Help with pinion angle on a lowered car?

I would try and get engine on level with carb,if 3 degs the shaft would be level,then try and see how the rearend will meet if more then 3 degs you may need the trans to be up and rear donw more.I would not exceed more then 3 degs at ujoints.
You may need to raise engine but keep carb level at ride height.

 

Would be nice to have some NUMBERS, but I'm guessing he is going to be WAY above 3deg on u-joint angle... It should be OK with more than that, but none of us will know until we have some NUMBERS...

 

Everybody is so sure about the parallel engine pinion solution being the only solution.

Run a test. Take a couple of 1/2 in drive extensions and some universal joints and hook them up so you have an extension, joint, extension, joint and extension. Play with them and discover that the action is smooth as long as both joints are working in the same angle.The angles can be both in the same direction or opposite.

 

tailshaft should always be 3 down, pinion angle should always be 3 up.

 

The Jaguar XJ6 and maybe other Jags have the motor level and the pinion 3 degrees. They use a 2 piece driveline though.

 

Yeah, guess. This is one reason I don't post much on here anymore. Some turn into a feeble attempt to become Einstein and to also reply with "did you do a search" pissing match. This is the weekend and I have 3 kids and a wife. I haven't been in the garage to get pics or measurements. Everything other than the driveshaft legnth and the measurements from the ground to each is posted in the first post. As I said earlier I will get measurements when I get back in the garage. The trans is at 3 the rearend is at 4. My problem is not your typical pinion angle question due to the rearend sitting higher than normal. There is so much on HAMB that the search will send you to page after page of posts. Did I look. YES. So I figured with all the rods that are doing this extra low ride someone would have been in the same boat.

Someone said to lift the engine up. The frame is Z'd and the 27 T body is channeled over the frame. If I push the engine up the valve covers will be over the cowl. Not much room in one of those.

 

welp' everyone has an opinion-guess not worth asking if you don't want suggestions for a set up only you know exactly what it is - only pissing here is you

 

that true,i'm talking in general

 

I will guess that the end of trans is at 8" above ground,and with the rear end angle down about 1 " 30div by 2 is 15 less 3 " for poinion and 1 " angle down would be 11"I think you are going to need a support bearing and 3nd ujoint.

 

Unless the driveshaft is 12" long, I'd say he'll be ok with it. That's only 3" height difference (and I think your numbers are probably pretty close). That's barely the diameter of the shaft...

 

Not true. There are many notable exceptions. It depends largely on the suspension design, and what type of driveshaft is used.

Next time you see one, take a look under a Land Rover (not a Range Rover). It will make your head hurt, and it works.

Here is a good read to get you started: http://pirate4x4.com/tech/billavista/PR-shaft/index.html

I know that it is 4x4 stuff, but it gets into how driveshaft angles and slopes work.

 

As for the OP, I would do this: Run a Double Cardan driveshaft. This will require a fixed yoke on the transmission output shaft. They are available for most transmissions. They require drilling and tapping, but it is not that hard to do.

This way, you can put the engine and trans where they fit best, or already are. Point the pinion directly at the tailshaft and lock it in there. The double-articulated joints at the transmission end of the shaft take care of all of the angle issues. The pinion angle, and how much it does or does not change, now becomes irrelevant. The slip-splines in the shaft take care of the length change during suspension cycling.

For a real-world example, look under the front of a Jeep Wrangler or Cherokee, in the front. Now picture that, upside-down, in the back. I run my car like this, as well as my 4x4 rigs (although not upside-down, mostly).

 

Simple solution really ... it's a roadster pickup right ... just install a VW bug engine and transaxle in the box of your p-up, problem solved. Told you it was simple.

 

It has been done.

 

If the engine and trans are there to stay at 3 degs,that would put the drive shaft level with ground you can,t go up u jointed maxed,Chevy 80s vans some had 3 joints.I,d put a support bearing in line with the drive shaft,parrelle with ground,about 10" from trans.Now it gives you another 3 degs to rearend.I would split the difference.Tilt the rearend down try 2 degs and middle ,uj up 2 degs.One thing with 3 ujoint they must be in phase.Cut up a van shaft with bearing for parts.

 

Did anyone read my post? Set the motor level or where you want it to look good then '0' the relative front angle and measure the pinion, should be nose down. Does not matter if the rear is above or below the tranny. You cannot look at at it and say thats looks "good' or bad.

If you have to raise the rear of the car to measure relative "0" so be it. The diff will always nose down. I use a digital angle finder that can be set to relative 0, so it makes things easier than plus this or minus that.

 

Here's how I teach engine/trans/driveshaft/pinion angle changes.
Rule 1. Always use the view of the vehicle from one side and the front of the vehicle as your primary reference point. If it's up, the forward is higher than the rear. Keep confusion out.
After that, many of our rules change depending on what a vehicle needs.
My option for this is somewhat a compromise is is best used with an independent rear suspension vehicle and will require a temporary driveshaft to adjust the parameters accordingly. Why? Because in a two u-joint shaft the angles going through each u-joint need to be within 1 degree of each other.
You can have the engine nose up at your standard 3 degree neighborhood and the pinion nosed down to make the angles throungh each u-joint to be complimentary and therefore cancelling rotation speed changes. \ _ / at an extreme that won't work.
The driveshaft length of this T should be in the 30" CL to CL area, depending on wheelbase and engine placement FWIW.
Gimpsy has also given good info as well as a couple others.
Last option, double cardan CV at the pinion end. GM did this a lot. Rearend choice decides this option because of bolt patterns or part sourcing to modify to make it work.
Help here if you want, gotta ask.

 

Gm used the double u-joint on extended s-10 pickups. We had plenty of problems with them mainly the slightest amount of wear in the centering ball would cause major vibration. We replaced many with a new drive shaft while under warranty. Years later when these were out of factory warranty it was cheaper to have a new shaft made up using the standard 2 joint set. Funny thing was the reg drive shaft did not seem any different as compared a new one with the cv.

 

GM tried with the S10. What I'm talking about is from the full size cars from the '70's. Incidentely, the S10 rearend will receive the same bolt and pilot pattern on the pinion companion flange.
S10 CV stuff is a nightmare especially if the vehicle is lowered. We don't warranty any repairs on a stock vehicle or modified vehicle S10 deal, although I used a shaft to help a customer build a '39 Buick convertible to get around needing a 2 pc shaft and deal with the stock X type frame like a '58-'64 Chevy.. Whole 'nother story, it works. Custom Rodder cover car.

 

All angles don,t have to be the same,What happens when you put big fat people in a car.Don,t they teach machical drawing any more.Unless you have a rubber drive shaft its no going to work.Look at the Chevy 1984 van or any 2 piece driveshaft.

 

Some thing pretty close is good angle wise with U-joints matched aline end to end,is same for steering with joint in shaft also.

 

I know what you're going through. My "T" is running a '46 banjo rear that the pinion sits higher BECAUSE the tires dictate it. I'm at the 3 up-3 down thing AND the Driveshaft is pointing UP from the trans at 11 degrees. Beating the hell out of U-Joints. I could raise my engine maybe 5" or 6" to address the problem but it would just look terrible .

 

I don't know why all the "experts" want to make this so damn complicated... This article talks about 4x4's, but the principles apply to all driveshafts...

Driveline Geometry 101

 

Interesting thread. I'm trying to figure the same stuff out right now for my T coupe. someone posted a great diagram of a crankshaft sitting below the level of the pinion, but maintained a parralel line between them. That one makes the most sense to me...as long as those 2 angle match, those lines stay parralel, and the u-joint angles are the same resulting in little to no vibration, and healthy shafts and seals. Kinda thinking out loud here. Then, for the sake of example, lets rotate those parrallel lines to, say, 45 degrees from horizontal. Still the u-joint angles match. I get all this, and it explains why in severely lowered cars you often see a driveshaft tunnel that gets higher as it goes back toward the rear of the car.
My question at this point is what happens with a car that is maybe running bags in the back, and it's set up at "normal" ride height, say 3 inch bags. Then you air them up to 6 inches. Does that change in pitch get absorbed by the u-joints?
I do love the idea of the dual cardan joint. My GMC pickup has one for the front driveline, I'm suspecting because the angle is so extreme. It's basically 2 u-joints that are close-coupled to a common yoke, but its smooth as butter.

 

It will be just fine. My 4x4 rig is set up with double-cardan joints, front and rear, and I pound the snot out of it on the street and the trail, to the tune if 8" of swing on the street, and 22" on the trail, all at high-speed, without a whimper from the drivetrain.

 

Did somebody hear something?

Not to complicate things further: Just remember that this isn't an isolated system and what you do here will have an effect on other systems (i.e. I wouldn't care about what the engine "looks like" as much as I'd be concerned that the carb base at the manifold is level for the floats unless you're running injection, etc.)

But hey, that's just me.

 

You can buy wedge (tilt) shims. They are common in marine applications. I run a 4 degree one on my ride.

 

Ah, some common sense...
The u-joint angle thing becomes most important under 2 circumstances: Maximium torque, and highest mileage. In other words, have the angles right when you launch the car hard, and/or when you are putting the most miles on it. (almost) Anything will work ok for a little while. If you want to cruise around the fairgrounds with it aired down some, it's not likely to fail.