View Full Version : rear suspension choices
01-09-2002, 12:54:00 AM
Here are some of the questions that I had thought of earlier in the day. in short, what would one use to determine what type of suspension to put into a car. you mentioned weight & quickness earlier ("kind of like how one choses a PG" I think you said, we will go there later).
I have two scenarios:
64 Nova, 428 SBC, Cast block, Aluminum heads, PG, 5500 stall converter, factory front end (for now), & original rear end. 9.90 somethings right now with about 125 HP NOS coming in with a progressive controller @ about 1/2 track. this is a 1/4 mile car with some (about 20 miles/week) street duty.
=> What would you recomend & why?
66 chevelle (Possibly a 'maro, but have always wanted a chevelle), SBC, either turbo or centrifugal blower, shooting for ~ 800 hp to get into 9's. this is going to be a race car with tags (no interior, radio, rear seat, heater, etc)
=> again, what rear end & why.
=> same car, what tranny? I am completly torn here. I want to say Th400, but LOVE the OD & see how many of the GN guys are out there Loving thier 200R4's. although, from what I have seen, I dont think that I can go wrong with a Mike trans, PG & a brake.
Thanks for the lesson, Prof.
01-09-2002, 10:51:00 AM
Bob the best suggestion I can make here is for you to pick up the book "Doorslammers" by Dave Morgan. What little expertise I can offer here is 99% Morgan, 1% fighting through his suggestions and trying to make it work on my toys. I'm going to be out of town for a day or so and will crack open the book and see if I can get some 'justified' answers for you. IMO it all comes back to just how much time you are willing to spend tunning the suspension. Not just the rear suspension, but the front too. There are a LOT of 9 second cars out there and you will see everything from stock suspension to elaborate 4link / whishbone setup's. If your not willing to spend MANY trips to the track making no other changes other than suspension, your fooling yourself with a bunch of adjustments. In short,, the more simple the suspension the quicker you exhaust the possibilities.
01-09-2002, 12:53:00 PM
Cool, sounds like amazon here i come.
01-09-2002, 06:14:00 PM
Man, $30, Plus $10.97 S&H, & 4 to 6 weeks for delivery!!! This better be a GOOD paperback.
thanks, now I can sleep well.
70 Z UC
01-09-2002, 07:04:00 PM
Where did you get the book from if ya dont mind. I'd like to order one.
A Little Power Is Good,More Is Better,To Much Is Just Right
01-09-2002, 08:07:00 PM
Me or Marv? I just hopped on Amazon.com & punched in his name & up it came. I tried using Door slammers in the search engine & it did not come back.
01-09-2002, 10:45:00 PM
Jegs sells the book pt# 622-chassis. $29. Its in the rear susp. section in my catalog.
70 Z UC
01-09-2002, 11:15:00 PM
A Little Power Is Good,More Is Better,To Much Is Just Right
01-10-2002, 12:40:00 AM
I just called Jeggie, they are out of stock also and don't expect them till Jan 31st. $29.99 + $6.something for shipping and handling (AND I PROMISE, worth every penny)
OK Bob, I did a little reading and searching and no one really has any solid answers to your Q. Once you get and read the 'suspension gospel according to Morgan' a lot of things are going to come to light other than JUST this choice of 4link vs ladder bars. But... In general keep these things in mind as you think about this.
A 4link is MUCH shorter than a ladder bar. The compact design will lend it'self very well to the Duce,,, where the long ladder bar is around 34-36" from the axle centerline to the front mount. That length would put the ladder bar front mount forward of the main hoop of the cage. I think you are going to see a lot of flex in that case. So for the Duce I bet you end up with a 4link if for no other reason but construstion simplicity. The 4link is usually only around 20" bars and a 5-6" bracket. That should fit in even the shortest chassis. Also the 4link does have the possibility of IC's that are just plain impossible with a ladder bar. (But REMEMBER rule "A") With a ladder bar you are 'fixed in IC length and are limited to IC's AT or below the frame line. It's next to impossible to get a ladder bar IC up high to make a car 'squat' to help weight transfer. With a 4link that's NO problem.
The bad side of the 4link in the Duce or the Chevelle is going to be durability of adjustment. The 4link is a HARSH suspension and beating it around on the street (potholes, speedbumps etc)isn't going to be a lot of fun. That and the harsh ride takes it's toll on the suspension components. I can set a 1/2 turn of preload in the upper right bar to carry a little more weight and reduce the body roll in my car. In less than a full season (100-150 passes or so) the preload has disappeared. Nothing is bent, the chassis is square and straight, the rod ends have not failed,,, but the preload has evaporated. Morgan explains this phenomenon like this. <font face="Arial,Verdana" size="2">Once sorted out, a 4link suspension will not seem complicated but it will always remain delicate to tune and sensitive to changes. The lighter the car and the greater the torque, the more this is true</font> Beating a car around on the street is going make that important. Once you find the 'right' suspension setting, you have to keep after it to make sure it stays there,, PLUS you start playing with wheel/tire combinations, ride height, vehicle weight and you change a LOT in the 4link.
BTW,,, if you find a 4link kit that has unequal bar lenghts,, RUN,,, RUN very fast and far. They are ancient technology and what happens is the IC changes as the suspension moves in it's normal path. They are WAY WAY WAY too critical of tiny changes in track, torque or weight. (Just what I've been told)
OK, 'RULE "A"' I picked this off Alstons site and from my experience I can tell you it is soooooo true.
<font face="Arial,Verdana" size="2"> A ladder bar has two or three adjustment holes that actually work; a 4-link might have 50! Actually, the 4-link doesn’t have 50 places that are better; it has perhaps three that are better, a couple that are the same, and a whole bunch that are worse. You just have a lot more possible intersect points. </font>
With all that rambeling about all I can say is a 4link IS better in you CAN find exactly what the car wants if you are willing to find it. A Ladder bar is a lot more forgiving but doesn't offer nearly the tunability.
01-10-2002, 01:06:00 AM
WOW, thanks. as you said, it is not what I wanted to hear, but I get what you are saying & can live with that. I am going to get the book, read it, understand it, talk with DJ & find out what is going to work best for his (Nova) application. once I get the 'Maro dialed in & get a race car (whatever it might be) then I will head that way.
thanks for all the information & digging for me (us). I look forward to tearing into it.
01-10-2002, 02:34:00 AM
Agreed on some points, the ladder bar will be more violent because you are unable to adjust the IC forward or back [just up or down] the 4 link allows for up and down and forward movement,but, its also a little more streetable because it allows more roll rotation without binding, they are very fickle, but, when set up correctly, they are unbeatable [some swing arm guys may argue].
As for packaging, the 4 link is shorter, yes, but, remember, its also Higher, a ladder bar tapers down at the front mounting points, 4 link brackets stay about the same, its not always easier to package a 4 link car, I have found its best to set the car up with no preload, and set the IC on the 4 link near the midplate, then adjust from there, also, find, borrow or steal a set of scales and weigh the car [4 corners] this will save alot of time, and can point out potential problems before you hit the track
use the bottom 2 bars on the 4 link to set the wheelbase, use the drivers side upper to set pinion angle, and the passenger side to set preload [when needed]
Also, make sure the rear end is both "squared" and "centered" before you make any passes.
01-10-2002, 04:27:00 PM
I have heard of people talking about putting a car on scales & setting them up for Auto Cross, but what are you looking for when you set them up for drag racing? I would assume that it is in that Door slammers book?
thanks for the insight. when push comes to shove I am thinking that this is likely to come down to how much effort he wants to put into dialing in the car & I can only guess that it will be a ladder bar, but dont know. he might just put a 4 link in it & dial it in until he is happy with it wheather or not it is right, or could be better. Dont know
thanks agian guys.
01-11-2002, 02:52:00 AM
Yes, its in the Doorslammers book, I also highly recommend the book, although its somewhat overly technical in parts, its very imformative there are several books out there that will tell you "Where" to set your suspension, the Doorslammer book tells you "why" you should set the suspension "where". I like to use my brain as opposed to someone else's. There are other books avaliable though, Jerry Bickel has one thats pretty good.
As for scaling the car, you can look for binding, or preload, in other words, the left front should be the heaviest corner on the car [front engine, driver on Left side] if it isn't there is a problem with preload or something is binding, you can use the scales for all kinds of things, especially if you keep track of corner weights, and the height of the Center of Gravity, etc
01-11-2002, 11:06:00 AM
T400 + gear splitter? that would give you a little more MPG, but if you want to go fast, why worry about MPG...what are you a ricer?
01-11-2002, 09:10:00 PM
"Ricer"? Goto my web page & make your own determination.
Some of us want more than just brute HP. I have said it a bunch of times, any idiot with money can buy HP, it takes someone that is skilled & crafty to make HP, with style & do it on a budget.
(with tounge in cheek) Besides, why not embrace technology, it is here to help you & to be your friend, it is not something to be afraid of.
01-11-2002, 09:11:00 PM
thanks for the intelegent response.
01-12-2002, 03:20:00 AM
Glad to help, good luck