CC57 Posted August 20, 2010 Report Share Posted August 20, 2010 What do you recommend for the Pinion Angle for the Pro Trucks? Thanks all Link to comment Share on other sites More sharing options...
Truck99 Posted August 20, 2010 Report Share Posted August 20, 2010 Pinion angle tends to be one of those areas that people love to argue about, so I hope we don't stir up a hornets nest here, but IMO, it's not that critical so long as the angle you use keeps the u joints in good functional alignment. In other words, don't look at X amount of angle to give you help with forward bite. If you have anywhere from 4 degrees down to level you'll be fine. Oops...on edit: sometimes my brain is still stuck in our leaf spring days. The above should have said "2 degrees down." Link to comment Share on other sites More sharing options...
trk31 Posted August 20, 2010 Report Share Posted August 20, 2010 Pinion angle tends to be one of those areas that people love to argue about, so I hope we don't stir up a hornets nest here, but IMO, it's not that critical so long as the angle you use keeps the u joints in good functional alignment. In other words, don't look at X amount of angle to give you help with forward bite. If you have anywhere from 4 degrees down to level you'll be fine. BZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ ZZZZZZZZZZ, thats the sound of a hornets nest. Link to comment Share on other sites More sharing options...
Truck99 Posted August 20, 2010 Report Share Posted August 20, 2010 OK, this should get it going really well: Does pinion angle produce forward bite or is it a product of forward bite? Ready......go! Where are you Nick? Link to comment Share on other sites More sharing options...
jwmbishop Posted August 20, 2010 Report Share Posted August 20, 2010 I have always started with pinion angle equally opposite to the trans output shaft angle (ie if trans shaft points down 2deg then pinion should point up 2deg) - tune from there. More fwd bite (and\or increased HP) will increase pinion angle (axle wrap effect) under acceleration - ideally you are equally opposite under full throttle (parasitic Horsepower loss occurs when the two angles are not equally opposite), allowing for both wrap and geometry changes from squat - static should not matter (As long as the angle is not too high - decell "un"wrap should not create any u-joint bind). Link to comment Share on other sites More sharing options...
Pacecar Posted August 20, 2010 Report Share Posted August 20, 2010 The trucks are a special case on LoneStarSpeedzone. They're different from the rest of the racecars.....just re-read their posts. Link to comment Share on other sites More sharing options...
Truck99 Posted August 20, 2010 Report Share Posted August 20, 2010 The trucks are a special case on LoneStarSpeedzone. They're different from the rest of the racecars.....just re-read their posts. They (we) are definately "special." Link to comment Share on other sites More sharing options...
Adam38 Posted August 20, 2010 Report Share Posted August 20, 2010 More pinion angle creates a faster bite but if the track has no bite it will break the tires loose faster. If you run less pinion angle it wont be as fast of a feel for forward bite but it will be more forgiving on a slicker track. Im running 4 degrees in mine. Link to comment Share on other sites More sharing options...
jwmbishop Posted August 20, 2010 Report Share Posted August 20, 2010 Does pinion angle produce forward bite or is it a product of forward bite? Both. They are definately inter-related! My belief is that the amount of traction available (FWD Bite) is a product of the surface (texture and composition) and the tires (compound, pressure and temp). The pinion angle affects the rate of tractive increase (the amount of time it takes to go from no fwd load to full fwd load without slip). In other words as you step on the go, a pinion angle that is less than equallyopposite the trans shaft angle wil take more time to go from no to full w\out slip load - and thus be more forgiving of anticipatory throttling (going to WOT too quickly), while a pinion angle that is more than equally opposite will go from no to full so quickly that you loose feel for the break loose point - in other words you feel like you have less traction as it breaks loose much quicker. And this is because you are tuning the parasitic horsepower losses inherent in u-joint alignment. Anyone who sets up machinery knows - the straighter the line under max load - the more power gets transfered thru the joints! And yes - as the track and tire temps change so does traction and thus pinion angle under throttle load! Picture axle wrap with a good surface and picture axle wrap in water. To get an even better idea picture a dragster doing a burn out (low traction) vs launch (high traction). The wheelie is very representative of bite affecting angle, while the burnout is angle affecting bite! Link to comment Share on other sites More sharing options...
Truck99 Posted August 20, 2010 Report Share Posted August 20, 2010 More pinion angle creates a faster bite but if the track has no bite it will break the tires loose faster. If you run less pinion angle it wont be as fast of a feel for forward bite but it will be more forgiving on a slicker track. Im running 4 degrees in mine. Can anyone back up this idea with actual testing data? I sure can't. Link to comment Share on other sites More sharing options...
Blue Moon Motorsports Posted August 20, 2010 Report Share Posted August 20, 2010 The trucks are a special case on LoneStarSpeedzone. They're different from the rest of the racecars.....just re-read their posts. They (we) are definately "special." And how..... Link to comment Share on other sites More sharing options...
Adam38 Posted August 20, 2010 Report Share Posted August 20, 2010 More pinion angle creates a faster bite but if the track has no bite it will break the tires loose faster. If you run less pinion angle it wont be as fast of a feel for forward bite but it will be more forgiving on a slicker track. Im running 4 degrees in mine. Can anyone back up this idea with actual testing data? I sure can't. LOL,,,I cant on paper but I can say Ive tested it by setting up my own cars for the last 15 years. Does that count Link to comment Share on other sites More sharing options...
Truck99 Posted August 20, 2010 Report Share Posted August 20, 2010 More pinion angle creates a faster bite but if the track has no bite it will break the tires loose faster. If you run less pinion angle it wont be as fast of a feel for forward bite but it will be more forgiving on a slicker track. Im running 4 degrees in mine. Can anyone back up this idea with actual testing data? I sure can't. LOL,,,I cant on paper but I can say Ive tested it by setting up my own cars for the last 15 years. Does that count I guess it counts for you if you've convinced yourself that it had a real effect.... Link to comment Share on other sites More sharing options...
Adam38 Posted August 20, 2010 Report Share Posted August 20, 2010 Well all I can say is try putting 17 degrees of pinion angle in and feel the car jump up on the tires then break loose (if the track is slick) cause of the instant bite then back the pinion angle back down and have the same feel just not as touchy on the tires. JMO...and maybe its different on pavement but I wouldnt think so. Dont beat on the rookie to hard. Link to comment Share on other sites More sharing options...
Blue Moon Motorsports Posted August 20, 2010 Report Share Posted August 20, 2010 Well all I can say is try putting 17 degrees of pinion angle in and feel the car jump up on the tires then break loose (if the track is slick) cause of the instant bite then back the pinion angle back down and have the same feel just not as touchy on the tires. JMO...and maybe its different on pavement but I wouldnt think so. Dont beat on the rookie to hard. If you have a motor you can stuff in your truck....I've got a sway bar yuou can use! Link to comment Share on other sites More sharing options...
poorboy Posted August 20, 2010 Report Share Posted August 20, 2010 Use enough pinion angle to keep the drive shaft in your car/truck and thats all you need. No help with bite at all. Link to comment Share on other sites More sharing options...
NickHolt Posted August 21, 2010 Report Share Posted August 21, 2010 On a typical three link the top link working together with the angles of the two bottom trailing arms provides the forward bite using a principle called anti-squat. Larry Bendele spent a great deal of time figuring out the optimum rear geometry for San Antonio Speedway. Basically, the greater the angle of the top arm, the greater the forward bite. This same principle is used in various forms in the drag racing community. However, playing with the rear geometry to obtain optimum forward bite at a given track is very common and often times playing with the rear geometry changes the pinon angle. So some figure it's the pinon angle doing the handing changes, but it's the geometry of the rear linkages that is making the changes. On a typical metric stock four link, some have discovered that freeing one of the two "upper" arms creates a "top link" from the upper arm that is still solidly mounted. I probably should stop right here because there are some "grey areas" in those "stock" four link systems that probably need to stay relatively obscure. Bottom line, any bind in a suspension changes the effective "wheel rate" and thus the handling characteristics, but the pinon angle has little, if any, effect on the amount of forward bite, at least on asphalt. Nick Link to comment Share on other sites More sharing options...
HiTech Posted August 22, 2010 Report Share Posted August 22, 2010 added angle in our leaf spring car ..sorta helped .but found it to be a crutch repair to cover the real reason for no forward bite .... left rear spring bind on throtle up .was the problem ..worn out slider .......... Link to comment Share on other sites More sharing options...
NickHolt Posted August 22, 2010 Report Share Posted August 22, 2010 When you change the angle of the rear portion of a leave spring you are actually changing the rear roll center in addition to adding a certain amount of mechanical anti-squat to the car. I have a diagram that I use in the suspension seminar that shows how to raise or lower the rear roll center height by using different holes in the shackle mounts. Nick Link to comment Share on other sites More sharing options...
HiTech Posted August 23, 2010 Report Share Posted August 23, 2010 When you change the angle of the rear portion of a leave spring you are actually changing the rear roll center in addition to adding a certain amount of mechanical anti-squat to the car. I have a diagram that I use in the suspension seminar that shows how to raise or lower the rear roll center height by using different holes in the shackle mounts. Nick so is it going to cost me$300 to get that chart ....or diagram ...before this piece went bad ..that car would squat an go .. Link to comment Share on other sites More sharing options...
NickHolt Posted August 23, 2010 Report Share Posted August 23, 2010 The diagram is free. You get it along with 75-100 pages of class notes I hand out during the seminar. It's the suspension seminar that costs $300. LOL If you don't believe the seminar is worth $300, just don't sign up next time it's offered. That will work for both of us because I only want students who realize the value of learning suspension engineering principles and want to learn. Similar courses are offered at a couple of colleges. Of course they teach it using proper engineering terminology and assume that you have a solid background in math and physics. And it costs a whole lot more than what I charge. A whole lot more. And I teach it using words that racers are already familiar with and the math is done for you in a computer program that I include with the seminar. Nick Link to comment Share on other sites More sharing options...
HiTech Posted August 23, 2010 Report Share Posted August 23, 2010 The diagram is free. You get it along with 75-100 pages of class notes I hand out during the seminar. It's the suspension seminar that costs $300. LOL If you don't believe the seminar is worth $300, just don't sign up next time it's offered. That will work for both of us because I only want students who realize the value of learning suspension engineering principles and want to learn. Similar courses are offered at a couple of colleges. Of course they teach it using proper engineering terminology and assume that you have a solid background in math and physics. And it costs a whole lot more than what I charge. A whole lot more. And I teach it using words that racers are already familiar with and the math is done for you in a computer program that I include with the seminar. Nick come on nick i thought for once seeing we are realy close friends .you could share alittle ... your courses are worth it .... you know somthing nick ..why dont you start a pay per answer system on speedzone .....lol Link to comment Share on other sites More sharing options...
NightFlyer Posted August 23, 2010 Report Share Posted August 23, 2010 why dont you start a pay per answer system on speedzone This would be great for Nick, but horrible for those asking the questions- Every answer will bring up at least two more questions. Great for repeat business, but cheaper in the long run to attend the seminar (not only would you get all the information, but I think you get about a year or two of answers after the seminar... (of course not in the open on the forums...)- he's answered my e-mails pretty quick!) Link to comment Share on other sites More sharing options...
jwmbishop Posted August 23, 2010 Report Share Posted August 23, 2010 This has the makings of a monty pythonesque routine: Gee would a pay per Q really be beneficial? Yes - thats 1.50 please. Hey Are you really gonna charge me for that? Yes - thats another 1.50. What kinda rip off is this? A good one - 1.50 more. Are you crazy? Im not wasting my money on stupid questions. 1.50 again! Link to comment Share on other sites More sharing options...
NickHolt Posted August 23, 2010 Report Share Posted August 23, 2010 LOL at Mr. Bishop! No sir. I have zero plans to put the course online or start up any sort of Question & Answer deal. I provide full contact information to my seminar students and they are encouraged to contact me at any time about anything covered in class, or even things not covered in class. Many do so on a regular basis. Some who took the class 20 years ago still call with questions. My goal in doing the seminars is to help racers understand suspension engineering principles. I limit the class size to 10 (15 in Houston to meet the overnight and travel expenses) so that I can give individual attention to those who may not understand some of the more difficult concepts. In fact, I frequently meet with students for individual tutoring sessions before class or even at another location on a different week night to be sure they are "getting it." But I do charge money - $300 per student - because the information I teach is valuable. Frankly, it's worth a whole lot more than what I'm charging. And before you ask, I have given "scholarships" in the past, but every single time I have done so that person will miss a class or two. That defeats the whole purpose because each session is built upon information discussed in the previous session. Nick Link to comment Share on other sites More sharing options...
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