Adjustable Rear Drop Link Attachment

[frankc]

Why does it appear that all the adjustable rear drop link products available (ER, Tarett, etc.) attach to the trailing arm at the spring plate eccentric bolt instead of using the OEM point of attachment found on the 78+ arms?

Is it because there are two types of trailing arms out there that used different types of drop link attachments (up to 77 w/ball & socket, 78+ w/bolt), and going with the spring plate attachment allows a common drop link to work with both types of arms?

Or is there some inherent advantage to going with the spring plate attachment, which looks weaker to me due to the cantilever, but it must be ok as I've never heard anyone complaining about the links failing due to this design.

Can I simply attach the adjustable links to the OEM position on the trailing arm (not using the eccentric nut)? Btw, I plan to use an OEM (non-adjustable) sway bar - I just want to eliminate the pre-load when corner balancing.

[Craig_D]

Hi Frankc, I did the exact upgrade you're talking about and for the same reason. Only difference is that I went to thicker Carrera sway bars on my '78 SC. You'll see in these pics that I just used the stock mounts on the banana arms and have had zero problems. It was a nice upgrade with no down side or ill side effects. You can see in a few shots that the stock end link from the Carrera sways was very...un-round!

Cheers,

- Craig_D

[frankc]

Craig_D,

Thank you - that's exactly what I was hoping I could do. I also went with larger Carrera bars (and later style trailing arms on my '77). Btw, are those the Tarett links?

Frank

[Chuck Moreland]

Originally Posted by frankc

Is it because there are two types of trailing arms out there that used different types of drop link attachments (up to 77 w/ball & socket, 78+ w/bolt), and going with the spring plate attachment allows a common drop link to work with both types of arms?

Yes

And yes you can attach directly to the 78-89 trailing arms with threaded mounting boss, just as Craig shows.

[Craig_D]

Hi Frank, glad I could help. Yes those are Tarett links. Sounds like we have a similar set up. The new links did a great job removing slop from transitions and turn-in. It's a great upgrade.

Cheers,

- Craig_D

[bkreigsr]

I've got that setup on my 85. I found that the heim joint was rubbing against the top knuckle, so I shimmed the bottom with some bronze phosphorous spacers form McMaster to get it to drop down vertical.
It looks like Craig has done the same, only he shimmed the top bolt.
Bill K

[Craig_D]

That is a good point Bill, and one I forgot to mention. I didn't like the clearance on the top, so I used some thick nickel coated washers on the top mount. I haven't had any issues with clearance since.

One other thing to do is to check the torque on all hardware after a few tank fill-ups. I had one side loosen up after a few hundred miles, so I retorqued them all and haven't had any problems for ~1000 miles of mountain use.

Cheers,

- Craig_D

[KTL]

If you wanna get fancy you can use rod end inserts that are designed to fit in the spherical bearing and space it away from the fixing point.

McMaster-Carr

[Craig_D]

I like that Kevin! I'm about to do a suspension refresh and will take a close look at those rod end inserts.

Thanks for the good tip (and link...no pun intended!)

- Craig_D

[frankc]

[I tried posting this once, but don't see it. Let me try again]

Perhaps it is because the suspension is unloaded in Craig's photo, but I don't see where the interference would be that requires spacers/inserts to be used. The new drop links are smaller in diameter where they attach than the OEM links, so I would think any interference issue would be improved with the new links. I'll look at where the links attach to the boss on the arms again tonight to see where the issue is.

[bkreigsr]

YMMV
I shimmed mine because I've gone through a few drop links (on different cars) as a result of binding somewhere on the bar/linkage.
I like the drop link as verticle as possible.
+1 on checking torque every-so-often. I usually find that there is some take-up available when I do my pre-track run-down.
Bill K

[GaryR]

Originally Posted by Chuck Moreland

Yes

And yes you can attach directly to the 78-89 trailing arms with threaded mounting boss, just as Craig shows.

Chuck, do you sell those style droplinks? I'd rather buy from you than someone else if possible.. I'm keeping stock sways on my hot rod, just upgraded the torsion bars slightly... and had the Bilsteins tweaked .. and put in RSR front spindles...

[Craig_D]

Originally Posted by frankc

[I tried posting this once, but don't see it. Let me try again]

Perhaps it is because the suspension is unloaded in Craig's photo, but I don't see where the interference would be that requires spacers/inserts to be used. The new drop links are smaller in diameter where they attach than the OEM links, so I would think any interference issue would be improved with the new links. I'll look at where the links attach to the boss on the arms again tonight to see where the issue is.

It's a little difficult to see but the top of the end link was very close to the mounting point on the trailing arm and I wanted to have a few extra mm of clearance for when the suspension moves through its range of motion.

I'll probably add these rod-end washer inserts: (Edit: this site doesn't direct to the actual product so click on the "Rod-End Inserts" and you'll see the "Washer Inserts": McMaster-Carr

Edit: I raised the car, and then put wooden supports under the wheels and lowered the car so that it was at stock height, but raised, so the suspension was actually loaded for this project. I've tried installing sway bar components on unloaded suspensions...tried..

Cheers,

- Craig_D

[universeman]

Sorry to kick such an old thread here...

I installed my Tarret drop links today, the sway bar seems too low and the links seem too extended. But this is where the holes lined up. Do I need to move it upward and move the links aftward, to raise the ground clearance? Any thoughts?

[Techno Duck]

Hard to tell from your picture but it looks like you have the threaded heim joint out all the way?

Thread the heim joint back in and push the end of the sway bar up to shorten it. You might need to loosen the center bushing clamp to get the bar to rotate.

[chrismorse]

I got the same washers from Pegasus. They are often referred to as "safety washers" and are required on some formula cars to prevent the joint from coming apart if there is a spherical bearing failure. Additionally the cone shaped protrusion on the washer allows more misalignment without binding - which is crucial for the bearing to live.

I used these washers to correct a misaligned and weak bar installation on my other car. The manufacturer used some thin aluminum tubeing for spacers. They weren't the correct length for proper geometry and they crushed and bellmouthed with very modest torque on the mounting bolt. The front link geometry was particularly tbad but the photos didn't come out very well.

I bought the adjustable drop links from chuck and a 85+ 18mm bar to replace the 74 stock rear bar, as well as 85+ rear spring plates to allow for height/cornerweighting adjustments.

Looking forward to finally getting the front done so I can drive the car!!! I'll do the rear overhaul later :-)

chris

[universeman]

Interesting. I got the joints tightened up and the bars sit much higher now. I did not use any fancy washers but maybe I should look into that.

Thanks for the help guys. Chrismorse, your clearance on your bars looks to be lower than mine were so I'm comfortable with where they ended up. You can see now that the helm joints are nearly tight - passenger side almost all the way; driver side a little longer due to preload adjustment.

Thanks!

[911pcars]

Reason why aftermarket sway bars use the control arm to mount the drop link.

IMHO, it's easier to manufacture straight sway bars then to introduce 90º bends on each end. The attachment point at the control arm is more direct.

In addition, aftermarket bars can use variable length arms to change the effective roll resistance. Can't do that with factory bars which are only available in a few sizes.

Sherwood

[winders]

Originally Posted by 911pcars

Reason why aftermarket sway bars use the control arm to mount the drop link.

IMHO, it's easier to manufacture straight sway bars then to introduce 90º bends on each end. The attachment point at the control arm is more direct.

In addition, aftermarket bars can use variable length arms to change the effective roll resistance. Can't do that with factory bars which are only available in a few sizes.

Sherwood

Actually, most of the rear aftermarket anti-roll bars I have seen want you to mount to the spring plates. That is true for Tarett and JWE (nee Smart Racing Products) anyway. The JWE folks say the geometry is better when using the spring plates too.

On my race car, I had to get special drop links from Tarett so I could use the trailing arm mounting method. Why did I use the trailing arm mount? Because my race car is quite low and the spring plate pivot point is raised quite a bit. The chassis longitudinal would get in the way and limit suspension travel. Not a good thing.

[911pcars]

Originally Posted by winders

Actually, most of the rear aftermarket anti-roll bars I have seen want you to mount to the spring plates. That is true for Tarett and JWE (nee Smart Racing Products) anyway. The JWE folks say the geometry is better when using the spring plates too.

On my race car, I had to get special drop links from Tarett so I could use the trailing arm mounting method. Why did I use the trailing arm mount? Because my race car is quite low and the spring plate pivot point is raised quite a bit. The chassis longitudinal would get in the way and limit suspension travel. Not a good thing.

Actually I agree. I meant the attachment point toward the rearward end of the spring plate where it clamps to the control (trailing) arm. Right rear spring plate shown.