suspension adaptation 3

[axman61]

I am posting here for the first time. I am not an engineer but a machinist at a Nabisco bakery. I want to adapt the suspension of a '95 240sx Nissan to a '66 Ford Mustang. The reason that I chose the 240 (S14) is that it is a rear-steer like the Ford with rack and pinion steering, disc brakes and strut-type suspnesion that also uses a tension rod connected to the lower control arm, also like the Mustang. I'm thinking that I will have to fabricate a mount to relocate the top of the strut. Can the idea work if the scrub radius is different than the application in the 240sx?

 

[hemipanter]

The difference in scrub radious may not be an issue other than altering the motion ratio. It all depend on the instant centre distance of the A-arm geometry. Sorry, but I dont know the specific geometry of the cars in question.
Regards
Goran

 

[carnage1]

yes it could, you can also adjust your scrub radius some by changing the offset on your wheels, as long as you have enough room in your wheel wells.

Luck is a difficult thing to verify and therefore should be tested often. - Me

 

[axman61]

Because I was unsure that my inquiry would be welcome here I left out some details. The lower control arms of the 2 vehicles are nearly identical in length and each has only one inboard pivot (the diagonal drag-link provides the fore-aft locating). The track width of the 240 is wider but the wheelbase is shorter. I read the Herb Adams book on suspension design and set-up. However because it is aimed at racing, he basically ignores strut style because it is not as tune-able for camber gain as a upper/lower control arm setup. I just want a good street setup with decent braking. I think that if I keep roll to a minimum, cornering should be decent (the BMWs in sedan racing do pretty well with strut suspension). A GM J-car rack seem to be the best steering rack to use as it has its link attatchment in the center (as opposed to a slider coming from a boot on each end). I've read that some guys make a plate to which they attatch a steering link a the same approximate length as the LCA. What should be my main concerns? Judging from the pics of 240 wheels that I have seen, the car has near zero scrub. I have machined adapters to mount the 240 lower ball-joints to the Mustang LCA. But the angle at which the ball-joints mount is different (with the 240 being at a greater angle, the Mustang nearly flat mounted).

 

[carnage1]

I would double check that the 240 ball joints will have enough motion left for full suspension travel if they are being mounted at a different angle, it might matter.

Luck is a difficult thing to verify and therefore should be tested often. - Me

 

[Tmoose]

Could you midify the adapters to hold the ball joints at the correct angle?

 

[axman61]

Actually, Tmoose, I think I could actually use the 240 LCAs as they are that similiar. However I am not sure of the relative, at rest positions as each is installed in their respective cars. I am currently looking for an S14 240sx salvage car from which to rob parts . I have a cache of S13 parts that I purchased earlier this year. Since then I have discovered that the S14 is probably a better choice. It's hubs even share the same bolt circle for the wheels as the Ford. There are kits available to convert the Ford to struts, but if I can do it myself without creating a dangerous handling car I would prefer to do so. On the Vintage Mustang Forum I've read many posts refering to these kits and there are quite a few shortcomings in them as well. And the prices are quite high.

 

[GregLocock]

Just from left field...

What on earth do you think you'll gain from installing a very similar suspension to the one that is already in there?

I'd ha' thunk that the rear suspension was far more deserving of effort.






Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[axman61]

Mr G. Locock, thanks for your interest. I consider the two designs to be very different. The '66 Ford is a upper/lower control arm setup with manual recirculating ball steering and manual drum brakes. I intend to go to a Macpherson strut/rack and pinion steering/disc brake set-up. Hopefully I will retain all non-assist functions. As previously stated, I have no intention of using the car on a track so I feel that the leaf spring rear is quite capable, providing I use a good quality shock and that I don't ask too much of it. About all I would consider for the rear is traction bars and perhaps a change in spring rate(which, if I desired to increase the rate, I would add a coilover to the shock).
As for the 240sx, its main benefit is that it is rear-steer, disc brake, rack and pinion steering and there is good aftermarket support fot the chassis.

 

[GregLocock]

Ah, OK, for some reason I thought the Mustang was MacP.






Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[hemipanter]

McP will put a limit to wheel back spacing, concerning scrub distance. You may also check out what SAI you is going to get. You must also pay attention to bump steer geometry. In general front and rear geometry should be allike, or else you end up with a more complicated balance tuning work.
Goran

 

[axman61]

The Stang did become MODIFIED strut beginning in '79. My car is a '66. Hemipainter, what is SAI? I've never heard that term before. As I said, I've read the Herb Adams book on suspension but it is more about tuning than design. Can anyone suggest a source that might give me specifics regarding that which I intend to do? By the way, thank you guys for the input so far. I really appreciate it.

 

[hemipanter]

SAI= steering axis inclanation. The older term is KPI.
It is a tricky issue to mix suspensions from different cars
together. Even if one knows what to look for, it will take its time to find the right "donator" to pick from. Books will most of the time describe the geometry and its calculations, but not really what to use. This is because the "use" is only known by the reader of the book.

Okay, your demand is something like a good everyday car, which may not look too advanced at first glance, but it still incorporate a few important things to be aware of.
I think the best is to find some one to speak with in person, who knows his stuff.
Regards
Goran

 

[axman61]

So it would seem that the real question is: if I install a setup from another car to my Mustang and succeed in installing it in such a way that I get (at rest) correct kingpin incline (caster, yes?), camber and adequate travel of steering, bump etc., will the car behave despite the fact that the Mustang has a different wheelbase, trac, weight and so on. However, I can't help but think of the cars built for Indy during the so-called 'junk formula' days. Men laid out chalk lines on the garage floor and built a car around what they thought would work. Then they drove around Indy at 125mph on 5" wide tyres(sic).

 

[GregLocock]

There's plenty of reasonable handling cars that use MacP/Hotchkiss as a combination (eg RWD Escort), so in itself it doesn't have to be bad. The high RC of the hotchkiss means that almost any front suspension will 'work'.

However, I do notice that a surprisingly large number of cars with a Hotchkiss rear end do use SLAs of various sorts, perhaps because larger cars tended to keep Hotchkiss later, and the simple MacP is perhaps less suitable for large cars than small ones, although it can certainly be made to work.

Anyway, your problem is that without doing a downtown job on measuring the geometry up, etc, and the implications thereof, then you don't really know what you are going to end up with.

The FAQ section has some recommendations on books, the default choice is Milliken and Milliken.







Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[carnage1]

you mention the brakes, have you considered the stock disk front brakes? For handling maybe a reinforcement bar between the shock towers. It just seems like their might be an easier way to get where your going if you are just after solid street handling.

Luck is a difficult thing to verify and therefore should be tested often. - Me

 

[axman61]

Yes carnage1, I have considered that. But I would still be stuck with the worm&sector steering which is poor in feel and SLOW. With the 240, if I could make it work, I'd get everything in one package, engineered together (except for the car itself!!!). Also, I've read about aftermarket R&P systems that are sold for the 'Stang and use the stock spindle. All the examples about which I have read, when installed, increase the turning circle. From the ball-joint to the tie-rod pivot on the stock spindle is approx 7". On the 240 it is 4'+. If I can install a R&P and there is no interference the steering ratio and the turning radius should inprove, not diminish. Am I correct?

 

[carnage1]

It does sound correct and like a better option as long as you enjoy the extra work.

Luck is a difficult thing to verify and therefore should be tested often. - Me

 

[izzmus]

http://suprang.com/

Food for thought?

 

[MikeHalloran]

Some Mustangs of that era came with disc brakes and faster steering boxes. The boxes at that time were also rebuildable with simple tools, so you might be able to find one in a junkyard that's good enough.

Sometime before 1972 Ford stopped using replaceable sector shaft bushings, and just ran the shafts direct in the cast iron housing, so junk boxes of that era, remain junk.



Mike Halloran
Pembroke Pines, FL, USA