Drive Line Angle with car lowered

[MikeStang 247]

Okay so this evening when I measure for my new driveshaft I am also going to check my drive line angles AGAIN.

The last time I checked them here is what I found out.

My Transmission was at -5 degrees and my rear end was at 0 Degrees.

I knew since I have a leaf spring car the rear should be 1-3 degrees down to compensate for the rise under load, so I installed a 2 degree shim and it brought the rear end down to -1 degrees.

I then proceeded to add a few flat washers under the transmission and brought it up to -3 degrees...the vibration I has seemed to improve but I thought you were supposed to have equal but opposite angles on the drive line?

Meaning one should be negative and 1 positive...If that's the case why is it common practice to have the pinion at a negative angle if the Trans is at a negative also?

Would like to correct any problems b4 the drive shafts arrives

[MikeStang 247]

Oh I also have Cali Track bars if that matters and 4.5 leaf reverse eye springs

[MikeStang 247]

Oh the drive shafts measurement at the rear end was +1 degree and at the Trans it was +1.5 if I recall, meaning the diff. Is lower than the Trans still lol

[MikeStang 247]

Think Im going to swap the shims around to the front of the perch and raise the pinion to a +2 degrees and see what happens.

It would seem -5 degrees on the transmission is a bit much to me

[barnett468 418]

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ok this is confusing

 

what is the angle of your tranny and the diff relative to the grond? . . this is not the driveshaft.

 

ideally, the angle of both should be exact;y the same and since the pinion rises as you mentioned, setting the pinion nose around 1 - 1/1/2 degrees lower than the trans is good.

 

the driveshaft should go down hill from the trans and uphill from the diff but it doesn't alway work out that way.

 

there should be at least 1 1/2 degrees of difference between the driveshaft and the trans and the driveshaft and the diff . . it should never be perfectly in line with either.

[MikeStang 247]

Barnett.

The Transmission WAS down 5 degrees and the rear end was at 0 Degrees

 

I adjusted it To the Transmission being down 3 degrees and the rear end being Down 1 Degree... 

So basically both the Transmission & The rear end are Pointing Down, which Is still from what I read INCORRECT.

 

Supposedly one should be Negative and one positive and at the same value Ie... -3Degrees on Trans and +3 on Rear end would be ideal for proper Drive shaft phasing and U-Joint operation

[barnett468 418]

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maybe these videos will help explain . . some things are like a hustler magazine...they easier to understand when you see them.

 

if you can not get your tranny up more, than you need to get the mose of your pinion up around 1.5 degrees above horizontal so when it is under load it will be at the same angle relative to the trans . . it does not need to be in line with the trans.

 

 

 

[Midlife 814]

Thanks for those great videos!

[barnett468 418]

Thanks for those great videos!

 

no prob . . i love both of those . . they explain it pretty well in jus 60 seconds.

[JayEstes 172]

The videos make it all clear!  Really good resource!  Thanks for posting that!

[RPM 1,190]

Yes, those vids are eye opening. I had no idea the speed change was possible till I saw the first vid about a year ago.

[MikeStang 247]

I understand the concept and know that I'm shooting for equal and opposite angles for the best vibration free ride and not overly concerned about max traction.

 

So last night I jacked the car up and leveled it and removed the driveshaft and took some measurements and here is what I found.

 

1. My transmission tailshaft is pointing down toward the back of the car approximately 4.3 degrees

2. My Pinion is Pointing up toward the floor Pan approximately  .9 degrees

3. The Rear end is still located below the transmission level.

4. The transmission tailshaft measures 1'-5 1/4" off the ground

5. The pinion measures 1'-3 1/4" off the ground

 

Keep in mind the car is jacked up and leveled to ride height

 

So my questions are as follows.

 

In order to get the Equal but opposite measurements I will have to either

 

1. Raise the transmission angle to .9 degrees down which I don't think I can make happen because it wont go up that high but it will be equal and opposite the rear.

 

OR

 

2. Rotate the rear end up even more to get to the 4.3 degrees of the rear end. which may cause binding

 

3. OR I can raise the trans as far as it will go and hope for 2 degrees down and raise the rear pinion up to 2 degrees positive and they will match and be opposite.

 

Opinions?

[1969_Mach1 333]

The videos are great.  I've never seen anything like them.  They never discussed any range of acceptable angles which would be nice.  MikeStang, good luck.  I'm sure you'll get it sorted out.  But I've never heard of or seen somebody with as many driveline issues like you have been having. 

[danno 128]

Agree with 1969_Mach1.  It seems odd you are having such trouble. I would guess you have checked everything for balance?  U joints are ok? Is driveshaft straight? 

 

 What would happen if you raised the back of the car, and put it on blocks. Then put a floor jack under your rear end to allow you to raise or lower it while in drive?  This will provide different angles, but without a load on the wheels it is probably of little value.

 

Interesting problem...

[MikeStang 247]

I have a Brand new drive shaft coming today.

 

My old shaft was the original shaft that came in the car that I had shortened locally. The shaft didn't have a single weight on it when I removed it from the car, and when I took it to have them remove the excess length I asked if they could balance it and was told they don't do balancing but could shorten it and that if it had no weights and didn't vibrate going down the road then it would still be right when they were done..... I knew this was bull shit but I needed a driveshaft Fast in order to make it to Cruising the coast last year, and to their credit they did a good job, and the vibration I experience doesn't really start until around 70 but increases with speed. 

 

The vibration is a thrumming sound that comes and goes in time... Its like thrum...thrum...thrum...thrum, and as you speed up the thrum speed increases...Never pushed it fast enough to see if it would just thrum constant LOL....But the sound is of the same pattern as shown in the videos when the joints are traveling out of whack at different speeds.

 

I did rotate the shaft 180 degrees and that actually seemed to help out some.

 

The U-Joints they installed in the shaft seemed Ok, but I decided to change them and when I took them apart I could see scoring on the insides of the caps and the cross shaft so that told me what I needed to know, so I swapped the U-Joints and installed a 2 degree shim to get the pinion down some which is what I thought needed to be done, then I shimmed the transmission up 1/4" and the vibration seemed to improve but its still present.

 

So it would seem I need to go up as high as I can on the transmission output shaft and hope to get it to 1-2 Degrees pointing down and maybe leave the pinion alone at .9 to 1 degree and try it out...

The cross member I used was one from one of the guys on the forums who makes the 4R70W cross member stuff.

 

Oh on a side note my FPA headers had 1 tube hitting the Idler arm on the frame and I called them about it and when I told them I had an aftermarket trans and xmember in the car his first answer was for me to loosten the transmission and shift it over some to get the clearance I needed because he said those  aftermarket X-Members are never right... I was like WTF I need like 1/64" MAYBE 1/32nd and your telling me to move my transmission alignment ?? REALLY??

He said they have a jig for their headers and build a lot of them and that he doubted it was off.

They had plenty of room to rotate the tube down and still have same ground clearance but im sure there is a reason the build them like they do.

 

Also my car feels more sluggish now that I have the Stepped primary long tubes as opposed to my home built / modified 1-7/8" shorties that leaked.... its sounds different, and runs different.... Not to pleased with the results of long tubes :(

[MikeStang 247]

I suppose I could add adjustable motor mounts and lower the motor there by effectively raising the tailshaft housing in the rear ?

[barnett468 418]

I suppose I could add adjustable motor mounts and lower the motor there by effectively raising the tailshaft housing in the rear ?

 

 

the adjustab;e urethane mounts increase engine vibration in the cab a little.

 

you might just need to raise the pumpkin up . . this works also but its not ideal.

.

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[MikeStang 247]

Yeah I will need to raise the transmission and try to get a degree out of it then raise the Pinion 2 degrees and it will be close enough to make it work okay

[barnett468 418]

Yeah I will need to raise the transmission and try to get a degree out of it then raise the Pinion 2 degrees and it will be close enough to make it work okay

 

keep in mind, if you trans is down 4 you want your pinion up 2.5 - 3.0 so when you drive at steady throttle like the freeway, it will hopefully be around 4 also.

 

the slower you go, the farther out the alignment between the two can be.

[Mach1 Driver 560]

Oh on a side note my FPA headers had 1 tube hitting the Idler arm on the frame and I called them about it and when I told them I had an aftermarket trans and xmember in the car his first answer was for me to loosten the transmission and shift it over some to get the clearance I needed because he said those  aftermarket X-Members are never right... I was like WTF I need like 1/64" MAYBE 1/32nd and your telling me to move my transmission alignment ?? REALLY??

He said they have a jig for their headers and build a lot of them and that he doubted it was off.

They had plenty of room to rotate the tube down and still have same ground clearance but im sure there is a reason the build them like they do.

 

Also my car feels more sluggish now that I have the Stepped primary long tubes as opposed to my home built / modified 1-7/8" shorties that leaked.... its sounds different, and runs different.... Not to pleased with the results of long tubes :(

Mike I'm a little confused about whose headers you used- in my post you said FRP (probably FRPP Ford Racing Performance Products) and here you say FPA (Ford Powertrain Applications). Did you resolve your fit issue above? I'm sure I'll have the same problem. Does this have anything to do with the special power steering bracket you told me about? Thanks

[MikeStang 247]

They are FPA (Ford Powertrain Applications) Yes I tweaked them a little bit with a big pry bar.... Didn't take much but I got it done and they fit fine now

The clearance issue was on the passenger side btw.... I actually had to remove the nut on the idler arm and grind the washer down that's on there because it was actually bigger than the damn idler arm casting body haha. 

 

The driver side fits wonderfully and doesn't hit anything. This is where the power steering drop bracket goes.... Its just a longer replacement bracket for the one that bolts to the rail that is in place now, it just lowers one end of the power steering ram a little to clear the collector area.

[MikeStang 247]

Well got some time to tinker with the driveline angles last night and was able to elevate the transmission some and rotate the rear end up some and here is what I ended up with.

 

Transmission - Negative 4 Degrees meaning the output shaft is pointing Down.

Pinion Angle - Positive 2.5 Degrees meaning the pinion is pointing up toward the transmission

 

I also adjusted my Caltracs so they are in constant contact with the front of my springs in an effort to stop the Pinion Climb as much as possible under hard acceleration.

 

Took it for a ride and it seems to have greatly improved in terms of less vibration at 70 and above.

 

I did notice some slop in my tail shaft with the driveshaft installed and since I have to get a new tailshaft housing anyhow for my new driveshaft I will eliminate that problem and hopefully the new driveshaft, new tail shaft and corrected drive line angles will make this thing smooth at all speeds.

[barnett468 418]

xlnt . . glad it worked . . just make sure you get the driveshaft balanced . . i get them high speed balanced but not many places do that.

[Mach1 Driver 560]

Since the angle of the transmission has to be the result of the engine mounts and your aftermarket transmission support, and I would likely have the same problem, do you remember whose you used?

[MikeStang 247]

I will have to look back through some stuff but I think it was Joe Persad if I recall.

 

The brackets are very nice and appear to be made correctly. I jacked the transmission up till it stopped and all I could get was about 3.5 degrees out of it and that actually lifted the mount bolts out of the holes in the bracket so you wouldn't be able to thread a nut on it.... Only way I know of to correct this would be to put drop mounts in and lower the motor an Inch or so and that would raise the back of the trans up above 4 degrees... It actually takes a lot of movement to make up a degree LOL.

So even if the cross member had a taller pad on it the transmission would hit the tunnel before you get under 3.5 degrees.

 

My motor mounts are just stock mounts for a 69 with a 351W.

 

I'm picking up my new tail shaft housing with new bushing and seal tomorrow for 60 bucks since my old one would not fit the new driveshaft, and not to mention the old bearing had excessive play in it.

 

So im hoping that the new shaft that has been high speed balanced, along with my adjustments will make her smooth as glass... If not its going to the frame shop to be checked out LOL