Author Topic: 73 Firebird Formula 400 - Ready for Spring! (Read 12209 times)

scottly · « **Reply #100 on:** September 14, 2020, 08:06:21 PM »

Quote from: Don R on September 14, 2020, 07:08:59 PM

Make sure the long and short shoes are in the proper places. I learned it on a 72 GTO. We had the short shoes on one side and long shoes on the other. I had to look it up in a manual to see which should be in front.

1+ Drum brakes on cars have one trailing shoe, and one leading shoe; the leading shoe is "self energizing", meaning as it contacts the drum, friction pulls it into the drum even harder.

The automatic adjusters only work when the brakes are applied when the vehicle is moving backwards, to the tune of one notch at a time on the star adjuster, so multiple taps on the pedal may be required.

dave500 · « **Reply #101 on:** September 15, 2020, 12:33:36 AM »

so long as the adjusters aint binding and clean and free,some people omit them?

CBJoe · « **Reply #102 on:** September 15, 2020, 09:15:35 AM »

So I have the shoes oriented correctly the shorter shoe facing forward. No leaky wheel cylinder that I can see.

I can say that I did NOT have either adjuster properly threaded out so light contact was happening. The Driver side was extended out more than passenger....so this is telling me the drivers side shoes were contacting drum before passenger.

Last night I adjusted them both out so they have the light drum contact...I'll go for a test driver later when i get it off the Jacks.

One thing that came to my mind in regards to the passenger wheel locking up during light dragging. I have a Limited Slip Diff....I was thinking of how this behavior would be in the diff if the Driver side wheel was braking BEFORE the Passenger Side. I was wondering if this could cause a power transfer hiccup to the Driver Side.

Proof is in pudding...i'll report back after driving later.

Joe

CBJoe · « **Reply #103 on:** September 15, 2020, 01:43:03 PM »

crap...no go. I tell you, visually the brakes are setup and adjusted correct. Light touch on drum. Both sides adjusted about the same and shorter shoe leading to the front. But under medium to heavy braking the right driver side still locks the wheel up super easy and seems hotter to touch than others.

Someone suggested the drum may be out of round....or I may just have gotten a bad wheel cylinder.

Someone else suggested that I should just go easy on it for another hundred miles to let the shes bed-in to the drums

But...I already had the wheels off things thing 3 times in the last day and a half...so I'm gonna take a break (no pun intended).

Joe

Don R · « **Reply #104 on:** September 15, 2020, 03:43:47 PM »

Limited slip works when the side gears push each other apart and/or small springs (for ice) compress the clutches. when off the throttle, the clutches should relax and allow differential action. Be sure to use a proper lube for limited slip or they may chatter on corners. I still have an empty can that once contained GM posi additive. I was told it contained sperm whale oil. I didn't know that at the time. Early 70's.
On my 9" fords I remove the springs and shim the new clutches until they just drag. My Hot rods never see ice but they lock up good.

jgger · « **Reply #105 on:** September 15, 2020, 07:37:03 PM »

Joe I was always told on drum brakes that you tighten the adjuster until there is moderate drag then back off the adjuster about 6 to 10 clicks. The self adjuster needs to be pushed back so you can back off the adjuster, so it requires 2 tools in the adjustment hole at the same time.

On another note you didn't put the right adjuster on the left or the other way did you. I think they are right and left threads depending what side they are on.

CBJoe · « **Reply #106 on:** September 15, 2020, 07:42:19 PM »

Hey Jgger,

I did indeed verify adjuster placement.

Also, I did do the back off by 5 clicks or so. Prior I had it way under adjusted and performance was same.

I think at this point I’m gong to do some short drives over the next few days with light braking for 100 miles or so while monitoring.

If it stays the same I’ll look to maybe replace all the pieces in the suspect wheel to be sure. If everything stays isolated to that single wheel...I cannot see it being anything to do with the Master Cylinder or the proportioning valve.

I suppose I could have a bad wheel bearing causing heating on the hub....but it feels fine when manually turning and I dont get any axial play. Cant imagine that would impact the braking.

Joe

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my name is nobody · « **Reply #107 on:** October 08, 2020, 10:57:38 PM »

Joe
Check the parking brake cable on the affected wheel to make sure it releases COMPLETELY. If one is stuck even
slightly, it will cause the condition you are having. use a flat blade to lever the parking brake cable actuator arm
rearward as far as possible, in effect pulling the cable out of its housing. This will ensure there is a little slack
in the cable , allowing the shoes to relax to their normally installed positions. they generally fit better at the top
and the slotted bar (strut) will be in the proper range allowing for proper adjustment. Shoes that are difficult to
installl and springs that seem too tight are hints that this condition exists.

dave500 · « **Reply #108 on:** October 09, 2020, 01:57:54 AM »

also check axle bearing end float,if the drum brake assembly is like the PBR type the park brake should be backed off to adjust the service brakes,then re-adjust the park brake,if the shoes etc are new i leave them a little loose on adjustment until it all squares away and settles in.

CBJoe · « **Reply #109 on:** October 11, 2020, 02:08:12 PM »

I broke down and took the car to a shop a friend of mine has work on his vintage cars. So dave...you are correct in part. The axle bearings were shot and have been replaced. But that is just one piece of the puzzle.

Something is funky with the center hole size and the drum fitment. Hard to describe, but either these Axles are not the original axles for a '73 firebird or something is fishy about the drums obtained form 3 different retailers.

Basically the shop finally figured out that the center holes on the drums are just slightly too small or don't have the right taper to fit flush against the axle. The passenger side one especially...what was happening is that the drum was not sitting cleanly against the axle face. This causes the drums to warp when the lugs are torqued down. The new drum I put on was well out of round. And the new one they put on cracked when they torqued it down....which is where it became super evident what the issue was.

But now that we know the issue we'll get it resolved. I'm kicking myself it the A$$ because I threw away the old drums so I cannot even compare them. I do know that the drums I threw away looked visually different than all the replacements I've been putting on.

Cheers, Joe

Joe

Don R · « **Reply #110 on:** October 11, 2020, 06:27:37 PM »

A lesson learned hard. Dang. I had it on a 68 chevelle, the new M/C looked different. The instructions said it would. Salesman said it might. The problem was it was for a Ford.

dave500 · « **Reply #111 on:** October 12, 2020, 12:44:51 AM »

yeah i was once supplied discs with the wrong pcd,its was metric not imperial,an idiot wouldve just impact gunned em home,i noticed the last lug wernt square and figured it out,dropping the rear drum on the disc the one hole ends up .5 mm wrong,on the old disc was perfect,so back to the shop armed with drum to prove,they gave me the more exxy discs no extra!!pays to be polite not angry.

Don R · « **Reply #112 on:** October 16, 2020, 07:33:09 PM »

Quote from: Don R on October 11, 2020, 06:27:37 PM

A lesson learned hard. Dang. I had it on a 68 chevelle, the new M/C looked different. The instructions said it would. Salesman said it might. The problem was it was for a Ford.

Oh yeah the Ford guy that got our Chevelle M/C was PO'ed too.

CBJoe · « **Reply #113 on:** October 16, 2020, 07:45:18 PM »

Ok....car is still in the shop having some extra stuff done to it that I didn't want to do (car lift just makes some things easier). But I went today and test drove it to sign off that the rear end stuff all sounds and felt good. It was great.

Bottom line is that it took 5 tries on Drums to find ones that fit correctly...and ALL of them were supposed to be for a '73 Firebird. Pretty sure that all of the auto parts stores are sourcing their drums from the same damn vendor whose center hole tolerance is shyte. If I just would have purchased drums form Ames I probably never would have gotten here. BUT!....the axle bearings were also worn pretty bad so at this point they've been replaced.

I know that this shop did a lot of labor and fiddling trying to get things sorted....but the price in the end was extremely reasonable. They went through the car top to bottom and didn't find anything that I wasn't already aware of.

I'll hopefully be picking it up late next week and going on a long country drive to REALLY shake it down

Joe

Don R · « **Reply #114 on:** October 16, 2020, 09:26:46 PM »

Awesome.

RAFster122s · « **Reply #115 on:** October 17, 2020, 12:03:57 AM »

Congrats Joe! Glad she will be ready for a nice country drive for you and Rose to enjoy!

dave500 · « **Reply #116 on:** October 17, 2020, 02:47:18 AM »

give it some full power thru first n second,hold second and let it wind down,repeat a few times,blows the cob webs out,wont hurt it,find a quiet outta the way place,dump the pedal from stationary,it oughta spin the wheels easy then snatch a chirp into second?

CBJoe · « **Reply #117 on:** October 17, 2020, 06:47:44 AM »

That’s the plan Dave ....I already confirmed it will do a burnout quite well

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Don R · « **Reply #118 on:** October 17, 2020, 09:11:18 AM »

When the local dealer had the last GTO on the lot I test drove it. My wife nixed buying it (because it was red) but that drive confirmed that I missed my firebird a lot. I'm trying to maintain a steady flow of parts to keep the Firebird project going. Later she liked a different red car. Nope. We can't buy a red car, remember?

CBJoe · « **Reply #119 on:** October 24, 2020, 04:31:13 PM »

Pretty sure Rose lifted her foot early

but still was a pretty good launch

CBJoe · « **Reply #120 on:** November 01, 2020, 12:51:58 PM »

At this point I hopefully have all the detrimental bugs shook out....done about 300 country road miles on it in the last week...fixed a few lingering issue and a few newly identified ones.

The Quadrajet Secondary Vacuum Break was non-functinal...so the doors could open at any time. I replaced that and also found the float height was way too high (.2"). Adjusted it to .375". Shake down run went great...and gas mileage went from around 10MPG to 14MPG...I'll monitor to see how it does in long run.

Engine Bay is looking 1000 times cleaner than when we brought it home....with the fresh paint on the manifold, valley, covers and now water pump and timing cover it looks nice

Hopefully we're driving it on the regular from now on

Cheers, Joe

RAFster122s · « **Reply #121 on:** November 01, 2020, 04:24:43 PM »

Glad you are getting kinks worked out and enjoying it. It is interesting how some people don't anticipate any maintenance or work on a new used car and are #$%*ing about sorting it out. It has gone up in value since you bought it as it is better running and the cosmetic work yields dividends personally in the pride you take in it as well.

Don R · « **Reply #122 on:** November 01, 2020, 08:46:25 PM »

My former race car partner was a quadrajet savant. He had a metal pan that he worked in so nothing would roll away. I even soldered the corners. He's working on a 41 willys now.

Stev-o · « **Reply #123 on:** November 02, 2020, 06:24:44 AM »

Quote from: CBJoe on November 01, 2020, 12:51:58 PM

Engine Bay is looking 1000 times cleaner than when we brought it home....with the fresh paint on the manifold, valley, covers and now water pump and timing cover it looks nice

Nice job Joe, looks tidy and sounds good too. Will you need to put it up for the winter or do you plan to drive it as much as weather permits?

My buddy picked up a Gen2 Camaro last week and I offered to take delivery and test it for him.
It is the Z/28 model which came with the LT1 [Corvette] motor -350/330hp w/4spd.
Had a fun drive out in the Hill Country with it!

Jerry Rxman Griffin aka MuthaF'er · « **Reply #124 on:** November 02, 2020, 06:56:09 AM »

Persistence pays off. Looks and sounds good.

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Author Topic: 73 Firebird Formula 400 - Ready for Spring! (Read 12209 times)