocks are only for compression and rebound, once the shock is moving, you have the same damping regardless of setting.

 

Thanks for all the input. I think I am going to go with c codes with an Extra leaf from Junior.


Now who sells 5100's that does custom valving?

 

Good choice, that's what I'm getting as well. Extra 1000lbs capacity as well.

I got my valved 5100's from CTPerformance. However, after 18-mo I wish I had either gone stiffer or with his custom valved dual shock setup. Bit too little damping and rebound control for my liking. I didn't want standard aftermarket duals, I've ridden in several rigs with them and at city speeds they pummel you to death. Soak up high speed bumps with ease though.