Suspension Adjustments and Modifications to the "R" Based on Subaru Donor Parts

[Scargo]

I've seen some info which I thought was very informative and felt like it needed to be here. Please add your own!

Jim Schenck emailed to Plavan:


Originally Posted by C.Plavan
"Chad,

Sorry for the delay here.
The low ride height is something we designed into the chassis to allow for building a dedicated track car only that you are willing to compromise any street use as well as things like trailer and lift access. The standard donor package still assumes the higher ride height so there is some sourcing of parts needed to do the low ride height.

What you need if you want to run the lower ride height (not recommended for street use) This ride height is also only set up for Sedan control arms.

Move the upper control arm to the top of the chassis and put 4 .815 spacers in the old arm mounting locations to strengthen the new mounting location. Longer bolts will be needed to mount the arms on the top.
Mount the front lower control arms in the upper set of holes on the front mounts.
For the rear bushing mount on the control arm the inner mount bolt should be spaced up by .875 and the outer bolt should be mounted on top of the plate with a .400 spacer as a starting point. The height of the rear mount can be raised if you would like to dial anti-dive into the chassis as a tuning tool.
Running the low ride height requires the use of a bumpsteer kit because the steering rack stays in the same chassis location. We used the Baer kit but drilled out the spindles and replaced the tapered shaft with a longer bolt for more adjustment.

In the rear the low ride height mounts will only work with adjustable control arms. The easiest and intended set-up is to use 13 inch long swaged tubes with 3/4 shank rod ends that have 5/8 holes. We then drilled the rear spindles out just a hair to allow us to use the standard size rod ends and a 5/8 cross bolt.

Hopefully that gets you started in the right direction, there is lots of adjustment that can be done and when you are ready I can also give you our baseline setting to start out from if that helps.

Jim"



I thought the part "In the rear the low ride height mounts will only work with adjustable control arms. The easiest and intended set-up is to use 13 inch long swaged tubes with 3/4 shank rod ends that have 5/8 holes. We then drilled the rear spindles out just a hair to allow us to use the standard size rod ends and a 5/8 cross bolt." to be particularly helpful.

[Bill Waters]

Thanks, Scargo.

Wayne has the control arms (per Wayne, "lateral link" and "toe link" - one each per side). They are nice. Reasonable price.

Bill

[nuisance]

Thanks, Scargo, we need to start gathering this information here.

Also note that the LCAs from the wagon will not work at the lower ride height. I have ordered the set from Wayne.

I am not comfortable with the front UCAs hanging off the bolts as suggested, and I am going to weld another plate on top to hold them. I will post pics as soon as I can get to it (still dismantling the donor now).

John

[Rasmus]

I am not comfortable with the front UCAs hanging off the bolts as suggested, and I am going to weld another plate on top to hold them.

I understand your concern. Ideally, all suspension pick up points should be in double shear. But before you go and give yourself a heep of work, consider that many production cars running double a-arms, mount the upper arm in single shear.


I know for a fact that my 6000lb 1968 Cadillac upper a-arm is in single shear.

[D Clary]

The lower control arms take a greater load than the upper, and since the rear suspension is mostly single shear I would not be concerned.

[Bill Waters]

I wouldn't, either. One of the benefits of double-shear mounting in most applications is to fortify the two (relatively) frail tabs into one very strong piece through the unifying clamp force exerted on the piece being mounted (as in a coil-over shock). In the front upper control arm application on the 818, that is exactly what is happening - it's just that the clamped piece is on the outside of the unified pieces in this application, and both tabs are unified by the spacer which is in serious compression, creating the single structure.

[Rasmus]

Running the low ride height requires the use of a bumpsteer kit because the steering rack stays in the same chassis location. We used the Baer kit but drilled out the spindles and replaced the tapered shaft with a longer bolt for more adjustment.

I know I read it here on the forum once, but now I can't find it. How far down do you mount a bump steer kit to eliminate the most bump steer when mounting the suspension at R height?

[C.Plavan]

Per Jim on the R bumpsteer spacers for the Baer Kit

"Spacers were 2-7/16 in the front. That give just a little roll toe-out which is what I like to see in the front. (you can also dial in a little bit of roll toe-in to the rear by adjusting the length of the upper trailing arm)"

[Rasmus]

Thanks Chad.

If 2-7/16" is the recommended spacer length for the Baer links what's the width of the Baer spherical rod end? In other words, what's the distance from the bottom of the steering arm to the center of the ball. What's the distance to the pivot point?

I ask because I'm thinking about making my own tie rods. Knowing the rod end I go with will probably be a different width than the Baer supplied unit will make the spacer's link vary.


I'm looking for the "C" dimension.

[Bill Waters]

I have a new-in-the-package Baer bump steer kit, Rasmus, so I will do my best to get it measured for you. I have to be away tomorrow, so someone may beat me to it.

[C.Plavan]

I just finished the Baer bumpsteer install and guide. I'll post it in a separate thread here titled "818R Baer Bumpsteer Install/Guide".

Rasmus- .75 is the measurement you are looking for (C).

[Scargo]

I'm looking at custom tubes and spherical rod ends (AKA Heim joints) for all of my R rear suspension. Rasmus and I have touched on it in his thread, starting about here.
I have looked at 1 inch swaged aluminum tubes (using 5/8" threads) for use in the rear suspension. Are they going to be strong enough for lateral links and trailing arms, etc? I have calculated that I can save well over a pound in partially unsprung weight by using these aluminum tubes for lateral links alone. Do I need to use 3/4" ends?
With 1" OD X .058" wall chromoly tubing and weld-in chromolly threaded 5/8"ends, I would save only one ounce per 17 inch tube (AFCO 17" swaged steel tube that comes with the 818). BTW, the cost would be about 4X.

Some sources say spherical ends/Heim joints can be had with grease fittings. Does anyone feel this is a plus? How do you lube yours? Are there good, better, best joints? I sure like the idea of chromoly ones. Especially after seeing one of my 3/4" diameter ones get bent in my STi.
I'm hoping for some input from sports racer types who know what works.

[Racebrewer]

I have seen Heims with grease fittings break and come apart where the grease fitting threaded hole is located. Having said that, it could have been a wear and tear issue and the Heims may have been way over due for replacement. Don't know, just had to clean up the mess in turn one at Bryar years ago.

John

[Rasmus]

I know that the static load rating of rod ends with grease fittings are always substantially less than the same rod ends without.

[nuisance]

So I did it anyway. I do respect all you guys and your opinions, but when I had to drill the holes out to 5/8" because the spacing was off in the frame, I felt like that was too much slop, and I went ahead and made a top plate and welded it in.

uca bracket.jpg

Next will be the front lower control arms. Now that they have such big spacers (.812" for the bottom one) single shear is making me uneasy. Will post a picture.
John

[nuisance]

I am still on the anti-cantilever bolt campaign (I don't call it single shear with the spacers). These perches are OK when you're running street ride height, but throw in such thick spacers, and I see problems. So, I added some more bracing. Also, the lower perches have no triangulation to speak of, I imagine that is what led SixStar to do his welding.

If I had it to do again, I would use an 1 1/4" square tube across the front, and space the upper braces up, so I could adjust things a little with washers. Too late now though.

John

bracing 2.jpgbracing 1.jpg

[Scargo]

With the effort you made to fix a problem, I am puzzled as to why you didn't just put the mount in the right place and eliminate the spacer. I do not like things cantilevered for racing, either.

[nuisance]

To cut the old mounts off, build new ones and weld them on would have been much more work. Spacers are easy, and they can be changed to play with anti-dive etc.