Homegrown independent suspension for the '68

[Eifelcharger]

During the many hours of cutting and welding the bad spots on the body I realised I was not going to be happy with 60's handling and brakes.
After also many hours reading interesting posts regarding upgrades I also realise it will cost dearly to get the level of performance I am after.
A visit to the local junk yard got me a front clip of a '07 Nissan 350Z Track Pack and full rear suspension including the steering column, clutch & brake pedal box and rear floor pan.
The idea is to fit all these parts and have a decent suspension for little cash, oh and the big Brembo's too 

Has anybody tried this kind of DIY full suspension change? 
I found some Corvette swaps but non like mine.

Any help is highly appreciated.

[Eifelcharger]

And the rear.....

[2Luke2]

Looks like a huge project haha... Just curious why you chose that model of car. I ask because a 350z is around 3300-3600lbs and would figure that you might want something that was built to handle a bit more weight?

[Troy]

Looks like a huge project haha... Just curious why you chose that model of car. I ask because a 350z is around 3300-3600lbs and would figure that you might want something that was built to handle a bit more weight?

How heavy do you think a Charger is? A 440 R/T (with the HD suspension and brakes) is about 3,900 or so - depending on options. Start with a small block automatic without A/C and it's probably a lot closer to 3,500 (my Challenger sticker says it's under 3,300). If someone plans to use that suspension then I doubt the rest will be stock so you might as well add some aluminum bits and ditch half the interior.

I have no idea how you'd make that all fit on a Charger. Lots of fabrication I imagine! There is one other project around here that has most of a Viper underneath so I suppose anything is possible. *IF* the width was close I suppose it could be done with the parts shown - but plan on losing the front inner fenders. The rear doesn't look like it would fit in the space you have so probably lots of cutting.

Troy

[Eifelcharger]

Hi troy, I agree.
The three-fiddy might seem a lot smaller than our pre historic beasts, but actually weighs about 3600 pounds.
I have not yet decided on engine, but it may very well be an all alloy late model V8 or force fed V6 which would again reduce the weight.
I was already counting on getting adjustable dampers from bilstein to "make it work".
The track is less than an inch off between the cars so that should work fine.

[Indygenerallee]

Looks like it's certainly doable! And with shorter front struts I would say the front inner fenders could stay with a hoop connecting the strut to the frame to support the weight better (since the strut mounted in the original inner fender would definitely flex under hard turns)

[Mike DC]

  
I wouldn't do this mod to be honest.  


Don't get me wrong, I would love an IRS in an old Charger.  But I have yet to see a way to do it that I really like.  The structure is very different between a leaf-sprung stick axle and any decent suitable IRS.  The retrofits tend to look like the hardware is welded into the wrong car body.  Wheel travel is too small, structure hangs too low, etc.  

Sometimes they incorporate a whole lot of the donor car, which does make it look a bit more natural.  But in those cases the retrofit re-uses so much of it that the donor is more like the base car, and the '68 is more like a body panel donor.  (At which point you might consider starting with a 2006+ 4dr Charger's platform, given that a bunch of people have done this retrofit already and there is knowledge to draw from.  They usually use a huge portion of the new car but I've seen a done at least once keeping the '68 dashboard.)

--------------------------------------

On the other hand you can call up RMS and get an AlterKtion K-frame and their Street Lynx rear suspension.  That's a helluva lot of suspension improvement for, what, maybe $7000?  If you can live with that live axle then it's hard to argue with it.  

Yeah it would cost more than a junkyard suspension.  But it's a mainly bolt-on job that doesn't completely obliterate all signs of the original chassis.  No big fabrication.  And it's actually sorted out well already.  It probably fits Charger's dimensions a lot better than any other car being retrofit.  It wouldn't surprise me if just the sorting & details of the RMS package produces a better handling result than the first try at retrofitting a theoretically better chassis.  

[HPP]

While there is a lot of personal pride in doing something like this and I certainly can't discount that, it also is a huge amount of effort for only a minimal improvement over a key selection of updated stock parts. Overall the geometry of the stock mopar stuff is very good, even by modern standards.  Reducing chassis flex, stepping up spring and sway bar rates, and modern shocks and tires will eaily improve your vintage Charger's capability to that of a new car.

But, it will be a fun project. Good luck.

[Mike DC]

  
It kinda starts boiling down to a live axle vs IRS debate, doesn't it?  Without the IRS the new car suspension retrofit idea gets pretty hard to justify.  But with the IRS demand it becomes pretty necessary to retrofit something newer.  



I would put an IRS into one of these cars if it had the kind of priorities that the factory would have had.  The aftermarket solutions all look too much like what they are - designed for a different chassis in the first place, and then built to impress onlookers more than survive potholes. 

[JB400]

Another question is whether this rear end will even survive under the Charger.  The Datsun made 300 hp and 270 ft lb. of torque.  Unless you're running a 318 or a stock 383,  I don't see this rear end lasting long.  Are there some aftermarket parts to beef it up?   

[Mike DC]

IRS conversion = the owner wants handling rather than drag racing.  The IRS's anti-squat & geometry limitations alone are enough to hurt the drag launch potential even if the differential wasn't weak.

Modern rear diffs tend to be using higher-quality metal in the gears to get away with a smaller diff.  They are often stronger than their size suggests to us old-schoolers.  



But yeah, the issue is something to watch out for.  Plenty of guys have put higher-quality metal gearsets into our original huge diffs just to keep them together.  

Some modern cars are actually electronically backing off the throttle at certain times to avoid over-stressing the drivetrain parts.  

[JR]

If you have the skills to pull this off, I'm all for this.

I would make triple sure to keep the geometry of the Nissan parts as they came, and also reenforce  the areas you mount them to. Its going to put stress on the body in different areas. For that matter,  stiffen the whole body anyways. Subframe connectors, fender well braces, strut tower braces, etc.

I wouldn't worry about the rear end holding up. They're plenty strong enough. I've been to plenty of track days and never once seen a Z break a diff.

Just so long as you're chopping up a base car and not an RT or a survivor I'll be all for it.

[Eifelcharger]

Thank you all for your thoughts, I knew this would be a controversial subject......

Anyway I spend my Easter the way it was meant to be.......in the workshop measuring and cutting.
The Z rear body mounts fall within the rear frame rails, this is something I had not expected, but it is very nice as it makes the mounting points look like they are factory fit.
The front ones will take a bit more fabricating but they are also in line with the front frame rails.
I plan to add reinforcements inside the boot to keep the old lady from tearing up 

The front suspension is a whole different story which will follow when the rear is done (I can always revert back to one of the ready made front sets)

[Eifelcharger]

Some images......

The part is not yet fixed and should be positioned a bit lower to match up with the original floor pan.

[Eifelcharger]

and another one

Yes I noticed that the fuel tank also needs a bit of modding to fit again ;-)

[RallyeMike]

Uncharted territory Very interesting. I'll be following along. Good luck!

[redmist]

Whats the Wheel mounting surface to Wheel mounting surface dimension on that rear setup??

[Eifelcharger]

Whats the Wheel mounting surface to Wheel mounting surface dimension on that rear setup??

Sorry, not sure.
Its close to original size.
Cannot check it now as the car is in a friends workshop 200miles away, might be able to measure the coming weekend.

Cheers

[Eifelcharger]

IRS conversion = the owner wants handling rather than drag racing.  The IRS's anti-squat & geometry limitations alone are enough to hurt the drag launch potential even if the differential wasn't weak.

Modern rear diffs tend to be using higher-quality metal in the gears to get away with a smaller diff.  They are often stronger than their size suggests to us old-schoolers.  



But yeah, the issue is something to watch out for.  Plenty of guys have put higher-quality metal gearsets into our original huge diffs just to keep them together.  

Some modern cars are actually electronically backing off the throttle at certain times to avoid over-stressing the drivetrain parts.  

Agree with you Mike,
I am not into drag racing and do not plan on doing lots of hole-shots which is the real killer for most diffs.
Handling, the occasional drift day and high speed stability is what I am looking for.
I live in Germany next to the holy unrestricted Autobahn, so I am more worried about the Diff temps at V-max and track usage.
May need to get a pump and cooler set-up from a EURO Nissan S13/14 to keep the guts alive 

[Mike DC]

Yeah you might. 



The placement of the ring & pinion gears has a big influence on much heat a differential produces.  When the pinion touches the ring at a lower place (closer to the ground) then the pinion teeth must be larger.  That means more friction, more strength, and more heat.  This is the big difference between the Mopar 8.75" rearend and the Ford 9" rear.  NASCAR racers always use big fluid pumps & coolers on their Ford 9" rearends.