Bkennedy's SAS and Rebuild Thread

[BKennedy]

We were going about as fast as the road allowed for what we were driving. I spoke to Dave at davesoffroadsupply.com, the vendor who I purchased the shocks from. He said there was no way I overheated the shocks and the oil must have been contaminated or something was already wrong with the seals. He has customers who race with the same shocks I have. He thinks its a fluke. He told me to fix them and enjoy.
He did offer to pay for the seal kits, but I declined. I am planning on doing just what he suggested. The only difference is I will not be too quick to recommend F-O-A shocks to others.

 

[BKennedy]

Pulled the valve shims out of the shocks and they had it set up very light (08) on compression and light (mix of 08 to 10 shims) on rebound. I now have it set up for medium/firm compression and medium rebound.

I also found some aluminum slivers and some orangish bits of something unknown in the ports.

When I completely strip the shocks for the reseal, can I spray them out with brake parts cleaner to flush them out? I want to get every bit of the old oil and any contaminates out of the shock bodies. If that is too harsh, I can put some fresh oil in there, shake it around and drain it quickly. I have a bunch of oil.

 

[FR-425]

I did some reading around on the FOA opinions.

Seems every person said that the first run blew the seals and produced metal shavings.

After the rebuild all was good for most, but some had to rebuild at least one a second time before the seals held.

 

[FR-425]

I think I would just use oil to clean.

That white chalky dust left behind by brake cleaner... .not so much.

Kings web site says, just oil and clean rags.

 

[BKennedy]

Here is a picture of the oil and another of the stuff I found in the ports of the shocks. There was more stuff in the other shock, but you get the idea. I think that reddish-orangish stuff might be thread sealant:

Rubbing pic:

Heavy wear on the spring stops;

I guess the way to purchase a F-O-A shock is to order it with new seal kits and oil, take it out of the box, dump out oil and throw it away, pull it apart and re-seal it. Use the fresh oil to clean it out, and put it back together. Then install on vehicle. If you go into it with that as a plan, then the price is still pretty good.

I sent them a picture of the wear on the spring stop and got no reply. When I put it back together, I will clock the spring to see if that, along with the Fox slider, helps.

 

[sirhk100]

I've heard literally that exact same thing many times. Step one, buy foa, step two, tear it completely apart, step 3, clean all, step 4, reassembly with fresh oil, step 5, enjoy cheap shocks that work pretty darn good.

.008 on compression is insanely soft!!!! What did you end up putting in it?


Oh, and once the shocks is fully stripped, clean it with pretty much whatever you want. It's just metal, no special coatings or anything going on in there. Clean it up, wipe it down, reassemble. Even the o-rings "probably" wouldn't be hurt in all honesty.

 

[BKennedy]

I've heard literally that exact same thing many times. Step one, buy foa, step two, tear it completely apart, step 3, clean all, step 4, reassembly with fresh oil, step 5, enjoy cheap shocks that work pretty darn good.

.008 on compression is insanely soft!!!! What did you end up putting in it?


Oh, and once the shocks is fully stripped, clean it with pretty much whatever you want. It's just metal, no special coatings or anything going on in there. Clean it up, wipe it down, reassemble. Even the o-rings "probably" wouldn't be hurt in all honesty.

For the compression, I went with all .015, and on the rebound all are .015 except the second to largest washer, which is .010 to lighten it up a tad.

 

[sirhk100]

It'll be interesting to see how the rebound goes. I don't have any experience and haven't read much on valving for straight axle but on TTB and I-beams I think most are running a 10 or maybe a 12 stack on rebound. But, with the straighaxle you've got more weight pulling it out so you may be fine. You should notice a pretty decent change though in general! That's for sure. If you find it's not good, sight unseen, I'd probably lighten up the rebound before you make any more compression adjustments. Crawling and on the street that may be good but I'd be worried that the front end may start packing with the rebound that high. Won't know till you try it though so who knows, you may be perfect even...

 

[BKennedy]

By packing you mean not rebounding in time for the next compression, right?
F-O-A has five shims per stack, and has four sizes of shims, .008, .010, .015 and .020. I micro'd all the shims and it was set up like (largest to smallest, 1-5):

Compression
1 - 5, all .008

Rebound
1 - .008
2 - .010
3 - .008
4 - .008
5 - .008

This also means they got the rebound I asked for completely wrong. I guess it doesn't matter now, but another issue with their quality control.
If I want to lighten up the rebound a little, which shims do you suggest I replace, before I put them all back together? Right now I have, from largest to smallest:

.015
.010
.015
.015
.015

Extra shims, I have (from largest to smallest, 1-5):

1 - 4/.008
2 - 2/.015, 2/.008
3 - 4/.008
4 - 4/.008
5 - 4/.008

Could I stick a .008 or two in the stack somewhere?
If I need different shims, please let me know. We can safely assume I don't know squat about coil over shocks. Any advise will be taken at this point. I can assure you, I won't come back and say you were wrong, since this is all educated guesswork, and if we get close, it will feel like a Cadillac to me.

 

[BKennedy]

As it sits with the original shim valving, the thing was bouncing up and down like a pogo-stick. It would bottom out, then rebound up way too fast and start on its way down before I hit the next whoop. Not good.

To help you help me decide on valving, I also am running heavier weight springs than most with SAS's Explorers, Most are running 150 - 200 uppers and 250 lowers. I went with 250 uppers and 300 lowers, and triple rate tender springs. I was afraid I would get too soft a ride, because I think most of the Explorer's with coil overs are too soft. It wasn't until later that I found out the springs mostly set ride height, and the valving does the rest.

 

[BKennedy]

I know I am posting like a crazed meth head on a **** site, but I have another question: I have a gallon of F-O-A's oil on the way (it was not expensive), but on hand I have a 1/2 gallon of King shock oil. You think I could refill both shocks with the King oil? If so, I will cancel the F-O-A oil order before it gets shipped. I just did not want to come up short. Maybe I should keep it coming as it looks like I might get into these shocks again in the future.

 

[sirhk100]

Yes, packing as in the front tires won't come out fast enough before the next bump/compression hit.

On the king oil, are you saying using it to top it off or to fully fill? Either way, I'd say yeah go for it. Is it right? Pros will probably say no, will it matter... Ehhh, probably not. I've mixed oils for just topping off. I do try to stick to one brand oil though cause the viscosity of the oil affects how it flows thru the piston. You can get different weight oils which can change your ride/valving. Just more tuning option type stuff. At the level we're all at though, I wouldn't be too concerned.


It's hard to try and put thoughts into words without using hand motions to go with it on some of this stuff. Your pogo stick example. Say you bump the compression up enough that it's not bottoming out. With light rebound valving your front would compress till it's stopped and then it simply quickly returns to ride height. Even if it did bottom out though, sure it may rebound kind of hard but that increased compression has now taken up a lot of the motion so that slapped bouncy type thing should have been drastically reduced. If it still rebounds so hard that it truly bounces off the ground the next compression is going to be even more effective to slow the motion.

LOL, thanks for not holding me to the fire with recommendations based on just typed description! If you can find a pro suspension guy that can dial it in this way, that dude is an extra level suspension god! LOL I'm thinking biggest (flat against the piston) to smallest...

.015, .010, .015, .008, .008

Kinda trying to find a medium between the 8's and the 15's there. If I'd done the opposite and put the larger 8's in and smaller 15's, I'd be worried it would just give the 8's a very easy fulcrum to bend around the 15's.

This is literally a crap shoot, I just know 15's on the rebounds sounds pretty stiff for rebound, I can't remember ever putting anything larger then a 12 on the rebound side for anything I've worked on but again, that's only a-arm and beams, never played with a solid axle. That weight hanging there may work fine with the 15's. The one difference though, you don't have a super heavy spring rate trying to rip the shock back extended. On my old a-arm toyota and the yota we race I run like a 650 over a 750 or 800 in comparison to your 250/300 combo. Think about on that difference alone how much the rebound stack is working to keep just the coils alone from extending the shock. Plus the leveraged weight of the hub/wheel assembly on the shock when installed. But like I said, you've got a nice heavy axle pulling yours down rather then a heavy spring rate so...

Although... Now that I think about it... With all that said, I mentioned the a-arm trucks, on our race truck we run a coilover and a bypass shock up front. We're running five .010's in the coilover and seven .010's in the bypass. Do those combined working to control the rebound add up to like a stack of 15's? Maybe I guess, not sure honestly. It's still a bit fuzzy in my mind when I really try to think it out. The bypass tube also comes into play though in that scenario.

Either way, I think you're going in the right direction, I'm just worried a straight 15 pack may end up making your rebound actually too slow. It's literally just a guess though and I could be wrong. Would be interesting to know what turbo has on the rebound side of his Fox's? I think Fox uses different lingo on their shim descriptions. Fox and Bilstein use their own lingo while everyone else uses the physical sizes for descriptions. OD of the shim and thickness...

 

[sirhk100]

BTW, sounds like you've already got a good habit of checking them with a mic! Definitely want to do that and not take their word for the thicknesses!

 

[BKennedy]

Thanks Khris. I will add the .008's in the rebound stack and see what happens. Worst case scenario, its going to be better than it was. I also understand you head is geared towards racing, and mine is geared towards mostly crawling, with occasionally go fast down a dirt road stuff.

I think the rebound needs to be lighter, like you said. The compression has the weight of the vehicle pushing it down, while the rebound is the spring pressure trying to get back to ride height. On your shocks, are the compression ports the same size as the rebound? On these F-O-A's, the rebound is about double the size as compression.

I think a lot of the crazy rebound was due to the oil having mixed with nitrogen. It would thin it up so the valves basically did nothing.

 

[sirhk100]

Ummmm, this is totally off memory but I don't think the ports are the same size. The thing is there's so many different pistons out there though that it's hard to keep track of.

And yeah, I'm definitely more on par with valving for the go fast stuff but from my experience, I haven't noticed any issues with a vehicle valved to go fast in crawling situations. The typical shock speeds and movement is so slow in comparison when crawling that the valving really doesn't seem to affect the performance much crawling. My gut feeling, I bet spring rate selection affects performance more then the shock valving while crawling where the valving comes into play on the highway and at speed in the dirt.

Between the valving change and cleaning up the shocks and getting the nitro vs. oil issue dealt with I'm betting you'll seat of the pants notice a pretty drastic improvement.

You're making quite a bit of changes all in one fatal swoop right now so it's going to be hard to dictate what's doing what improvements wise. But I'm looking at it as this is hopefully a big jump to get you much closer in the ballpark and then from here you can make single changes to see what's doing what as you have reason/motivation/need/etc to do so.

This is a 9 minute video of the race truck with footage from the 3rd and 4th test sessions ever on it. I really like a couple of the suspension shots... Neat to see what leaf springs are capable of and I'm sure this isn't a benchmark, I'm sure there's others out there dialed in even better then we are.

1:27 and 6:23 are suspension shots, notice on top of the frame at the 6:27 clip, that's the striker for the hydro bump, we don't really use it too much. Notice on the rear we don't even run hydro bumps but in the 6:23 section you can see we don't get into it that often either. The shocks are doing "most" of the work...

https://www.youtube.com/watch?v=EgebrxhBru8

 

[BKennedy]

Okay, that was a pretty cool video. I do love the go fast trucks, but last time I was in one was late 70's. Trophy truck pre-running the Baja 500. Got a ride across the dry lake bed by Mikey's Sky Ranch at over 100 MPH. Fun stuff.

If I bring you a new pair of "Western Safety" gloves, you think I could get a ride??

I like that you kept the truck a 4x4. I think I need two off roaders, one for all around general wheelin and crawling, and a go fast model. My neighbor builds Baja Bugs. He brought a 66' home he was planning on fixing up, but might sell it. I was thinking of getting it for a project. I used to have one when I was in high school. Serious fun for little money.

 

[turboexplorer]

Either way, I think you're going in the right direction, I'm just worried a straight 15 pack may end up making your rebound actually too slow. It's literally just a guess though and I could be wrong. Would be interesting to know what turbo has on the rebound side of his Fox's? I think Fox uses different lingo on their shim descriptions. Fox and Bilstein use their own lingo while everyone else uses the physical sizes for descriptions. OD of the shim and thickness...

I have #60 on this chart for compression and #90 for rebound. From the sounds of it my rebound may be a bit high and my compression is a bit low. But again hart to judge since solid axle I imagine does act different than an A arm set up.

But adding in my experience. I do need a bit more spring rate like a 250 upper and stay 300 lower. Also I agree with Khris spring rate may come more into play in the actual slow motion crawling.

Also I do believe I need more compression valving as well. From the factory the fox was a #30 compression and #90 rebound. So the #60 stack was a decent jump for me to start out. Made a nice difference and my on road manners and offroad improved. But haven't changed anything since. For me it's a pain to unload the front suspension to make changes with the small jacks I have. Need to make some big jack stands to hold the rig up since right now have to lift frame 4" or so just so when I remove the 37" the rotor won't hit the ground. So I should do a bit more adjustments as well so we can all get a better feel for our rigs in solid axle tuning if a few of us can experiment and post results.

Also lots of variables still. I bet I weight at least a few hundred lbs more up front. I run a trussed HP44 with 37"s. I bet my full front axle weight is near 800-1,000lbs including wheels and tires. (Tires are 78lbs a piece just in the rubber) and each of our definitions of "fast ish" on dirt when wanted. Since it's obviously not real pre running speeds.

Anyways that's what I have in mine. Refer to the chart for actual shim sizes. Typing the # is faster. Also unlike the a arm set ups. My shock is fairly close to wheel travel. Where as an a arm with shock mounted 1/2 way up the arm has less total shaft travel and more leverage against it during that travel. That math involved also has a huge impact on what works for what. Example: two rigs both with 14" of wheel travel but one with a 14" shock on a solid axle and another with a 8" shock on an a arm. They will not require the same spring rates or valving to control that travel. As stated by Khris their spring rates are super high in comparison.

Khris can give us good places to start but as with all rigs need tuning from there for each rig. Key now is being able to properly describe what the rigs are doing. Then can make educated changes from there.

 

[BKennedy]

I think I (we) are on the right track here. I am going to go with all .015's on compression and the mix Khris suggested for rebound and see what happens. This thread has a lot of real good information.


Turbo, you have more weight up front, but also more leverage on the shocks with the wider axle. I know what you mean about jacks and suspension travel. My Hi-lift isn't even close to working without strapping the axle to the frame. Right now, the Explorer's front axle is sitting on two 6x6 pieces of wood under the knuckles, with the frame on the Harbor Freight heavy duty jack stands all the way up (4 of them). I have to jack the axle up to get the tires off the ground, then pull the tires, drop the axle down on the 6x6's, then jack up the frame and get the HF jack stands under it. The HF jacks are not tall enough to remove the shocks. To remove the front shocks, I need to jack the frame up one side at a time with another trusty piece of 6x6, 20" long on top of my floor jack pad. I jack it up by the sliders so I have a wide, flat and stable area. Once I pull the shocks, I drop it back on the jack stands. Pain in the rear. If I had a lift, it would take minutes.

Having it sit like it does right now, actually made it easy to change out the wedgie bushings to get the caster to about 4.5* positive instead of 7.5. I could slide the front axle back and forth with ease. The wood made good sliders on the concrete floor. Took me about an hour start to finish.

 

[sirhk100]

LOL, I'm right there with your misery of jacks and jack stands and stuff! Such a pain sometimes! The new truck I'm building had a pretty scary moment yesterday actually regarding jackstands. Standard cab F150 right so fairly short... I had the stands on the frame rails behind the radius arm mounts. All seemed fine. Pulled the front tires, dropped the front suspension all the way out with no shocks on it. I then jacked up the rear about an inch to pull the rear tires. I was swapping wheels... I pull the spare off the back, then go to pull the first of the two rear tires. I pull the first one and the darn thing teeters and the rear lifts and the front drops to the ground. CRAP!!! I didn't realize I was so close to the balance point where my stands were and it scared the crap out of me when it rocked forward! Good times!!!


Agreed with what turbo said... The .015 rebound stack might be fine. It just seems really thick though compared to what I'm used to but that's just what I'm used to, it may be fine in reality. I'm sure a physics or mechanic engineer could do some math for us and figure out how much down force say your solid axle setup is doing vs. a leveraged a-arm shock setup taking the extreme difference in coil spring rates. Heck, they may even almost equal out for all I know... I'm trying to mentally visualize the different factors and I could convince myself either way in all honesty. LOL


Side note... Notice the thickness on all of those fox shim packs of the smallest diameter shim? That's kind of interesting. It's like they go thick to allow for the pack to really open to flow some oil when needed. And notice the REALLY thick one on the rebound? I've got no nifty explanations for that....

 

[turboexplorer]

Wonder if they use it as a support for the shims rather than a valve that actually moves? Or as like a washer of sorts? I'll look closer next time I have them off.