Flat Springs on a 2019 377

[Hoopy Frood]

I tried to buy the 4,000 lb. springs from Dexter, but the time frame just wasn't going to work. So I ordered from Lippert, got them in time, and saved myself a couple hundred dollars to boot. The issue I ran into was knowing what length spring to specify. Lippert specs the springs at 24 7/8" eye-to-eye, but Dexter and most other places spec them 25 1/4", or 26". It would appear that different places measure the springs a bit differently. The 24 7/8" is unloaded dimension, 25 1/4" or 26" is what the springs measure when loaded with the weight. When I removed my springs, they measure 26" eye-to-eye unloaded. They were shot. My new ones measured 24 7/8"-25" eye-to-eye unloaded.

FWIW, the new springs are 7 leaf vs 6 leaf for the 3,500 lb springs. So you need new/longer U-bolts. I had a heck of time finding the right length on line: 8", so I ordered some from Etrailer, but again the time frame wasn't going to work. I ended up sourcing them at a local spring shop, and saved myself another $100.

[Overtaxed]

Thanks Hoopy, I can't seem to find the 8in Ubolts that will fit a 7K axle, any idea where you found them on etrailer?

Best I can find is this:
https://www.speedwaymotors.com/8-x-3...aign=CSEGOOGLE


This look right to you:

Spring
https://www.etrailer.com/p-DX74XR.html

Bushings:
https://www.etrailer.com/Trailer-Lea...71-291-00.html

Wet bolt (I have one with a broken off zerk that I'll replace while I'm in there):
https://www.etrailer.com/Trailer-Lea...ine/126B2.html


Alternative spring option (quite a bit cheaper):
https://www.truckspring.com/trailer-...e-mts-055.aspx

Any idea if that would work, the length is a little different, but, given the way the equalizer works, I think it would fit?

[Hoopy Frood]

I can't find those U-bolts on Etrailer either. I paid $11 each locally so yours look pretty comparable. The cheaper springs are 8 leaf instead of 7, and the length is probably measured when loaded, but couldn't swear to that. Those are most likely china made steel, but it's likely the ones from Etrailer are too, so your choice. Good luck with it.

[Overtaxed]

I can't find those U-bolts on Etrailer either. I paid $11 each locally so yours look pretty comparable. The cheaper springs are 8 leaf instead of 7, and the length is probably measured when loaded, but couldn't swear to that. Those are most likely china made steel, but it's likely the ones from Etrailer are too, so your choice. Good luck with it.

Well, hopefully I've got everything I need. Here is what I ordered; I'll update and let everyone know if it worked or not:

U-bolts (the longest I could find, this price is ridiculous):
https://www.etrailer.com/p-MR66ZR.html

Springs:
https://www.etrailer.com/p-MR66ZR.html

Bushings:
https://www.etrailer.com/Trailer-Lea...de/MR46ZR.html

Note: I ordered the whole kit because I need a few things from it, I have a shackle that's lost a zerk (and I can't fix it because they are press in), need the bushings from it for the new suspension and I need a new standard wet bolt, I'm going to keep the rest for spares because the price was similar ordering just what I needed vs the entire kit).

Right around 1K out the door. As long as these springs don't go flat quickly too, I'll consider it money well spent.

Thanks for the help!

[Hoopy Frood]

Reconsider that kit from Etrailer for the U-bolts, and source ones from a local shop. Those are the ones I was going to use, but after pricing them locally for half the cost, I bought local. Make sure you check all the wet bolts to be sure they will pass grease. I had one that had to be finished drilled. And think about getting a cheap 9/16" reamer. All of the bushings I pressed into the spring ends, deformed enough make it impossible to get a bolt through them. A reamer will make your day at that point. I got my springs from Lippert, but I'm sure the quality is comparable.

The wet bolts should have scew-in zerks. Press-in zerks should be returned post haste.

[huntindog]

Well, hopefully I've got everything I need. Here is what I ordered; I'll update and let everyone know if it worked or not:

U-bolts (the longest I could find, this price is ridiculous):
https://www.etrailer.com/p-MR66ZR.html

Springs:
https://www.etrailer.com/p-MR66ZR.html

Bushings:
https://www.etrailer.com/Trailer-Lea...de/MR46ZR.html

Note: I ordered the whole kit because I need a few things from it, I have a shackle that's lost a zerk (and I can't fix it because they are press in), need the bushings from it for the new suspension and I need a new standard wet bolt, I'm going to keep the rest for spares because the price was similar ordering just what I needed vs the entire kit).

Right around 1K out the door. As long as these springs don't go flat quickly too, I'll consider it money well spent.

Thanks for the help!

Hopefully those ubolts are not too long, and interfere with the frame. Cutting off the excess after the install is a real pain. BTDT.

[Hoopy Frood]

With 3" axles, and 7 leafs/leaves, an 8" U-bolt is just about right. And it's not a big deal to cut off excess. The local thought he was doing me a favor and made mine longer, but it was the work of a few minutes with an angle grinder to remove the excess. Power tools are a wonderful thing.

[huntindog]

With 3" axles, and 7 leafs/leaves, an 8" U-bolt is just about right. And it's not a big deal to cut off excess. The local thought he was doing me a favor and made mine longer, but it was the work of a few minutes with an angle grinder to remove the excess. Power tools are a wonderful thing.

Agree. I have many along with welders, Chop saws and just about anything to work with metal.
When I had to cut my ubolts down to size, I chose not to use any of my angle grinders. I did not want to wear my PPE for this task to keep from inhaling the particles, and I also did not want any sparks finding their way into/onto a bad spot. I used one of my sawsalls. It worked OK for the job and was the safer choice.
But I was thinking that the OP might not have as large a selection of tools , and at any rate, this is not a case of bigger is better. The right size is the right size and, avoids having to cut anything

[Hoopy Frood]

Absolutely agree. I specified 8" and he gave me 2" too long. Didn't think that much about it until I mounted it and saw it would interfere with the frame on compression.

[Overtaxed]

Did the first side last night. The parts above worked perfectly, everything fit exactly right. I will say, even though the price for the ubolts is ridiculous, they are some really nice bolts (seriously). The nut they come with must be close 1in deep! Compared to what was on the RV stock, they are an obvious level up in machining.

Do you guys dress the threads on the ubolts with locktite? Those backing off could be a real problem, I was thinking of doubling up the nuts or locktite; I never had a problem before, but just wanted to get some opinions.

One surprise, my stock/factory springs on the 351M did have bronze bushings in them. DID being the operative word. They were nearly destroyed in some of the eyes, and all of them were basically shot. The new springs came with the nylon bushings, I pushed them out using a hydraulic press and put in the bronze bushings, but not exactly confidence inspiring to see what ~10K miles did to the factory bronze bushings. And yes, I'm pretty religious on greasing the wet bolts; however, after seeing the damage to them, I'm going to step up the grease schedule significantly. I was greasing about 1X per month (when I'm using the RV), roughly every 1-2K miles. I'm going to go to greasing every time I tow now and see if it can get me a little more life out of the brass bushings.

I also had to replace one of the shackle wet bolts; it was one of the bushings that had failed and the bolt wasn't round anymore, I could feel a flat spot with my fingers. Figured that one has reached it's EOL.

I did buy the whole wet bolt kit so I'd have spares, glad I did as I needed some of the bushings from the kit (which I knew) and as mentioned, already needed one of the shackles. I'm going to have spares, but if anyone else is doing this, I'd suggest just getting the whole kit so you have what you need; shackles, wet bolts, bushings, nuts, etc.

Direct links for everything I purchased:

8K Dexter leaf springs:
https://www.etrailer.com/Trailer-Lea...le/DX74XR.html

Ubolts:
https://www.etrailer.com/Trailer-Lea...de/MR66ZR.html

Hardware kit (shackles, bushings and wet bolts; I'm only using what I need from here, will have plenty of extra/replacements):
https://www.etrailer.com/Trailer-Lea...de/MR46ZR.html


Total OTD cost ~1,100 bucks.

Thanks for the help everyone, I'll post up some pictures when I finish it up (hopefully tonight), but not a whole lot to see. The new springs are going to add some height to the RV, both because they're not flat and because they have an extra leaf. Hopefully I'll still be below 13'6", but I think I will.