Adjustable Rear Drop Link Attachment

[Techno Duck]

Pelican also has a tech article with some good pictures about hardware order. I was a bit confused with the Tarrets because they have no instructions of any kind, i noticed the heim joint was at a pretty extreme angle without using the eccentric spacer provided when bolting to the trailing arm. My confusion was that spacer is used for installing on the spring plate, but also used for connecting to the trailing arm.

I plan to connect the sway bar to the spring plate when i overhaul the suspension in a few months.

Pelican Technical Article - Porsche 911 (1965-1989) - Standard and Adjustable Drop Link Replacement

[universeman]

Thanks Techno Duck. Below you can see what my shot stock drop links looked like. One had been struck on the road, I believe.




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[Busta Rib]

Reviving an old thread...is there a drop link solution for 77 and older cars that have the old-school ball & socket connection for the rear sway bar? I purchased thicker after-market sway bars and the rear bar did not come with drop links. Thanks in advance for any advice.

Jim

[Robind]

Originally Posted by Busta Rib

Reviving an old thread...is there a drop link solution for 77 and older cars that have the old-school ball & socket connection for the rear sway bar? I purchased thicker after-market sway bars and the rear bar did not come with drop links. Thanks in advance for any advice.

Jim

+1 can the ball be modified to take bolt on drop links, could it be tapped to take a bolt? I don’t really want to change to later Ali arms especially as our 75 versions have just been refurbished

[Mahler9th]

I studied this problem a bit. No one I know of has ever removed or modified those ball connections.

One company used to sell some adjustable drop links designed for this application: TRG. Their concept is shown in the pix below. Designed to use the factory plastic cups to snap around the balls.






I do not think these are available any longer, but you get the idea. Easily replicated with some rod ends, jam nuts, alu, and drill and tap.

I decided to fab up something on my own. I bought some appropriate rod ends. And I bought some metal shaft collars (with set screws) from McMaster Carr. Their ID is virtually the same as the ID of the early-style fixed factory fixed drop links (into which the plastic cups are pressed). I drilled out and tapped the collars for a larger metric stud that matches the rod ends. I made the studs out of bolts (cut off their heads). Then I screwed the studs into the collars and had them welded in place.

So the result is a rod end that attaches to the bar, and an opposite end that uses the factory plastic bushing cups that snap over the trailing arm balls.

I have one of the excellent Tarett rear ARBs.

See picture below.



I have not yet completely tested this arrangement-- just a few laps in September and October at Sears Point. I think it will work fine. Of course it is very important to make sure that whatever you fab up cannot behind in the range of travel you need. Binding = bad news.

[Robind]

Thanks Mike that looks great, do you think you could drill and tap the arm?

[Mahler9th]

You are welcome.

I cannot any longer recall my exact process of inquiry regarding the modification of those balls, but it is likely I asked folks with vast street and race car experience, including those with IMSA and Porsche factory race team experience. I think those ball inserts are somehow glued in, and even if you cut them off, there is not enough remaining material there for a simple drill and tap. So I think you'd have to glue or weld in some material to drill and tap.

I should note that in my application, which is a very low race car, using the spring plates may not provide enough clearance, but I have not made confirmation. I decided to go for the arms first. I need to confirm my solution works and doesn't bind through the range of travel.

For the vast majority of applications out there, the spring plate attachment point makes sense. I am pretty sure that SRP/JWE (Watkins and Woods) did actual engineering work to support their design efforts-- check out their instruction books for more perspective. The way that their drop link set up is designed is very clever and well-sorted.

The Tarett rear ARB design (which I have installed recently) is sorted out with similar attention to detail.

The Tarett drop links are available separately and I have been told that they work very well. And they can be used with later-style factory bars. And of course you can create extra holes in these later-style bars for some adjustability (I just sold such a bar earlier this year).

One thing that folks need to ensure with the spring plate attachment point is that the fasteners are properly torqued and secured. It is well known that the fasteners for toe and camber can get loose under a variety of circumstances, and when that happens, the height drops, the rear goes to max negative and toe out. None of these things are likely good for handling.

[chrismorse]

Originally Posted by Mahler9th

You are welcome.

I cannot any longer recall my exact process of inquiry regarding the modification of those balls, but it is likely I asked folks with vast street and race car experience, including those with IMSA and Porsche factory race team experience. I think those ball inserts are somehow glued in, and even if you cut them off, there is not enough remaining material there for a simple drill and tap. So I think you'd have to glue or weld in some material to drill and tap.

I should note that in my application, which is a very low race car, using the spring plates may not provide enough clearance, but I have not made confirmation. I decided to go for the arms first. I need to confirm my solution works and doesn't bind through the range of travel.

For the vast majority of applications out there, the spring plate attachment point makes sense. I am pretty sure that SRP/JWE (Watkins and Woods) did actual engineering work to support their design efforts-- check out their instruction books for more perspective. The way that their drop link set up is designed is very clever and well-sorted.

The Tarett rear ARB design (which I have installed recently) is sorted out with similar attention to detail.

The Tarett drop links are available separately and I have been told that they work very well. And they can be used with later-style factory bars. And of course you can create extra holes in these later-style bars for some adjustability (I just sold such a bar earlier this year).

One thing that folks need to ensure with the spring plate attachment point is that the fasteners are properly torqued and secured. It is well known that the fasteners for toe and camber can get loose under a variety of circumstances, and when that happens, the height drops, the rear goes to max negative and toe out. None of these things are likely good for handling.

I was fortunate enough to start out with 20/18 Carrera bars on dad's car, so, I bought an 85 18 mm rear bar, chucks drop links and am also planning on drilling a few adjustment holes in the bar arms, for adjustability.
I have only cornerweighted one car, (77 308 Ferrari - see earlier pics of rear bar links), and decided to do what I could to facilitate getting dad's car "right".
I just purchases a set of used sway away adjustable spring plates to offer easier height adj.
If you drive in the wet, I recommend having the female rod end in the dominant position to avoid filling her up with water. Please, please do not misconstrue my ranting for sexist inclination. Perish the thought.
Juggling "safety washers" and regular washers is a good way to get the lateral link alignment near vertical.

Cheers,
Chris

[3Ddesigns911]

My car is an 87 so these links are a direct fit for me, but we had to use a couple of washers on top and also did not need the eccentric spacers that were included.

[douglas bray]

Good luck drilling new holes in the Carrera bars. I gave it my best shot on my milling machine and broke several tools. Gave up and got an Eibach 25mm hollow rear bar. I think I was customer #1 as they have since emailed me and told me the real hardware is now in stock. Killer bar for dirt cheap.