Rear Suspension for street application

Well the aftermarket sway has plates on the ends that are meant to be mounted up on the inside of the factory CA's. Since the factory ones are non boxed you can slide the plate up in there.

I have the UMI tubular set on my GN, non adj uppers and an ATR sway bar and i love my set up. I first installed the lowers and sway bar because of my messed up stockers and left the uppers til a later date. I noticed right a way better traction and control. The uppers didnt change much in the way the car felt. I do get the popping when going over bumps because of the sway bar. I didnt know that you shouldnt use regular grease on the poly bushings, so i guess i learned something today. But i dont think you can go wrong with the UMI setup. I have KYB shocks all the way around and my car handles excellent.

"Pinion angle" and "instant center"...

Could someone please explain what is meant by "instant center" and "pinion angle"?...I know that the "pinion angle" is the angle of the pinion vs. the driveshaft...as for the "instant center", well, that's where I am a little confused...
Thanks

Claude

Rearend

Have boxed in stock lowers, no-hop bars, and airbags. Hooks nicely. Most Buick guys I know took off the Southsides and either threw em away or made a door stop with em'.

DragStuff.com

Go to Dragstuff.com go to Tech articles some good stuff . Actually I'd read this article 1st Drag racing suspension setup and tuning using digital video. It was a easier read for my dumd a## and made it easier to understand setup . There is an article 4link Instant center vs. geometry fairly in depth to the top Drag Teams this becomes a Science specially when they are dealing with thousands of horsepower to put to the ground. For me setup and tuning was easier to apply. Especially the part what to watch for put it all into perspective. A cool/funny article to read is You've got an old Car and you can't afford a New one. Way out of my leauge.

So far my basic understanding of instant center (might be incorrect haha) is just to draw imaginary lines through your upper and lower control arms and see where they intersect. On a GN the instant center is behind the car, so my assumption is that the UCA's are at a downward angle towards the rear housing, the LCA's come at a flat or slightly upward angle towards the rear, so by the time you draw straight lines through them, they wouldn't intersect until some distance behind the car...

I've found a few articles on line I just wish I could find a few simple diagrams to make sure I'm learning this correctly.

Start here: BaselineSuspensions.com.........Launching A Drag Car

Good read here, tons of info here if you search: http://www.turbobuick.com/forums/dr...016-results-stock-suspension-plotted-out.html

Nobody hasmentioned the Global West Del-a-lum / Spherical bushing rear arms yet. They make sense to me, unfortunately the price does not.:frown: Is there a better priced alternatiove than these?
I'm seriously considering just boxing my stockers and new 1LE bushings until I can decide what I want to do.

I'll take a different route and answer your questions.First of all,the holes that get ruined are the holes in the frame that the LCA's are mounted to not the holes where the bars mount to the rear axle. The reason these holes are stressed is because the solid bushings allow the bars to pivot up and down but they don't allow the bars to twist.Imagin how these bars would need to move if you drove your car over an uneven surface where one tire would move up into the wheel well and the other side would move down away from its wheel well. THE BARS NEED TO TWIST IN ORDER TO ACCOMPLISH THIS,BUT BECAUSE OF THE SOLID BUSHINGS THEY CAN'T. IT'S THE SOLID BUSHINGS THAT CAUSE THE STRESS,NOT THE FACT THAT THE MOUNTING POINT AT THE AXLE HAS BEEN MOVED. The squeeking is caused by the bar twisting and putting big stress on the frame bracket that the bar mounts to. The constant twistig eats away material on the frame mout and the bolt becomes lose. The SS bars also change the pinion agle because they are effectively longer. This rotates the axle moving the pinion downward. The next thing you'll want to understand is why they would move the point where the LCA's mount to the axle downward. Imagine that the rear tires are welded to the ground and you're trying to break them loose with the throttle. The tires want to move the car but they can't. If the axle could break free of the control arms instantly it would rotate in the opposite direction that the tires want to rotate.Under accelleration your axle is always trying to move in the opposite direction that the tires are moving. When this happens the upper bar is being pulled on and the lower bar is being pushed on. If the lower bar travels uphill to the frame and the rearend pushes on the bar the bar will pivot downward.This creates downforce on the rear tires and that's a good thing for traction. Since the tires can't move downward the rear of the car lifts. This is why they're called lift bars. These bar don't effect ride quality in any way. If you draw your imaginary lines with this setup they will intersect in front of the rear tires. While this is a very effective setup for traction,it moves the instant center up too high in the car. While the lower bar is being pushed on the upper bar is being pulled on. How can we use this pulling force to our advantage. Move the point where the upper bars connect to the axle upward.Now the upper bar travels uphill to meet the axle.When the twisting force of the axle pulls on this bar the bar wants to pivot downward. This creates downforce and moves your instant center in front of the rear tires and lower in the car. This is the correct geometry for our four link cars and is the same geometry you'll find under every paralell four link susspensioned race car on the planet. So,you don't want to use LCA's that have a relocated mounting point at the axle and you don't want to use solid bushing. Even the poly bushings create too much stress when asked to twist. The only way to go is with control arms that have spherical rod ends. They can move in any direction and never bind. You can go to dickmillerracing.com to see a set-up like I've described. If you don't change the geometry you won't create traction exept if you use an air bag or a stiffer sway bar. If you use the set-up I've described you won't need either and you can adjust the pinion angle with the adjustable uppers and you can preload the passenger side by shortening its bar so the car leaves straight and doesn't twist.

I am in the process of installing the TRZ 8.8 Ford kit in my G-Body which uses the spherical upper bushings in the housing and heim joints at both ends. They are basically the same as their G-body double adjustable arms and cost $550 Let me tell you the quality is second to none. I will be doing a full write up once I have finished the complete swap. Right now I am working on getting the parking brake working with the rear discs. Please note the braces are hotchkis and not included in the trz kit.

Well, hopefully something here helps clear some things up on all this for you. It definitely can be very confusing, especially with so many different products & ideas out there. The basics (from what we found during testing & development + customer feedback) is this:

SSM style bars or any bars with a very small nylon or delrin or especially aluminum sleeve will not only tear up bolt holes and welds on the brackets, but they bind up the suspension a LOT.

The brackets that lower the rear mounting point will change the INSTANT CENTER. That is the imaginary meeting point if you draw lines thru the mounting points of the uppers & lowers (front to back on the car) as you would look at it from the side. They were designed to get extra front end lift on slower cars, in the 12-14 sec range.

That was the "good" point of them. The "bad" points are that they can easily come loose if just bolted on. I believe NHRA/IHRA may have put in the rules they need to be welded on, after seeing too many break off or come apart & make a BIG mess on the starting line (if lucky not to happen down track). If you weld them on, they must be EXACTLY the same side to side. Anyone can EASILY get them out of whack from each other because the rearend can be moved just about any position as you try to line them up. If this is off, the car will drive to one side, handle poorly, and could cause a wreck. Even if they are the same side to side, depending on how they are rotated/located on the housing, they can ALSO effect the pinion angle. With both lower rear mounting points loose like that (before welding), you can get almost any pinion angle setting you want (or don't want). I have heard some cars having so much pinion angle put into it (from rotating the brackets back too far) it needed a longer driveshaft to reach the transmission! This can get VERY tricky for people unfamiliar with putting these on.

On faster cars, the drop down brackets will "hit" the tires too hard & usually spin them and/or react violently. They can also make the car move around a lot more under braking at the top end. If the suspension is working properly, there is really not much benefit at all with these, especially considering all the downsides associated with them. We personally don't recommend these to anyone, except in some cases where the car has been lowered a lot & need to fix a terrible instant center situation.

Adjustable uppers will never have any noticeable effect on instant center, and will just change pinion angle. They can also help center up the rearend in the car, and in "old" days were used a lot to preload the chassis.

Some after-market arms have such a small poly bushing, they smash or split when under power very easily. There is not enough cross-section there to handle the extreme force put on them. Then the car is all over the track, and becomes very dangerous & hard to control. Only way to tell that is the issue is to take them off the car & inspect them.

We use a bigger & tougher poly that has graphite in it & a custom fit that won't bind or squeak like the cheaper mass-produced "poly" upgrade bushings can. And for the faster cars that still want to drive on the street AND go really fast, we are almost finished with an updated design of our delrin bushing upgrade we had for years. This will allow more articulation (like a rod end) for even better suspension movement than our poly bushings we currently use. This will also provide an almost solid connection front to back like a true 4-link for instant power transfer, but gives just enough to not tear brackets off or beat you out of the car like rod ends would/could do. Look for updates on TB.com and/or our site coming soon!

On the rod end style, that is more for "race-only" setups. They will ride a lot rougher on the street, and every little bump is transmitted immediately thru to the chassis. That also can oval out bolt holes and rip brackets off the frame. Anyone running this setup on the track needs to check welds on brackets & brace it all up as much as possible. These are things you do NOT want breaking or coming loose. When you start going 125 mph +, you might want to think STRENGTH more than price or weight savings.

On round tube vs rectangle tube, there are several differences. We use rectangle tube on our arms because we get a MUCH stronger weld attaching the ends. The reason is the actual amount of weld or surface contact you get on round vs tube. On a 1.5" dia tube, it is approx 4.7" around (Pi x dia.), giving you 4.7" of weld connecting the ends to it. On a 1.5" x 2" rectangle tube (like our G-body arms), there is approx 7" around (1.5 + 2 + 1.5 +2), minus a hair on the slightly rounded corners. So that is a LOT more area to weld, making the end connection about 50% stronger.

Then the welding process can also add even more strength & integrity there too. We put the biggest weld possible there to give it the most strength & tie it together the best. It is obviously cheaper to weld less distance & put a smaller weld down, and that is one reason it's done. Plus we have seen many round tube "cheap" arms bend up on faster cars, but never seen a rectangle tube arm bend up. On our non-adj uppers, the rectangle tube also allows the weld to get right out to the corner of the "U" bracket end that goes on the upper ears on the rearend. This adds a HUGE amount of strength, since the uppers are trying to be pulled apart. We have seen top name chassis builders using round tubes, and either the U bracket pulls & stretches out & lengthens, or the tube breaks off from not enough weld attaching it.

And sorry to make this more confusing, but any round or rectangle tubing can be made/purchased in raw form with EXTREMELY varying ultimate and/or tensile strengths & other characteristics. So for any "general" statement of round is stronger than rectangle (or opposite) probably isn't very accurate. Basically it boils down to:

1) Round is usually lighter due to the less length of cross-section (not thickness), which is due to less weight per foot.
2) Rectangle tube can allow a LOT stronger weld to the ends to be made, but costs more to do in time & materials.
3) Stronger grade tubing (in round or rectangle) costs more too.
4) Either will probably work fine on slower street cars.
5) Probably most true and most importantly, and we all have heard it a million times, YOU GET WHAT YOU PAY FOR.

Unfortunately, we are all on budgets & usually #5 decides what parts get added to our cars. We are actually finalizing a new line of fully adjustable uppers & lowers for race only that will be way better than anything out there, but also probably be more on the high end of the price scale too. There is just no way to make super high quality parts with top grade components at low costs using USA parts & building them in the USA with USA pride & craftsmanship & customer support. Just one rod end on these at our cost is more than 4 on some of our competitors version. Again, you get what you pay for. We are also looking into a more economical version of everything for the lower HP guys that don't plan to go 10's & faster & just want something better than stock at reasonable prices. There is a need for that level & a place for those kind of parts, and we should be able to build a better "mousetrap" than our competitors & be very reasonable in price too.

Just always compare VALUE on parts, not just price, and expect the fine print many never tell you to be what you are missing for the reduced price. We could always purchase raw materials of a lower grade steel that nobody would ever notice & save money and/or lower prices, but we choose to make a better & stronger product, without going "titanium" crazy

Hope that covers it & helps!!! This is really just the tip of it all (if you can believe that!) The little (rarely mentioned) details of every little part of the materials, processes, components, procedures, etc, etc, can make HUGE differences in the quality and integrity of a product.

It's not the size of the bushing that tears up the mounting points. It's the fact that they're bushings and can't twist when the rear end articulates. There is no good bushing. As far as your adj. uppers with stock mounting points goes,They're totally ineffective for preloading the susspension because they don't create any downforce because they mount in the stock location. Untill you create down force with the uppers by moving the mounting point at the axle upward,there's no way that you can adjust the bars to create more downforce on one side as opposed to the other. You say adj uppers don't have any effect on instant center. Of course not. The adjustability of the bar has nothing to do with this. It's the angle of the bar or susspension geometry that changes this. Once you move the mounting point at the axle upward and you're truly creating downforce the adjustability of the bars can be used to change pinion angle and preload the passenger side susspension.You say spherical rod ends ride rough. This statement couldn't be more wrong.This is a silky smooth ball and socket joint. The ones I use are teflon lined. My care has never had a nicer ride. You say round is weaker than rectangle,yet every prostock car on the planet uses round.You talk about the tubes being pulled off the U brackets. When you move the upper arms mounting points to the axle upward with the setup I use you don't have a U bracket. There's no way that Burger King will ever say that Wendy's sells a good product. That's why I would never ask there advice about Wendy's products. When someone asks you for advice on susspensions you'll always say your products do it better because you sell them. It's not wise to take advice from someone who might stand to profit from you taking it. Untill you sell an upper bar with a relocated mounting point at the axle, your bar does very little (in and of itself )to improve traction and is ineffective at preloading the susspension.The reason you sell a fat sway bar is because your arms can't be adjusted to preload the susspension. With the setup I've described you don't need a swaybar/bandage.

Paul has a excellent product, and has spent years testing what works and what doesn't. Your bars that you are showing there with heim joints will not last under street conditions period. They will become worn and noisy once the dirt sets in within months.

Melissa has the tubular UMI's with an ATR rear sway bar with no problems

Was it tricky to get that bolted up? The other day I came across an old post where someone said they couldn't fit a big sway bar between the tubular UMIs no matter how hard they tried.

nope..went right on .. sometimes some things need a little persuasion

Sounds good, 1 3/8 sway bar here I come.

As far as all the other discussions in this thread, I dunno what to think anymore. I really don't see how dropping the LCA mount an inch or two is going to "severely bind" the suspension. The control arm can still move... it's still in the same spot... just at a slightly different angle. Instant center is fundamental to a good launch so I would think it's something worth adjusting.

Looks like I opened up a can of worms. I guess I will just decide on my own when I see how much money I have left after my other mods.

I also have the UMI Tubular lowers and adjustable uppers.
Had no problem putting on the Full Throttle 1 3/8 sway bar.

I agree with Grumpy!! "Some things need a little persuasion!" The UMI tubulars I had were a little tricky to get the ATR bar between, just get yourself a BFH and go to town! My biggest problem with the tubulars were the mounting surface between the bar and the arm. Mine binded badly.

if it comes in a box you make it fit should do a Hybrid car