I know... You are a wonderment to the aftermarket auto industry. May I kiss your ring? If you feel you are doing it correctly, why are you letting your post eat at you? All you had to do was offer your opinion. Of all the posters on this thread, is there any particular reason that you chose me to vent on?
pinion angle discussions always get nasty. lol.... here's my bottom line: 3º down at the trans & 3º up at the differential. i can't imaging anyone having problems with such a setup...
I had a vibration in three cars I owned (at the same time) and figured I had screwed up and was doing something wrong (not hard to imagine ) ... turns out the cause of the vibration on all three cars was the wheels. I made up a jig that allowed me to use a dial indicator to check the wheels for up and down and side to side runout and they were all JUNK ... total CRAP (I had three complete sets of 80-81 Z28 steel "5-spoke" wheels, 1 1/2 sets of the std "Corvette rally" wheel (15x7 and 15x8), and around 6 full sets of Cutlass rally wheels from the early 80's. Every single one of those wheels was garbage). My suggestion is this ... if you are correctly checking pinion angle and the numbers are good (say "3 degrees down and 3 degrees up") that would suggest to me that your problem lies elsewhere. Hey Dragsta ... good to hear you made it to Florida.
i have to agree with Da Tinman, thats kinda industry standard for building cars, lol, and he has prolly build more cars than any any one on this post. he just smells funny, and has a big pussy
I worked full time in racing for 15 years. The company I worked for built about 300 oval track cars a year, and our customers literally won 1000's of races each year. With a 3 link rear end, we set the pinion 3 degrees down. Under acceleration, the pinion will come up. You might not need 3 degrees in a street car, but I don't think up is going to work. It sure won't give you any traction. I have read all kinds of stuff written by engineers and their theories on this and a lot of them are way out in left field, but I guarantee you this: A high horsepower car with the pinion at zero or up is going to have a hard time hooking up all else equal. Marker
None of the above matters. Put you motor where you want it, then make sure your rear axle pinion face is parallel to your tranny pinion. It matters not one iota what the angle in relation to the horizontal is, as long as they are parallel. There is a school of thought that states they can be opposite angles, rather than parallel, but we won't go into that here.
While the discussion seems to primarily have turned into a pinion angle seminar, that may or may not be your problem. Some of the other posters gave you some other things to look at; so here are some ideas to look at: 1. Take your driveshaft to a truck shop that specializes in making driveshafts and balancing them. Have them check it for straightness and balance. Put in good u-joints like Spicer etc. 2. Have your wheels and tires balanced. Are you running old spoke wheels? Are they straight and round. These can be hard to balance. Mock up your wheels without tires and check them with a dial indicator for side to side run out but more importantly on the circumference. Thirty thousands runout is a lot for a racing wheel, but if you have .060" remember that is almost 1/16" so run out can make a difference. It may take an "old timer" to balance some old wheels. Some times old age and skill overcomes the computer balance! 3. Is your ring and pinion making noise? 4. Transmission? 5. Do the cars start out vibrating, or start to vibrate after a time. I had a truck where the heat shield to the exhaust fell off, shortly after the truck developed a vibration at highway speeds. Turns out the heat from the exhaust started to produce slop in the driveshaft/components. The heat shield was there for a reason! 6. Are you using bias ply tires? They may have a tread noise at a certain speed. 7. Is there one thing these vehicles share in common? A key part transferred from one vehicle to the next? Maybe someone else has some other areas for you to look at or things to try. Hope some of these help. Good luck! Marker
This is clear as mud! But if you do all that up and down shit as parallel canceling angles - what about the offset of a 9" when viewed from above? Should you angle the engine slightly to point at the pinion yoke? or is it also parallel canceling angles? Just to add to the muck...
I have no concern how you do it. I have even less concern that you continue going about it as you do. My only concern is that you are not a tech in a shop or build cars. The above line was quote from Kultulz And what concern is it of yours? I am not a 'tech' in a shop, my hands get real dirty and i do build Top Sportsman; ProMods and Funny Cars - when i give advice it is from hard earned lessons. I don't refer to quotes from 'Car Craft' or other tech articles nor do i regurtitate second hand 'information'. And i when advise you to do something you'd be very smart to grab a fucking wrench and start making changes - you sound like that dumbassed knowitall i ran out of my shop last monday that knew all about how to build a 1000hp mustang he just needed somebody to do it for him. You are close enough to know me or of me, i'm the guy that broke the track record at 75-80 with under a 4.30 pass. I know a thing or two about pinion angle for sure.
Uh... Can you either provide a direct quote or post # so I can see what I supposedly posted? OJ... or Mr OJ... This is not the only board that this subject has neen beat to death but is the only board where most all are master vehicle designers/builders and all seem to have completely different ideas concerning a fairly simple subject. I was also not aware of your world wide renown building accomplishments. As soon as you provide the subject post I will reply. I post TECH ARTICLES to show a certain train of thought. If CAR CRAFT is wrong, they will be challenged. I suggest you contact them and explain to them in no uncertain terms why their tech contributors are wrong. I do not see you with a publication offering your theories. Nor have I noticed any SAE papers authored by you. As soon as you can stop patting yourself on the back from past life successes, please direct me to my post and not just hearsay from you. I bet you are also retired ex-special ops also. BTW- I doubt I would ever seek advice from you.
Too bad, my advice is freely given. btw - check my photo gallery of cars i have built, you might recognize one or two - they might be in those magazines you read.
You shouldnt level the frame if it doesnt ride level... Put the vehicle down on the wheels and point the pinion right at the tail of the tranny or the front part of the drive shaft, then angle the shaft 5deg down. This allows the Ujoints to lubricate and it allows for axle wrap when the pinion jumps up from a heavy foot.
oj, I have no idea of why that post put a burr under your saddle. I was responding to another nationally known car builder. Where did I personally attack you? As for car mags, I have not read one since SUPER FORD went out. GM causes me to break out. I am old and what I learned during all of those years is what will stay with me. If I offended you in any way, I apologize. But even you must admit that there is a setup for competition and another for a street vehicle. The whole damn subject is not all of that damned complicated.
Wow... something so simple cam get way out of hand! I keep seeing opinions about how level the carb should be and making sure the frame is level.... none of that has a thing to do with the driveline angles. One person was correct in stating this! Pure and simple.... if the CS centerline, driveshaft and pinion are in a straight perfect line, it will vibrate. Someone else kept mentioning "working angle" but never clearly defined it. There HAS to be at least 1 degree angle difference in at least one of the u-joints to create this working angle. In other words, if everything is in a perfect line, adjust the pinion up or down 1 degree. If the engine sits higher than the pinion (elevation NOT angle), there is already a working angle going for you. The crankshaft and pinion need to be as close to the same angle as possible for a street driven vehicle. There have been some nice illustrations posted on here but no explanation to go with them, but the one Buzz4041 posted is the best and if you look at the relationship between the different illustrations the working angle becomes quite clear. And notice that no where in those illustrations does it mention WHAT angle the car is sitting at! But the vehicle must be sitting on the ground to measure everything right! Pinion down on a drag car... as much as 7-8 degrees in some cases.
The older style tool to check driveline angle sat on the the driveshaft and measured the angle of other u-joint cap that was fixed in the slip yoke or companion flange. It never measured engine or pinion angle but you were working from a factory car. For an illustration of working angle try Mark Williams tech page.
And this surprises you with all of these overly qualified builders? My first post (and this will be my last as the fairy tales keep coming and getting all the more ridiculous) refers to TRIM HEIGHT The reference to carb pad level was meant for those that are setting an engine into a chassis. If you cannot comprehend carburetor calibration then there is no reason to go on. One could roll the car over on its' top and set the angle if one kept the compressed suspension height. NOTICE! All CARCRAFT and other tech materials removed as most here are light years ahead of basic theory anyways...
Er, skim read through and tried to filter out all the backchat. One thing I wanted to say, don't measure engine angle from the carb base - it is often slanted relative to the crank centerline. Not quite sure where I stand on some angular pre-load of the diff nose. I think if I has a well located four bar setup, I'd not dial in any pre-load angle. The diff deflection will be minimal under accelleration and decelleration. With a relatively soft sprung parallel leaf setup, it must be tempting to put a little in, maybe just 1 degree. but then what happens when accellerating hard or decellerating? I suppose on decelleration the torque is limited so vibes shouldn't be a problem. I am currently putting a 41 pickup together with a Y Block and 9 inch rear on parallel springs. I will get it at full roadgoing running height and carefully measure the angle of the engine and trans. I will then set the pinion exactly parallel and check the angles are not too severe (shouldbn't be, but I already have an offset pinion so that will inrtroduce some angle from the getgo). I will ensure the driveshaft is perfectly in phase and balanced. If I get vibes when driving along that get slightly worse when accellerating, I will adjust the pinion down a little with thin wedges. And see what happens. It shouldn't be that difficult, should it? Mart.
Quite simply, no, it doesn't. It has to be parallel to your tranny output flange, which is angled down. And as for the noise, that could be outer axle bearings. Does it increase if you go round a corner hard, throwing more weight on the bearing?
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