I bought two coilovers with remote reservoir to put in the front of my CJ. They have been homebuilt by a machinist I know. Since I havent been able to talk with him for week, I have some questions maybe you will be able to answer
- What kind of oil do this need ? I've been told to use hydaulic oil, but, well, there is a ton of variety of hydraulic oil. I have some synthetic tractor hydraulic/transmission oil ... will this oil be fine for my use ? What should I buy ?
- It seems that the shock need misalignment spacer on each end. At one end, there is a spherical bearing 1/2'' hole and at the other end there is a standard chromo rod-end 1/2''. I looked a lot to see what guys are using as spacers in built thread, but it looks like everyone already got their spacers they need when they bought their airshock/coilover. Should i buy something like this : www.ebay.ca/misalignmentsspacer....
I would not change the bore to a bolt smaller than 1/2". A HIGH Misalignment spacer like the one you attached the link to is going to reduce the bolt size to 3/8".
As for oil- I don't know what your friend intended to use in "his" shocks, but most aftermarket coil-overs run 5-7 weight fork oil commonly found at motorcycle shops.
And another question about coilover spring (im in the reading of the coilovers bible of billavista to calculate the rate I need)...
- I have 16'' travel coilovers shock and wondering if the main coil and tender coil are the same length and only have different rate ?
- Shops that sell spring say that spring are 16'', but it is the really lenght of the spring? Or that " 16'' " mean the spring must be on a 16'' travel coilover shock ?
Thx a lot for your answers to my newbish question
(Yeah I know i have lot a to read and understand before I buy my springs !)
If you need me to ship the std. spacers to Canada- no problem. Easiest way is via USPS flat rate- especially for something small like these spacers.
As for the coils- a 16" coil is 16" in length. I'm not sure what will work with your coil-overs as they are custom & home built. Typically on a 16" travel coil-over you might see spring combinations such as 16" over 16", 14" over 16" with a triple rate kit and tender coil, or 14" over 18" etc. Most 16" TRAVEL coil-over shocks fit 32" or more of free-length coils at full-droop with the pre-load adjuster at the top of the shock.
As for spring rates- get sprung corner weights for your rig and keep reading a bit. Typically, you see a higher rate over a lower rate, but some rock-crawlers run it opposite to get less of a step-up ratio once the dual rate slider hits the stop. The split in spring rates is usually 100#'s, but may be 0 or as much as 200#s. Many factors to consider. Do you coil-overs have dual rate sliders? Do they have dual-rate stops? How about a picture of what you are working with...
They seem to be typical coilover shock. Yes , it has dual-rate slider but I dont know what you mean by dual-rate stops... is it a ring to stop the dual-rate slider ? A picture worth a thousand words, so there it is (not mine but it is exactly the same that I have).
Yes, they engage the dual rate slider and stop it from any more up-travel thus keeping only the lower coil spring rate in play for the remainder of up travel. Talk to your machinist friend and he should be able to come up with them pretty easy. I don't see any on your shocks. They are one of the advantages of a coil-over as you get two spring rates throughout the travel of the shock vs. just one combined rate.
Let's say you are running 250#/350# coils on the front of your Jeep. Pretty common numbers give or take 50#s. Your combined spring rate would be 146#s. When the dual rate slider hits the dual-rate stop, your spring rate would "step-up" to 350#s if it was the coil on the bottom. You then can set up your suspension so that the last 2-3" of up-travel have a heavier spring rate to help from bottoming out when you jump or hit a big bump at speed.
This is very interesting ! I really need this dual-rate stop !
My jeep is in fact a CJ tub over a '91 F-350 frame. It has a 460BB, huge zf 5 speeds tranny and np205 and I'm building a cage on it. It's gonna be heavy... do you think I should get something like 400 or 500 for the main coil and 100 or 200 for the upper coil to both help from bottoming and not to be too stiff ?
What happens if the split is too high ? The upper coil will compress too easily and only the main coil will support the weight of the corner ?
Springs via USPS would obviously not fit in a flat rate box- but could be shipped that way.
Based on the information you provided about the rig- it will most likely need a little heavier coils vs. the standard CJ or TJ. I would not want to guess at the corner weights and shipping coils back and forth would get expensive for you.
Any chance of getting it weighed somewhere for corner weights? This would be the best approach. Then you can subtract out the weight of your axles and tires- unsprung weight.
As for the spring rate splits- you don't want too much of a split or you would basically just have a top coil that is blocked out/fully compressed. Again, you kinda lose some of the benefits of a dual-rate coilover. Let's say you ran 300/450. Your combined rate would be 180#. When the dual rate slider stops you would then "step-up" to 450#. Just over 2x's. If you ran 100/450, your combined rate would be 82#'s that would step up to 450#'s. About 5.5x's the combined rate. That's a rather large step-up ratio.
Have you read the Billa-Vista coil-over articles? Even if you are getting lost in some of the detail and math and skip through some of it- they still have some really good guidelines to follow that may help you better understand spring rates, wheel rates, frequencies, and step-up ratios etc.
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