Puting a 4 link on a unibody???
Puting a 4 link on a unibody???
(OP)
ok this might be crazy but, i'm in the process of putting a ford 302 in a 1992 nissan 240sx. It's a unibody car with independent rear suspension but that is not good enough so I'm wondering the process in changing that into a 4link. i would be using a ford driveline(engine, transmission, drive shaft, and rearend). so if you know of anyone that put some type of solid axle in the rear of a unibody let me know i'm sure a couple of mustang guys did it.





RE: Puting a 4 link on a unibody???
Realistically your main problem is deciding on arm lengths you can package and position that give reasonable control over the pinion joint angle. This is a classic 4 bar link problem, there are many solutions. The V8 supercars over here use long, parallel arms, and then a Watts link. Our sedan used the same (the one is based on the other), but we had a shorter upper arm, angled inwards and down, for roll steer and to help toggle the pinion angle.
You may need to biff the floor to create clearance for the diff.
Cheers
Greg Locock
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RE: Puting a 4 link on a unibody???
I doubt that your car has adequate strength where you'll want the upper link(s)* to attach, and adding only local panel stiffening around any additional brackets may not be enough either. It wouldn't hurt to 'overbuild' a bit here for stiffness as well as for strength, as you may find you have wheel hop under either hard acceleration or hard braking where there would be some sort of impact factor involved. At least the few extra lbs would be more or less over the "right" wheels.
* Depending on what you're going to do with the car, you may want to consider a torque arm suspension (a la GM's 3rd/4th gen F-body and a fairly common retrofit to the Fox Mustangs) or a 3-link (as in the latest S197 Mustangs and also a retrofit for the Fox/SN95 axle, and I suspect is also used in Greg's supercars and sedan) instead of the triangulated 4-link.
Norm
RE: Puting a 4 link on a unibody???
The Mustang guys swapped out the IRS for reasons of dragstrip durability, but I'm guessing that's not the environment where this particular conversion is headed.
Norm
RE: Puting a 4 link on a unibody???
'When in doubt, make it stout, out of stuff you know about.' (It'll help plant the rear tires and give a better weight balance too.)
RE: Puting a 4 link on a unibody???
Unless you're drag racing this 240, why would you get rid of the IRS? What's not "good enough"?
RE: Puting a 4 link on a unibody???
Goran
RE: Puting a 4 link on a unibody???
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Puting a 4 link on a unibody???
because i was told that the car would handle poor on the road and this would be a bit better.
ok the car is going to be a street/strip but down the road i might just make it into a full out drag car not sure.
I think im going to be tubing it, to free up a bit more space, and there will be a cell going in the hatch of the car so that there is even more space for the diff and suspension components.
the drifters just use a infinity rear end i am pretty sure its a 2.0 or 1.5 lsd not that sure on any of that but i need or i guess i want a possi just so i can launch the car as hard as possible and go straight down the track.
But what i want is a solid drag car with a rear end that will almost never fail so what do you guys recommend for my setup/
RE: Puting a 4 link on a unibody???
f you are serious about your drag racing put in a Detroit locker or an air shift type locker. A Positraction won't cut it.
If you run substantially bigger tyres and/or slicks you will need substantial reinforcement of stock dimensioned suspension arms and their mountings and the chassis platform in those regions.
Normal method for moderate increase is to box in the channel sections and to add thicker plates at the mounting points, but if the power and more importantly the traction increase is substantial, you will need fabricated arms with more robust construction, but same lengths and the mounting points should be on the links that link the font and rear chassis sub frames, or to cross members mounted to the sub frames or chassis links.
Regards
Pat
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RE: Puting a 4 link on a unibody???
Regards
Pat
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RE: Puting a 4 link on a unibody???
So in your case a shorter rod 4 link is to prefere. It should be adjustable for different instant centre to be able to run unparallell when racing, then go back to parallell when driving home. The trick at the strip is to set "rise" or "antisquat" to produce tire plant during start. Then you should have special Dr shocks where you use the extension dampening to alter the time duration vs force of tire grip. If you got the money, buy doubble adjustable shocks in order to be able to alter the after 60 foot distance grip.
Springs are usually quite soft, and you might even use a heavy swaybar to set off the line side to side preeload.
Get the picture?
Goran
RE: Puting a 4 link on a unibody???
RE: Puting a 4 link on a unibody???
Regards
Pat
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RE: Puting a 4 link on a unibody???
im not to worried about weight i will just make that up with a couple more HP and will also make up for it with fiberglass and possible some carbon fiber. I have a 9" already so i might try to save some money and just use it.
i really want to get rid of the IRS so a 9" with axle hubs is not for me but thanks for the good advice.
yeah patprimmer is right a spool is not a option for the road.
but what do you guys think of that 2link i guess thats what it is called with the coilovers it look like the easiest one. the 4link just has to much involved for how much time and money i got.
it would be nice to run mid 10s to 10s if possible but that is a lot farther down the road i'm thinking right now 11s or high 10s.
RE: Puting a 4 link on a unibody???
The one redeeming feature is that if you snap a half shaft you can still get home, but one wheel drive does have some 'interesting' characteristics...
RE: Puting a 4 link on a unibody???
ladder bars bind in roll. They also need a Panhard rod or Watt link to control sideways movement.
The bind in roll or a single wheel bump makes them very inconvenient on the street. For dual purpose you need a 3 or 4 link setup with a Panhard rod or Watts link.
I will enquire about fabricators in your part of Canada.
Regards
Pat
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RE: Puting a 4 link on a unibody???
RE: Puting a 4 link on a unibody???
RE: Puting a 4 link on a unibody???
www.hemipanter.se very fare down the site. Sorry that my camera battery went drained so there is only ONE image.
Goran
RE: Puting a 4 link on a unibody???
another question is there any good books or forums on how to build any of these setups?
RE: Puting a 4 link on a unibody???
Regards
Pat
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RE: Puting a 4 link on a unibody???
The lighter your car gets, the stronger I think the argument gets for using one of the other solutions. Other arrangements may be able to give you a better combination of anti-squat/SVIC location and roll steer with less structural reworking.
Norm
RE: Puting a 4 link on a unibody???
Rod
RE: Puting a 4 link on a unibody???
if it would work, could you explain it like what angles and stuff that is very important. pretty much how do i start?
what parts should i buy to make this go smoothly and successfully with very little knowledge going into this project.
RE: Puting a 4 link on a unibody???
Regards
Pat
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RE: Puting a 4 link on a unibody???
The angles are important. I suggest you copy one that works, exactly, or else hire someone who knows how to do it, or accept that you may have to modify your design after building it.
Your big problem with attempting to design something is that you probably don't know what you really want, so even if you knew how, you wouldn't know what to aim at. That is not an insult, defining the requirements from a blank sheet of paper is very hard.
The excellent program susprog3d has a template for this suspension.
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Puting a 4 link on a unibody???
RE: Puting a 4 link on a unibody???
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Puting a 4 link on a unibody???
In 1980, I reworked a 3 link plus Panhard that had been fabricated by Strange Engineering of Chicago to a setup very similar to the OEM, ie, using the lower V link (A link to some) and two upper links attached directly above the forward mounting points of the lower V link---Not at the OEM mounting points. This simplified the mounting system and eliminated the Panhard bar. It also lowered the roll center a bit. The OEM problems of broken axle center section was easily corrected with proper reinforcement at the bottom attachment point in combination with the longer upper links...something the Lotus works seemed to miss? Also, to continue along the lines of cleaning up the underside of the chassis, I mounted a 7/8" tubular ARB in the boot with the links going forward through slots cut in the wheel wells to links above the ends of the rear axle. The bar mounting trunnions were bolted to brackets welded to the rear supports of the roll cage. I still use this method of mounting the rear bar on our current Lotus Cortina.
Giving credit where credit is due, even after all these years...Help with this setup from Steel Therkelson (one of the Cortina works techs and later for Chapman) His experience was invaluable.
Rod
RE: Puting a 4 link on a unibody???
Look up how Ford did the 4 link setup on the Mk1 Escorts to convert from leaf springs. Essentially they cut slots in the floor and welded in boxes. Simple, quick, and effective.
RE: Puting a 4 link on a unibody???
but if i did that how would i make my front end to last? i heard something about capping the frame rails from the front to the back would this work?
RE: Puting a 4 link on a unibody???
I know plenty of drag racers who are very satisfied with their 4 link designs, in fact, I would think it is the most popular design for cars with rear suspensions.
This link has examples of both types.
Regards
Pat
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RE: Puting a 4 link on a unibody???
However, it is not used in top fuel or funnycars, but these are entierly different cars.
Goran
RE: Puting a 4 link on a unibody???
Regards
Pat
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