Heres the deal I have a 28 model A tudor tub and I want to start putting a car together. I have a 83 BMW 5 series with the independant rear end. I was going to use the entire drive train but a 429 came my way. How should I make a frame to fit this rear and have any of you done this kinda thing before? I am eager to learn some new skills here and I would really like all of your help.
Sounds like a mess. I like to use the KISS method, and independent rears don't fit with that. I would also hazard to guess that the BMW rear couldn't handle the torque of the 429. Use a 9" Ford and call it easy. P.S. to Fatty: Don't embarrass us Iowans by starting off-topic threads about songs and such. This isn't a "scenester" board.
I think the 5 series probably has a decently strong rear but I don't think it'll last behind a 429, well at least if you put your foot into it. I like the Jag rears, especially the XJ12 ones (they come with posi). Are easy to install and have a Dana 44 center section so gearing is not a problem. You should be able to sell off the 5 series stuff for more than you'll pay for a Jag rear. I get them for around $100 pulled...
What the hell is a scenester? Are you saying Iowans don't listen to music? How did I embarrass you. Oh I get it your calling me a poser. Real cool sorry I will no longer enjoy good tunes I will represent the corn state proudly. I apologize for not being cool enough for you.
Will you gain better traction by using a independant rear? Does it handle better then a solid rear? If I go with the independant rear do I have to do something different with a frame? I lack any knowledge of building a complete car from the ground up.
better traction? well, not off the line you won't... that's why you don't see independant rears in drag cars. The way a solid axle is attached to the rest of the chassis, by means of a torque tube, ladder bars, 4 link, etc, allows the torque reaction to push the tires harder into the ground (think of how drag cars "jump" off the line) An independant rear is not able to do this, because the differential is attached to the chassis, and not the suspension. However, you might get a better ride, and better handling out of independant rear. A straight axle rear can come close on smooth roads, but independant is better handling if the surface has imperfections. I would say, if you want this thing for the looks, or REALLY want to give'er around corners, go for it, but otherwise just throw a normal rear in there. Actually, if I was to do an independant, I'd just start with the centre section, and scratch build the A-arms, since most production IRS's have design problems. If you wanted to go this way, there's a lot of engineering involved, but there are also a lot of books available on the subject.
You don't see IRS in drag cars because they aren't designed for that type of abuse, typicaly. IRS is for reducing "un-sprung" weight and theoreticaly if you install this properly and match the springs and shocks to the new car it will handle very well and ride pretty nice. Now for the negative part. If you don't have any experience with BMW or other IRS systems and don't know how to caluclate spring rates and such chances of you making this car match performance figures of the BMW are VERY slim. Not to mention it will look a bit out of place under there. The Beemer rear is pretty cool looking with all the fins and such but you will see the whole thing and outside of the fined diff there isn't much to look at. Stick with a 9"
I used to have a 5-series rear, it was going to be used on a truck. Anyhow, they're ugly. The sides where the arms anchor on stick out to the inside part of the tires... unless you had fenders to cover it up, i'd advise against it just for aesthetic reasons. IMO, from everything i've read, light-weight cars don't really benefit from independent suspension like larger heavier cars do. Light cars just kinda bounce over holes, while heavy cars try to drop in them, hence the need for better wheel control.
That doesnt seem right... the unsprung weight reduction in a light car is more important, because the greater the ratio sprung to unsprung weight is, the better the tire will follow the road surface. Bouncing over irregularities means it it will spend more time not in contact with the road, and when its not in contact it has no traction... But I think a Independent setup isn't always the best solution ( even for performance reasons ), because of the complications of setting a Independent suspension up correctly. To benifit from the atvantages a Independent can give, you might have to mess with the Rollcenters without messing up the geometry, and that is a lot easyer to do on a solid axle. ( which can give a beam axle car an edge in performance, sometimes...)
this website might help http://www.kugelkomponents.com/ what are you doing for front suspension? Paul
I dont see how that would help. There is nothing traditional about that monstocity... But given the other posts I have seen from you, you were probably just trying to start shit.... again.
I was just trying to help. I know it's not as traditonal as a 1983 bmw rearend, but I thought it might offer some good advice. abd don't worry, no offense taken thanks! Paul
I suppose you could argue that using a junkyard part for a Hot Rod is more Traditional than ordering a Billet part out of a catalog, even if the junkyard part is to new. But if you dont get that, I am not going to try and explain it to you Good, I was worried that you would...
I would say 90's tbird/mark8 rear....takes stock ford 8.8 guts...simple to mount. you can use FWD spindles in the rear with custom CV shafts. I think it would hold to 429 since you will never get it to hook like a solid axle will. the kit car guys do this alot. if you used say a later gm midisze spindle with a 2 bolt strut mount you could easily fab a bracket to hold an upper H arm (plus they are AL) simply mount a tierod to the frame to adjust toe. not to mention instant disc brakes. that is prob as low buck as you can do it. 75% junkyard parts off some common cars. only a minimun fab work needed you could setup a pushrod shock mounting that tucks up in the bodywork so there are no exposed shocks/springs. I was working on a IRS design that would bolt onto a parallel leaf rear
I would not put this rear end in the car not because of what it is but because it is overly complex and probably wont help except maybe in hard cornering. I would use a straight axle personally (front and rear) and they handle really well if they are set up correctly. An IRS may not be able to launch as well as a solid axle, but if you have ever seen a bug with a swing axle take off quickly then you know that they manage just fine. Just decide what is most important to you and how much work you want to do. I would also look at the weight differences in these rear ends, and dont forget to factor in the extra weight of the brackets and crossmembers that you may need. Also the BMW axle may be too wide, just a thought.
Didn't someone's fairly hot, solid axle '38 Ford get whupped last year at the HAMB drags by an "old man" in a Mercedes sedan? and didn't said Mercedes have IRS? They can scoot if they are designed right and set up right for the car they are in. They (IRS) gotta at least be better than a solid axle with parallel leaf springs locating the axle with no torque control bars, and drag strip 1/4 mile acceleration isn't everythig a hotrod's built for. They need to be able to handle turns too, especially if they are pretending to be a roundy-round type modified. (Or if they plan on going on a "Ranch Run" type of cross country and mountain climb jaunt) Along with factoring in weights you need to be aware of C/Gs front and rear and where the roll centers are. the IRS (unless it's a VW type swing axle) is going to be near or sometimes below ground level while leaf springs teld to locate the roll center about half way up between the spring eyes and the center bolt. So if ya keep the buggy spring and beam axle up front the front roll center is going to be higher than the rear... Not the most common set up, for handling anyway.
Unless you are an experienced fabricator with a well-equipped shop I'd pass on the IRS. One EZ to install IRS is the '89 +up T-Bird/Cougar..pretty much four bolts gets it installed BUT it's much too wide for an "A" and too ugly for a highboy.
I am not saying that the solid axle is superior, especially to a modern german car. I am saying that is extremely close to the same thing when you have IRS in a car that was not orginally engineered for it. That is not a fair match up, if you can find a test of 2 of the same car one with independant and one with solid axles and put them through the road course etc. then you may have something. Just because your friends Ford beat a Chevy doesnt mean that all Fords are faster.
In some cases it might be though... Given enough time and resources a Independent can be made to perform a lot better, but most of us dont have that. With a solid axle you eliminate Camber and Toe in/out changes right from the get go, and even though that isn't always the optimum it at least doesn't move away from whatever setting is the optimum. Spring Rates, Shock settings, Roll Centers and Swaybar stiffnesses ( if the car has them ) are more than enough to mess with, to try and get a car to perform right. Putting the extra variables in that a Independent brings, will open up a whole new can of worms. I'm not saying it can't be done, but I wonder how many 1 800 IRS/IFS Hot Rods have had that kind of development... To quote a race car builder that has written some good books about suspensions ( Allan Staniforth ): Reaching the right objectives with reasonable precission is better than reaching the wrong ones with infinate precission...
Its kind of tricky to measure exactly how much performance is lost by using a solid axle instead of a IRS. And the only way I know of to compare the two is in a form of racing where both are allowed and used. Solid rear axles are used in Nascar but since they all are using it there is no way to compare it. English Clubmans Racing allows IRS rear suspensions but Mallock Racing uses a solid rear axle on a lot of their Race Cars, and they are proven winners. These are modern Race Cars with push/pull rod operated double adjustable coilovers, etc... ( see pic, you know I was going to include a Mallock in this...) And Ferrari experimented with a DeDion on their Formula 1 cars as late as ( I believe )1978. Besides the fact that a Solid axle doesnt have the Camber and Toe in/out changes that a IRS can have, it also has a lot less power loss ( Arthur Mallock found out that the losses in the drive shaft are less than the losses of the two halfshafts combined, giving more power to the rear wheels ) Who knows, Race Tracks are a lot smoother than they used to be, maybe some High End Team will try it again...
go for it with the BMW dare to be different, tired of 350/350 and a 9" combo Like a good friend told me as we viewed cars at autorama you don't need overdrive to back it of a trailer
i think these are the key words here....but,there is nothing with that, we all had to learn sometime..i admire you for being willing to jump in such a difficult project with your skill level...but on you first project , you should keep it simple...learn as you go, ask questions , get help from knowledgable friends..get all the catalogs from chassis bulders like Pete & Jakes ,TCI , etc and see how they do it...AND KEEP IT SIMPLE...use an 8" or 9" ford rear....ladder bars or 4-bar.....coilovers are easy to install and gives you some flexibility in ride height...i know this stuff isn't traditional, but it's easy to work with
The Jalopy Journal
