Shock tuning - advice needed

[benjy]

With the new power from the 6.0, the need for a good shock tuning session has become increasingly apparent. The front end seems fine, but I feel like the back end bottoms out too easily on hard hits, and I get bucked around a lot. Any minor whoops or uneven ground I feel out of control at any sort of speed. I'm not afraid to tear down the shocks and change the valving and spring weights, but there is simply an overwhelming amount of information/theory on how to best setup coilovers that I'm afraid my trial and error would take years.

The rig: 4300lb (guess?) TJ
Shocks: Fox 14" 2.0 Remote Res with 2.5" bumps, 7" up at ride height
Springs: Eibach Front 275 over 200 Rear 250 over 175 IIRC

Am I asking too much of little 2.0 shocks? Is there anyone locally that has a good amount of shock tuning experience? Should I make a go of it on my own? Should I hold out until I can make it out to one of Wayne's (pirate zukizzy) shock tuning sessions? http://www.alltechmotorsports.com/Tuning.html

Could there be enough interest on the wasatch front to fly him out for a Saturday?

It's to the point that I'd spend the coin on bypass shocks if it would help, but I would like to think my current setup should do all I need to. The most racing I'll do with this is OSRC and the short course regionals at Miller. All just for fun.

 

[neagtea]

Is it pogoing off of the whoops (bucking)? Or just bottoming using all of the bump stop travel?

Try playing with the secondary spring adjustment and N2 pressure in the bumps. Depending what it is doing.
Then go at the valve stack before going to a bypass upgrade.
You should be able to make work for your application.
Remember, you will still have to tune bypass shocks and take the valving out of the CO although it will have a cool factor.

 

[neagtea]

Also I forgot,
Video it and you can see what it is really doing.
Are your bumps 2.5" diameter? What travel?

 

[RockChucker]

Do you know how much Wayne charges? I would be interested in a session. But I won't be ready for that for an undetermined amount of time since my coil overs are sitting in boxes in my closet. Have you read the spring tech thread on pirate? Wayne has some intriguing ideas on choosing your springs...

This is all new to me. Just trying to research a lot and set them up right when the time comes

 

[benjy]

Is it pogoing off of the whoops (bucking)? Or just bottoming using all of the bump stop travel?

Try playing with the secondary spring adjustment and N2 pressure in the bumps. Depending what it is doing.
Then go at the valve stack before going to a bypass upgrade.
You should be able to make work for your application.
Remember, you will still have to tune bypass shocks and take the valving out of the CO although it will have a cool factor.

Also I forgot,
Video it and you can see what it is really doing.
Are your bumps 2.5" diameter? What travel?

The video is a great idea, that would probably be very helpful. I think it's using most of the bumpstop travel on a hard hit, but I don't think they're completely bottoming out. I don't recall the diameter of the bumps, but I have them reduced to 2.5" travel. They were at 4" when I bought them, but I felt like I would have been riding on the bumps like that too much, so I shortened them up.

Do you know how much Wayne charges? I would be interested in a session. But I won't be ready for that for an undetermined amount of time since my coil overs are sitting in boxes in my closet. Have you read the spring tech thread on pirate? Wayne has some intriguing ideas on choosing your springs...

This is all new to me. Just trying to research a lot and set them up right when the time comes

I read the thread awhile ago, and you're probably right that reevaluating my spring rates should be first priority. It looks like he charges $350 per rig for a group session. I know there have been groups to fly him out, which would increase the cost.

 

[neagtea]

If you are not using enough travel in the stop, You may want to take a little oil out of the stops, could be going hydraulic too soon. Also try dropping the N2 pressure.
I cannot remember how many CC's to use when limiting a 4" travel stop to 2.5", I will check.
I talked to Todd from Fox last year about this and he gave me a figure.
He doesn't answer the phone much but one of the other guys at Fox may know the amount.
Video will help,
also slide down the o rings on the shafts and see where they end up after driving hard through the bumps
Not much but hope it helps.

 

[cruiseroutfit]

You might check with Dustin @ DP Custom Fab, super talented fabricator and well knowledgeable on shock tuning as well. We were able to work a deal with him to come out to Delle with us for some testing in our Baja race car. Totally worth the investment as the car never rode better after his tweaks and suggestions. His is far more desert racing oriented so I'm not sure he would even be willing to tune a 4x4?

 

[RockChucker]

I read the thread awhile ago, and you're probably right that reevaluating my spring rates should be first priority. It looks like he charges $350 per rig for a group session. I know there have been groups to fly him out, which would increase the cost.

Good to know. I will have to keep that in mind. I'm sure he has a minimum number of rigs though so it is worth his while...I think I remember reading in that spring tech thread that you can send him a video of your rig in action and he can help put you in the ball park off of that.