70 chevelle lower arm dimensions

[dug]

Hey all, I'm looking to see if anyone has a stock 1970 chevelle front lower a arm that they could measure for me. I want to design and build my own and I'd like the current dimensions to input into my CAD design. I was planning to pull apart my own car and take the dims 2 weeks ago but we are in a "shelter in place" and my car is 2.5hrs away at my parents shop.




It would take some effort on your part if you have the arm available and you're willing. Theres a few critical dimensions that I need and I can start my design. Hell, if you're near the bay area and have one you could let me borrow that would be even better!


Any help would be appreciated.Thank you

[raustinss]

I'd probably just buy an aftermarket one , cheaper and easier I'm sure .. and I'm even a fabricator lol

[dug]

I'd probably just buy an aftermarket one , cheaper and easier I'm sure .. and I'm even a fabricator lol

I knew that comment was coming. Thanks for the info.

[raustinss]

Lmao , if I had my stock stuff I'd give you any and all measurements but , I tossed it all and havent replaced all of it

[Juice.Lee]

Hey, Im in the Bay Area and have a stock set I can sell you cheap if your interested....?

[dug]

Hey, Im in the Bay Area and have a stock set I can sell you cheap if your interested....?

How cheap are we talking? Where are you located?

[Juice.Lee]

How cheap are we talking? Where are you located?

$60 for the set...I’m in San Ramon.

[dug]

$60 for the set...I’m in San Ramon.

Alright. To be honest I don't have it in me to spend $60 right now strictly to pull dimensions and then toss it away. But I do really appreciate the offer, don't get me wrong.

[SShep71]

What dimensions do you need? What is your end goal here, are you trying to change the geometry of the arm or are you just making an arm for the hell of it?

[dug]

What dimensions do you need? What is your end goal here, are you trying to change the geometry of the arm or are you just making an arm for the hell of it?

I want to make a new arm with some slight adjustments in geometry. I need to start with the existing arm dimensions and tweak it from there.

[raustinss]

Out of curiosity what do you you need to change that an already made and engineered part doesnt offer . Or what dont these parts offer you ?

[dug]

Out of curiosity what do you you need to change that an already made and engineered part doesnt offer . Or what dont these parts offer you ?

I could buy an off the shelf aftermarket part and I'm sure it would work great. I'm just looking at designing my own parts thats all. It's been a goal of mine and I think I'm finally capable of doing the design work with fusion 360.

[raustinss]

Oh ok so nothing really more than just to challenge yourself, was wondering if you had some knowledge to throw my way

[dug]

Oh ok so nothing really more than just to challenge yourself, was wondering if you had some knowledge to throw my way

Yes you're correct as far as challenging myself. If I did have some extra knowledge I'd be happy to share it. Best I can find from aftermarket manufacturers is that the lower arm has an extra couple degrees of caster built into it. I do plan on documenting the process on the forums. I can't really find any chevelle builds out there where the person built their own front a-arms so hopefully I can provide something for people in the future.

[jetmech442]

I'm getting ready to pull the lowers on mine. It's been very slow going with the quarantine, but I could def take some measurements once they're off. Always willing to help out a fellow gearhead-especially one intent on using Fusion.

[dug]

I'm getting ready to pull the lowers on mine. It's been very slow going with the quarantine, but I could def take some measurements once they're off. Always willing to help out a fellow gearhead-especially one intent on using Fusion.

Awesome. Well I'll shoot you a PM. Thank you.

[jetmech442]

Hey Dug,Sorry it took so long. Below are the dimensions I recorded off the passenger lower.I noticed the ball joint horizontal location has about 1/16 of error, I'll try to get back in there and see if I can get that tighter.

The big box in the middle is a top down view showing locations of the BJ to the bushings.
The bttm Left is showing how the BJ angles away from the spring seat. I leveled the spring seat first, then measured the BJ angle.
Bttm Right is showing the vertical distance of the BJ seat to the centerline of the bushings.
Oh, and one thing still missing is the spring seat height relative to the ball joint seat.
As I'm typing I realized I'm missing the spring seat height relative to the BJ seat and bushing centerlines.
When I reference the ball joint seat, I mean the underside of the arm, that the BJ physically presses against.

I didn't measure the ball joint hole diameters, because I figure mine are way too old to hold onto whatever the intended tolerance was. I did note that the factory arms let the BJ go with a few pumps of the hydraulic handle, where as the tubular speedway arms gave significantly more fight.

I hope this helps you on your way, please don't hesitate to ask for clarity(I was re-drawing the sketch during a very boring meeting so my handwriting isn't the best(nor is it anyways lol)). And if you need more dimensions let me know.

Edit, I pulled the pic because the Bj centerline was given from the bushing edge and not the arm edge. Will correct and reupload.

[jetmech442]

Okay, remeasured everything just to be sure, and corrected the dimension. I think a better way to report the horizontal location of the ball joint is from the centerline, just like i did the vertical dimension. Centerline of bushing to centerline of BJ, horizontally is 3.24. I didn't add it to the pic because I didn't want it to get to busy, plus I did it in pen like an idiot so...you know.

[dug]

Okay, remeasured everything just to be sure, and corrected the dimension. I think a better way to report the horizontal location of the ball joint is from the centerline, just like i did the vertical dimension. Centerline of bushing to centerline of BJ, horizontally is 3.24. I didn't add it to the pic because I didn't want it to get to busy, plus I did it in pen like an idiot so...you know.

First and foremost, thank you very much for doing this! I really appreciate it.

Edit: I deleted some questions I posted a couple hours ago after doing some 2d cad drawings copying your layout. I'll throw up a dimensioned drawing to make sure everything checks out to you. Do you have the diameter of the hole for the bushings?

Lastly, I didn't realize you had a cutlass for whatever reason. Do you know for sure if these arms are 100% compatible? Some quick searching didn't yield anything for me.

[dug]

Ok I looked around and saw some aftermarket suspension kits that they list chevelle/olds/gto etc. altogether. I've never paid attention to those descriptions because I've always looked for "chevelle" and nothing else. So sounds like the suspension is compatible.