Group buy: Front Lower Spherical Bearing Shells

[zok15]

Would the flat spacers help you with the stock steering shaft fitting better? I imagine you would only need spacers half the height of your tall front misalignment spacers (vs the shorter rear ones) to get the front LCA pivot dropped the same value.

[The Dark Side of Will]

With the wedges I aimed for an arbitrary 1" at the axle centerline to see how well that worked. It worked great. I'll go for flat spacers 1" thick. That will still stretch the steering shaft. I have seen nesting D-tubes intended to make collapsible steering shafts... I'll see if I can assemble something easily reproducible.

[pmbrunelle]

The spherical bearing shells are now installed in my Fiero's LCAs.

The tool works pretty much as it should. I wouldn't change it. I was able to install/uninstall bearings with the force available from a 4" bench vise.

Axial dimensions of the shells and spacers are good. I wouldn't change those.

The outside diameters of the shells fit my LCAs fine. Not too loose, but easy to slide in. I would leave those alone.

I think there are some points which could be improved:

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I got my LCAs (and bearing shells, but not the bores) painted with POR-15:

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I had spent much of this week's evenings with a woman I met, so I didn't have the time to paint the LCAs as planned to follow my car assembly schedule to get my Fiero ready for an upcoming road trip.

Last night was my third date with this woman; after dinner, we each painted an LCA in my basement. That was pretty cool to meet romantic and car project objectives in one go. She was good at meeting (exceeding) my painting specification for the LCAs.

I think she unlocked a cheat code in getting me to like her

[The Dark Side of Will]

Ask @Series8217 about his first date with his now wife!

Just curious, but were you using an app or did you find her in the real world?

Wall thickness of the seal bore under the weld:
I had some issues with this in my installation as well. It's a compromise. Once I measure the eccentricity required by the '84-'87 front suspension, I may be able to find a seal that can tolerate that amount of eccentricity. And yes, it is more convenient--and cheaper--to use the same part for early and '88 cars, especially since that's what GM did as well.

Bearing tool guide taper/chamfer:
I see your point and I could add that to the next batch.

Radius on ends of weld journals:
I could do that as well. (Is the wall too thin or not? LOL)

Lead-in chamfer for bearing installation:
My drawing specifies a 45 degree lead-in chamfer, but the ID of the clearance bore on the outboard side of the snap ring groove limits how large the chamfer can be and be effective. The snap ring doesn't need support on that side, so I *could* have the chamfer take out some of the wall of the snap ring groove. There is a small (I think 45 degree) lead-in chamfer on the OD of the bearing race as well. Did you have any problems starting the bearings straight?

The interference fit with the bearing diameter is not very large, the preload torque for the installed bearing being the eventual metric for the "right" interference.

[pmbrunelle]

Spherical bearings:

I finally installed the bearings into the '84-'87 rear control arms I had welded and powder coated
Here's one with the snap ring that retains it. The press fit is rather light in order to keep the preload torque in a range that it reasonable for a suspension pivot. Most of these are in the 30-40 inlbs range. The bearings are easily installed with a bench vice and the installation tool I designed.
Yes, there is a gap between the tips of the snap ring and the ball. However, that doesn't really matter much, since these bearings won't see any misalignment. The worst that could happen would be that the snap ring lobes would score the ball a tiny bit, but that part of the ball would never be under the race, so meh.

The snap ring is punched from a sheet of metal. When punching, the cut-out part (just like a typical washer) has a side with sharp edges, and a side with rounded edges.

With the supplied Rotor Clip stainless steel snap ring, installed rounded-edges towards the bearing, there was more than adequate clearance between the snap ring ears and the ball.

For the '84-'87 cars, both bushings are installed from the front. I designed the shoulders against which the spherical bearings seat to be forward so that they, rather than the snap rings, would take brake loads. The '88's (and '84-'87 rears) install one from each direction and it just happened that direction means installing the bearings from the inside. It's not a big deal at all... I'd call it a non-issue as installing the bearings is very easy no matter which way they go.

Looking at the front of my Fiero's RH LCA:

Snap Ring Visible.jpg (357.52 KiB) Viewed 1329 times

Due to the differing diameters on the OD, there was only one orientation possible when inserting the shell into the LCA. For both pivots, the snap ring is visible at the front. This means that braking loads are taken up by the snap ring. I would prefer if the shoulder and snap ring were flipped around...

Lead-in chamfer for bearing installation:
My drawing specifies a 45 degree lead-in chamfer, but the ID of the clearance bore on the outboard side of the snap ring groove limits how large the chamfer can be and be effective. The snap ring doesn't need support on that side, so I *could* have the chamfer take out some of the wall of the snap ring groove. There is a small (I think 45 degree) lead-in chamfer on the OD of the bearing race as well. Did you have any problems starting the bearings straight?

I had no problems getting the bearings pressed in straight. It's just that the force was a bit high (perhaps twice the steady-state pressing force) to get the press-fit started. This point is more of a suggested refinement; it's not a real problem.

Just curious, but were you using an app or did you find her in the real world?

I was using an app (Facebook Rencontres).

I think it is good to diversify one's dating strategy, so I was also chatting up people in the real world whenever I could, but in this case I found this person via the app.

I doubt I would have crossed paths with her in the real world, despite her living just a 10-minute walk from my workplace.

[pmbrunelle]

Here is a photo I took of the most misaligned pivot (viewed in the direction that most accentuates the misalignment). By tracing lines on top of the image, I should be able to figure out the misalignment angle.

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As a reminder, my Fiero is mostly stock, but its forward LCA pivot has been dropped down 3/8". This is not much different than a stock Fiero, so I think this data point remains representative.

[The Dark Side of Will]

For the '84-'87 cars, both bushings are installed from the front. I designed the shoulders against which the spherical bearings seat to be forward so that they, rather than the snap rings, would take brake loads. The '88's (and '84-'87 rears) install one from each direction and it just happened that direction means installing the bearings from the inside. It's not a big deal at all... I'd call it a non-issue as installing the bearings is very easy no matter which way they go.

Looking at the front of my Fiero's RH LCA:
Snap Ring Visible.jpg

Due to the differing diameters on the OD, there was only one orientation possible when inserting the shell into the LCA. For both pivots, the snap ring is visible at the front. This means that braking loads are taken up by the snap ring. I would prefer if the shoulder and snap ring were flipped around...

Well fudge... did I have that completely backwards in my head? That's definitely an improvement to make for the next revision.

Just curious, but were you using an app or did you find her in the real world?

I was using an app (Facebook Rencontres).

I think it is good to diversify one's dating strategy, so I was also chatting up people in the real world whenever I could, but in this case I found this person via the app.

I doubt I would have crossed paths with her in the real world, despite her living just a 10-minute walk from my workplace.

Awesomesauce, man! You really lucked out

[The Dark Side of Will]

Here is a photo I took of the most misaligned pivot (viewed in the direction that most accentuates the misalignment). By tracing lines on top of the image, I should be able to figure out the misalignment angle.

Misalignment.jpg

As a reminder, my Fiero is mostly stock, but its forward LCA pivot has been dropped down 3/8". This is not much different than a stock Fiero, so I think this data point remains representative.

The seals I was looking at specified eccentricity in inches/mm. The angle can translate to that, but the linear dimension is what will be needed to make that work.

[The Dark Side of Will]

I'm setting up for the next batch, which means revising the drawing. Time to incorporate this great feedback.

For some reason, I had it in my head that the OE bushings installed from the front. This doesn't make sense, because braking force would tend to unseat the bushings from the control arms. Actually measuring the control arms (again!) makes it clear that the OE bushings are installed from the rear. Thus braking loads tend to seat them more firmly in the control arms. D-Ohh.

1. Correct orientation of bearing seat relative to control arm
2. Lead in chamfer for removal tool access
3. External radius for paint adhesion
4. Lead in chamfer for bearing installation(?)

I have a lead in chamfer in the bearing bore specified at 45 degrees, but only out to the ID of the bore "outside" of the bearing bore. The difference is minimal, so the chamfer is minimal. You're thinking a shallower 20 degree chamfer. You are thinking in the sense that the axial dimension of the chamfer will be greater than the radial dimension?

[pmbrunelle]

I have a lead in chamfer in the bearing bore specified at 45 degrees, but only out to the ID of the bore "outside" of the bearing bore.

Technically, if you want to spec the chamfer large enough to ensure that there always will be a chamfer (very small chamfers may not appear in the final part), the chamfer could go out to a slightly bigger diameter than the bore "outside" of the bearing bore, as the snap ring is never pushed in the direction where it would have to bear against the chamfered face. But, this is a detail; I'll leave this area to your discretion!

You are thinking in the sense that the axial dimension of the chamfer will be greater than the radial dimension?

Correct, that is what I meant.

[Jalisurr]

For some reason, I had it in my head that the OE bushings installed from the front. This doesn't make sense, because braking force would tend to unseat the bushings from the control arms. Actually measuring the control arms (again!) makes it clear that the OE bushings are installed from the rear. Thus braking loads tend to seat them more firmly in the control arms. D-Ohh.

Wouldn't be that unusual for GM to make this mistake. My C6 corvette had this exact problem on the race track due to the way GM assembled the upper control arms. The rear arm would pull forwards off its bushing and the control arm would actually bend from the brake torque.

IMG_3221.jpg (533.46 KiB) Viewed 447 times

[The Dark Side of Will]

For some reason, I had it in my head that the OE bushings installed from the front. This doesn't make sense, because braking force would tend to unseat the bushings from the control arms. Actually measuring the control arms (again!) makes it clear that the OE bushings are installed from the rear. Thus braking loads tend to seat them more firmly in the control arms. D-Ohh.

Wouldn't be that unusual for GM to make this mistake. My C6 corvette had this exact problem on the race track due to the way GM assembled the upper control arms. The rear arm would pull forwards off its bushing and the control arm would actually bend from the brake torque.
IMG_3221.jpg

Well that's pretty wild. Were you on slicks when that happened?

[The Dark Side of Will]

Also, if you're interested in a set of the spherical bearing shells, I'm starting Group Buy #2

[Jalisurr]

Well that's pretty wild. Were you on slicks when that happened?

Nope, just street legal track tires generated sufficient braking force (specifically the Toyo R888R at the time). I ended up having to go to a delrin bushing setup that pressed in from both sides to fix it.

Also, if you're interested in a set of the spherical bearing shells, I'm starting Group Buy #2

I'm good on this one for the moment - I've got Tubular LCAs with rod ends installed on the front of mine

[draven]

Put me down for a set for my 88... I'll pm you with my email address

[The Dark Side of Will]

Put me down for a set for my 88... I'll pm you with my email address

Thanks! I added you to the list on Pfiffle. Maybe I should cross-post that here.

To answer your implied question, the '88 Fiero kits include shaft seals to keep dirt out of the bearings.
The '84-'87 cars can't use those seals because the control arm motion is eccentric at the bearings.

[pmbrunelle]

I took my car (with the spherical bearing shells) for a quick spin yesterday, and the ride quality was fine (by my standard anyway; I suppose that this is subjective).

One might think that metal-on-metal would be rough, but there is still the main spring and shock working. I intentionally drove over rough spots such as sewer grates to evaluate ride quality.

[The Dark Side of Will]

I took my car (with the spherical bearing shells) for a quick spin yesterday, and the ride quality was fine (by my standard anyway; I suppose that this is subjective).

One might think that metal-on-metal would be rough, but there is still the main spring and shock working. I intentionally drove over rough spots such as sewer grates to evaluate ride quality.

I've read on other forums that maybe spherical bearings result in a slight increase in higher frequency noise, but have never heard of a ride quality complaint. As you noted, the suspension still works.