Crusty Rusty Leaky Squeaky 67 Step

[lolife99]

Just a question.
With your lowering blocks installed the way you show them,... wouldn't that make the rearend's pinion point toward the ground more, than without the angle cut on them?
I would think you would want to turn the blocks around,... to get the pinion pointed up.
(trans points down x-degrees,... pinion points up a matching x-degrees)

I assume you are using a 1-piece drive line.

[Vic1947]

Originally Posted by mcbassin

Couple of questions, do you think 3/8-16 is sufficient for U-bolts? I thought the originals are like 3/4-fine.
What is "proper" pinion angle on our rear ends? I used my old rear diff. to set mine, now I wonder if it's binding or, something. When I drive it, it just doesn't feel right? there's a little noise coming from the drivetrain I'm not used to. Anyway, thanks for posting all the cool Ideas.

You're correct about the u-bolts that attach the trailing arms to the rearend housing. However, what I meant was that the airbags are held in place with 3/8" hardware. The original bolts for the rear coil spring retainers were 1/2". But the hole thru the trailing arm where the bolt screws into the spring retainer is actually 5/8" so I needed to bush it down to fit the 3/8" bolt for the bag.

As for the pinion angle, the main thing you want to achieve is to have the centerline of the pinion gear and the centerline of the transmission output shaft parallel... preferably under normal load. Under hard acceleration, the pinion tries to climb. This is more noticeable in a vehicle with rubber mounts, short trailing arms, flexible links (like leaf springs) and etc. Even with racing four link setups using heim joints, there will be some deflection. So if the imaginary centerlines intersect at rest, you're probably in for some driveline shimmy. As for the proper amount - several degrees is good if the physical configuration permits. Personally, I think pinion angle gets blamed for a lot of problems that it doesn't cause. As long as it's not waaay out of whack, it's pretty forgiving.

[Vic1947]

Originally Posted by lolife99

Just a question.
With your lowering blocks installed the way you show them,... wouldn't that make the rearend's pinion point toward the ground more, than without the angle cut on them?

That's correct. At the outset, (i.e. without any lowering block installed) the pinion angle was satisfactory. When I put the unmilled blocks in, it caused the front of the pinion to go up (away from the ground). To get back to a zero sum, I needed to move the front of the pinion back down. Thus the orientation you see in the photo.

Originally Posted by lolife99

I would think you would want to turn the blocks around,... to get the pinion pointed up.
(trans points down x-degrees,... pinion points up a matching x-degrees)

That would be the case if the centerline of the trans output shaft was pointing down. Mine (for whatever reason) is pointing a couple of degrees up relative to the pinion angle. You are exactly right that if the [trans points down x-degrees,... pinion points up a matching x-degrees]. However, in this case the converse is also true that if [trans points up x-degrees,... pinion points down a matching x-degrees]. You gotta do what you gotta do to make the centerlines as parallel as possible.

Originally Posted by lolife99

I assume you are using a 1-piece drive line.

Yes

[lolife99]

Thanks for the great explanation.
I had no idea the trans in your truck would be pointing up.
WIth the frame level,... I always thought the trans would be pointing down a couple of degrees.
Plus converting to drop springs or bags in your case,... usually pivots the rearend's pinion angle into negative numbers, (due to the new angle of the trailing arms) depending on how much you drop the rearend.

[Vic1947]

Originally Posted by lolife99

Thanks for the great explanation.
I had no idea the trans in your truck would be pointing up.
WIth the frame level,... I always thought the trans would be pointing down a couple of degrees.
Plus converting to drop springs or bags in your case,... usually pivots the rearend's pinion angle into negative numbers, (due to the new angle of the trailing arms) depending on how much you drop the rearend.

Ahhh, the operative phrase here is "with the frame level". Instead of saying "for whatever reason", I should have pointed out that the frame wasn't level when doing my measurements. I had the rear up on jack stands, the springs out and used a floor jack on the center crossmember. At this point, I set the distance between the frame and the rear axle tubes to the dimension I thought would be ideal for the final ride height. This height, while not as low as it can go, is a compromise that allows me to keep my existing rear shock setup and not have to install C-notches. This distance sets the geometry between the pinion gear and the trans output shaft. Relatively speaking, the trans angle doesn't matter; only its relation to the pinion. Once the imaginary centerlines are parallel, you're in business.

My goal is somewhat different than the average builder bagging a truck. I've only done static drops in the past and the lower they rode, the less I ended up liking them. I wanted bags not so much to lower the truck (although I do like them lower than stock) but rather to compensate for trailer tongue weight. The more I looked into it, the less it seemed that I could get away with two rear bags and Schrader valves for load leveling. Next thing you know, I've got four corner bags with position sensors and a computer that controls each corner independently. Gonna make hauling gravel a cinch, though.

[jlsanborn]

Originally Posted by Vic1947

Gonna make hauling gravel a cinch, though.

Dump bed????

Although my thread is stone cold, I have been dinking around with ho-made cross member and engine stands. Did a bunch of searching to find out if there is a standard or preferred centerline angle. A 3 degree decline front to back came up in my searches more than once so that's what I shot for.

Truck is looking great Vic. Can't wait to see some sano pneumatic plumbing!

[Vic1947]

Originally Posted by jlsanborn

Dump bed????

Although my thread is stone cold, I have been dinking around with ho-made cross member and engine stands. Did a bunch of searching to find out if there is a standard or preferred centerline angle. A 3 degree decline front to back came up in my searches more than once so that's what I shot for.

Truck is looking great Vic. Can't wait to see some sano pneumatic plumbing!

Thanks, John. I'd agree with your findings. Three degrees of trans down angle matched with 2-3 degrees up pinion angle should give smooth results.

I've been mulling over a design for mounting the top of the bags to the frame that will keep me from having to drill into it. Should make it much easier to plumb the lines also. Stay tuned.

[Vic1947]

So, after bolting the lowering blocks in place and mocking up the ride height, it dawned on me that I'd be pushing the upper limit of the SS-7 bags (12") if I needed a bit more ground clearance. Since this isn't your run of the mill, "in the weeds" chassis mod, I'd have been okay without the blocks. However, inspiration smiled upon me as I realized I could now build spacers for the top of the bags that would not only eliminate the need to drill holes in the frame, but also give me a much more convenient route for the air lines.

I started by marking circles on some flat stock and hacking it out with my plasma cutter. Then I used the bandsaw to trim the edges to the line. I drilled a center hole in each of the four plates and then stacked them together with a 3/8" bolt I'd center drilled. Set it up in the lathe with the live center snugged up tight to keep the turning tool from yanking the whole mess out of the chuck. Several passes later, I had some nice round plates that would form the tops and bottoms of my spacer assembly. Two plates got the hole pattern for the top of the bag - including the opening for the 90* air connector. The other two only needed the 1/2" hole to match the location of the original in the frame used by the coil spring retainer.

Next step was to cut some angle to form the vertical supports. Milled them all to 2" lengths. I figure three supports arranged 120 degrees apart should be more than adequate for the job. Welded them out, cleaned up everything in the blast cabinet and trial assembled them on the bags. Looks like it will work okay. I've ordered some stainless reducer bushings for the air fittings and will post up a photo of the final assembly.

[Vic1947]

Here's a couple of photos of a spacer on one of the bags...

[SamsAutoParts73-87]

That is some excellent looking fab work!
-Sam

[jlsanborn]

Very cool! Stainless? Weld bead looks a goldish color?

[Low Elco]

Slick mount job!

[mcbassin]

Excellent work as always Vic. I must have read wrong earlier when I thought you were making bushings for your U-bolts.
I just saw the picture and it looked like a U-bolt hole.

[Vic1947]

Originally Posted by jlsanborn

Very cool! Stainless? Weld bead looks a goldish color?

Hey, John. Filler rod is silicon bronze. I like to use it when I need to minimize the distortion or draw. It's not quite as sturdy as a steel alloy, but there should be very little tension or shear on the parts, mainly compression.

[Vic1947]

Originally Posted by mcbassin

Excellent work as always Vic. I must have read wrong earlier when I thought you were making bushings for your U-bolts.
I just saw the picture and it looked like a U-bolt hole.

Thanks, Mike, I figured that might be what got you off track. All three holes do look the same in the stock trailing arms.

[Vic1947]

Originally Posted by SamsAutoParts73-87

That is some excellent looking fab work!
-Sam

Originally Posted by Low Elco

Slick mount job!

Thanks, guys. Engine swap is looking good, Chip! I don't have a Hurco, but if you need something whittled out quickly when the crazy train starts barreling down the tracks, just let me know.

[Low Elco]

Thanks, I appreciate it. I couldn't begin to pay you back as it is!

[Vic1947]

Installed the bags temporarily in the rear and set it back on the ground. Front is shaping up to be a tester. Right off hand, it looks like the 7" OD bags are too big for the space. AZ Performance sells that size with their kits, but it really looks like 6" would be a better choice. It also appears that the bolt-on, stock style sway bar is going to have to be converted to a link setup. I think I can cut the ends, drill and tap them and mount heim joint links to a relocated boss on the A-arm. Removing the pad where the sway bar mounts would free up some space and make it more feasible to run the 7" bags. There's still the problem with the upper mounting plates though. Right now it looks like they locate the bag too far to the rear for my custom A-arms and will rub. I need to call Travis tomorrow and see what he recommends. Nobody said it would be easy.

[Low Elco]

You already know this, I'm sure, but everything I've seen saysgo big as you can on the bags. Doesn't someone sell a "cup kit" that you could use to clearance/reinforce the arms? 'Course, a chunk of 8" pipe and one of your plates, plasma plasma bang bang, you're there.

[Vic1947]

I've run into a problem with the lower control arms. The PO had installed a set of tubular arms with dropped pockets to lower the front end statically. They allow about a 2" drop with a stock height spring. When I talked to Travis at AZ Performance this morning, he said that style control arm doesn't work well with air bags. He also strongly urged me to find a way to use the 7" bags as anything smaller would compromise ride quality and limit the range of the front suspension.



I could tell before I even removed the first control arm that it would take a lot of re-engineering to fit the bags in the existing arms. Upon removal, I could see that the existing spring retainer isn't centered. I'm guessing the a-arm was built to add additional caster. That might be one possible reason the spring isn't more centrally located. Regardless, in order to make this work, I'd have to shift the lower and upper bag mounts about 1.25" forward of the factory spring centerline.

Travis said the bags and mounts are really meant for a stock lower control arm. So, the hunt is on.

[Low Elco]

Well, hell. I was at the yards today, coulda got ya a buncha them. Anything I can do, lemme know.

[Elliot949]

Coming tomorrow Vic... Can't wait to see this truck... do you need anything from Classic Parts?.. I will be there in the morning...

[knomadd]

You could go with Porterbuilt arms! I'm running their lowers with a 1" forward offset. The set moves the wheels forward in the wheel opening by an inch if you do both upper and lower, but about 1/2"-3/4" with just the lowers. Stock arms would be cheaper though.

I'd send you mine, but one is beat up. If you feel like straightening one of the bushing mounts, and replacing the ball joints/bushings, I'll let you have them for the cost of shipping. Let me know if you're interested and I'll take some pics.

[Vic1947]

Originally Posted by Elliot949

Coming tomorrow Vic... Can't wait to see this truck... do you need anything from Classic Parts?.. I will be there in the morning...

Way cool, looking forward to it, Dan. I'm good right now on Classic's stuff. However, I'm sure I'll think of something the moment you get here.

[Elliot949]

I will keep you posted when we are actually at CPA.