Hello, Finishing up my radius rods, coil spring plates and shock brackets, I will soon be welding my rear up. I have been told that a pinion should always fall to direct center, but I have seen pinions offset from the tail shaft of the trans. I am figuring that I will make sure axle flage front to anxle flange front are identical measurements from each side of the portion of frame rails over the rear. Basically measuruing to make sure that rim/wheel are both equal distances from the frame on each side of teh vehicle? I have a 65 Tbird, 9 inch, with different axle lengths, which would mean that my pumpkin can or will not be centered? I haven't really measured anything, as the brackets I have been fabbing can slide anywhere I need them, and I have been focusing more on the frontend since I started thyis thing. I figured I would ask any pros for a lesson today before I go down in the garage after laundry for work tomorrow. Thanks, Pork
Same on my 9 inch in my model a. It's from a 78 Ford pickup. Do a search on here and you'll get the whole science behind it.
There is absolutely no need for the pinion to be centered. It obviously was not centered in the host car that it came out of. The only time that centering comes into play is if you are running a narrrow driveshaft tunnel on a channeled car.
The roadster I'm trying to finish has a 9" and the ch***is was built as part of a rolling ***embly by Brookville. They centered the housing bulge, not the driveshaft. As a consequence the driveshaft is offset approx. 2" to the left at the rear U-joint. I'm thinking they have set up lots of these, and this must be OK. I have friends with full on doorslammer drag cars that are on the verge of getting into the 4's in the eigth mile and they center the drive shaft, not the bulge. But they're putting a huge amount of power more than any street car into that rear. The thing would look odd as all Hell from the rear with the driveshaft centered and the bulge offset, since you can see the housing from the rear! Dave
An offset pinion doesn't hurt a thing as long as the axle is square to the ch***is. Manufacturers probably offset the punkin to keep the driveshaft tunnel in the center of the car. Good aesthetics dictate we center the punkin in our roadsters and coupes so they'll look right.
I don't want to start a huge argument on here but, WHAT!!!! are you guys talking about "they dont have to be centered"???? Ever heard about compound angles on a driveline or the vibrations they cause? If the driveline is not centered you will surely need a Double cardin joint in the rear. The reason thet a 9" has diffrent axle lengths is because of the way the axles slip into the carrier. Center the pinion with the ****** and make sure the pinion angle is right this is important. Don't worry about the bulge on the rear. It should be offset. Again I don't want to start ****....Line the pinion up with the Centerline of the ******. Bill
I have a stock early Bronco 9" in my model A truck and the pinion is off the centerline by about a 1 1/4". If I would have centered the pinion the wheels would be offset. I'm sure the rear wheels om a Bronco are not offset from the factory. I ***ume many 9" axles have an offset pinion?
I know of some guys buying a 9" rear end that's a couple inches wider than they need, then narrowing one side of the housing to get the width they need and also centering the pinion at the same time.
The internet is a great source of information, both correct and incorrect. Millions of cars and trucks have been manufactured and driven billions of miles with the center of the pinion offset from the transmission tailstock when viewed from above the car. They have performed with no problem. If this configuration is to terribly incorrect, how can that be explained?
They do not have to be centered. I was worried about this when I was getting ready to put a 9" in my "53 f-100. Then I realized that the stock rear wasn't centered either. Just get your rear axle housing in square and your pinion angle correct. V/8
I have a '69 Ford truck rearend. the pinion is off centered. I measured from the backing plates and noticed a spine, or rib that was the center. I figured it was there for a reason too... My .02 Jay
the straight line thru the pinion and the straight line thru the trans have to be parallel up and down and side to side. .some cars have the engine offset to the side for clearance.
I have seen them both ways. In 57 when they pulled a nine inch to drop in a 32 Ford, I don't think they worried about the bulge being in the center or the pinion being in the center. It was the right width.
I'm not saying that the pinion is in the center of the rear. I'm saying that the pinion needs to be in line with the transmission. Of course the pinion is off center of the rearend.
No such thing as a compound angle with a driveshaft. Regardless of vertical or horizontal offset, there's only one angle.
Early Broncos have the engine off-center to clear the transfer case in the narrow frame, so the axle corrects that somewhat. As C9 said, there is no compound angle, the driveshaft doesn't care if the offset is vertical or horizontal. As long as the transmission output is parallel to the pinion, the u-joints will do their job.
Don't worry about centering the pinion. Center the WHOLE rearend! Unless you are having axles cut to your application you may end up with one wheel sticking out farther on one side. The best way to do this is to string the car. Set the front end up with zero toe and tires pointing perfectly straight ahead. Set strings up that run the length of the car so that they are PERFECTLY parallel to the front tires (distance between the string and the front and rear edge of the rim will be the same). If your rear is centered the measurement between the string and the rear will be the same on both sides. To square the rear the distance between and front edge and rear edge of the rear rim will be the same. Be sure to use the same offsets on your wheels.
All of the so called "technical" arguments that the driveshaft needs to be centered are conjecture and pure malarkey. The function of the U-joint is to accomidate misalignment and changes in alignment. I like the reasoning, Relic Stew, that "the driveshaft don't care."
That is a correct statement if you really get down to the simple facts. But when you work Dana's angle program, they consider the combination of vertical and horizontal angle changes to be compound. So do the guys a their tech services dept, they know me. FWIW, write this down folks, if you want to know how much to move something to get an angle change to what you want, here's your formula. 1/4" change in al***ude at 12" equals one degree of angle. 1" at 4 feet, etc. I use this when I need to correct driveline angles on cars, medium and heavy trucks that have been modified. Having an offset or centered pinion doesn't matter in most cases unless it is a drastic difference, like putting a GM powertrain in a 83 Landcruiser with the pinion offset to the p***enger side by about 12". Had to build a shaft with a 1310 series constant velocity at the transfer case end, and a Toyota CV at the diff end to make the shaft have u-joint angle capability at highway rpms. If the rig only went down the road at 15 mph, it wouldn't have needed to be so complicated.
----------------------- It's a car. Drive it. Get what you want. Work with what you got. Function before bling. ------------------------ 29nash said it all! Even his signature is correct!
There is alot of mis-information regarding 9" housings. I have narrowed hundreds of them so I will give you the facts: -On any 8" or 9" housing, to have a centered pinion, the left side axle will end up 4" shorter than the right side axle, regardless of housing width. -A housing that has equal length left and right side axles will have the pinion offset to the right 2". -You cannot have a centered "pot" which is the portion of the housing that the centersection is bolted to if you have a centered pinion. -You can center the "pot" on a housing, but the pinion will be offset 3/4" to the right and it will require custom length axles. -The only reason Ford used equal length left and right side axles on some vehicles was as a cost savings measure where driveshaft tunnel clearance was not an issue.
In an ideal world your poinin will be centered in your ch***is. You have different length axles because the pinion sets to one side of the ring gear. Measure from your axle flanges to the pinion to see if it is centered between your flanges. But even if it isn't unless your drive shaft is only about 12 inches long you shouldn't have a problem. Granted if it is off by a tone you should try and get it a little closer to the center. Yes set your wheels centered on your ch***is. Some really particular builders set the rear first then set the engine. That way they can offset the engine to get everything centered up. The rest of us just live in an unperfect world.
the reason for the offset pinion angle is for the u-joints to move around,if they don't move around they'll burn up the needle bearings in the cap,Ford offset the driveline to keep the caps moving,Mopar offset the engine,etc...this is common,the only reason for driveline vibration is due to,a bad u-joint,driveshaft not balanced,engine driveability vibration(misfire,wrong flexplate,etc)I've seen some pretty extreme driveshaft angles on lifted 4X4 trucks that were smoothe on the road.
No such thing as a compound angle on a driveshaft???? On several Rock crawlers that I know of for a fact including mine. If the pinion is not in line with the ****** and your pinion is lower than the ****** or above the ****** it is a compound angle
Offset pinions to reduce U-joint wear? I don't know about that,many vehicles have no offset and slight driveshaft angle and the u joints last as long as anything else.Yes,I know there's a theory about needle bearing needing to roll around, but in real life it may not matter.
Here's the deal on why you have driveline angles and excesses. A universal joint needs to have at least 1/2 degree angle going through it to make the needles rotate in the cap. Maximum operating angle is determined by what rpm the shaft operates at. Dana says, for maximum u-joint life, that a shaft that spins 5000 rpm can only have 1 1/2 degrees through the u-joint. 1500 rpm, 11 degrees operating angle. Most Chevy pickups have same length axles on both sides. Most Ford pickup axles are different for each side. But, 2" of offset at let's say 5 feet of driveshaft length isn't much angle change to worry about at the speed typical road cars operate at. Pinion angle, engine/trans angle, and driveshaft angle are more important. If the vehicle has two or more shafts, it's critical--sometimes one degree angle change will make the difference in keeping transmissions and differentials together, u-joint angle problems causing the driveshaft to vibrate bearings apart and causing gear wear.
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