Can I copy your pinion angle maf homework?

[EddieE]

I know this is easy for you, but it's hard for me.  I'm using a magnetic angle finder to figure this out, so I have tapped it about a hundred times to get my readings.  I don't know the difference between a positive or negative angle, so I will give you a narrative.

When I put the car up on the lift, I put ramps under the front tires and a floor jack under the differential of the 8 and 3/4" Sure Grip.  Then I lowered the lift until the car was resting on the ramps and the jack.  The angle on the front of the yoke was 0 degrees.  The driveshaft is at 2 degrees, meaning the drive shaft is higher at differential than it is at the A833 transmission tailshaft.  Maybe that's 2 degrees positive or negative, if I knew I would not be copying your homework.

Here are the questions:

What is the formula for my current situation?
If I need to add shims, what shims should I add?
The springs are original (I think) and they may be very tired so am I better off gettings new springs then shimming from there?
If I need new springs, which ones can I get to keep the low stance that I currently have?

[Chryco Psycho]

I would use a 3* or 4* if you can get one , you want to tip the nose of the diff downward, this will be your vibration ,  the nose of the diff is already 2* higher than the driveshaft & it will get worse under power , you need to have the iff yolk lower so it is below the driveshaft

[EddieE]

Thanks for remembering my vibration posts Chryco!  I think we're onto something with this thing way out of whack.  At least I think I need to get this right before I can find anything else.

I really want to replace these springs to get a firm platform, or at least a constant in this equation.  Which springs would you go with to keep this semi-low flat stance?  Also, are there any peripheral items that you would replace with the springs?  This vibration is making me crazy...

[Chryco Psycho]

My Chall sat like yours , the springs were fine just sat lower then I liked , you could add a couple of 1/2 leafs going forward only & U bolt/ clamp them .... if you replace them I bet it will sit higher no matter what you order , then you have a new problem to deal with . I bet this solves the vibration though !

[Chryco Psycho]

I see youhave the draded BFG tires too , I have seen them with more than a 1/4 step in the treads so check them too

[EddieE]

I am going to get new springs.  I am as defiant now as I was when I put Dunlop GT Qualifiers on a 68 Firebird convertible, even though they looked like snow tires!  You gotta admit the TA's are at least better looking.

If you HAD to suggest which springs to buy, even though it's the wrong thing to do (I can always take them back off) which ones would you recommend?

[Chryco Psycho]

Eaton makes the best spring ,
 Springs & Things / Espo would be my second call
 Hotchkiss I believe has springs too
OR you could go to lightweight composite springs as Brad did .
 Get new U bolts , you may have trouble getting the front bolt out of the spring eye after 40 years they do not remove easily , I coat everything with anti sieze when I re-install .

[EddieE]

I ask to copy homework and I get a homework assignment.  You are a cruel professor.

I'll check on all my options and report back on the results.  Thanks.

[EddieE]

Well, now I'm a little cluelesser.  I went under the car to lube up the nuts on the u-bolts in anticipation of the shims that will be here on Monday.  I counted the leafs on my springs...there are only four on the passenger side and five on the driver's side.

I thought the spring assembly with more leafs (leaves?) would be on the driver's side if they were not equal.  Also, I went on Eaton's site and the only 4-leaf spring listed from 1970 to 1974 is on an A body with light horsepower.

These springs are bolted to an 8 and 3/4" Sure Grip in a 1974 'cuda.  WTF?  Now I'm worried that if I replace the springs with the right springs that it may affect the driveshaft length.  I just had this one made at Denny's!

Will someone smart (calling all Chrycos) talk me off this ledge and let me know the next best steps?

[Chryco Psycho]

Where are you counting the leafs ? there should be more in front of the diff than in the rear , typically there are more on the passenger side but not nessisarily on the rear .
 So Eaton is wrong , my 70 Chall R/T N code 4 spd had 4 leaf spring packs & sat just like yours . I could see an R/T N code Auto maybe having  4 leaf springs but a 4 spd
 There is no reason the driveshaft should change length , the wheel has to center in the wheelwell & the trans is not being altered , the anlge change will only affect the driveshaft by 1/4 or so max as the diff is tilted

[EddieE]

You're right again.  I was counting behind the axle, and I think I even miscounted those.  Here's the pics of what's there.

[EddieE]

Couldn't figure out how to add text after the pics.  So does this look legit, and are the existing springs on the correct sides of the car?

Hey, while you guys are under there you can give me your opinion on this bar that somebody welded across the rear.  The rear tracks perfectly and doesn't wear out the tires, so I'm guessing this was to strengthen it not to straighten it.  Is this a drag strip thing?  The car has definitely not been abused, and it's an original Sure Grip car according to the plate, so it's anyone's guess as to why the rear was modified... 

[Chryco Psycho]

looks right to me , the bar is a brace to stiffen the diff

[EddieE]

Hate to derail my own thread, but is the installation of that brace on the rear end common practice?  What circumstances would prompt someone to do that in a 74 small block car?  It seems like a lot of work, but the rod is bent very uniformly and the welds are pretty so it looks like someone knew what they wanted and did it correctly.  I just don't know why.

[Chryco Psycho]

 Generally I have only seen it used on car running slicks .