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Please help me square away my S10s rear suspension

5K views 34 replies 4 participants last post by  ericnova72 
#1 ·
Hey everyone. I wanted to double check some information I found on the net and make sure that I am going at this the correct direction. I have a mid 80s S10 that was back halved at one time and this is a drag only vehicle. The rails are square to the front end f the chassis and are level from side to side. The original owner put ladder bars on it and had kept the factory leaf springs with a 3" drop. However the leaf springs were welded directly to the housing not allowing the ladder bars to do their job.

I noticed that to have the pinion pointing up 3* to meet the drive line angle (going down 3*) the adjusters are all the way out and only have a thread or two of engagement. So I looked into "Proper setup" a little further and chassis engineering recommends that the ladder bars have a downward angle to the front of the vehicle about 4-6*.
http://chassisengineering.com/documents/3608_000.pdf
Figure 9 Page 5

Mine are the opposite.....

Also the front mount are just 3/16" plate welded to the frame rails with just the single adjustment. I wanted to get the competition engineering front crossmember with the radius holes for adjustments without adjusting the rod ends.

So here is the question. Should I cut the brackets off the rear end housing and the frame rails and fix the ladder bar angle and setup. Chassis engineering recommends that the rod ends are setup at a certain amount of turns from being bottomed out in the ladder bars.

Am I on the right track? I have never really setup anything like this before and would like some input from people with more experience.

Onto the coilovers.....

According to this article BaselineSuspensions.com.........Launching A Drag Car
You want to figure out ride height and then find out the upper and lower mounting points. Then find a set of coil overs where the shock is compressed 2/3 of the way at ride height.
Then from there I will need to probably scale the car to figure out spring rates.

How far am I? Am I on the right track?

I am very interested in learning this so if anyone can provide information, books, and online articles I will gladly read them and learn.

I will not have the truck to the track until next year and wanted to swap to coil overs this winter so figured this would be a good time to fix things and make sure that I don't have any problems when I finally get this thing to the track next year and can finally race it.

Thanks for your time and input. I will post pictures sometime late this week if needed.

Shane
 
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#3 ·
That ChassisEngineering info is for stock-type suspensions that have a lot of flex. Your pinion is not going to "rotate" with ladder bars, so you'd be better off matching the driveline angles as you first mentioned. I'm still pondering on your original statement that "the leaf springs were welded directly to the housing" :eek: Once you weld or even drill a spring (of any type) it is compromised and just waiting for failure. Of course, swapping to coilovers will cure that...

Russ
 
#4 ·
I would re-bracket the housing if it was me, to get the pinion angle correct and get the adjusters and rod ends threaded in to their proper depth (this depth is a strength issue), then go with a new front mounts for the ladder bar, either you fab or use the crossmember kit you listed. The 4-6° downward slope to the front, of the bottom ladder bar tube, is quite important to get the suspension's instant center correct.

1-2° max down at the pinion compared to the trans angle is all you want for ladder bars.

Don't confuse ladder bar lower tube angle with pinion angle, they are not the same thing. This leads back to why you will likely need to re-bracket the axle housing to get both these angles correct at the same time.

That shock kit will get you started and on the track, but you may find the lack of shock dampening adjustment will have you buying real single or double adjustable shocks down the road. What you are looking at will usually work down into the 10 second 1/4 mile range okay, as long as you aren't going to several different track that have better or worse track prep than your "home" track.

I would expect to see a rear spring in the 120-150lb range to be correct, scaling is the best way to nail that down, but about 130lb is where I would start if I had to just "wing" it with a steel box floor and tubs.

You are definately thinking in the right direction :thumbup:
 
#6 ·
Thank you Russ, Eric, and ProStreetBob. Your posts are very helpful and I will go about and first cut the brackets off the housing and then, cut the front mounts, and reposition the ladder bars according to the correct documentation. I will then get the coil overs situated.

Eric,

When I got the truck the motor and trans was down about 9* so I cut the engine mounts off and dropped the engine so the oil pan was about 3/8" from the crossmember. This put the engine and trans at about 3-4*. Hopefully this will put me in a good spot.


Here comes the zinger.... Should I worry about the length of the ladder bars and possibly measure them and make sure they are the correct length? I believe I need to find the instant center in order to find the correct length. Want me to measure the length and post if it will be close enough? I am not trying to launch an 8 second car or any crazy contraption. Its a turbo motor that will do most of its pickup at the top end so I am not sure how critical the correct length will matter getting out of the hole but if you feel so I will adjust the rod ends and measure center to center.

I planned down the road to swap to a better adjustable shock setup once I work out the 1000 other hiccups I will have and have the extra $$$$ but I am sure that will be two to three years down the road.

Thanks for the pictures. I will definitely use them to get an idea on what I should be doing.
 
#7 ·
Length of the ladder bar is not a big deal in your case, a really small car like a Vega would need a short 32" just because of the lack of space under the car, and a big car like a '66 Impala will prefer a longer 36" set.

You'll be fine with anything in this 32-36" range, as long as the mounting points and bar angles are correct.
 
#8 ·
Alright cool. Thank you very much for the input. I don't think I am going to have time in the next couple weeks to tackle this. (recently laid off so money is short and time should be used elsewhere like finding employment and selling crap I have been hoarding for no reason). I can at least pull the rear end drain the fluid and put my alignment bar in the housing so the heat from cutting the brackets does not warp the housing and this give me a chance to weld on the brakes as well. I will post pictures of the rear end as I take it apart and fix everything.

Thanks again for the help
Shane
 
#9 ·
Something I would check before you re-bracket the housing....

Remove the bolts from the front ladder bar mounts and block the front of the bars up so that you have the ladder bar's lower bar on the correct angle, then set the rod ends and/or adjusters on the rear of the bars(at the housing brackets) at the correct thread depth. Then check the pinion angle...because the brackets on the housing may be in the correct place/angle and won't need to be removed and replaced...leaving the only problem being that the front ladder bar mount was simply not placed low enough on the frame.

Worth a check, maybe you'll avoid some unnecessary rework and expense.
 
#11 ·
So I am digging this up. I finally had sometime and extra money to focus on this. I got everything measured and setup this weekend. I decided to go with this kit http://www.summitracing.com/parts/cee-2765/overview/.

My biggest question/concern is how do I know what length spring I need? I see in the documentation from competition engineering that I need a 2.5" ID spring. I am going to go with eric suggestion and start with 130lb springs and go from there.

Let me know,

Thanks!
Shane
 
#14 ·
I have to rebracket the housing. When I dropped the front mount for the 4-6* downward angle and adjusted the rod ends so 3-4 threads were showing (per competition engineerings instructions) the pinion was still pointing down 6-7*. The adjustment brought the pinion up some but dropping the front negated that change. I had to order the correct line up blocks for my alignment bar before I cut the brackets off. Waiting for them to come in and I can cut the brackets off and fix the angle and weld the brakes as well.

One other thing... The front of the ladder bars had this metal loop that goes around the front rod end yeah I said had. I am assuming this is for safety incase the rod end breaks it holds the rearend from coming out from underneath the vehicle? Is it a big deal if the previous owner cut them off? I was planning on getting a piece of steel rod and bending it into a U then welding it on incase the rod ends ever broke. Does this make sense to fix this or should I not worry about it.


Thanks for all your help and input. It has helped a lot.
,Shane
 
#15 ·
I'd want to have the safety links. You can get replacement kits from Comp Eng, or just make your own like you said. Some tracks will make you have them, and I think they are mandatory after a certain ET is reached, but I'd have to look it up.

TechInspector could likely tell you, maybe shoot him a PM.
 
#16 ·
I agree. I would think since I am this far into everything it would be silly for me to overlook this small thing and then have tech turn me away at the track.

That would suck. So do they sell just the safety links that way I do not have to try to make them out of some scrap metal? I googled real quick and nothing jumped out. I will look deeper when I have time at work today.
 
#21 ·
Okay so I got a lot done this weekend and came back with more questions than I could have imagined.

So I started by double checking all my measurements to make sure everything was where I thought it was.

We first checked how straight the housing was. One side was straight but the other was bent a little. We started by cutting all the brackets off the housing. We then cleaned up whatever little weld, and extra that was left over from cutting. Checked the straightness again nothing changed.

Mocked the housing under the truck on jack stands. Made sure it was even side to side and square to the front lower shock mounts as well as the sway bar link on each lower control arm. Everything looked good on the housing. We created some car board templates to figure out the shape of the ladder bar mounts on the housing since the housing is too wide and the ladder bars would not be able to go on the 3" axle tubes. (See pictures below).

So we then tipped the housing up 2-3* (to match the trans which is ~2-3* down.) We then held the brackets up to the housing (mounted to the ladder bars) so they were as perpendicular as possible to the axle (by eye) and down 5* (instructions say 4-6*) Then tacked in 4 places on each bracket. Repeated procedure for other side.

I have the center of the axle at 13.5" to simulate the short side of a 26-28" tall tire.

Now here is the issues I am having. The front of the ladder bar is only ~5-6" off the gound not including the mount. Is this correct? Seems awfully close to the ground but then again it should not be compressing that much at that point.

The other issue I am having is that I moved the rearend forward a couple inches to center the wheels in the wheel well and now the front mount is right about where the previous owner back halved the car. So I may have to move it back but the mount may be low enough to clear. I need to have a fresh set of eyes look at it.


I am going to have to remove the bump stops or at least trim down the excess piece of metal that sticks out on the inside of the frame rail.

Also there is a tube that goes corner to corner but I believe it will need to be moved for clearance. I also have some 14ga sheet metal to box in the frame in the rear to help keep things rigid.



Soooo... I guess my questions are regarding the front mount and clearance.


Coil Overs:

The installation instructions for the coil overs say to keep the shops vertical. Unfortunately as seen in the pictures with the frame rails being narrowed and the width of the housing I cannot mount the coil overs to the axle tube. Going to have to mount to the housing. So do I just ground down the bracket so instead of contouring to the 3" axle tube it contours the shape of the housing?

Back half

How bad does this look? I have never done this before so I have no idea the correct procedure or things you usually want to check for or maybe materials that you should use etc. The welds look like garbage..... I talked with my friend who is a good fabricator and welder and he suggested grinding them down and going over them so we get better penetration.

Any input?


Sorry lots of questions I just wanna make sure I am going at this correctly. I will upload more pictures in more posts since I can not upload more for this post.

Thanks
Shane
 

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#23 ·
and even some more pictures

One other questions. How close can I put the ladder bars to the frame rails? I imagine once I get the panhard bar isntalled the side to side movement will be very limited.

Thanks
Shane
 

Attachments

#24 ·
The front mount on the ladder bar will look real low, but it is really no closer to the ground than it is at the axle housing bracket, except for the 4-6° down angle to the front. If you look at the posted pics earlier in the thread by ProStreetRob of trucks he's done, you'll see that all his look really low also at the front ladder bar mount. If this point can ever hit the ground, you've got bigger problems that just digging into the pavement...

I would weld the crossmember in with the initial set-up of the ladder bar angled down as you have it, and in the second hole from the bottom on the front 4-hole bracket.

You can cut on the shock bracket to fit the housing, common to have to do this with the big web housings and fabbed sheetmetal housings...it's just a PITA time-wise is all. I would use an upper crossmember for mounting the top of the shocks, not the side of the frame rail, even with the rail boxed.

Where the frame was cut and narrowed...I would cut out the gussets and old brackets, clean up the welds and redo whatever you think needs it, then box that section of frame for 6-8" forward and backward from that point, then put the gussets back on. I would use 10 gauge for boxing here, close to the same thickness as the original frame. The long round diagonal brace tube is a good thing try to keep it, even if you have to move it.

Assuming about a 24" long panhard, side to side movement during suspension travel will be less than 1/8". I always try to keep the panhard mounts nearly as far apart as the frame rails are, and still get it to clear...don't just go to the top of the pumpkin like a lot of the street rod guys do.

For clearance to the bump stop, figure the suspension will only need about 1-1/2" to 2" upward travel.

You've got a good grasp on the rest. :)
 
#25 ·
Thanks for the reply Eric!!

I ended up running down to the local millwrights and grabbed a length of 1 3/4" .220" pipe for the upper shock mounts (Smallest wall thickness they had).

So if you say ~1/8" then I should be okay with the ladder bars being 1/4" from the frame rails. I am also going to try to make the coil overs as wide as possible on the back side of the housing.

Other than boxing and rewelding the back halved area is there anything else I should be concerned with how is was done?

This is the panhard bar kit I am looking to order http://www.summitracing.com/parts/cee-2037/overview/


Thanks again!
Shane
 
#27 ·
Depends on how the coilovers attach. Do both ends have misalignment bushings? Check and be sure nothing is in a bind. Side-to-side angling is OK because there's no binding, but fore-and-aft angling can result in the attachment points getting bound up...

Russ
 
#29 ·
Thanks for the replies. The Coil Overs have "eye" type connections at the top only. The bottom connect to the Mount with a Steele bracket on each side of the lower busing that a single 1/2" bolt holds in place. These two brackets then bolt to the brackets on the housing . The coil Overs are almost dead on side to side but they do tip back about 7* which is what I would consider for and aft. I might be safe to break the tac welds and just reposition them.
 
#34 ·
No this is without the springs or weight on the vehicle. This is just the mockup of everything tacked without weight in the rear suspension yet I will have to fine tune the ride height with the adjusters on the coil Overs.

But the brackets on the rear end since it is a webbed housing they didn't not end up at the same heights on each side so its like 3/4" difference between the end bolts on the shock and that is at the lowest setting.

I'm assuming I want the shocks as close as possible. The springs I can adjust but I keep hearing 2/3 compressed as a good number.
 
#35 ·
I always went for between 5/8 and 2/3 compressed, like you've got planned.

I would rather cut some more on the shock bracket on the housing, to make them the same height, but that' s just how I would do it...I try to make stuff as symmetrical as possible on locations side-to-side and up-and-down....don't want it to look too "hack-y".

It might also make a difference if/when you switch to a good double adjustable shock.
 
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