84-87 suspension knuckle bumps (Page 1/1)
pmbrunelle DEC 27, 04:10 PM
What is their function?

Can they be safely cut off? Looks like an easy weight savings.

84-87 front knuckles have them.
84-87 rear knucles have them.

[This message has been edited by pmbrunelle (edited 12-27-2020).]

ltlfrari DEC 27, 05:36 PM
Not totally sure and i'm too lazy to actually go and look but on the front I think it is a steering lock stop. Probably on the back because the back is just a front suspension that's been locking in place.

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Anything I might say is probably worth what you paid for it, so treat it accordingly!

Dave

www.ltlfrari.com

theogre DEC 27, 07:04 PM
Likely is that...

Yes Fronts knuckle hits stops on LCA or other metal parts when turning so tires don't hit whatever.
Fronts rub and often make noise if you turn and hit pot holes etc. as well because no-one ever lube them w/ thin film of brake grease.

So fronts stop areas are bigger to handle full suspension up/down while turning.

Fiero Backs are front end parts off another GM car. Might save some weight by cutting/grinding but do this wrong and causes problems as can start stress risers etc.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

pmbrunelle DEC 27, 07:39 PM
In the Fiero front, steering stops are included in the brake caliper brackets:


So the steering stop function is already handled by the feature on the brake caliper bracket, in the 84-87 Fiero.

I found a photo of a front knuckle on PFF, and I circled the front knuckle bump:


Maybe its a vestigial bump because the front is also parts-bin?
Will DEC 28, 08:55 AM
That's a steering stop for the other direction.
pmbrunelle DEC 28, 12:28 PM

quote
Originally posted by Will:

That's a steering stop for the other direction.



Talking about the bump on the front knuckle? If both my caliper brackets have stops that hit the LCA, then these knuckle stops would be redundant, right?

At right full lock, the RH caliper stop should hit the RH LCA.
At left full lock, the LH caliper stop should hit the LH LCA.

Makes sense?
theogre DEC 28, 07:43 PM
Yes nearly all vehicles not just cars one part of knuckle on each side hits stop turning L to L.

Fiero FSM seems doesn't cover this.
Not crawling under car in winter to look how done or exactly where stops contact.

If front knuckle has "spare metal..." Could cut/grind but have same warning as above.
Is likely ductile iron but can break if someone screws up cause stress risers and related problems.

[This message has been edited by theogre (edited 12-28-2020).]

DimeMachine DEC 28, 08:03 PM

quote
Originally posted by theogre:

Yes nearly all vehicles not just cars one part of knuckle on each side hits stop turning L to L.

Fiero FSM seems doesn't cover this.
Not crawling under car in winter to look how done or exactly where stops contact.

If front knuckle has "spare metal..." Could cut/grind but have same warning as above.
Is likely ductile iron but can break if someone screws up cause stress risers and related problems.




If a guy were to cut off the chunk with a thin cut off wheel and then smooth the area that was cut with something like a 36grit roloc disk - that should minimize any risk of stress risers - or is there a better method? I still find it hard to believe newer cars use aluminum knuckles - i would think much weaker than iron...?

[This message has been edited by DimeMachine (edited 12-28-2020).]

pmbrunelle DEC 29, 12:33 AM
I'm not too worried about stress concentrations.

As I transform my Fiero from lowly econobox into my vision of a high-end sports car, rough cast parts with visible parting lines are smoothed into fancier-looking parts.

Some benefits:
Making smooth surfaces and gradual transitions between sections reduces stress concentrations.
Without jagged corners, paint film thickness becomes much more even, so you're less likely to get rust starting at the outside corners were the paint is thin.
Looks nicer!

Here is an unmodified GM Metric caliper:

Unsightly...

Here is a GM Metric caliper that I ground and sanded smooth:

After I sandblast and recoat this shiny red, it's something that I could display behind an open-spoke wheel.

For smoothing castings, I use a combination of:
Angle grinder / thin cutoff disc (for cutting off huge chunks)
Lathe/milling for more "controlled" material removal
Angle grinder / flap wheel
Angle grinder / grinding disc
Files
Sandpaper
Wirewheel
Will DEC 29, 09:10 AM

quote
Originally posted by pmbrunelle:

I'm not too worried about stress concentrations.



The load on the tie rod is pretty low anyway, so not much of a concern.



quote
Originally posted by pmbrunelle:
As I transform my Fiero from lowly econobox into my vision of a high-end sports car, rough cast parts with visible parting lines are smoothed into fancier-looking parts.

Some benefits:
Making smooth surfaces and gradual transitions between sections reduces stress concentrations.
Without jagged corners, paint film thickness becomes much more even, so you're less likely to get rust starting at the outside corners were the paint is thin.
Looks nicer!

Here is an unmodified GM Metric caliper:

Unsightly...

Here is a GM Metric caliper that I ground and sanded smooth:

After I sandblast and recoat this shiny red, it's something that I could display behind an open-spoke wheel.

For smoothing castings, I use a combination of:
Angle grinder / thin cutoff disc (for cutting off huge chunks)
Lathe/milling for more "controlled" material removal
Angle grinder / flap wheel
Angle grinder / grinding disc
Files
Sandpaper
Wirewheel



You know, at least for the Camaro version of the Metric caliper, PowerStop will sell you reman ones that are already powder coated red. RockAuto carries them.