Rearend Girdle

[IMPALAMAN1]

Hey fellas.... i am just about ready to put the rearend in the impala. and during the dazed and concused stage of ponderning putting it in... it looks like the pan hard bar may hit the diff cover. i have the trick flow cover with the screw in bearing cap locks...... will the pan hard bar hit them on full suspension lock up and decompress? has anybody delt with this yet? how did you get around it?

[wendell]

You're the only one that knows if it will hit. I can tell you this; a rearend girdle, unless applied to your wife or girlfriend, is just about useless.

[IMPALAMAN1]

OH SHE DOESNT NEED ONE im happy with that rearend.... and ill "hit" it all day..... but i get what you are saying... if the bearing caps werent enough .... then they would be built bigger...

ill try to post pics of it when i get it together.

[wendell]

We've got similar tastes. I steer clear of rear end girdles under all circumstances. You should too.

If there's a interference, I can't think of a other solution other than going back to the stock cover. Pic will help.

[IMPALAMAN1]

HERE ARE SOME PICS





the screw in studs have a p.o.s allen head on them to tighten them and then the lock nut. well when you tighten them both and want to snug up the lock nut...... guess what happens to the allen ..... it breaks out of the side.... so the guy who put it together asked if he could weld a 12 point head to it... i said sure.... so this is what it looks like now.... but the allen head part stuck out about 1/2 inch further.... so i gained a tad bit there....... but you get the idea. with the pan hard bar in place.... i hope that it clears.....

[NOT A TA]

I feel your pain. Just installed a new rear with a Moser (TA performance made) cover last night in the 14 car. Tomorrow night I'll be relocating the fuel system! The cover's going to interfere with the fuel filter.

[IMPALAMAN1]

Take Pics.... Please.

[Martin71RS]

I installed the moser (TA) on my axle last week:


I chose this one and it´s good I did....the locknuts are recessed so the part with the engraving is the highest part when mounted.
I have a flowmaster exhaust system with the muffler behind the axle and it just clears.

[IMPALAMAN1]

what about the panhard bar?

[IMPALAMAN1]

HERE ARE SOME MORE PICS!

[IMPALAMAN1]

[Tony@AirRideTech]

If you are having interference problems... just build a bent PH bar that clears the rear diff cover....

[Norm Peterson]

I'd relocate the axle and chassis side brackets back the necessary amount and/or skew the PHB itself in plan view slightly before I'd even think about using a bent PHB. In one cornering direction, the PHB is under compression, perhaps 1500 lbs worth even if you aren't sliding into something like a low curbing or pothole, three times that or more if you are. Bent compression members are things to avoid using (they tend to buckle rather suddenly). Especially for something as mission-critical as rear axle lateral location.


Norm
BSCE

[IMPALAMAN1]

Tony, i too have thought about this.... but im not sure how much it would change the geometry and possibly swing it into the driver quarter panel.... i dont know how much leayway i have....

GOOD POINT Norm...

what are your opinions on pushing the pin further out to get min clearance on it.

i am also considering doing a watts link that would possibly may my life easier and just have the piviots out far enough.

[Norm Peterson]

Ignoring the stiffness/flexibility of the PHB, the PHB geometry is defined only by where the pivot points at the ends are located. A little plan view skew of the PHB means that it begins to compete with links or arms that run in the purely fore/aft direction*. IOW, you'll probably induce a very small amount of resistance if you're running anything other than rod ends everywhere and the amounts of lateral axle movement and roll steer will shift slightly. But these will all be small effects as long as the skew is kept to no more than a few degrees.

* If your LCAs have any plan view skew, you have a similar situation already in that the lateral component of the LCAs competes with a purely lateral PHB.

Moving the PHB rearward doesn't affect the chassis side much unless it makes it trickier to fit things up. On the axle side, it means that the cantilevered axle bracket might need a little reinforcement because of the additional length that's in bending and a little more width to spread the increased loading on the axle tube out a bit. Some aftermarket PHB arrangements even include a strut of some sort that ties the end of the axle bracket back toward or actually to the pumpkin.


Norm

[IMPALAMAN1]

OK i did some mock up this weekend.... seems i need to push the phb from its stock location back about 1.5" to clear it is a total of 1.75" spacer. i have a 1.5" dia. steel slug that im going to drill out to accept the bolt. now the question is.... a 4.5" 9/16" grade 8 bolt is going to be what holds this bad boy in place is this going to be strong enough? is the 1500 lbs of compression that you are talking about enough to snap the bolt?

[Norm Peterson]

Understand that the 1500# above was a really rough estimate and includes no factor of safety. For quick and dirty only, I assumed 1g cornering and 1500# rear weight distribution.

The strength of that 9/16" bolt will depend on whether it's mounted in single shear or double shear and whether there are threads in the shear plane. Either Machinery Handbook or Mark's Handbook for Mechanical Engineers probably gives values. I don't have mine handy, but I'd guess that a 9/16" Grade 8 bolt in double shear and no threads in either shear plane would be good for 10,000 lbs or so. The PHB itself may not be that good in compressive buckling.

Eventually, you'll need to check the whole load path for whatever design load you end up going with, from the axle bracket attachment to the axle through the axle end bolt, rod end, PHB, rod end, chassis-side bolt, chassis-side bracket, any supplemental structure (which I hope includes a PHB brace from the chassis bracket region to a frame member on the other side of the chassis), and the ultimate attachment(s) to existing chassis structure.


Norm

[IMPALAMAN1]

Thanks Norm.... every thing is factory. rearend location and control arm location and length. bracketry. the main difference being the mounting point on the rearend has been pushed to the rear of the car. factory frame mount and factory length phb. no threads will be in the shear path.

as far as the phb brace are you saying to tie both frame rails together at this point?

[IMPALAMAN1]

well it all works..... but now im thinking of the watts more and more.... the tires rub the fender skirt on the driver side... so that needs to be adjusted.....