well its in and bolted up, but the pinion angle is pointing at the north star, everyone said the 72- 9 inch would bolt right up and they were right on the money there, nobody said anything about the perch mounts in the wrong place, the shock mount I knew about already and I haven't even looked at the drive shaft yet,, im working on a 48 Merc truck flat head 8...….. any feed back out there, maybe someone been down this path thanks
I thought I was going to have the same problem with my Pinto build in 1977, 289/C4. I used the hooker header kit for the build and the instructions said that a 1959 Ford, 9" rear end would bolt right up. And it did. I had no pinion angle problems. None at all. Has nothing to do with your build but I thought it might help in some way. I guess if you realign your perch mounts that it might help your pinion angle.
Sounds like you have parallel leaf springs. You can adjust the pinion angle by either making the front shackle longer or shortening the rear.
It might help us help you if you are a little more specific about how far off the angle is. The north star is kind of vague...is it off by 30 degrees? or five or ten? Do you have the equipment necessary to cut off the perches and weld them on the correct angle? and to measure the angle? We love pictures, too...
Get it on it's wheels and with all the body and other parts on the truck( deck fenders etc etc. before you decide to change anything. The pinion angle will change as the springs load up and the shackles rotate some. DON'T PANIC YET!
Stop ! Don’t go into a melt down yet ! As stated load your springs with everything and put it on the ground with wheels , you will see you are correctly looking the right direction . I have done this swap 3 times , it will work correctly for many a fun mile .
You don't want 0 pinion angle. It will destroy u-joint bearings. Here's some research. https://www.jalopyjournal.com/forum...how+to+set+pinion+angle&o=relevance&c[node]=5
As 97 And Deathrowdave said, don't do anything with it until you have all the weight of the truck sitting on the tires/axle to see where it is actually going to be when all is said and done. When it is all setup the angle of the output shaft on the trans and the pinion shaft should be on parallel lines if you were to draw lines though both of them. You don't want them in an exact straight line but you also don't want them at non parallel lines with single U joints on each end.
I like to point the pinion down about a degree from parallel, to make up for the axle housing torque reaction when you are driving.
Squirrel is correct the pinion wants to climb the ring gear. So a bit of downward angle might be needed in some applications. I set the 9 inch in my 55 parallel with the trans. however The rear shackles can be adjusted up or down as needed. I haven't got that part sorted yet. I probably will add some weight to the rear. Unsprung weight is dead weight. and weight on the front 25 to 35% of the vehicle is dead weight. Sprung weight at the rear helps traction. IF more rear sprung weight is needed Old valve covers filled with lead bolted as far back as possible help traction.
this is great info while I got ya all here another problem , dana 41 drive shaft to short and yoke to small ,what has every one done
...yet they generally run a long time if you don't get it straightened, and you don't go crazy with the welds.
To check if any axle or rear is straight . You put a set of matching bare rims on it. Set it in a known to be straight H beam if you have 4 contact points on each wheel its OK. Never had to straighten any rear when I welded spring perches.
On the U joint, the diameter of the U joint cup is what's important, not the center to center on the U bolts. Also the width of the U joint. Likely going from 1310 to 1330. 5-134x is the number
Truck shops have caster shims tat you can use to help set your pinion angle if it's not to far off but you are going to have your car loaded. Google Truck Caster Shims they came in different degrees. So you can adjust your rearend if it's close you won't have to cut and weld on your housing
There is only one way to straighten a rear end properly. You have to have 4 plugs to fit the bearing pockets. 2 at the wheel end and 2 for the carrier bearings. These have to have concentric holes that fit a precision ground bar that goes through all 4 if the rear end is straight. I used to build the 9 inch rear ends for Penske Racing and after you build a few, you learn where, how and when to weld to keep warping to a minimum but they ALWAYS warp no matter how little you weld on them.
It's pretty easy to tell if a Ford 9" (or 8" for that matter) housing is warped. If the axles will pull out or install with hand effort or light prying to pull or light tapping to install, it's straight enough to use. Slide hammer to remove or serious beating to install, it's bent enough to shorten bearing life. Make sure the bearing bore in the housing is clean/undamaged before deciding, and the third member needs to be in place.
I use a big precision ground bar like Pete mentioned - first of all it helps me ensure that my setup is correct (before tacking housing ends in place), second it lets me test/see how much misalignment is going on. You put the inner carrier bearing pucks in first, then slide the housing ends (with the puck inside them) to setup the alignment - making sure the pre-weld fitment is spot on. Then, you take the pucks back out after all your tack welds and weld it up. Afterwards, you see if the pucks will easily slide back into the bearing ends - you'll probably find that they won't - so the housing needs straightening. If you're ordering a new 9" housing - do all the welding on spring hangers, shock hangers, traction bars, panhard bars, etc - BEFORE you weld on the ends -- then do the ends. If the housing is already together, then use the alignment bar to check for straightness before/after welding.
Here are some pictures of my home made jig for narrowing rear ends. The cut off rear end "ends" are bolted or clamped to the outermost uprights. They are bolted on the inside surface of the uprights. That means that when I measure each "side: of the upright and get the same dimension, the ends will be parallel to each other and perpendicular to the center housing. The center uprights simply support the main housing and the dummy centersection. The dummy centersection has bushings which fit where the bearings would go, but are bored to accept the diameter of a long round bar. The bar passes thru the dummy rear and extends thru each "end" of the housing and on thru some bored holes in the outer uprights. About the only thing I have to do is measure the end jig uprights for parallelism and everything is in alignment.
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