Pre-Runner Springs - lots of rear wheel travel

[Rusty PW]

I have a feeling I just bought into an expensive hobby...

When you jump into the rabbit hole. There is no bottom.

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[piroman683]

Happy Sunday everyone! I finally had a chance to take more more measurements ad data points on the spring design I'm finalizing for production. The photos show truck ride with and without 266lbs of pre-running gear in the bed. With 266lbs of gear the rear sits about 15/16ths of an inch lower which is to be expected. I also include photos of pinion angle at ride height and at full droop. Please note that for full droop and flex testing I put back on the longest Fox 2.5's which have 13in of shaft travel (-076 part number). These shocks are the only shocks that will enable you 18.25in of rear wheel travel. With the Fox 3.0 bypasses you are limited to about 16in (this is due to the compressed length being about 18.8in which is too short to fully utalize), this is also why the -075 results in about the same max wheel travel). I will eventually, closer to production and website launch, creat a detailed breakdown of the whole thing (geometric limitations, shock limitations, etc.)

At full droop with shocks extended to 32.25in the current development springs do unseat by about .5-.75in. I spoke to the supplier and this is because they settled more than production due to the different winding process used. 1 of custom sprnigs typically settle about .5in, more when the ratio of coil diameter (not wire diameter) to free length is large, especially if the ratio is more than 1:4, and in this case the coil diameter (OD) is about 6in, and my free length is 25.75in so this is to be expected. Production should see a settling of about .125in. more to come on that later.

This is the pinion angle with 266 lbs in the rear, I forgot to take a photo with the rear empty, but it's pretty negligable given that the resulting height change is 15/16ths.

Images of full droop with pinion angle:

Also, after I complete the NORRA 1000 with these springs I will install another development pair in the rear that are 125-130lbs/in. The current ones are 142. I have a few reasons for wanting to test this: 1st when I was watching my videos from Barstow I noticed the rear kept floating up a bit too much over some of the whoops. Noting alarming here as I was already doing over 60pmh, but still a good data point. #2: 10 lbs less is only 180lbs-ish of less total jounce which is not a deal breaker, and will result in the rear being lowered by less than .5in. One thing I need to keep in mind is how that impacts towing as the 142lbs felt great with 600lbs tongue load + 300lbs in the bed (6k total trailer weight). However, pre-runners dont typically tow trailer haha.

Other notes: you can absolutely kick some desert ass with the Fox 2.5's (-076) or the Fox 3.0's (for the Raptor). However, with the Raptor 3.0's you will loose about 1.5in-ish of droop/wheel travel. But, you gain so much more by having a 2.750in piston vs. 2.25 along with cooling circuit and rebound adjustments. The 2.5's will get HOT though so I'f you'regoing at it non-stop all day be prepared to service your shocks more frequently, and PLEASE change shock fluid! Just like when oil gums up from ignoring maintenance, shock fluid does the same.

As always feel free to ask any questions either here, or PM, or now you can email me at [email protected]

one more dangeling carrot: I am working on a custom shock set up for these springs, these are truly unique and will be a 3.0 size starting with 12in of shaft travel, possibly up to 13, and a unique approach to bypasses. I have filed 1 patent on the design and have a second provisional patent currently filed. That's all I'm saying for now.

 

[piroman683]

well crap, i forgot the flex photos. When I had the stock fron sway bar + rockjock rear along with Clayton front springs, Synergy rears coupled with Fox 2.5's (11.19in shock travel front, 11.97 shft travel rear) my front flex was 32in and the rear was 30. The front springs were a bit too stiff to really flex.

With these springs i was able to achieve 38.5in front, and 37.25in rear. Now I also installed the rock-jock front sway bar (softest one). The truck flex is now awesome, and I'm curious to see what it does with the finalized springs. I will be going with a slightly thicker front wire for the coil which reduces the # of coils needed, but puts me just above the infinate stress thresholdby about 3%. This should make adjusting the front bumpstops and adding the sanp on bumpstops easier. But still need to test that out.

 

[piroman683]

quick update: I ordered 1 more set of R&D rear springs, it will lower the rear height by 1 inch so I'll be retaking photos once I have them. total jounce is reduced by about 110lbs, but there is more compressible margin with reduces the stress at full bump which improves life!

Currently expecting pricing to be less than $280 for a pair of front springs and under $370 for the rears. I am still sorting out shipping costs while starting to look for a web site developer/builder to get thing ready for product launch.

I know the quest will come up regarding the big price difference between the fronts and rears. The rears are much longer and thicker wire than fronts, and thats about all I can say about that. Shipping is not as straight forward either as I'm right on the edge of having to pay extra due to the weight of the rears which drives shipping costs more than packaging size, so we are looking at creative ways to minimize additional costs right now (shipping wise).

 

[piroman683]

Alright everyone, after a lot of merchandise issues and platform issues I finally launched my GoFundMe: https://www.gofundme.com/f/2024-norra-1000-race

I have 1 more set of rear springs I want to test that arrive next week, then it's time for the rally!

I'll have starlink with me during the rally and will be posting videos and trying some live streaming so be sure to check out my Instagram to keep up to date with things.

Stay dusty my friends!

 

[Hdog911]

Color me impressed by your research, work and the driving. I have a JTRD with synergy with ads triple bypass and hydro bumps. Im guessing there's some extra work involved to make your setup work for a diesel.

 

[piroman683]

Color me impressed by your research, work and the driving. I have a JTRD with synergy with ads triple bypass and hydro bumps. Im guessing there's some extra work involved to make your setup work for a diesel.

The diesel requires a lot more for the rear because the Rock Krawler Pro-X doesn't fit with all the emission stuff in the way. The pro-x is what is key to getting the rear to have the freedom to utilize the full range of wheel travel. Without it the rear goes int bind from the 5 link design regardless of adjustable arms or track bar (or worse, track bar bracket).

The springs would still fit, but range of motion would still be a challenge.

In my most recent test I fully loaded up my truck with all the fuel, tools, spares that I would have during the Mexican Rally and my weight came in at 6040 lbs, it was split at 2880 lbs in the front and 3160 lbs in the rear. Empty it is about 500lbs lighter, but in both cases the rear springs were still a little too stiff to allow the axle to float smoothly over the whoops. Next weekend (April 13/14th) I'll be installing the final development set of rear springs and give it a rip. They are only .25in longer and 15lbs lighter in spring rating so it will sit more level while working better in every way (except having about another inch of squat when fully loaded and connected to a trailer)

 

[Hdog911]

The diesel requires a lot more for the rear because the Rock Krawler Pro-X doesn't fit with all the emission stuff in the way. The pro-x is what is key to getting the rear to have the freedom to utilize the full range of wheel travel. Without it the rear goes int bind from the 5 link design regardless of adjustable arms or track bar (or worse, track bar bracket).

The springs would still fit, but range of motion would still be a challenge.

Is it just the DEF tank that's in the way of one of the upper control arms? One could find a way to delete it.

 

[Teh_Stormtrooper]

Just read thru this whole thread. I can't wait to see where this heads. Nice work!

 

[piroman683]

Good morning everyone! Quick update on the Springs:

• I've installed the next version of the rears which came in at 129 lbs/in. This dropped the rear height by about 3/4 of an inch (empty) and it looks and rides better than the previous set at 142 lbs.
  • I also increased the free length by .25in to ensure a preload of at least .5in at full droop when connected to a shock that has a 32.5in extended length
• this slightly lower rating as also resulted in better tuning of the 3.0 bypass shocks I am currently running

This Friday I head to Ensenada for the NORRA 1000 rally. It will be 1,300ish miles of offroad and I'm hoping to maintain an average off-road speed of at least 40mph - this will be tough as I only achieved 37 when pre-running the Parker 500 race course, but I feel the truck is running better now so we will see.

As far as I know, right now the only shocks that will allow you to achieve the 18in of rear wheel travel these springs are designed for are the Fox 2.5 dsc's part number 883-26-076. I did a bunch of testing and the best you could compress the rear results in 18.75in of compressed shock length. This is also after cutting the exhause out as the track bar mount on the axle will smash through it.
When the rear is tucked up (compresses) to the limit (18.75in bolt to bolt for the shock) your remaining spring height is about 8-8.25. This was very difficult to measure, but the nice thing about these springs is they can compress as short as 7.4in so we have great margin there.

For the fronts, the currently designed spring does allow for 13in of travel, however; at full droop, when measuring from shock bolt to shock bolt, the max extended length is 31.5in. I actually repurposed my old Fox 2.5's (-075 part) and installed them in the front and they fit well, and have 11.97 (12in for rounding) of travel. Unfortunately to gain 1 more inch of travel you need 2 more inches of extension, that just how the math works. I am designing custom shocks, but those are pretty far out from being ready.

While in NORRA I plan to live stream from my truck starting Sunday April 28th. Each day I'll stream some of the race from the truck cab and some of the aftermath each evening. Be sure to check out my instagram page for updates and details, and if you're interested in helping I have a go fund me page that includes really nice merch for different supporter tiers. (as well as some sneak details about some 3D printed things I'm working on)

Instagram: https://www.instagram.com/fundamentalmotorsports/
( @fundamentalmotorsports )

goFundMe: https://www.gofundme.com/f/2024-nor...t&utm_campaign=p_email+html_summary_donations

 

[piroman683]

Hey gang, I am back from the NORRA 1000 and it was a huge success on multiple fronts.

First thing - Springs: They worked awesome and showed no signs of issues, premature wear, and handled the whoops with no issues!!!

I sent in the final designs to begin he production process, I will have lead times and final pricing ready by end of week.

Second thing - Shocks: If any of you have been following on my instagram channel @fundamentalmotorsports you have definitely seen some videos and images of 3D printed bypass shocks. These kicked ass during the race, better than expected. However, I still have a lot of development work to do to make them lighter, easier to hone, and drive down pricing.

Third thing - dana 44's: I blew my ring gear while hitting large whoops and passing built raptors at about 45-55mph at the end of day 1 of the 6 day rally so I had to finish the whole thing and drive back home from Cabo in front wheel drive, and I dont have a locker on the front. The good news is, suspension wise, what I've developed is more suspension than I would have expected. The bad news is now because you can handle these bigger whoops/speeds the dana 44 is the weak link (rear specifically). So just keep that in mind.

Back to spings! I want to produce and start shipping out springs right away so I am looing into using Venmo for now while also incorperating a quick docusign page to confirm order/liability. The reason for this is I dont want to delay things any longer with trying to get my website situated with all the proper links, buttons, and other things. I will be working on that in parallell, but my focus is producing springs and shipping them out right away.

Once I release pricing I will provide my company email for us to chat and finalize orders.

cheers!
- Mike

 

[Rusty PW]

How much lift does these springs give?

 

[piroman683]

How much lift does these springs give?

about 3-3.5 inches. and a 40in tire at full bump in the rear still has clearance (and thats without bump stop pads)

 

[aFatBird]

Seems mighty temping. Keep the updates coming.

 

[piroman683]

Final design was locked in Monday, and we are waiting on final material quotes. Once I have the quote I can make the initial production run payment and then it is 6-8 weeks max. I can then also provide details on pricing and shipping costs. I am unable to afford free shipping right now, but it looks like I should be able to reduce shipping costs by about 50% when compared to normal individual rates.

I spoke to my accountant and I'll need to set up my shopify account and take order through that so that will be my focus over the next week. It will be set up as pre-order for now since I dont have any inventory on hand.

Also, for those local to Long Beach/LA I will be personally delivering things if you'd like.

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