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Shock Sizing

RDC247

Active Member
I'm building a pre-runner based on a Honda DelSol that is LS/Fields automatic powered. My guess is the car will weigh somewhere around 3000 to 3200 lbs when finished and I'm currently trying to understand shock sizing. I'm not having a problem with figuring travel numbers, just sizing and I haven't been able to find any "charts" that give you any clue as to what size shock I should be running.

For the a-arm front, I'm getting the impression that I'll need 2.5s based on the weight of the vehicle and what I've been able to decipher on here and other forums.

For the rear, I'm getting the feeling that running dual shocks is the way to go....coilovers and bypasses. If this is the case, I'm guessing I'll need a pair of 2.5s or 3.0s.

Shocks aren't cheap and I'm not loaded so I'm hoping to buy the right equipment the first time. Any help would be appreciated!
 

jon coleman

Well-Known Member
shock formula; $+ size wanted+ size that will fit+ how fast +for how long( before fade)÷ realities of your$ factor= size for car.that or slap on some junk yard bilstiens, cant go wrong.sorry , i just read back my stupid post, really you should wait for the right deal, be patient, and do all the math on what size will work.bigger is Usually better, Dont accidentally buy wrong size/ bent/ broken junk. ( thats why i am seriuos about bilstiens, they are oem on a Lot of cars& trucks, find ones off a similar car/ weight- geometry, ect.good luck.im sure you'll get more info.good luck
 
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Fifty

Well-Known Member
It seems that every time i tried to find out what diameter shock to go with, I kept hearing that if I went too large in diameter that I would have a hard time with getting the shock to work. Or I would have a hard time getting valving right.

so For a 4800-5000 leaf sprung rear, and a arm front it was 2.5 coilover and 2.5 bypass front and 3.0 bypass rear.

they said anything more and i would never keep the shock in working temp and not being able to get flow through the piston happy.

wether this is true or not? I don’t know.
 

RDC247

Active Member
I appreciate the replies...

Jon, if I knew what the math was, I'd certainly use it! I've been searching for the formula or chart or whatever is used to size shocks but haven't been able to stumble on to it. If you can steer me that way, I'd appreciate it!

And I really don't see me buying used either. I'm in North Carolina and if I can't see them before I buy them, it ain't happening. As far as what fits, I'm still building the cage so at this point, I want to get the right shocks and work around them.

partybarge-pilot, I was under the impression that I wanted to get the shock as close to the upright as I can get it. Up front, I'll realize an honest 18" of travel (after straps) as seen from the end of the snout. If I try and get the shock as close to the upright as I can get it, I'll need 14s but if I push the lower shock mount back towards the frame a little, I could use 12s. The cost isn't that big of a factor when it comes to shock length it seems so I was leaning towards the 14s. Which way would you go?

Fifty, the fluid temp observation is an interesting spin on this. It makes a good argument for not going oversized but I've also seen where people say it's easier to tune an oversized shock than it is an undersized one...

Thanks again!
 

jon coleman

Well-Known Member
location×3, i feel your pain, living in San Diego, one can get spoiled living 10 minutes away from Baja& Fox shox, they have good customer relations last time i checked, plus there are Always good shock & other parts deals on rDc.
 

partybarge_pilot

Well-Known Member
Go with 12's. With 14's, if your actually using all the shock you will see some really high shaft speeds and it will be harder to tune.
 

RDC247

Active Member
I'd love to be able to buy stuff off the classifieds but I don't think people want, or need, to ship this stuff. Everything seems to sell locally and honestly, I can blame people for wanting to sell this way.

Partybarge_pilot...I'll have to think about that for a while before I really understand what you're saying....

Thanks guys...very helpful
 

Fifty

Well-Known Member
I’m hoping a 3 inch will be enough for my leaf sprung 16 inch travel 5k truck
 

partybarge_pilot

Well-Known Member
I’m hoping a 3 inch will be enough for my leaf sprung 16 inch travel 5k truck
1-1, the problem will be getting it not to beat you up. Watch the spacing to the top out washer. At least 2 overlapping comp tubes. Bleed poppet in the short tube.
 

Fifty

Well-Known Member
I thought the goal was to get as close to 1:1 (ie a straight up down mount) motion ratio for rear leafs.
As for tube placement that was my plan 2 up and 2 down and one to lead into the other as much as possible.
the gent who is actually doing the building and ordering or the shocks was recommended to me by accutune.he Definitly knows more than I do (which isn’t hard).
Trying to learn as much as I can though because the next rig I’ll try home built again.
My first was home built and “ok”... this one my plan was to have smart people do it so it was Sorted ( but I swear it’s cursed)
As I’m getting more on the mend I believe and the kids getting out of diapers, the next one, pre 75, I’ll build based upon info learned on this one and my mistakes on the last one...
 

JerryB

Well-Known Member
I'm sorry, but am I the only person who picked up on or am impressed by the fact he's building a Honda Del Sol "pre-runner" with an LS??? All the shock advice given could be right/wrong, doesn't really matter, he's building a pre-runner based on a Honda Del-Sol with an LS!!!! All I want to see is the finished product.
 

RDC247

Active Member
So I stumbled onto the follwing recommendations at..Radflo


SIZE: The diameter of the shock absorber body must be matched to the vehicle weight and intended use. Larger diameter shocks contain more oil for greater operating efficiency, as well as larger internal components and mounting hardware for strength.

2.0" Shocks are recommended for light weight vehicles (up to 5,000 lbs) and street applications. Multiple shocks per corner must be installed for heavier vehicles.

2.5" Shocks are recommended for medium weight vehicles (5,000 – 7,500 lbs) and recreational or racing applications. A single 2.5" shock is comparable in performance to dual 2.0" shocks.

3.0" Shocks are recommended for heavy weight vehicles (over 7,500 lbs) and professional racing applications. A single 3.0" shock is comparable in performance to dual 2.5" shocks.


Thoughts?
 
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RDC247

Active Member
Being in NC, I don't have first hand access to much of this so I'm flying by the seat of pants here...pictures and post is about all I have to work with.

So I've discovered that as an alternative to using just a single coilover up front, it's pretty common to use two shocks instead...a "spring carrier" coilover working in tandem with a bypass. Seems like tandem 2.0s seem to be popular on even some of the heavier rigs.

As I'm still building this thing, now is the time to figure out if a twin shock setup is a viable way to go. The first question I'd have would be....how much room do I need to run both of these together, side by side? Fox shows that the spring on the 2.0 has a 2.5"id which I'm thinking is around 3" OD but I really can't find a spec on the diameter of the bypasses.

Any suggestions?
 

jeff

Moderator
I had to double check the date the original post was made... :)

The external bypass shock diameter will depend on the can size, manufacturer and tube layout. Until you select all of that nobody is going to give you an exact number you can use to build a car. Keep in mind the vertical tube position will also vary. You'll either need to buy the shocks before you start building OR talk to one of the nicer shock companies (or fabricators) to see if they can send you a basic 3D CAD rendering of the shock. That should get you dimensions (for that specific shock) and you'll be able to get a better idea of how much room you need. This link gives you an idea of what I'm talking about:


Another option is to source an internal bypass shock. Maybe you could find some cheap SxS take offs near you? With a spring rate change you might be able to source a very adjustable shock option for not a lot of money. A modern SxS will go 75-mph through big stuff with a single shock and can do it reliably for the length of an offroad race. Running 2 shocks per wheel may not be the "yuge" benefit you are hoping for.

The Radflo recommendation might work for some daily driver pickup truck or SUV applications but for a specialized off-road use vehicle that info could be way, way off.

Aloha
 

jon coleman

Well-Known Member
i see sXs take offs all the time for sale , shocks, A arms , radius arms, whole can- am suspensions like new,( i had crazy idea once , 'heck, it looks like it would fit my subaru'!.....
 

RDC247

Active Member
Thanks for taking the time to reply!

I've see the SxS shocks being used around here in more conventional "woods" buggies but they aren't that heavy or powerful. They seem to be a good match for that sort of machine (making them kind of hard to find around here) but I think I"ll be too heavy to use those without really working hard at it. 15 years ago, I'd be all about "trying" and "might" but at 58, I'd rather pony up and get as close as I can the first time!

So yes, the budget is a concern but I don't have a problem spending the money as long as I buy the right equipment. Buying twice is a budget killer for sure. and as I hope to keep riding for years to come, overall ride quality is going to be as important, or more so, than my ability to run flat out for extended periods of time.

And based on what I've seen sized here in various threads and in the classifieds, I got the impression that the Radflo chart might be a bit optimistic. I've also been looking at the various shock sites and have seen the "clocking" configurations that are offered and yes, it throws a whole new dimension into things!

With a little more confidence, I'd be willing to pull the trigger and buy what I think I'll need. And while I should reach out to the professionals to ask questions, I won't waste their time until I'm ready to pull out the credit card. There seems to be a wealth of good advice here so I'll keep typing away...

At this point, I'm torn between a single 2.5 coilover or running dual 2.0s, one coilover and one bypass. The single 2.5 would be easier to package but not as sophisticated as the tandem 2.0s and therefore, wouldn't provide as smooth a ride either.

Any more info would be greatly appreciated.
 

partybarge_pilot

Well-Known Member
If you end up going with the coil-over/by-pass, please do not run the C/O without valving or resi. It has an important role to play in how the car handles.
 

jeff

Moderator
You are building a Del Sol prerunner... Everything is going to require "really working hard at it". ;)

Aloha
 
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