73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Brakes, Frame, Steering & Suspension => The Lows (Lowering/Drops) => Topic started by: SBC384 on March 16, 2008, 08:17:34 pm
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HEY AFTER I INSTALLED THE REAR DROP MY PINION ANGLE IS NOW POINTED UP A LITTLE WHILE SITTING ?S THE PROBLEM OR CORRECTION METHOD? ???
THANKS
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I am wondering the same: I used the drop shackles/hangers and got a 4 inch drop in the rear. Can I use the same wedges they sell at 4x4 shops? The pinion correction blocks?
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Yes the same shims are used. You want about 3.5 -4 degrees on the pinion.
Generally you see this when using shackels/hangers.
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3.5-4" DOWN I ASUME...
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O YEA,SHOUL THE DROP SPINDALS MESS THE AIGHNMENT UP ? MINE IS...
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Yes, you need an alignment after any suspension changes.
BTW turn your caps lock off.
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i have 2 degree angle shims and its still up slightl should i put 2 more ?
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If you are guessing, you are not going about this correctly. You need to put an angle finder on there and get the measurement. I haven't ever had to use more than 1 shim.
BTW, the yoke should point up...
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the angle at the back on top of dshaft should be the same as the angle at the bttm of the dshaft at the front , right ?
also thought the angle shoulb be slightly down on rear end yoke due to the rear end turning upwards during acceleration?
thanks for the help...
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The engine trans should point down about 4 degrees and the pinion should point up 4 degrees.
You actually get more bite running the pinion lower on the track but it will kill the u-joints. The point this way to keep the u-joints in phase.
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Chris, You should have a PM. If you don't please let me know. Lorne
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PM ? sorry not sure ? u mean
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I got it, that was a typo. It should have said lower not higher.. I corrected it..
PM = Private Message...
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The pinion angle is the difference in the angles between the rearends pinion yoke to the angle of the
trans/transfercase output shaft. the driveshaft is the straight line that connects the dots. Your pinion angle is going to change anytime you change anything regarding the rear suspension or trans mount.
Get a protractor and measure your angles before you start shimming things. If you post your results here we can help get you set up. you're going to want a negative pinion angle.
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Lorne no PM.... I HAVE AN ANGLE FINDER WILL TRY IT TOMORROW.. OH YEA AFTER I LOWERED IT THE DRIVE SHAFT WONT GO BACK IN ABOUT 1/4 TO 1/2 " TO LONG
THANKS FOR EVERYONES HELP KEEP IT COMING €!!!!!
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how did you lower the rear?
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Where do we take the measurements at?
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hangers and shackles 4"
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Sbc & Others, The PM was for Chris. The pinion angle can be measured several ways & with several (special) tools. The most common for average guys is to put an angle finder on the backend of the transmission output shaft, you will get a number, say 92*, write that down, now go to the rearend & put the angle finder on the flat across where the U-joint straps go, this is where it gets a little tricky. I'll try to explain so it's understood, you want to read from the other side of center if your finder reads 180*(if you were looking at the tool from the Right at the transmission, when you put it on the rear, look at it from the Left. On angle finders that read every 90*, you have to be careful, the one number is really less than 90* & the other the more than 90* unless the vehicle is perfectly in line (which it won't be or shouldn't be). I hope that makes sense. The ideal condition is to have the two angles added together equal 180*. This is for normal everyday, most manufacture, ect. use. This is what Capt. was getting at & is correct. In vehicles built with other goals, (lifted real high or a low vehicle with big rear tires) some compromises may have to be made to keep the U-joints from binding. In a vehicle being set-up for drag racing, the pinion should be downward slightly from this equation (varying amounts due to how well the suspension controls the axle rotation) so the driveline is straight under power (this is the most efficient), however if used at steady speeds on the highway, most likely will have noticeable droning due to not having the "break" between the tranny & rear.
Sbc, If your driveshaft is slid all the way in & you can't get it in the rear yoke by a 1/2", the shaft was too long before you lowered it, lowering it (to some point) does make the distance shorter, but not to that much of a degree in 4". Any questions or differences, please speak up. Lorne
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i already have 2 degree wedges under leafs & rear end yoke is still pointed up to much what to do now ?
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Sbc, I see 4* shims from Lakewood @ Jeg's pt# 620-20510
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should they go in from front or back to make rear end angle go down
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Sbc, Your axle is still on the bottom of the springs, correct? If so, The wide end would go in the front. Lorne
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thats the way ii have them they are the wedges from jegs still pointing up.....confused.............
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Sbc, What numbers are you getting? The pinion could be "straight" & still be correct depending on what your getting at the transmission. My original rear lowering plan was: I moved the bed floor brace & installed the dropped shackles, removed the original rear hangers from the frame & let the jack down until the shackle was 1/4" from the bed floor & drilled new holes in the hanger. Then I removed the front hangers from the frame & let the jack down until I got to where I liked it. The rear angle ended up at -4* so I left it alone. The simple way to fix your problem if your ok with the rear of your truck a little lower is to do the rear hanger. Lorne
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still need to get the rear end yoke down ... has anyone ever heard of cutting the leaf pads then getting the angle you need then rewelding them? (SORRY)
thanks
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How are you measuring your pinion angle? Are going off of true vertical from horizontal with the truck down on it's wheels? Are you then comparing this to your driveline angle from the transmission? What is your actual pinion angle measurement?
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Sbc, Not to be Post Patrolman, But it would be easier to follow & you may get answers to your questions (front brake pads) if you keep the posts separated. I thought it was good to start a new post about the pinion angle, but there is allready 2 pages in your spindle post because you asked there & now your asking about front brake pads in the pinion post. Maybe Chris can move the pinion angle part to this post, it would make it easier to follow what has already been discussed. Just a thought, Lorne
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is it ok to stack the pinion angle wedges to acheive the desired angle?
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I certainly wouldn't. Again, how are you measuring your pinion angle? I don't understand why it's so far off.
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Do not stack them.
You need to tell us what your numbers are when you measure them and how are you getting them. A shackle flip shouldnt ever need more than 1 2 degree shim for correction. The pinion is SUPPOSE to point up so if you are trying to make it parallel with the ground, you are going about it the wrong way...
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i dont have the first short stiff spring in doest it make a differance ? checking pinion agle now bbl
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The helper spring makes no difference at all...
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i put the helper spring in and took the first spring out with the the 4* wedges installed now the rear end angle is 4* looking up
but im sittn on the bump stops pretty hard... going to put other spring back in tomorrow
ounce again thanks for all the help despite all the remedial information im giving yall.. Chris
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Sbc, Something is a miss here. I had asked before, your axle is BELOW the springs, correct? My truck is lowered more than 4", more like 5". I still have a little over 2" till the bump stops hit the axle. Is there alot of weight in your bed? You had said "The driveshaft won't go in". This all sounds like too drastic of problems for hanger/shackles. I'm wondering if someone had done something to the truck before you got it (lowering springs,axle flip)? How are you coming up with the + 4*number? It's not impossible, but just doesn't seem right. Lorne
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I REALLY would like to see a visual of what we are working on too...
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axle is under springs...with the angle finder shows 4* it was on the bump stops because i had to many leafs out.. put them back in looks to be fine i guess i was thinking angle should be down more.. will know more the weekend when i have more time. will try to get pics kaos..
thanks again
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Sbc, Are you saying when you put the angle finder on the rear yoke, it is 4* from 90?
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yes, angle is slightly pointing up. hey read my post in 73-87 trucks section under rotors
thanks
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Ok, Are you sticking the angle finder on the end of the yoke, then rolling it out on the top...1-2-3-4* & now it reads 90*? If so this isn't correct. The pinion angle has nothing to do with the ground,level,plum,horizontal,vertical & the like. As was mentioned earlier, it is the angles of the transmission output shaft & the rear end pinion. The vehicle needs to be on the ground (or the axle supported by stands). Now once you get the sum of the two numbers to equal 180* (ideal) For a drag race set-up with leaf springs, the pinion should then be rotated down 4-6* from this point, as I said earlier, how much depends on how well or poorly the suspension controls the rotation. I hope this gets you going in the right direction. Lorne
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As Haulin it, said, the floor has nothing to do with this. It is the drivetrain angle you are working with not the floor. If you are getting 86 degrees pointing up, you are only halfway there...
I would put it on jackstands and pull the driveshaft.... But, you can measure off the face of both, with an angle finder on the output seal flange lets say you come up with 86 degree (trans is pointing down) that is -4 degrees drivetrain angle. Then go to the rear yoke and put the finder across the u-joint saddle (driveshaft should be removed) and it says 84 degrees (pointing up) that is +6 degrees. Then add the 2 together -4 + +6 = +2 degree pinion angle, for a leaf setup you would shim it up 2 degrees so you would have the pinion +8 degrees.
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thanks guys going to work on it more tonight going to pinks all out tomorrow
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Chris, Meaning no disrespect, but I'm not sure I agree with your last post. We go about how we get the numbers a little different, so I don't want to say "your wrong!" however the numbers aren't adding up. The way I've always figured it is in a "normal" vehicle the sum of the two numbers should always equal 180*. As I stated earlier, on highly lifted 4x4's this likely is not possible because the U-joints will bind. Also on a "pro street" type vehicle, the same problem only reversed. The real problem I'm having is with the +8, this to me is incorrect. How you went about getting the +2 on the surface seems ok, just not the same way I do it, or relate to it. On a drag race set-up, the pinion should be, again, depending on the ability of the suspension to control the rotation, DOWNWARD from the "equal to 180 number" (about 4-6* on leaf spring vehicles) not necessarily downward to the ground or looking at it, just downward from the "correct phasing". Say you come up with 88* at the transmission, the rear end (assuming you don't want/need to move the transmission) has to be 92* to be in "correct phase", from that, the pinion should be DOWN 4-6* from this point to allow for the rotation upward of the axle as the power is applied, ending up ideally straight with the driveshaft, again this is not ideal for normal vehicles (some droning likely will occur) at a steady speed. Where's Vile with "proper procedures for pinion angle" out of some manual? There is always more than one way to skin the cat, there are other "special tools" that go in the U-joint caps & take the reading differently, ect. I'm just not sure we are all on the same page here. On another note, I feel the pinion angle itself can not effect traction (like many believe) unless it is so far off it binds the U-joints & stops the rotation of the axle, it's the changing of the pre-determined amount of rotation (suspension changes) that effect the traction. Feel free to all to agree, disagree, comment, ect. As I said Capt, Please don't take this to mean anything but to clear up a few things. Lorne
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Where's Vile with "proper procedures for pinion angle" out of some manual?
Excuse me dude, but if you are insinuating my knowledge comes out of some pop up book you're mistaken. I'm not the one photo copying and plaguerising everything in text be it internet or your old how to books. All of my information comes from my own knowledge and I rarely quote print unless I'm copying and pasting a service procedure, TSB, or spec's. I don't know why you are dragging my name in here only to take pot shot's because you still have a diaper rash over your last rant or something. ??? Stop trying to sound like a know it all and put it in plain English with a viable procedure if you really want to help this guy set his pinion angle. There are many simple methods of checking pinion angle. It's a simple comparison of the 2 connecting driveline angles. Spend a little less time trying to be Mr. right and try to be Mr. Helpful here Lorne.
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ive got 85 on rear end and 95 on tranny = 180 is this going to work?
thanks
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Vile, No sir, You misunderstood me, Again. I have commented before about how well you do produce GOOD VALUABLE information & say it in a way that can be understood. I was sincere in asking for a little help! Yes, We had are differences on the port match thing, I hoped that was behind us. You obviously have ALOT of knowledge & come up with very good wiring diagrams, ect. all the time. The other day you posted info about the Trailblazer 4WD problem & I thought "wow!" Great info at a moments notice. I don't really get you, I think we are really both just trying to help other guys with similar interests & learn a little as we go. I feel the Capt. & I are not seeing quite the same & want to either help them understand it better or maybe I don't do it/think about it the same way as others. If anyone has the "rash" it must be you. I'm fine, I would like very much to get along with EVERYONE on here, including you. I PM'd The Capt. & explained my thought & asked him if we should/could talk about it in the post & he said Ok. RELAX a little Ok? Lorne
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Well Lorne, it certainly sounded to me like you were rippin on me stating "Where's Vile with "proper procedures for pinion angle" out of some manual?" but if that wasn't what you meant then I sincerely apologize but you surely didn't come across that way. If you wanted help explaining it why not just ask? I have no grudge with you but I read what you wrote 5 times and it came across to me as a cheap shot. Again if you didn't mean it like that forget I went off please.
There are zillions of how to's on setting pinion angle and no need to reinvent the wheel. There is no set specific way to do this and you may find one pinion angle works better than another. I must agree unless there's a severe pinion angle it shouldn't effect traction. A pinion angle finder will make life easier and will probably come with recommended instructions http://www.tunerschoice.com/xq/aspx/dept_id.354/display_id.689/qx/Product.htm
Articles
http://www.wolferacecraft.com/pinionangle.aspx
http://www.stu-offroad.com/axle/pinion/pinion-1.htm
http://www.ssz28.com/tech/Pinionangle.html
and so on
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did you guys happen to see the numbers i posted? 95* and 85* is that going to work??
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Sbc, You'll have to wait a moment we're about to kiss & make up. No seriously, that sounds like you are on the right track now. How did you achieve those numbers? What did you do different or change from before? If this is a drag only truck, I would lower it a little more if you can easily, if not, it will probably live as long as your springs aren't too soft & allow it to roll up a bunch. Lorne
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drag truck only, 85 on tranny rear seal and 95 on rear end + or - a * only reads in 5* increments
thats with the wedges? what do u think?
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Run it! You really need an angle finder in 1* increments for doing this, but it sounds like your in the ballpark. That's what is tough about helping over the internet, what can be shown in a few moments sometimes takes many posts. Did you get you driveshaft length figured out? How much lower is the back of your truck now than it was prior to the shackle/hanger install? Close to the 4" as expected? Lorne
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thanks guys! driveshaft should be ok yea its about 4"
i'll halla