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Suspension Sag

one finger john

Active Member
When setting up a coil over rear suspension, do you figure that suspension sag under normal conditions ( two, 200 lbs passengers plus 50 lbs. fuel) wiil put the shock at approx. 1/3 compression. Or will it be 1/2.
I.E. with a 12 inj shock, should the car settle down to 8 in or 6 in? I have heard that the "sweet spot" is approx. 1/3 of total height
Better yet, how many inches will the whole car settle (when completed) from when first mocked up w/no engine, trans., or fluids.
I would like to make bolt in bars to substitute the rear shocks at the all up ride height.

Thanks in advance, John.

Was I clear?
the best way i found to do it is to find out the install height from the manufacturer, that will be the length you make your mock up rods/shaft...

when you order your springs is when the weight becomes a factor.. if your way off on your spring rate, your ride height will be way off... if you get the correct springs, you use the threaded adjustment on the shock to fine tune the spring rate for the rear weight of your car, when you get that correct your ride height will be where your mock up rods were at while you were in the building process.. i hope i explained that ok..

if you know someone locally that has a set of scales, either a hardcore dragracer, or most all sprintcar, or mini sprint guys will have portable scales.. if you get scales all the guess work dissapears...

I just got a set of coilovers pretty cheap, i'm going to mount them at about a 20deg angle, and i'm going to order a set of 125#or 140# springs to start with, i'll probably go with 140#, think i'm going to be a tad heavy because i'm running a steel body and bed .. also set your ride height using the middle hole on your lower shockmount, that way you have a little room to go up or down if you need to. pay particular attention past where it says (figure C)
Some times this is like reading the Sunday funnies, but I need to remember that, I too was once a dummy on all this stuff.. hehe :) there is no (one) right answer, as the springs can be mounted 10 different ways and they will do 10 different things or act 10 different ways, same goes for shocks, if you have a strong spring, use leverage againest it, to make it work in a light car.... think, NUTCRACKER... :)
if you're buying new coil overs, ask if you can exchange the springs. most will allow this if there is no cosmetic damage to them.

ted...glad to hear we're intertaining you.

Thank you Brucer for your explanation. Because of space and transportation limitations I don't have the luxury of building my frame or setting my suspension points. My plan is to purchase a semi finished frame from CCR (designed by we know who) and bolt a vast majority of the components on. I don't have a truck to lug the frame to a fabricator so I have to trust the the initial construction and design of the frame. You do not know what it is like to dream of a secure two car garage w/power. Maybe you do. As it is now , I will probably have to rent and I would want to finish the project as soon as possible.
I'm think I'm clear on the theory of coil over placement. Shock angle also makes sense.
The small article that you supplied was very informative and to the point. Nothing worse than to figure for 5 to 6 in. of pan clearance and then come up with 3 in. of actual running clearance.
Keeping these little cars safe, control-able, and behaving like a normal car is my goal. I don't need 55 mph shakes or darting or bump steer. Just want to load two fat guys and and full tank of fuel and go.
Also any recommendations on shocks and springs? The actual manufacturers? Are springs consistent or can there be differences from mfg. batch to batch. On sports cars, I tend to spring a little soft, then make up with sway bar and shock. Any recommendations for the front shocks? Perhaps motorcycle shocks?
Lastly, any experience with watts linkage?

Ted, I hope you understand that everyone's experiences in life are different. And everyone's wants and needs are also different. When I post here some times it is for theory on construction and sometimes just intelligent conversation. If I were a dummy I wouldn't be here.

Thanks, John
When I say dummy, it is in a funny way, not to be taken so seriously... as with anyting new to people, it all seems greek at first, so no offence intended or taken I hope... as i am the first to say I am a real dummy on these computers... There is way more to building these cars than most people will ever dream of, in their life time, so be safe and build what You like :) PS, There is no real good reason to go buy new special parts (springs and shocks. etc.) when you can go to your local wrecking yard and find most everything you will need to build a very fine working T Bucket... I am not one for coilovers unless they are used like the Jag rear setup, lots of leverage and not much travel... Just my thought on this, Thanks :)
the coil-overs i have used are Afco, Qa1, and Aldan.. all seem like good products..

Afco has recently been bought out by speedway, and Afco shocks seem pricey... over the past couple years i think afco's quality has went downhill. The last set of thier streetrod shocks i saw were very nice though, but as i stated previously, they are expensive..

Qa1 shocks seem to be more like a race shock, the only ones i've seen seem to not have as good of finish than other brands, but for a drag shock they're hard to beat..

on my T i'm going to go with Aldan coilovers .. the ones i've used in the past always worked good and had a good finish..

Tci has a painted set of shocks for around $270, shocks are black, springs are black. thats at Zig's Streetrods they are the shocks called All-Americans
Zig's Street Rod - Suspension - Rear Components if you go to the chrome ones the price goes way up.. The Aldan shocks are at the bottom of that page, plus aldan sells from there own site also.
I have noticed an ad in street rodder magazine for coil overs from Linblad Chassis (502-234-8283)Northbrdge Mass. Linblad sells t bucket chassis kits and plans also. The coilovers are advertized for light cars at $ 100 ea. i don't know any thing about the product but it might be good enough to get a project on a tight budget on it"s feet and if they are a standard length they could be upgraded later. Monroe also still has the original load leveler shocks for sale (shock w/coilover)made to replace standard shocks in overload conditions for full size cars&light trucks, probably have to spend some time at the parts counter figuring out which would work,length,ends,etc.
might be an affordable solution for now??
Keith Bowman
Keith Bowman said:
...Monroe also still has the original load leveler shocks for sale (shock w/coilover)made to replace standard shocks in overload conditions for full size cars&light trucks, probably have to spend some time at the parts counter figuring out which would work,length,ends,etc.
might be an affordable solution for now??
Keith Bowman

If you can get a spring rating on them, then you could get something close to what you want... they however will not be adjustable...

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