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shock valving for heavy unsprung weight

4K views 11 replies 7 participants last post by  94toytruck 
#1 ·
I am running a first gen toyota pickup with a taco v6 toyota cases dana 60 up front 70u out back trail readys and 41in radials. Truck weighs in at 5500 lbs trail ready and majority of that is in unsprung weight. I am running fox 2.0 resi shocks with 2.5in travel air bumps all around. My issue is now that I have gone from toy axles and 38s to tons and 41s my shock package is struggeling. Springs are custom deaver leaves and are pretty soft without the shocks mounted. With the shocks mounted the truck feels very stiff and slightly rough. At speed in the rough stuff it feels pretty good but the shocks have heated up enough to turn the rear resis a goldish color. My biggest issue is at exactly 50-60 mph i am getting a tire hop. It is not a death wobble and doesnt feel like a tire ballance or square issue. anywhere below or above this speed it is smooth. It is an up and down motion that feels like im riding on basket balls and seems to get worst with higher tire pressure. Best pressure I have found is 20 psi all the way around. Reason I am pointing finger at the shocks is I ran it hard in the dirt at street pressure for a while working the shocks hard and then jumped back on the street. The hop was almost gone till things cooled down? My question is how can i soften up my ride quality and yet get more controll out of these shocks to hold the tire down on the street? It is currently un bearable so i have to run 45 or 70 everywhere. Feels as if I dont have enough shock as the truck dives hard under braking. I am a virgin to shock tuning and had Lee at race shock set these up the first time but I have yet to find a valving that prevents fatigue on the trail, is controlled in the fast stuff and holds the tire down on the street. Are my fox 2.0s just not going to cut it? Should I add a second shock up front (feels like the front is the issue) like a bilstein with a soft valving to help it or do I need to start over with a different shock all together? Any ideas would be appreciated.
 
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#3 ·
Tires are ballanced and run true at any speed other than the 50 mph area. I thought about ditching the stick on weights and trying air soft to see if it helps but I still dont feel like its a shake....its a hop. The shocks were ordered generic and came with way way to stiff of valving for my toy axles. Lee pulled a freezer zip lock bag out of them to get them closer to where they needed to be and I had no issues with them with the old toy axle set up. He said they were probably set up for a diesel truck single shock application so he pulled shim to make them suitable for my use. I can not remember the exact valving he said he put in them...:confused: Wish I did so I had something to go off of. Front 12in shocks are mounted close to straight up tipped ever so slightly in and back and are slightly favoring droop over compression but i have about 5in of up travel. Rears come through the bed and are mounted like this / \ . I dont think the back is the issue. Is it possable for a shock to almost lock up at one point while trying to control movement? Possibly there is a spot where the tire is not fully happy the spring is fighting it and the shock is trying to control it causing almost a locked up feel? Im torn on this. In the desert at speed it feels pretty good unless i get into deep whoops and im not on the gas hard then it starts to bottom the front pretty good. If i can keep the front light it feels good. Sorry for not having more specific valving info. Would like to have a valving idea from someone with experience with heavy unsprung rock crawlers to give to my desert guy to start with or to teach myself how to valve them....I would love to learn so I can play with it till its :grinpimp: any help is appreciated
 
#4 ·
What do you mean pulled a ziplock bag out? Did he reduce the oil level? If so it cause the shock to lockup by stopping the floating piston from moving.

Removing oil from a resi shock is not a valid tuning method. Also you should find out which disc was removed.
 
#5 ·
No he did not remove any oil that I know of. He did replace the oil in them with fresh shock oil while doing the service. The bag contained shims from all 4 shocks. He said he had not seen so many shims in any shock he had ever worked on and he has like 30 years of experience so they must have been for a very heavy truck. Would fox have any idea as to a starting point for this? Most of the shock tuning guys I am finding are desert guys and are not used to limited up travel and heavy unsprung weight...
 
#6 ·
I may pull these shocks off and throw on my old pro crap ones to see how it feels. If that doesnt work I could rig up a temporary second shock to just see if it solves the issue. Would at least tell me if I need either more shock or more valving? Just ideas
 
#7 ·
I'm going to say it's a tire problem. The hop is coming from somewhere.

I've had several sets of tires that have a hop at certain speeds. May just be a balance problem, may be a bad tire.

Borrow a set of tires off someones tow rig that are known to run smooth at all speeds.
 
#9 ·
Well as much as I thought my tires were not the issue they are....Two out of 5 have now become square..... How round are the 42in mtrs? If I cant fix this issue I may go this route...Would love the toyos but my 6.17 gears can not go smaller than the 41s I have...
 
#11 ·
5500lbs and most of it is unpsrung weight? I don't think so.
 
#12 ·
First thing I thought as well, the entire weight thing seems wrong. I have a 94Xcab toy with tons, 40 Trep's, beadlock's, linked front and rear with 2.5 CO's and caged and it tip's scales at 4100 ready to rock for a weekend.


Even if it is your tires take the time to find out whats in your shock's and or go tune with someone. My rig is night and day since tuning with Wayne. I was on the right track but it would have taken forever for me to get it right making small changes.
 
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