1972 MC 350/Auto - Suspension Upgrade

[jft69z]

6 minutes ago, B-Man said:

so that I can look for the code and compare it against the list that @jft69z posted and linked above? 

Thanks again everyone.  Super helpful community here.  Hopefully @Rob Peters cashes my check soon and updates my account so I can be even more active!!!

You can usually find the stamped code near the valve stem area. You'll have to remove the trim ring. The date codes are usually stamped in the lug nut area.

If you look at your profile, Rob changed you to a full member. You should also see the silver 'FGMCC Member' badge there too.

[Blackhawk]

I was mistaken on the location, stock wheels should have the code on the face of the wheel near the valve stem.

http://chevellestuff.net/qd/rally_wheels.htm

[jft69z]

37 minutes ago, Blackhawk said:

I was mistaken on the location, stock wheels should have the code on the face of the wheel near the valve stem.

http://chevellestuff.net/qd/rally_wheels.htm

I added that link to the above list on our forum, Thanks Cody!

https://www.firstgenmc.com/forums/index.php?/topic/26766-gm-rally-wheel-id/#comment-247088

 

[Rob Peters]

1 hour ago, B-Man said:

Thanks again everyone.  Super helpful community here.  Hopefully @Rob Peters cashes my check soon and updates my account so I can be even more active!!!

Brendan,

Yes, I picked up your check at the post office box yesterday and also deposited it yesterday. 

Just in case you have not noticed yet Brendan, as of yesterday evening your profile has already been updated to reflect that you are now identified as a Full Fledged Dues Paying member of the club.  One way to identify this is has been done is you will now see this badge  to the left of each of your posts, below your screen  name.  

You should also notice you have some additional "Forums" have been opened up for your viewing pleasure.  These additional forums are only available to full fledged dues paying members of the club.  Just a note, if you are looking on some cell/mobile phones you may not see the FGMCC Member Badge but you will see it on most tablets, laptops and computers.

rob

[B-Man]

@Blackhawk, ok near the valve stem.  I will check that out and post a pic tonight when I get home.  That should be the final piece to me then confirming some numbers / fits / clearances and then getting some tires ordered

@Rob Peters, awesome, thanks for the update.  I will start poking around further and will update my profile, etc.

[MCfan]

Brendan,

If your rims are actually 15x7 with a measured 4.25" backspace, they should work beautifully with 255/60s both front and rear.  Having a measured 4.25" backspace on a 7" wide rim gives and offset of +6 mm (versus a -6 mm offset with the same backspace on an 8" wide rim).  That means your wheel/tire combo will be moved .5" further inboard (compared to an 8" rim) which increases your rear wheel well lip clearance.  All of my initial calculations and examples were based on your assumption that you had an 8" wide rim (not counting the lips) so you can disregard that reply if, in fact, you have 15x7 rims with 4.25" backspace. 

Honestly, it sounds like you may have a set of factory Monte 15x7 rallys with the 4.30" backspace.  If you do, you should be good to go. Good luck.

[B-Man]

@Blackhawk, sorry about the above post. It's a misfire / issue with the editor. I can't seem to delete it

--------------------------

REAR LOWER CONTROL ARMS BOXING - I've got the rear lower control arms off, and I have the boxing inserts ready to weld in. But ... I didn't note FWD and AFT on the control arms when I took them out. Yikes!!

Is the hole in the top (circled in yellow) supposed to be FWD?

What orientation to the inserts go? As shown or other way?

[jft69z]

Most pics of new boxed arms have the round top hole in front, and an oval one at the top rear.

 

https://www.lever-family-racing.com/lever-family-racing-home/control-arms-version-2/gm-a-body-64-72/10-bolt-12-bolt-difference/create-12-bolt-arms/boxing-control-arms

[B-Man]

@jft69z, thank you for that link. It's pretty helpful. I also came across that this morning during Googling!

I agree that the top hole should indicate FWD. That's the way I went anyway. It does seem like the arms are symmetric but I wouldn't bet a paycheck on it.

I couldn't find a template anywhere on the Internet. So I had to make some measurements and guesses and go for it 

The sway bar mounting holes measure 6in apart on each side of the sway bar. And the inserts, although just imprecisely bent sheet metal, are pretty consistent and also measure 6in arc to arc.

The rear lower control arms measure just shy of 25in long tip to tip. So I measured to the 12.5in mark from the FWD end and called that the centerline. I then set the FWD sway bar hole 0.5in AFT of centerline, then the AFT sway bar hole 6in AFT of the FWD one. 

I eyeballed a good height location for the sway bar and ended up converging on a hole center that is 15/16in down from the edge of the curled lip on the sides of the control arm. I'd go 7/8in if I did it over again.

I drilled 1/2in holes in the measured locations. And then I set the boxing inserts down in with a hammer. The holes lined up really well. But as I mention above, reducing the vertical distance of the holes to 7/8 would get a more free fit with the inserts in. It works though!

The control arms are currently on the weld bench waiting to get zapped in place. This was WAY easier than I had anticipated. Though I'm leveraging the metal shop at my work, and buying the welder a 12 pack of his favorite beer

At some point when I do a full suspension upgrade I will donate these boxes control arms to a good cause and go with the solid billet ones - me likey likey!

[B-Man]

So here is what the rear lower control arms look like after welding. Pretty cool! I kind of enjoy the 'patina' so I'm going to leave the metal uncoated - our media blaster is awaiting replacement or I would have cleaned them up and painted them black. Maybe later

I should be able to get these control arms and the new sway bar reinstalled this afternoon. So all in all this was a pretty quick and easy morning / afternoon project.

 

Oh, and my new Bilstein shocks came in too!!! More on that later

 

[B-Man]

Success - boxed lower control arms and a sway bar installed! Today was a good day for sure. Everything went right. I will have to tuck this one away for all those days that go to crap.

During installation of the control arms I found I had to use a heavy duty cargo strap to pull the rear end forward a bit in order to get the AFT bolt to line up. I installed the FWD bolt first. I put the cargo strap between a drain hole in the frame under the door, then back to a wheel stud sticking out of the brake drum.

I also found that installation of the sway bar means I lose the ability to put jack stands under the rear end - bummer. I also now have limited access to the rear end pumpkin to use as a central rear jacking point - bummer. I had to put a 2nd set of jack stands under the AFT control arm bushings in order to move the 1st set out of the way for the sway bar to be installed. Lucky I have 6 jack stands for whatever reason!

I'm done for the day. Tomorrow I will get the Bilsteins installed as long as wifey lets me spend another day in the garage. She's a keeper and so I want to keep her

And after the Bilsteins I'm done with the suspension for now, other than tires. Oh, and a Jeep steering box I guess.  I will move on to the starter replacement (other thread) and the previous owner wiring mayhem I've uncovered - ugh!! I will get it done though. Easy peasy.

Thanks for all of the help so far everyone. I really appreciate all of the info and guidance. Such a great group!!!

[stangeba]

Love it! I remember doing mine way back but did not box the arms, just bolted the anti sway bar in place.

Many years later, my nephew welded some more metal on the arms. Mine isn't as nice as yours.

[B-Man]

13 hours ago, stangeba said:

Love it! I remember doing mine way back but did not box the arms, just bolted the anti sway bar in place.

Many years later, my nephew welded some more metal on the arms. Mine isn't as nice as yours.

I was going to do the same thing. I had the sway bar in my cart on Summit. Then of course the site 'recommends' the inserts for $32 or whatever. I bought them figuring I would install them with the sway bar and then weld later while installed. But the solid bushings that come with the sway bar - to brace across the inside of the arms - wouldn't fit with the inserts in there. So, here I am having done the job properly. Who would have guessed, haha! Honestly, the whole thing was incredibly easy to do. A good, fun project for the day. 

Enjoy the rest of the weekend everyone!

[B-Man]

 

Well guys, I'm glad I had a great day yesterday boxing in the rear lower control arms and installing the sway bar.  Because today was an absolutely HORRIBLE day installing the Bilstein shocks, or trying to anyway.  So horrible.  In fact, I've just plain given up after having only sort of installed one of the rear shocks.  I have more time invested trying to get the rear shocks installed than I put in on the lower control arms and sway bar yesterday.  No kidding!

First ... the upper bolts for the rear shocks are nutted on the back side, against the bottom of the trunk floor.  There is zero visual access to the nuts and very little finger / hand / tool access.  Who does that?  My god, what an absolutely stupid setup.  There's plenty of metal there, and I'm not sure why they wouldnt have just threaded it through the thickness or had floating nut plates or something ... anything but a blind nut.  So, that took a while to figure out the right acces and set of tools to use.

Then ... when installing the rear BIlsteins P/N 24-009294 I realized that the hardware through the bottom bushing was not going to mount to the mounting plate on the axle.  It didnt have a standoff on it.  Dang it!  Wrong part or is this just the way they do it?  I ended up cutting the riveted washer off of the studs, then pulled them out of the bushing.  I then went to press the old / current studs into the bushing and a nightmare ensued.  I only have an old bench vise and a selection of sockets to make this happen.  I ran to the local harbor freight to grab a bench top arbor press, but no dice ... out of stock.  I spent hours trying to get the new Bilstein bushings pressed onto the old stud and into the shock.  I got one done but ended up sort of stripping the threads on the stud accidentally.  The shock is installed in the car, but I'm not happy at al with that lower bushing and stud.

I tried for quite some time to get the second stud / bushing / shock together and finally had to throw it down in disgust and walk away.  So now I'm in the market for new studs and bushings.  I may end up buying a cheap set of shocks just to get the studs and bushings since I dont seem to be able to get them separately.  Once I figure that out I will just bring all of the parts into work and use the hydraulic press there to get it all together - hopefully!

So, today was a really unfortunate fail.  I could NEVER have imagined rear shock, or fronts that matter, to be so unbelievably difficult to install.  I cant believe it.  I'm beside myself with frustration.  Ugh!

More later ...

[B-Man]

I just ordered some cheap Dorman rear shock bolts/studs and bushing sets.  They're probably going to be a little bit of a hack, but we'll see.  If anyone knows where to get some high quality ones, and new Bilstein-quality (?) bushings, please let me know!

[cny first gen 71]

I think there all pretty much the same unless you can find poly bushings which I don't really know is a thing.

[cny first gen 71]

I guess I'm not really understanding why the bottom mount wouldn't work,  the stud should slide through the hole in the bracket in the rear end.

[Michael Boyte]

I'm with you Steve, doesn't make sense to me either ! Unless the shock is too long by chance .  And the uppers required a long extension and a swivel socket, if memory serves me correctly. Definitely has been a few years ago. Long before we bagged it. 

[cny first gen 71]

Yea the tops are a pain for sure tough to get to. We used to just cut them off with the torch but when body bushings were new it was easier to get in between with a wrench if needed and to put the new bolts in, we would just drop them down through holes. As far as being to long or short I don't think that's his problem. 

[B-Man]

Gents - here is a clearer picture of the issue. The Bilstein shock bolt/stud isn't double-ended. It's just got a flat washer flared onto the end. If I try and put the threaded stud portion of it through the mounting plate, the tubing of the shock hits the plate. That's why I pulled that bolt out and tried to install the ones from my current shocks. Hopefully the Dorman parts work. What a bummer though 

 

[MC1of80]

Use a spacer/washer on the threaded end between the rear end and the shock, space it out for the clearance you need. Then bolt it in. 

[cny first gen 71]

Tom is Correct that will move the body out and give you the clearance you need.

[B-Man]

@MC1of80 and @cny first gen 71 , adding a spacer in would then eat up the length of the available threaded stud.  You can see the 'spacer' that's on the stub / bolt that I removed from the old shock and tried to install on the Bilstein.  That spacer, plus the thickness of the mounting bracket and a washer wouldnt leave very many threads for the nut.  Call me crazy, but I like my bolts to go through the but completely with a few threads showing!

So ... no, you cant just add a spacer, bolt it up and go about your merry way.  Trust me, I tried to convince myself of that as I was laying on my carboard creeper under the rear of the car.

I've got those Dorman hack assemblies on order.  And they might be good enough.  If I can find good, replacement, 1-piece lower rear shock bushings by themselves I will grab them and then use a proper press and fixtures to insert the stud / bolt into them and into the shocks.  But for now I will go with the Dorman parts when they come in.  I will post some pictures once I have them installed.

Thanks again for the input

[jft69z]

Looks likes there's plenty of thread there for a washer or two to me.

FWIW, I worked in the chemical industry for a lot of years and bolted up thousands of instruments and flanged pipe joints in the harshest environments/chemicals you could imagine. DuPont had specs for everything, as long as the threads weren't below the face of the nut, that was acceptable.

In fact, the opposite was true, if too many threads were showing, that was considered bad too. (In corrosive environments, too many threads would make the nuts difficult to remove, plus the painters would ALWAYS slop paint all over the threads making it a pain in the arse to disassemble. Sometimes we'd have them with us as helpers, then they realized the error of their ways pretty quick 😁)

[cny first gen 71]

There is a formula for that depending on bolt diameter and thread pitch. My brother was telling me about it when I put the wheels on my car and I put longer wheel studs. Of course I don't know the formula,  the government has a formula for everything.