51 replies to this topic

[Heath]

Is anyone running anything more exotic than a Panhard bar with the standard triangulated four link rear suspension setup? 

 

I want to see what's been done with 3 link setups, single piece top links, watts linkages and so on.

 

I am particularly interested in setups where the cars still retain the rear seats, but anything that improves on the standard setup is probably worth sharing.

[TerrA LX]

I was thinking of using a falcon hat on the B/W for a watts link but have not looked as far as locating it to the chassis (clearance to tank etc etc).

[Heath]

Yeah well I have a BW78 in my car already and I can tell you they have packaged that area TIGHT - there's no room behind the diff without changing the fuel tank arrangement and even the roll of the UC floor is very close. I personally am not afraid to change both of those things, though.

 

I feel that introducing a Watts Linkage to a car that has triangulated top arms is a bit of a misguided effort. The top arms are going to fight the lower roll centre of the Watts Linkage and sure it is going to have binding issues.

 

What I'm really interested in is better trailing arm configurations. I have a one or two ideas but I would be very interested in seeing others'.

Edited by Heath, 17 July 2015 - 04:49 PM.

[76lxhatch]

You hooked me with the title, but didn't deliver anything...!

I have one of the Falcon watts link hats and originally had that idea in mind but my diff (R31 Skyline) is nowhere near centred, I don't think any Borg Warner/BTR conversion would be so its non-starter in that configuration. I reckon it would be a nicer setup and easier to build a good frame between the chassis rails with minimum bulk (to clear tank/diff) if the ends were mounted on the diff instead anyway.

My pipe dream would be a 3 link with the watts link, if you turned the rear seat into a two seater (hatch seat basically is anyway) with an armrest in the middle you'd have room for the centre arm front mount. The arm could be shaped a bit and go up over the diff for maximum length, and the diff bracket could bolt to the rear cover face, perhaps with a brace at the pinion bearing area. Given the short length of the factory upper arms it wouldn't be too hard to make a worthwhile improvement, even if it were still a bit of a compromise.

[TerrA LX]

Some guys run a pan hard with one upper arm (for racing regs the other upper arm is in place, but the bushes are so soft to negate binding).

[TerrA LX]

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[hawk]

I have been thinking about this a lot myself as my UC sort of rolls to the side around corners with the pedders black shocks and lowered springs.

After a bit of reading I found a few things have been done. The most common are the adjustable arms and panhard rod. The member axistr has used similar to coil overs in his as well as the springs which I have a photo of below courtesy of his build thread.

Have you considered an irs setup? You might remember the silver UC at that autobarn show about 6 years ago that had irs.

My thoughts would be towards a custom subframe that uses a common centre like a commodore or skyline one with standard arms off another model car. Then use driveshafts that would best bring the track width as close to standard as possible. Then modify the shock towers to withstand coilovers.

Not sure if what I wrote makes sence and im no expert but surely it could be done.

Anyway something to think about.

Attached Files

•  post-393-0-14258700-1426741039.jpg   175.28K   8 downloads

[ls2lxhatch]

From this post
 

 

 
The above was probably inspired by the Clark Hopkins hatch.

Looks like the Clark Hopkins hatch may have been a UC.
 

 

 



 

 

Edited by ls2lxhatch, 17 July 2015 - 06:46 PM.

[TerrA LX]

I ran the factory swaybar that bolts to each lower arm which seems to stiiffen up lateral movement if there is anything in that.

 

The above photos are pretty full on and probably beyond any registered street car.

Edited by TerrA LX, 17 July 2015 - 07:01 PM.

[rodomo]

I have a vague memory that the F@4d hat doesn't bolt up to all BW diffs?

[TerrA LX]

Hey rob, howz your IRS conversion going?

[rodomo]

BzzzzzT!...................fail at the moment. Haven't touched it since I bought my house. Full on renos for the last 2 1/2 years.

[TerrA LX]

I know the feeling, it goes on for another 7yrs if you throw kids in the works.

[Bigfella237]

To say I've given this subject a little thought would be the understatement of the year, I more or less decided to go with a parallel centred 3-link with a screw-adjustable Watts Linkage (for roll centre adjustment), not using any of the factory mountings so as to fit the longest trailing arms possible.

 

An offset 3-link is a slightly better design because it will reduce torque-steer but I have to consider the packaging, I don't want to end up with a stripped-out two-seater race car with bar-work running everywhere. (I didn't draw this but it's close to what I was thinking)

 

 20131021_rear_susp.png   440.74K   9 downloads

 

The sway bar and Watts Link need to be mounted to the body not the diff, unsprung weight is something that needs to be reduced as much as possible, I even gave some thought to a dry sump system for the diff, that may sound weird but the diff oil accounts for a couple of extra kilos of unsprung weight, you'd have to remove a lot of metal to make up 2kg.

 

As 76lxhatch said in post #4, I'm pretty confident that a centre trailing arm to body mount can be made strong enough yet still retain two rear seats, the only load should be fore/aft as the Watts Link accounts for any lateral load?

 

You would need to relieve part of the floor pan above the diff centre to make room for the upper mount but that space is wasted below the false floor in a hatch anyway so no loss there. You'd also have to modify the boot floor / spare wheel hump (which means custom fuel tank) as well as adding a couple of extra cross-members between the rails for mounting points, but you should still get away with that without it becoming an ICV?

 

I'd want to incorporate a vertical screw adjuster to the body-end of the upper trailing arm instead of simply having a couple of holes though, this is the anti-squat adjustment and without a threaded adjuster you'd have to remove half the rear trim and have two people to fine tune.

 

 Top Link Remote Adjuster.jpg   4.58K   9 downloads

 

I've read good things about using a tuneable torque-box in the upper arm to absorb some of the shock-loads too.

 

 Top Link Torque Absorber.jpg   25.67K   6 downloads

 

Most of this comes from Ron Sutton's thread over on the Pro Touring Forum, well worth the read if you haven't already.

 

[Heath]

God that gunmetal car from NZ has a LOT of things going on that could really all deserve their own respective discussions. 

 

The high mounted 3rd arm is an interesting idea. Certainly must be tremendous for torsional loading on the diff. Not sure if I wanna compromise the rear seat with a thing down the middle but it is a logical suggestion.

 

On the internet it's easy to find kits for American cars (notably shitloads of F-bodies) where you can put a long arm down next to the tailshaft and it pivot it up near the back of the gearbox, although because this is also mounted low on the diff, it obviously doesn't pivot where it meets the diff - just has a static adjustment for pinion angle. 

 

Can anyone outline the basic disadvantages of this style vs what the gunmetal hatch has? Because it seems fairly employable and doesn't compromise interior space at all.

 

 

This is clearly a factory version:

[rodomo]

That's what they used to call a torque tube. Geminis had that set up........sorta

Edited by rodomo, 17 July 2015 - 10:31 PM.

[rodomo]

More: The bloke that balanced the tailshaft on the grease slapper told me that it was near impossible to balance a solid shaft that was going to experience more than 5000rpm.

Might be why F@4d went alloy?

Having said that, you might find that your UC shell has mounting points for a centre bearing as I believe the 4 cyl UC's had a split shaft for the RPM experienced for the 4 cyl engines.

[rodomo]

Ti dico solo che , hmm , prendo che indietro

[Heath]

Certainly does. The mounting point for that centre bearing is nowhere near substantial enough to mount the pivot point for a third link though. It just attaches onto the spreader plate for the inner seat mount I think.

 

Ford went alloy... tailshafts?

[rodomo]

Yes. Alloy tailshafts but still had problems. See if you can find a pic of a Gemini diff, the pinion housing was 600mm? long. Maybe look in Clints threads?

I was only referring to what the drive shaft builder had told me reguarding a centre bearing. I didn't mean for you to use the holes as a mount other than a centre bearing mount.

Other OLD cars used torque tubes. Chrysler??

[Heath]

Alright here's an idea. Have to cut the boot floor a little for clearance for the balljoint hanging off the arse, might make exhaust clearance a bit tighter... doesn't affect the back seat at all. I've drawn bushes but it would need Heim joints to avoid binding.

 

Excuse the hand drawn sketch, I'm not really proficient enough with CAD to draw bent tube haha

 

 Rear End Sketch.jpg   161.64K   5 downloads

[UCgazman]

This help Rob? - http://www.gmh-toran...unting-designs/

[ls2lxhatch]

RRS in Sydney have been making bolt in three link setup for Fords for years.

 

http://www.rrs-onlin...-am-3-link.html