Matching Springs to Load Carried

[KevinP]

So measuring last night the spring arch height...

Left Front 1.375"
Left Rear 1.375"

Right Front 2.125"
Right Rear 2.0625"

I was surprised on how little the right side is compressed... only an inch if the free arch is 3".

We are the second owners of the unit. When we purchased it in the spring of 2017 I didn't look at the conditions of the springs. I did check to make sure it didn't have the 5200 lb axles that some of the early 323's had. It is possible that they have been in this condition since the day we got it.

Well new springs are certainly going on in the very near future.

I am leaning (ha!) toward following Rob, Pat and others fix on the 303 and going with a heavier spring on the left (3500lb) and staying with stock rating (3000lb) on the right.

[Cate&Rob]

Hi Kevin,

When Pat & I were trying to figure out what was going on, I built a spring compression fixture that I could use with my Sherline scale to measure arch height at different loads. You have probably seen the attached buried somewhere in the many threads on this topic. Re-attached here for reference . . .

We were focused on 2600 lb and 3000 lb springs so, only the 3000 lb spring info will be applicable to your situation.
At 2000 lbs, the arch height of a 3000 lb spring is about 2" See page 5 of the attached . . . this confirms your right side weights/measurements.
At 2500 lbs, the arch height of a 3000 lb spring should be about 1.7". Your left side springs are 0.3" less than this . . . indicating deformed springs.

I don't have numbers for 3500 lb springs, but following the logic that worked for Pat & I, I would concur with your plan to replace the left side springs with 3500 lb ones. From the summary chart attached to the Arch Height Measuring info, note that my new vs old 2600 lb springs on the (lightly loaded) right side made an insignificant arch height difference. You probably don't need to replace the right side springs.

When you pull the springs, you will likely find the OE plastic bushings are worn out. This is a good time to upgrade to the MORryde kit for heavy shackles, wet bolts and bronze bushings.

Rob

[KevinP]

Rob,

Agreed that I don't have to replace the right side springs as they seem to be doing fine.

If I have everything off to replace bushings, shackles and possibly the equalizer might as well do the springs too.

Question for you.... do you still have drum brakes or have you upgraded to disk?

[Cate&Rob]

Question for you.... do you still have drum brakes or have you upgraded to disk?

Hi Kevin,

I upgraded to disc brakes . . . best safety investment that I ever made!
See https://www.mygrandrv.com/fo...tem-Hydraulics and https://www.mygrandrv.com/fo...-System-Wiring for that story . . .

Rob

[KevinP]

Just a quick update on what I decided to do. I am going to replace both sides with 3500 lb 6 leaf spring packs. My primary concern is loading and flat spring not lean.

To help ease some of the shock the stiffer springs could transfer to the frame I am upgrading to the SRE-4000.

I know it won't change on the front and rear spring hanger as those are still a solid mount. Providing a little give in the center hanger is better than nothing.

[webpilot]

Be sure you include the X Factor Crossmember when you put in the SRE 4000 to give you additional side to side support on the center hanger.

I did what you are doing on our 337. I first replaced the springs with 6 leaf 3500# springs and a couple of years later put in the SRE 4000 with the crossmember and heavy duty wet bolt kit. The springs made a huge difference and I did not see them as having a harsher ride than the flat 300# springs I had on before. I thought that the ride was much better.

Best wishes on your upgrade!

George

[KevinP]

Thanks George.

I did order the 735X kit which has the X Factor brace for the center hanger. I am holding off on the end hangers. Looking at clearance for the rear hangers, the spare tire would have to be moved to mount the brace.

Did you do the end braces or just the center?

[webpilot]

Hi Kevin,

I only did the center brace, not the end hangers.

George

[KevinP]

I installed the new 3500lb springs all around, SRE-4000 and X-Factor brace on center mount and the MorRyde wetbolt kit for factory Correct Track system.

All went well. The trailer does sit better on the left/street/fridge side since the springs are rated higher, have a thicker stack and aren't beaten down.

As expected there still a lean to that side.

And as expected with the Correct Track adjusters all in the neutral location, the left side wheels are still closer together than the right.... by 1/2 inch. I'm thinking that with the 1/2in difference in spacing that the axles are not parallel to each other and the tires are slightly out of alignment.

George or Paul.... have your axles been adjusted (with correct track or not) so the wheel are the same distance apart?

[Gyro Gearloose]

Well I'm late to the party (been head down trying to get property insurance again in Calif., Stinking Calif. Fires!)

Did some dry camping after Vegas Rally, full water tank etc., and had no issues with tire rub or being out of level, so the 3K springs on the drivers side of my 303 did their job. Also still seems to sit level after being pounded to death on the nasty California roads.

Because X Factor was brought up I thought I would provide my thoughts on the forces. When you turn sharply, the axles move in opposite direction latterly, so the the side loading on the center hanger is basically nullified, so less side loading on the center hangers (probably why you don't see them break often). So the end hangers are the ones seeing most of the side loading and probably why they are the ones that break more often. Just my opinion, but if I were to install X Factor, I would do them on the outside hangers.

So I don't hijack this thread, here some links associated to the subject of spring hangers that will keep you busy for awhile (if you care ):
https://www.mygrandrv.com/fo...Spring-Hanger!
https://www.mygrandrv.com/fo...n-Modification (This project will hopefully get installed in the next month or so.)

Pat