Drive shaft angle for Everett Morrison

[mjhcobra]

I am running the short toploader, 428, with a 5 bar link 9" rear axle. My drive shaft angle is 8 degrees and EM says I need to be between 3 and 5. All mounts were welded in place by EM, so I am confused why the angle does not work. I am using the 24" toploader with all mounts that they suggest and the 5 bar link is set to their specs.

My options are to custom make a trans mount which will lower the trans at the rear and will reduce the drive shaft angle, but this then begins to drop the side pipes so they are no longer parallel to the body. EM does not have any suggestions other than lowering the trans. Any ideas???

[Jerry Clayton]

The Cobra drive line is too short to successfully run a live axle --they really need have a IRS rear.

However---you can severely limit the travel of your rear end and get the angles under control----if you need to adjust the sid pipes you have a choice of driving or having your pipe alignment look good while your car sits alongside the road with the u joints tore out

[Clois Harlan]

How are you measuring your angle? Also, if your trans bracket that bolts up to your frame rails needs to be dropped a small amount to achieve your desired angle why not put some spacers between the bracket and the frame rails to lower your transmission a little. I would try that first before I started making any bracket.

[mjhcobra]

I measured the angle with a magnetic angle finder stuck to the drive shaft with the car on the ground and the suspension weighted.
My removable trans bracket does not allow for shimming so the options are to make another removable bracket that the mount attaches to or find a thinner trans mount.
Will changing the pinion angle from 0 degrees to a little more positive be an issue? This would help the angle a little. The real issue is the angle as the drive shaft comes out of the trans. The trans just looks to be high and needs more down angle or slope to the rear.

[Jerry Clayton]

So===you have measured the driveshaft angle relative to the ground???? That is not the correct way to do this

[mjhcobra]

Yes, the car is on a level concrete slab with the suspension loaded. If this is not correct, please tell me the correct way, I really could not think of any other methods.

[mjhcobra]

May have figured out one possibility for severe angle. It looks like I may have a shock that is too tall. According to the EM catalog, I should use Aldan 658's, with 200 lb springs. This shock has a range of 11.5" to 16.5" with a 12" spring rated at 200 lbs. Looking at the rear of the car, I think there is at least 3" from the top of the tire to the fender well and I do not have any room to adjust the shock.
If this is the issue, the shock may be to long. By using a shorter shock, the rear end will rise within the frame and the angle will lessen.

I suppose there may be a problem with the EM manual for the shock selection or the spring. A 10" spring might be the answer, which would provide adjustment or a shorter shock. Any ideas???

[Jerry Clayton]

driveshaft angles are the angular differance between the pinion shaft,drive shaft and transmission mainshaft--the angle to the ground has nothing to do with it--
Now , having said that, if the only means you have fir measuring angles referances to the ground, you can correct the numbers to what the drive line is----

take the springs off the shocks and block the car/suspension to what you want for ride ht.
Adjust the drive angles---then figure out what distance you have for the spring at ride ht and go from there----you will probably be in the 10 in size

[DanEC]

Originally Posted by Jerry Clayton

driveshaft angles are the angular differance between the pinion shaft,drive shaft and transmission mainshaft--the angle to the ground has nothing to do with it--
Now , having said that, if the only means you have fir measuring angles referances to the ground, you can correct the numbers to what the drive line is----

take the springs off the shocks and block the car/suspension to what you want for ride ht.
Adjust the drive angles---then figure out what distance you have for the spring at ride ht and go from there----you will probably be in the 10 in size

Yeah - you need the angle between the transmission tailshft and driveshaft - and the angle between the driveshaft and the axis of the rear pinion shaft. The angle to the ground is meaningless. Turn the transmission yoke until the yoke arms are oriented top and bottom and put the angle gage on the bottom of the yoke arm and measure the angle from horizontal. Then put the gage on the driveshaft and measure it from horizontal. Subtract the two and your have the front deflection angle. Repeat this for the rear.

[Dwight]

I did not read the whole article but check this link out

http://www.carcraft.com/howto/91758/index.html


http://www.markwilliams.com/driveshafttech.aspx


Dwight

[mjhcobra]

Originally Posted by DanEC

Yeah - you need the angle between the transmission tailshft and driveshaft - and the angle between the driveshaft and the axis of the rear pinion shaft. The angle to the ground is meaningless. Turn the transmission yoke until the yoke arms are oriented top and bottom and put the angle gage on the bottom of the yoke arm and measure the angle from horizontal. Then put the gage on the driveshaft and measure it from horizontal. Subtract the two and your have the front deflection angle. Repeat this for the rear.

According to EM the pinion angle is to be 0 degrees. I verified by checking that the pinion angle in the loaded position was 90 degrees to the concrete slab or 0 degrees. I verified that the transmission output shaft in the loaded position was parallel to the concrete slab in the loaded position or 0 degrees. If pinion angle is 90 degrees to the slab and the transmission is parallel to the slab, then the drive shaft angle would be what the angle finder is reading, which is 7 degrees. This is only possible I believe, when the pinion is perpendicular to the slab and the trans is parallel. Otherwise I would need to add or subtract from the drive shaft angle.

Most of the cobra pictures I see indicate the rear tire slightly inside the top of the fender flare or even with the flare.

I have not purchased my wheels and tires jet, but may need to soon to check clearances. I will be running 295/50r15 with 9.5" rims on the rear with the normal backset. Anybody foresee any clearance issues?

[Wbulk]

I went through this same issue a few years back and read everything I could on the subject until I understood it at the time really well. In reading a lot I found that many articles were poorly written and confusing. I even called a few of the big axle companies and talked to the bosses about the concepts. I have forgotten of lot of what I learned, but I can throw out some of the concepts to keep in mind as you are going through the process.

There are some variables you need to be aware of. Big engines with a lot of torque may have the pinion angle lower or more negative in relation to the drive shaft than smaller engines. This is because as the power is applied the torque will rotate the pinion angle up. So when resting, it would seem to be off, but under power it is right on. The type of link bushings also needs to be considered. If you have the big rubber bushings (stock type) the pinion angle may be more down than a thin rubber bushing, but as you apply the power the big rubber bushing has more give so the pinion rotates up more.

When I set mine up as I remember there were the three angles to be concerned with: The output shaft of the trans, which is the whole engine trans angle, the pinion angle of the rear axle, and the drive shaft angle. So as not to confuse the issue in setting mine up I set the frame lever on stands and shimmed it level front to back and side to side. I then set the axle at ride height and level with the frame from side to side. I then put the angle finder on a flat spot of the rear yoke coming out of the trans. The object of this process being so under load the trans and the pinion angle are within a few degrees of being parallel. Meaning the trans angle was 2 deg down and the pinion angle would be maybe 1 deg up under load in relation to each other. The other angle would be the drive shaft angle in relation to the other angles. There was a maximum difference that was I believe something like five degrees but I am not sure of that figure. So you could have the angles correct from the trans to the pinion but the drive shaft angle is too severe.

In setting up mine it was a compromise. I got the angle within a few degrees so that when under power the pinion would rotate up and be within a degree of being parallel. I have thin rubber four link bushings and a 302. If I had a 427 and big rubber bushing then I may have set the pinion 3 deg down or more in relation to the output shaft. If you get it all within a few degrees you should be good. I ended up shimming my trans angle down about 5/8”. I hope this was of some help.
Wayne

In the picture you can see shims under the axle housing to get it right before I adjusted the four link heim joints.

[Michael C Henry]

As I understand straight is the strongest, but if there is no movement in the joints the U-joint caps, trunions, and needle bearings will have all the wear and tear in the same spot causing flat wear spots. Once wear has occures, it will be noticed when the driveline is removed there will be a noticable catch or hesitation when rotating the joints and caps by hand. Easy to move and smooth with no rattle or shifting is the desired feel. Just the drag of the grease.

[Jerry Clayton]

post 4 says you had the car on the ground and weighted(don't know how you got under it to measure) and now post #11 says you don't have your tires and wheels-------

[mjhcobra]

Each of the 4 tires (on stock steel 15" rims with a 26.5" tire, probably 20 years old just to roll around the garage) are blocked up about 4" or so to allow me to slide under the car to check angles.

I am going to now block the frame, support the rear axle, and remove both rear shocks. Hopefully, I can raise the rear axle to get the rear ride height, which should reduce the drive shaft angle and close the gap on the tires in the rear wheel well.

Looks like EM may have made a mistake on the rear shock length. Thanks for the comments, they were all helpful.

[mjhcobra]

This appears to solve the issue. I removed the rear shocks, raised the rear axle to fill the wheel well more, and the drive shaft angle is around a degree or so. The shocks that EM suggested were 16" long and 15" weighted with no adjustment to the spring. The new dimension between spring mounts is about 12.25" unloaded.
I will contact Aldan on Monday and see what they suggest. I would like to know from anyone who has an EM and the 5 bar link, what length shock they ended up with on the rear.

[Tom Cimino]

I just went out to the garage and measured the length of my Alden shocks and they're about 14 1/4 inches bolt to bolt, loaded. 1995 Everett-Morrison 4 link rear suspension with panhard bar. All linkage and shocks supplied by E-M. I have to take the car off the jacks tomorrow. I'll get you the extended length of the shocks and post it then.

[strictlypersonl]

You want to set your car up so that, at the proper ride height, the shock is at roughly mid-stroke. Once you've found the correct shock, the ride height must be adjusted by the spring length and/or rate. Don't change the shock length outside of the first parameter: It will reduce your available wheel travel in one direction or another.

[Tom Cimino]

Ok, I measured my fully extended shock length and came up with 16 1/2 inches. I went on the Alden website and the shock that fits that length is Part # 658. Also the spring rate from the Everett-Morrison book is 200#.

My rear axle has a 3 deg pinion angle as it was originally set up for a small block. The angle of the motor and trans is the same as the pinion. 34,000 miles and never had a problem with u-joint wear or vibration.

[mjhcobra]

Thanks Tom. I have that same shock with the same spring as I ordered mine from Aldan using the part numbers in the EM book. My pinion angle is 0 degrees, again based on the EM book. What trans mount are you using?

Where do you have the adjusting nuts (rings) on the shocks set?

Do you have the removable cross member for the trans mount?