another pinion angle question!!

It does matter if the trans is lower than the diff. if the trans is lower than the rear end, the u joint angle will be greater than if the trans were higher.because, with the trans angle down, and the driveline angle down to the rear, you "subtract" the two angles to get the joint angle. if the trans is down and the driveline is up to the rear ,because the rear is higher, then you have to "add" the two angles to get the u joint angle. you also do not want the trans lower because the angles will increase further as the suspension works.

 

It helped me, Rod-thanks

 

man I lone kadetts , drag cars,way toooooooocool

 

ok call me stupid but with the trans lower and set at 0-1.5 deg down then the rear should be o or +1-2 up?right now its about 3 down.

 

does anyone know if im right or wrong?

 

I'd be more concerned with the trans pointing below the rear. Any chance you can bring up the back of the trans so it's pointing more toward the rear?

 

the trans is about a 1/4 inch from the floor.so that would be a no.i was thinking about cutting off my motor mounts and lowering the front but the oilpan is only 3 1/5'' off the ground and it is already hard to get it on my trailer now.i also want to build a new oilpan to hold a couple more quarts of oil and a side pickup.the only way i could do this is to keep the depth the same and just make some side kickouts.the oily problem with this is i will have to put the oilpan on after i have the engine in it!!i guess this isnt that big of a deal but i already have to put the intake and carb on after i put it in because of how far back i put the engine.

 

ok i just went outside and checked everything again.trans is 3/4'' lower then rear.trans is at 0 deg.rear is at 5 deg. down,with full weight of rear of the car.i just started reading about a set of floaters for the rear.they say you have to have them with a leafspring ladderbar setup.does anyone have a pic. of a set of rollers on there car?would like to know how it will keep the rear located.

 

just trying to get some help.

 

Google came up with this
http://www.superchevy.com/technical/chassis/suspension_steering/0602sc_guide/index3.html

3/4" isn't bad, but the floater will probably add to that. I'd look carefully at doing all the work to add floaters. They are heavy and by the time you do all that work, you may be able to do a coilover conversion for the same time/money. This will work with the ladder bars, be lighter and allow more changes to spring weight and ride height.
Check into your options is all I'm saying.
http://www.carcraft.com/techarticle...ension_tech_guide/drag_racing_simulation.html


http://www.competitionplus.com/2004_10_21/chassis.html

 

thanks.rsr.but i really would like to keep the leafs.the roller kit from jegs was only $100.00 but i still dont enderstand what happens to the locating pin and what keeeps the rear located.

 

The lower plate has a hole for the pin. The spring is sandwiched between the lower plate and the tubes with bolts. This locates the housing back and forth. The housing can still pivot around in the ring gear plane, until the ladder bar is connected. This allows the rear to move within the circle of the bracket, so the rear is not held in this plane by the spring AND the ladder bar, removing any bind. I would guess that the big rectangle of metal toward the left is welded to the axle tube inside the bracket to keep the housing from moving side-to side.

 

thanks for the pic.but does anyone have a pic of one on there car?

 

Here's an episode of Gearz TV that covers installation of a floater set up. I wasn't thrilled with the design and other literature on them read "Not for Street Use". I pictured having to grease that set-up like they used to grease the Grease Boxes on railroad car axles. I'm setting my Henry J up with a shackle at the front of my ladder bars to off-set any contrary movement of leaf spring travel. It seems cleaner and easier.
http://www.gearztv.com/showdetails.php?episode=33

 

well im not going to go with a set of rollers.just the top bar on my"ladder bar setup"i thought i could leave the spring perches on but i just figured out that i will have to cut them off.its not worth it to me.i talked to some other racers with ladderbar setups and some are running mid 10's with out a problem.im still not sure about the proper pinion angle.i think it should be 2 deg.down.but am not sure with the trans lower than the rear.some said just take the pic.from an earlyer post and flip it.then does that mean 2 deg up?

 

bttt.is anyone else having problems with the hamb?

 

The Direct Connection Chassis book calls for 5-7 degrees nose down on the pinon with super stock springs on a drag car.

what this means is the angle of the driveshaft on the rear end should have 5-7 degrees more angle than the front. Yours is going uphil towards the rear end because the trans is lower than the axle, so it will be your front angle MINUS 5-7 degrees.

So if your front joint is at 1 degree up toward the rear, the rear should be 4-6 degrees nose down.

Confused yet?

 

so i should put the driveshaft back in it and check the angle of the shaft?the trans is at o deg.but i didnt check the driveshaft.

 

Slightly off topic, but if I lower the rear of my truck(from 2 1/2 to 3 1/2 or 4" using lowering blocks, will I have to also change the pinion angle? Thanks guys

 

no because you are not changing the angle,just where the springs are mounted.

 

I've seen so many threads and articles on this subject and so many different answers to this question that the only conclusion I can come up with is that no one really knows for sure what the proper combined angle is. Almost EVERY answer contradicts the last one and that includes from thread to thread and magazine article to magazine article.

 

I am not sure why you are convinced something is wrong with your set-up.

Except people have 'told you it is wrong', but it sounds like they haven't told you what is right. For your own sake, stop listening to the jerk-offs that show up at the track with no car, then criticize everything about yours and your set-up. That was the biggest mistake I made when I started racing.

It looks like you bought your car mostly the way it is set up. Perhaps the driveline is not optimum, but in older stuff, and with a short wheelbase, sometimes that's just the way it is.

I don't think the 60' times and ET's are slow for a car that has 350-400 rwhp. Perhaps it could be going high 10's, but you are not far from that.

It picks up the one front wheel a bit higher than the other, but I have seen far worse.

My point is, for a car that is an older build, short wheelbase, and sitting high, if it launches decently, I think it's about where it should be.

I can tell you do not want to make major changes to the car, so I don't think you can expect major changes in performance.

Edit: It's ok to listen to so-called help, but perform your own testing to really see what happens. Try one simple change and check the results. Don't overcomplicate it.

 

thanks but i built most of it.{in 2 1/2 months}and no i dont want to do a whole lot of major changes because it is going straight down the track.just want to go over some of the stuff i did and make sure it is the right{or atleast right enough}.i lost most of my build pics.when my computer crashed.but here is two.

 

I meant no offense about the build quality, I just meant that it did not appear to be a high-dollar chassis shop job. And again, sometimes you have to make small sacrifices from optimum design to package a lot in a small space, as you have.

Like I said, I think you're doing pretty well with it. Many cars like that (short and high) are so squirrely that nobody can get them down the track. If it's going straight, you're doing fine.

Best wishes.

 

More to think about. If you access to a copy of the Goodguys Gazette Magazine January 2010 check out page 198 with an article by Brent Vandervort called Smoother Cruising. His shop sets up drivers with the normal hot rod rake with the rear up and nose down with rear axle at dead zero. Also, warns about over tightening U-bolts.

 

as i said earlyer in post me and don built most of the car in 2 1/2 months to make it to thompson gasser reunion in "06?"some of the car was started many years ago buy someone who seamed like they knew what they were doing.{put in frame rails some of front suspension{which we changed alot} and did the part of the cage.we took it from there.i was going to put motor way up and try to conforme to the gasser rules but decided that i didnt like the way it looked and was afraid of how it would handle with so much weight up front and high{crank center 24'' off ground}so i slammed it back and bown as far as i could get it.it had alot of chassie flex so we kept putting more 2''dom 1/4 wall tubing in it till it wouldnt move.we also tig welded everything.i think so far i have under $5000.00 in it.{i paid $2300.00 for car}.so with that said no there isnt alot of money in it just some time,and alot of fun.this was deff. a learning exp.for us and im still trying to learn.i guess im rambling just wanted to let you know.thanks

 

bttt

 

so who's wright?

 

It seems to me that if nothing flexed, twisted, squated or moved your U-joints should be at the same angle front and back or none at all. Since U-joints speed up and slow down as they turn you want the front and back doing so at the same speed. I suspect what many people are doing is trying to guesstimate where the pinion is going to end up under hard acceleration. A stock leaf spring set up is going to twist up more than a ladder bar set up. On top of that when the car squats upon launch the angle from the tranny the the pinion changes. I've seen 4 X 4 guys strap a camera under their rigs to see what goes on. They have more extremes to deal with in drive-lines than drag racers. Also you might look under a dump truck. They are dealing with a lot of torque and more mileage than your average drag car.

 

im trying to find a cheep video camera to put under the car just so i can see whats going on down there.pluse i think it will be cool to watch a run from start to finish.i also think im going to set the pinion angle 2deg down.from what i have read this is the best angle for a ladderbar setup.