72 Lwb

[Super73]

Personally I don't feel you "need" coil overs in the rear. Here is why.

Spring / shock location change 2 things. Leverage ratio each item see's and rate of speed each item sees. A spring and or shock in front of the axle has more leverage put on it than a spring behind the axle. A spring and or shock placed in front of the axle is going to move slower than one placed behind the axle. So, what am I getting at here.

Tuneability is what you need. Understanding what the suspension needs and being able to compensate for it.

In the rear, again, I would go with stock location and a long light spring if you have > 100% antisquat

If you are < 100% A/S I would go with a slightly heavier spring to help keep that energy from being lost.

Now for shocks..

If you have an adjustable shock, the question you need to ask yourself is what do I need.. Having the shock behind the axle is going to make your adjustments more noticable for each click compared to if it was in front of the axle and you may not need to use as many adjustments (IE 12 way shock you may only use adjustments 3-6). Now having the shock in front might require you to use the stiffer settings 5-11. Again, do you have > or < 100% A/S as that is going to come in to play here a little too.

[djracer]

I ran coilovers on my old 71 street truck and I have them on my 67 now. If your truck isn't crazy low you can fit a coilover behind the axle with just a tubular upper crossmember!

[Outlaw72]

That's what I was thinking and looks like the way I need to do it if I choose to go that route. Thanks..

[71Dragtruck]

This is what you need.

[Outlaw72]

It's funny you post that cause I was just looking at those today....lol

I'm guessing the rear will need the 250 spring..

[71Dragtruck]

Originally Posted by Outlaw72

It's funny you post that cause I was just looking at those today....lol

I'm guessing the rear will need the 250 spring..

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depends on what length and if you mount them straight up or not.

[Outlaw72]

Hopefully I can mount them straight up and down..I will get the kit and see what happens.

[bigjimzlll]

I have a nice set of Aldan double adjustables with 200lb springs that are 14" tall...PM if interested

[Outlaw72]

PM sent..

['72customdeluxe]

Sorry if this has been asked before, but what are your front and rear wheel widths and offsets, how much is your truck lowered, and what size are your front tires? Your truck has the stance I want for mine. Thanks.

[Outlaw72]

Originally Posted by '72customdeluxe

Sorry if this has been asked before, but what are your front and rear wheel widths and offsets, how much is your truck lowered, and what size are your front tires? Your truck has the stance I want for mine. Thanks.

I am at work currently and do not have this info handy so this evening I will give you the items I do not know. Right now, I can give the items I do know.

I don't know exactly how much it's lowered but the stance is due to 3" DJM drop springs in the front and 4" DJM drop springs in the rear. There is also a Chisolm tubular upper control arm on the front. The fronts are 15x7 and the rears are 15x10 w/4.5" BS (these will be for sale soon). Not sure on the front tire size or the front wheel backspace just yet. The rear tires are 315/60/15 ET Street Radials. They measure alomost 12 inches of tread.

[Outlaw72]

The front tires are 235/60/15 and the backspace on the front 15x7 is 3.5"

[bigjimzlll]

Originally Posted by Super73

Personally I don't feel you "need" coil overs in the rear. Here is why.

Spring / shock location change 2 things. Leverage ratio each item see's and rate of speed each item sees. A spring and or shock in front of the axle has more leverage put on it than a spring behind the axle. A spring and or shock placed in front of the axle is going to move slower than one placed behind the axle. So, what am I getting at here.

Tuneability is what you need. Understanding what the suspension needs and being able to compensate for it.

In the rear, again, I would go with stock location and a long light spring if you have > 100% antisquat

If you are < 100% A/S I would go with a slightly heavier spring to help keep that energy from being lost.

Now for shocks..

If you have an adjustable shock, the question you need to ask yourself is what do I need.. Having the shock behind the axle is going to make your adjustments more noticable for each click compared to if it was in front of the axle and you may not need to use as many adjustments (IE 12 way shock you may only use adjustments 3-6). Now having the shock in front might require you to use the stiffer settings 5-11. Again, do you have > or < 100% A/S as that is going to come in to play here a little too.

While I'm not an expert on suspensions...my understanding is all the spring does in the rear is to hold up the truck. The shock controls how much seperation(anti squat) or compression (squat).

[kwhite4]

Here is the only pic i have of my coil overs , kinda hard to see the coilovers but you can see the tubing I welded in to connect the dots.
Then again the truck is way low and I dont have alot of bed room left.
Might get something like this under the bed or maybe they will work at a slight angle ( like tilted towards one another ) for extra clearance. Dont think I would angle them, just thinking out loud.

Attachment 333341

[Outlaw72]

Is that bar welded to the stock frame? Or is that a backhalf?

[djracer]

not sure about his but mine is similar and my frame is stock!

[kwhite4]

Truck was a leaf springer but now it has a S&W ladder bar suspension and except for small c-notch the frame is stock.
Has Moser Fab rear and S&W coilovers which are kinda cheap but soon as my bank allows it I will spring for better springs. LOL

[Outlaw72]

Originally Posted by kwhite4

Truck was a leaf springer but now it has a S&W ladder bar suspension and except for small c-notch the frame is stock.
Has Moser Fab rear and S&W coilovers which are kinda cheap but soon as my bank allows it I will spring for better springs. LOL

Truck looks good!!

[Outlaw72]

Well guys...I made a big score over the weekend. Found someone willing to sale their 496 shortblock for a killer deal.

Studded 468 block....line bored and ready for hone...clearanced for stroker
Cat 4340 4.25 stroker crank
Manley 6.385 H-Beam rods with arp cap screw bolts
NIB SRP 10.2:1 pistons
Used JE 13:1 pistons
Comp Magnum 1.7 rockers
Comp Magnum pushrods
Crower Solid Roller Lifters
Billet timing cover
Timing chain
Some nasty lift race cam that I will not use - solid roller
ATI Damper
SFI Flexplate

The price was so low I couldn't pass it up

[djracer]

cool! That should be strong!

[Outlaw72]

Yea man I'm pretty excited. I have a proven combo I am gunna copy that puts out mega torque and peaks the hp right in my prefered sweet spot of 6400 rpm...the combo uses as cast AFR 305's and a solid roller off the shelf cam.

[djracer]

That should be awesome! Good luck with the build!

[Outlaw72]

Thanks....I will keep you guys updated with the progress. I will be building this one myself with the help of a friend.

[Super73]

Originally Posted by bigjimzlll

While I'm not an expert on suspensions...my understanding is all the spring does in the rear is to hold up the truck. The shock controls how much seperation(anti squat) or compression (squat).

Jim,

I hate to say this, but that is not how I understand it. Seperation and squat are relative to the instant center of gravity vs center of gravity. If your instant center of gravity line (which for our trucks is a line drawn from the rear tire contact patch through the front hole on the lower control arm) is bellow the center of gravity than you will induce squat, if it is about, you will induce seperation.

For a ladder bar car, your ICG is where upper and lower are welded together. For a 4-link you have to draw a line for the upper and lower arms. Where they meet, that's your ICG.


The spring will see a different leverage ratio if placed in front of the axle centerline or in the rear of axle centerline. It will see different leverage ratios based on different distances in front IE different distances behind. The weight placed over the rear (or front for that matter) will act differently on that spring due to location. In our rears, with the stock mounting position, There is quite a bit of leverage placed on the spring compared to if the spring was behind the axle. This requires you to have a stiffer rate spring in the stock location or a longer spring of the same rate vs if it were behind the rear. But, due to the leverage ratio, if you are able to induce antisquat, having the spring in front of the axle will give you more potential travel. Same goes for the shock.

The shock is controling the rate the suspension travel. Now if your shock is in front of the axle, it is subject to more leverage ratio as well as the spring. The shock is going to see less speed in front of the axle vs behind it but requre a stiffer setting to act the same as it being behind the axle in a softer setting.



What I'm getting at is with out your ICG/CG being 100% your are going to squat the rear and loose energy planting the tires in to the suspension. If you are trying to get sepperation, you need at least 101%.

Paired with the right spring having stored energy and a soft setting for expansion rate on the shock, you are going to allow the rear to seperate quickly forcing the tires in to the ground lifting the rear frame.



If you get a chance, Dave Morgan sells a book called "Door Slammers: The Chassis Book" He also has just released a DVD out based on one of his seminars. He has been doing chasis for Alston for the better of 15 years. He explains it much better than myself..

[Super73]

Here is a spreadsheet I threw together. http://73-ls1.com/63truck/weight_sheet_revision_2.xls

It allows you to calculate leverage ratio for both front and rear. Should aid in figuring out spring rate/length. I have another one somewhere that allows you to figure out anti squat ect.. Actually, the Pirate4x4 site has a killer one for that..