ajm8127

iTrader: (8)

I am trying to figure out what the diameter of the hole is in the LCA that receives the ball joint. If anyone knows this information off-hand, or has an LCA that they could measure with calipers, I'd be grateful. I am only interested in the 4th gen LCAs. Thanks.

jac121479

iTrader: (10)

i have an old ball joint i can measure. it pressed out really really tight so the measurement should be within a thousandth. i'll check it out tomorrow.

ajm8127

iTrader: (8)

Thanks. I actually went to Advance Auto and got the guy to give me a Moog K9818 to measure. The diameter of the ball joint where it presses into the LCA is 41.08mm according to my Mitutoyo calipers. One thing I didn't measure is the distance from the flange on the bottom to the lower edge of the snap ring groove. If you could come up with that dimension for me that would be awesome.

You are really enjoying that panhard rod, huh?

jac121479

iTrader: (10)

i'll get it for you. and yes, the panhard was an awesome investment. in my opinion this mod is just as important as an LSD. huge difference man.

jac121479

iTrader: (10)

it's .46" to the bottom of the retaining ring groove and the ring grooves gap is .09".

ajm8127

iTrader: (8)

Thanks for taking those measurements.

jac121479

iTrader: (10)

no problem man. you looking into compatible roll center adjusters? i've been looking at Moon Face ones for a 240sx. need the tapered neck measurements from my Maxima one but need to get a hold of calipers.

ajm8127

iTrader: (8)

I'm actually designing a bushing that can be pressed and welded into the LCA to accept a spherical bearing. That way you can run a regular bolt and spacers to adjust roll center once the knuckle taper is bored to a straight hole. The inboard mounting points to the chassis won't be adjustable (for caster and camber) but that's not what this is designed to do.

jac121479

iTrader: (10)

you've probably already seen it but here's a link similar to what you described. may have some helpful info.

http://zilvia.net

ajm8127

iTrader: (8)

Post 17 is exactly what I'm trying to accomplish.

jac121479

iTrader: (10)

it's a great idea but i've been trying to figure out how you keep the spherical in place. wouldn't it eventually be able to work it's way up or down?

ajm8127

iTrader: (8)

The part is designed so that there is a lip of steel at the top that holds the bearing in place. On the bottom, there will be a snap ring. The majority of the force on the bearing is side to side or front to back. The up and down force is relatively small and consists of mostly of trying to get the other wheel to the same position through the sway bar.

98SEBlackMax

iTrader: (9)

You would have to machine a steel bushing with a big enough lip in it to accept a spherical bearing and hold the weight. Not that hard if you have a decent lathe and the patience to work that kind of steel.

This would provide a nice non adjustable way to correct roll center without having a rod end holding up the wheel hub. I would make the modified control arm slightly longer than stock to get a little more negative camber. You could also replace the front LCA bushing with a rod end on the control arm to get some caster/camber adjustability.

Combine that with 0.5" ~ 1.0" engine/trans spacers, tie rods with bumpsteer adjustment, and a panhard rod rear suspension to make a much better handling car. It would make aftermarket springs much more effective by reducing the front/rear roll couple and you could run softer springs and still get decent handling.

jac121479

iTrader: (10)

i wouldn't say the rod end holds up anything other than itself. the rod end along with the hub go where the spring/strut tells it to go.

98SEBlackMax

iTrader: (9)

Just a manner of speech.

Matt pointed out in another thread that you don't want to use a rod end on that part of a street driven car. It puts a large amount of stress on the stud portion of the rod end. Potholes being the worst problem and the roads up here are so horrible, I like the idea of a spherical/ball stud/steel bushing. As long as the welds of the bushing to the control arm are good enough.

This was also the concern of the guy working on those ALCAs for me, using a rod end on the outer part of an LCA is a bad idea. I didn't believe him until Matt mentioned it.

jac121479

iTrader: (10)

it makes sense. i've decided i'm not lowering even after coilover. these cars just weren't meant to be low and there's no correct and easy way to do it.

98SEBlackMax

iTrader: (9)

I found running a 0.5"~1.0" drop was the best comprimise with the GC coilovers and the spring rates I have that are good for the street/track. I was running 0.5" drop last year and noticed worse handling, so this year I will go back to a 1.0" drop and see how it goes.

Also if I get my rear suspension switched over to a panhard rod setup I will see if the guys at 2J racing will make the spacers to drop the engine/transmission on my car. IIRC they lowered the VQ35 a couple inches on their B15 track car, I am looking to lower it about 0.5"~1.0" from the stock height. This will lower the CG without changing the front roll center and reduce the roll couple. I was also wondering if they could fab up a front under tray/splitter as well.

It is to bad we are coming up with this suspension stuff now and not 10 years ago when the 4th gen still mattered.

ajm8127

iTrader: (8)

That's clever. They always say use the crankshaft as an estimated height for front CG.

The 4th gen matters to me!

I am getting the parts professionally machined. We deal with a company at work that does all of our small run prototype stuff. The owner is supposed to deliver some parts soon. I'm waiting for him to drop by so I can get a quote.

If this works out I'll post up a mechanical drawing of the part so that it can be reproduced by any competent machine shop or shade tree machinist with a lathe.

ajm8127

iTrader: (8)

I talked to the machinist today and he was saying that for four parts, he could do $50/part. Once he realized that this was a personal project and not affiliated with my job, he said he could give me a better price. I plan on using ASTM A513 DOM 1.875x1.125x0.375" tubing and having the bushing turned from that.

Based on the machining, sphericals, and odds and ends, it looks like this will be about $250 in parts.

aackshun

iTrader: (3)

Soooo.... Where did this get off to?

ajm8127

iTrader: (8)

The steel is at the machinist. He got some rush work in that takes precedent.

ajm8127

iTrader: (8)

I've got parts.



Now I just need a set of LCAs and I can weld these in.

aackshun

iTrader: (3)

Bump!

ajm8127

iTrader: (8)

I just got the rod ends I need for the tie rods. Have to change where the tie rod mounts to the knuckle if I am going to change the angle of the LCA. I needed FK's SJM10T and Summit had them, but they were back ordered. Anyway, I got them, so I will start taking the final preparation steps to make sure the install goes as smooth as possible. Life is busy so work is a little slow on this project.

ajm8127

iTrader: (8)

Has anyone ever taken the necessary measurements to calculate the roll center of the front of an A32? I think I know the answer to this but I figured I'd ask anyway.

ajm8127

iTrader: (8)

I did a little work on my project tonight. I need to move the tie rod end to the underside of the knuckle to have any chance of getting my bump steer as close to zero as possible. To do this, I am using male rod ends threaded into tubes that I will weld to the inner tie rods.



I am using a 5/8-18 tap. The tubing is DOM HSS. I taped a brake cleaner straw to the tube parallel to its axis as a point of reference so I could drill it to the proper diameter and then thread it. Without the tube, It's much harder to get the drill bit and tap square to the tube.



Here's the result. Those are 5/8-18 grade 8 bolts with a special corrosion resistant coating. It's supposed to be able to withstand salt spray for five time longer than the typical zinc chromate coating on grade 8 bolts. I'm not sure if I'll be able to use the conical spacer between the rod end and the knuckle. I'll have to wait and see how the bump steer works out.

The plan is to put all of this stuff on this weekend. I'm excited. Not only will the roll center be raised and the roll couple reduced, but the roll axis will be less sloped downward towards the front, which should help further reduce under steer.

ajm8127

iTrader: (8)

So I got the car on the road last night. The delay was due mostly to me not being productive Sunday due to something called "Hillbilly Beer Bash" my friend threw Saturday night. Here are some pictures.










I ran into a few unforeseen problems. First, it was difficult to bolt the knuckle to the strut. The guys who have done this before have coil overs, which makes it easy to adjust the free length of the strut. I have Eibachs. I had to get the bottom bolt in first, then use a jack to raise the hub until I could get the upper bolt in. Second, I had some rubbing between the LCA and the brake disc. Because the bolt connecting the knuckle to the LCA is angled, putting in the spacer moved the bottom of the knuckle a little closer the the LCA. I had to grind a little bit of material from the LCA to get the discs to clear.

As far as how it drives, there is definitely less roll, so I view it as a success. It turns in considerable better. My mouth was agape the first time a turned the wheel at any kind of speed. I haven't come close to pushing it, but under steer feels reduced. That could be a number of things from teh roll center axis to the better camber curves as the suspension compresses. Over all, I would do it again.

The rear still rolls way to much, but that's a project for next year, after I get the SFCs installed.

aackshun

iTrader: (3)

I want some!

ajm8127

iTrader: (8)

I actually have three bushings left over because when you get parts machined, there is always a large initial cost and then adding additional pieces causes the per piece cost to drop rapidly. So I got five done.

This is the snap ring I used. The spherical bearings are NHBB ABWT12.

aackshun

iTrader: (3)

Sooo I Can Has

ygpm

98SEBlackMax

iTrader: (9)

Nice work!

Looks like you lowered the roll center about an inch? That should help in alot of ways as long as it clears the brake rotors and your cars' rims. Combine that with a panhard rear end and it will be a great handling car.

My only concern is that if you ever get a BBK you may not be able to fit this piece as you already have to grind the LCA to clear the stock rotors. But people are willing to get more creative with the A32, so who knows what is possible anymore.

ajm8127

iTrader: (8)

There is a conical spacer and a cylindrical spacer that add up to about 1.5 inches. This actually raises the roll center. I never took measurements to know exactly how this affected the position of the roll center, but it should be close to stock considering the 1.7 inch drop of Eibachs in the front.

There is still ample clearance on my 17 inch rims for more roll center raising. I could always used a thin spacer between the hub and the rotor for a BBK. I am reluctant to do that, though, because I want to be able to fit my stock 16s with snow tires for winter. The stock size disc with stock calipers and Hawk HPS pads are fine for now. I don't do any road course racing.

98SEBlackMax

iTrader: (9)

I forgot roll center gets raised when you make the ball joint pivot point lower.

That was the other questions I had if you were on lowering springs and your on the Eibachs.

You might be able to have a few more sets made&sold for those who want to correct their front roll center.

jac121479

iTrader: (10)

well done Sir. i'll definitely consider this for the future.

sergofast

iTrader: (22)

Did you custom make these as well or get them from a place like mcmasters?

jac121479

iTrader: (10)

i'm sure your leftovers are already spoken for so how much would your fabricator charge to run another batch of these? do you have a phone number for them and maybe a point of contact for this specific part? do they take orders over the phone? also, where did you get your bolt/tapered sleeve set up from. do you have p/n? sorry for all the questions.

ajm8127

iTrader: (8)

I used this and a hack saw.

[EDIT] If you meant the conical spacer, I got those here. They are sold in pairs.

ajm8127

iTrader: (8)

I can speak to the machinist and see how much more would be. I'd expect 40-50/ea. for a batch of four. It might be cheaper per part for a larger batch, but either way I would need money up front. I think I have enough raw material left to make four more bushings, but I am not positive.

I used Atomatic Manufacturing and dealt with the president (owner?), John. If you mention Tony from Qinetiq he should know what you are talking about. He did ask for a bearing to use while machining so they they could ensure a tight slip fit for the bearing into each bushing. The bearings are expensive (50/ea.) and I don't have any more.

The bolt is from McMaster, and check the post above for info on the spacers between the LCA and knuckle. I used a 4.5 inch bolt* and it fit the nut perfectly with a 1 inch spacer. I'd recommend a larger spacer than 1 inch, however, because right now my LCAs sit level. I orded 4.5 and 5 inch bolts, and am going to experiment with a 1.5 inch spacer soon.

*EDIT: Revised the length of the bolt used from 4 inches to the correct length of 4.5 inches.

sergofast

iTrader: (22)

That's really interesting. I would like to know what the largest spacer you can use with the stock 16" rims.

I do have a question. Because you are angling the control arm down with the spacer does it pull the wheel in and decrease the amount of camber? Say if you don't have camber plates and are running eibach springs, so a mild drop.

jac121479

iTrader: (10)

short answer, yes.