C2-C3 trying to help with a rear spring install

[IH2LOSE]

OK so its been quite a while since I had to play with the rear spring on a C2, A freind is in the midst of rebuilding the rear end on a 68 and questioned me on what he should torque the spring down to.

I said let me gather some facts first.

I know or should I say I knew but have forgotton what the correct procedure was .(I dont know how you guys remember all of this stuff)

Can some one tell me the correct procedure for torquing this down as I remember if it was done wrong you would snap the ears off of the rear case
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[ChuckG]

I can't tell you what the torque numbers are without looking them up in the AIM, but here's the trick.

With the car in the air, install the spring and tighten the 4 bolts under the diff "just snug".

Take the car off the jack stands and let the weight of the car settle the spring. THEN, torque/tighten the 4 bolts. If you try to tighten them without the weight of the car on the spring, you risk snapping off an ear. Chuck

 

[IH2LOSE]

Thank you Chuck.

I knew there was something important about this.

I am embarresed to say I still have a rebuilt carrier and trailing arms and a eaton spring sitting in my garage waiting to go into my 66 probaby close to 18 months allready. I am just hoping that the paint I got for the spring from quanta hasnt hardened in the can allready

 

[ChuckG]

The idea of tightening the 4 bolts with the car "on the ground" makes sense. When you put on the spring, the "arch" created when you put on the bracket needs to be compressed.

If you try to tighten the 4 bolts with no load on the spring, you're really trying to compress the spring. You need to put so much force on the bolts, that you'll snap an ear off the diff cover.

Also, be careful of the length of the bolts you're using. There are different lengths for 7 leaf and 9 leaf springs. It's not that important on the 2 rear bolts, but the 2 front bolts are blind tapped into the case.

If you use a bolt too long, you'll crack through the bottom of the case, causing a potential gear oil leak. It's usually not too much of a problem, as the bolt will seal the leak, BUT it's not "good form". Chuck

 

[JohnZ]

The bolts for the 7-leaf (F-40/41) spring are 9/16"-12 x 3-5/16", and those for the standard 9-leaf spring are 9/16"-12 x 3-9/16".