Driveline angle sensitivity (1 Viewer)

[LandLocked93]

1993 FZJ80

If driveline angles get horked simply as a result of a change in body height, how can one possibly maintain correct driveline angles if they have about 500 pounds of removable gear in the rear?? Even still, as the suspension travels during normal trail rides, at no time will the angles stay correct.
Do you adjust for angles with the weight out or in?
I seem to get a different explanation from every person who claims to know. From the folks who did the lift (Slee, whom I trust wouldn't you?), to the folks who rebuilt my tranny (s***hole 'A' transmission), to the drive shaft people ('A' driveline service). All have thoroughly different answers.

The driveline service folk claim OEM driveshafts are good for only one degree of angle. Well, that gets shot way out of spec over the range of suspension travel. In fact, it gets shot out with just minor undulations on the highway. Driveline clatter/rumble/vibrations ensue.

Slee says a tranny rebuild shouldn't change driveline angles, however mine changed 3 degrees after the rebuild. But then, there was no change to the angles after Slee did the actual lift - which came before the tranny rebuild - and I would concur that I had ZERO driveline vibes or issues following the lift. AND the 3" lift is actually closer to 4" in the rear.

If I were to do nothing more than what is necessary to resolve the angles as they are now (without the extra weight in the vehicle), what will happen to the angles when I add the weight back in?? Will they not change again, requiring additional adjustment to the angles to keep within the 1 degree Toyota demands?? And if I were to then adjust the angles to spec with the weight in, would the angles not be horked again upon removing said weight???

I guess my question is what is the friggin' tolerance of the drive angles and how could they ever be within spec when you have significant removable weight?
And furthermore, isn't any amount of runtime with the angles out of spec "chewing" my gear sets to pieces? (diffs/ t-case)

It's not rocket science I'm sure. But after the driveline service guy was under my truck for 10 minutes measuring angles and came out talking about how my IFS was worn out...I just shook my head in pure, amazed disbelief. Then pointed out to him the solid front axle under which he'd just spent said 10 minutes. He was as amazed at that as I was to his IFS comment.

Are there any knowledgeable AND honest mechs in Colo Springs?? I have yet to find them. Please point me to them if you know one.

 

[BILT4ME]

The thing to get to is what is the "factory angle" at Curb Weight and where are you now?

Yes, drive line angles change as the suspension goes through it's range of motion. The "resting drive line angle" needs to be an average of it's range so that it does not exceed it's failure points before it reaches the limits of the suspension.

The further away from "average" will increase wear.

No, drive line angle does not damage or wear out your diffs / gear sets / tcase, but it can place extra loads on the input or output bearings and cause seals to fail due to increased vibration and bind. It will, however, wear out your U-Joints and can cause them to break due to over-wrapping or binding in extreme cases.

I don't have the math that should tell you the change in drive line angle that will occur with each inch of lift (or lower) of the suspension.

A transmission rebuild should NOT affect drive line angles in any way. UNLESS the mounts were changed at the same time, thus, "correcting" the angles back to what they were supposed to be. A change of 3° is significant!

There are many folks on this forum that get into the weeds when it comes to drive line design, and they can speak about it more knowledgeably and eloquently than I (@nukegoat ). but unless you're going for huge lift, massive tires, and 3-link suspension, I doubt you should be having significant problems unless bushings are worn out, wheel bearings are loose, and driveshafts need U-Joints.

 

[Dissent]

I 2nd what @BILT4ME said. I'd also recommend focusing less on drivelines initially and focus on replacing the 24+ degraded rubber bushings on all the control arms, panhard bars and sway bars along with engine and transmission mounts, before ever getting into the weeds on the driveline angles. My bet is your new tranny mount accounted for your 3 degree change. My truck tightened up 300% after all new OEM bushings were installed.

I lived the driveline angle nightmare for 2 years and came to the realization that the load does matter but when I set my rear pinion angle (using adjustable LCAs) I set it about 2 degrees negative so that when torque is applied and the axle wrap occurs, it's spot on. My variable weight is 2x people and the other 1/2 of my gear which is probably about 400-500 lbs total. I don't have any vibe issues anymore at highway speed so I must have done things right. For the record, most people use adjustable upper control arms to keep their axle centered in the wheel well but my lowers worked fine for me, the tire only moved about 3/8" and nothing rubs under flex.

The front is another matter. I ended up with a part time kit and love it. It was that or a ball cut and turn which I don't have the talent for. My DC experiments never quite worked out and that 1-2 degree "off" makes all the difference.

I learned so much more than I ever cared to about drivelines and angles but if you do your homework and buy a magnetic angle level, you can wrap your head around it and understand how YOUR truck works pretty quickly. Just remember the secret is in the "Equal but opposite angles". Not much more to it. If the front of the shaft is a 3 degree angle, the rear of the shaft needs to be 3 degrees. If you throw in 500lbs and those angles change (i.e. 4 in front and 5 in back), you may need to get some adjustable control arms and adjust to find your truck's sweet spot.

My buddy lifted his truck the same height (2.5" lift, gainng 4" including OEM spring sag) and never had a vibe issue. I had lots of vibe.

 

[Dissent]

Here's the angle level I have, works great!
Amazon product ASIN B002LL0BIC

 

[LandLocked93]

I 2nd what @BILT4ME said. I'd also recommend focusing less on drivelines initially and focus on replacing the 24+ degraded rubber bushings on all the control arms, panhard bars and sway bars along with engine and transmission mounts, before ever getting into the weeds on the driveline angles. My bet is your new tranny mount accounted for your 3 degree change. My truck tightened up 300% after all new OEM bushings were installed.

I lived the driveline angle nightmare for 2 years and came to the realization that the load does matter but when I set my rear pinion angle (using adjustable LCAs) I set it about 2 degrees negative so that when torque is applied and the axle wrap occurs, it's spot on. My variable weight is 2x people and the other 1/2 of my gear which is probably about 400-500 lbs total. I don't have any vibe issues anymore at highway speed so I must have done things right. For the record, most people use adjustable upper control arms to keep their axle centered in the wheel well but my lowers worked fine for me, the tire only moved about 3/8" and nothing rubs under flex.

The front is another matter. I ended up with a part time kit and love it. It was that or a ball cut and turn which I don't have the talent for. My DC experiments never quite worked out and that 1-2 degree "off" makes all the difference.

I learned so much more than I ever cared to about drivelines and angles but if you do your homework and buy a magnetic angle level, you can wrap your head around it and understand how YOUR truck works pretty quickly. Just remember the secret is in the "Equal but opposite angles". Not much more to it. If the front of the shaft is a 3 degree angle, the rear of the shaft needs to be 3 degrees. If you throw in 500lbs and those angles change (i.e. 4 in front and 5 in back), you may need to get some adjustable control arms and adjust to find your truck's sweet spot.

My buddy lifted his truck the same height (2.5" lift, gainng 4" including OEM spring sag) and never had a vibe issue. I had lots of vibe.

The thing to get to is what is the "factory angle" at Curb Weight and where are you now?

Yes, drive line angles change as the suspension goes through it's range of motion. The "resting drive line angle" needs to be an average of it's range so that it does not exceed it's failure points before it reaches the limits of the suspension.

The further away from "average" will increase wear.

No, drive line angle does not damage or wear out your diffs / gear sets / tcase, but it can place extra loads on the input or output bearings and cause seals to fail due to increased vibration and bind. It will, however, wear out your U-Joints and can cause them to break due to over-wrapping or binding in extreme cases.

I don't have the math that should tell you the change in drive line angle that will occur with each inch of lift (or lower) of the suspension.

A transmission rebuild should NOT affect drive line angles in any way. UNLESS the mounts were changed at the same time, thus, "correcting" the angles back to what they were supposed to be. A change of 3° is significant!

There are many folks on this forum that get into the weeds when it comes to drive line design, and they can speak about it more knowledgeably and eloquently than I (@nukegoat ). but unless you're going for huge lift, massive tires, and 3-link suspension, I doubt you should be having significant problems unless bushings are worn out, wheel bearings are loose, and driveshafts need U-Joints.

Now THAT'S what I'm talking about! Thanks so much guys. Both of your comments are about all that need be said on the subject. Can I get a witness?

If there is more than the one tranny mount you can see easily near abouts the t-case, then the one I'm looking at does not look new or replaced.

I'm working the bushings sector. Rear LCA's are done with the UCA's sitting in a box to go on, as are the F&R panhards. All OEM. The front LCA's need the four rear replaced but I don't have the parts yet.

Alot to chew on here, but you've helped ease some concerns and given some useful guidlines. You're aces in my book.

 

[nukegoat]

The thing to get to is what is the "factory angle" at Curb Weight and where are you now?

Yes, drive line angles change as the suspension goes through it's range of motion. The "resting drive line angle" needs to be an average of it's range so that it does not exceed it's failure points before it reaches the limits of the suspension.

The further away from "average" will increase wear.

No, drive line angle does not damage or wear out your diffs / gear sets / tcase, but it can place extra loads on the input or output bearings and cause seals to fail due to increased vibration and bind. It will, however, wear out your U-Joints and can cause them to break due to over-wrapping or binding in extreme cases.

I don't have the math that should tell you the change in drive line angle that will occur with each inch of lift (or lower) of the suspension.

A transmission rebuild should NOT affect drive line angles in any way. UNLESS the mounts were changed at the same time, thus, "correcting" the angles back to what they were supposed to be. A change of 3° is significant!

There are many folks on this forum that get into the weeds when it comes to drive line design, and they can speak about it more knowledgeably and eloquently than I (@nukegoat ). but unless you're going for huge lift, massive tires, and 3-link suspension, I doubt you should be having significant problems unless bushings are worn out, wheel bearings are loose, and driveshafts need U-Joints.

This guy cruisers

 

[LandLocked93]

Here's the angle level I have, works great!
Amazon product ASIN B002LL0BIC

Just about to ask...

 

[Dissent]

Now THAT'S what I'm talking about! Thanks so much guys. Both of your comments are about all that need be said on the subject. Can I get a witness?

If there is more than the one tranny mount you can see easily near abouts the t-case, then the one I'm looking at does not look new or replaced.

I'm working the bushings sector. Rear LCA's are done with the UCA's sitting in a box to go on, as are the F&R panhards. All OEM. The front LCA's need the four rear replaced but I don't have the parts yet.

Alot to chew on here, but you've helped ease some concerns and given some useful guidlines. You're aces in my book.

LOL, I hope it helps! Good luck!

There's just the 1x mount under the transmission. Not sure why you would have seen any change in angle from a transmission overhaul. I'm surprised the lift didn't change anything.

 

[BILT4ME]

LOL, I hope it helps! Good luck!

There's just the 1x mount under the transmission. Not sure why you would have seen any change in angle from a transmission overhaul. I'm surprised the lift didn't change anything.

I just went through and replaced all the rubber on the bottom of my truck and it made a HUGE difference in how it drives!

I changed the rear transmission mount (I still need to do the front two engine mounts), all suspension bushings and I found the upper rear control arm bushings were the worst. The PO of my truck had hit a couple things on the right side of the truck and had damaged suspension that showed up later in life as damaged bushings.

You may want to check the front engine mounts in the event they are broken or "melted" from oil contamination, as that can change drive line angle relative to the original setup.

Ironically, now my driveshaft is making noise because I changed the pattern it has been riding in for 150,000 miles. Time for U-Joints too, it looks like.

 

[shocktower]

Body lift does nothing to the drive line now a suspension lift there is a bit of a change, I think it is about 2* per 3" , I checked mine, but the Motor I have with stock motor mounts and a 4" lift mine looked good I measure them with a little angle finder and they are really close within the +- 3* , if your not having drive line issues, don't sweat it and don't listen to tranny guy's about your drive line @nukegoat is pretty good for some info

 

[mudgudgeon]

Yep agreed with most of the above.
Ignore your tranny guy, and your drive line guy is full of s***.

You want to shoot for as close to stick angles as possible when in your standard trim.
You want it to be 95% correct for 90% of your use.
What happens when carrying an abnormal load, or off-road is what it is. It's not going to trigger the zombie apocalypse.

PS @nukegoat will confirm, your head gasket is the cause of all your drive line woes

 

[baldilocks]

1993 FZJ80

If driveline angles get horked simply as a result of a change in body height, how can one possibly maintain correct driveline angles if they have about 500 pounds of removable gear in the rear?? Even still, as the suspension travels during normal trail rides, at no time will the angles stay correct.
Do you adjust for angles with the weight out or in?
I seem to get a different explanation from every person who claims to know. From the folks who did the lift (Slee, whom I trust wouldn't you?), to the folks who rebuilt my tranny (s***hole 'A' transmission), to the drive shaft people ('A' driveline service). All have thoroughly different answers.

The driveline service folk claim OEM driveshafts are good for only one degree of angle. Well, that gets shot way out of spec over the range of suspension travel. In fact, it gets shot out with just minor undulations on the highway. Driveline clatter/rumble/vibrations ensue.

Slee says a tranny rebuild shouldn't change driveline angles, however mine changed 3 degrees after the rebuild. But then, there was no change to the angles after Slee did the actual lift - which came before the tranny rebuild - and I would concur that I had ZERO driveline vibes or issues following the lift. AND the 3" lift is actually closer to 4" in the rear.

If I were to do nothing more than what is necessary to resolve the angles as they are now (without the extra weight in the vehicle), what will happen to the angles when I add the weight back in?? Will they not change again, requiring additional adjustment to the angles to keep within the 1 degree Toyota demands?? And if I were to then adjust the angles to spec with the weight in, would the angles not be horked again upon removing said weight???

I guess my question is what is the friggin' tolerance of the drive angles and how could they ever be within spec when you have significant removable weight?
And furthermore, isn't any amount of runtime with the angles out of spec "chewing" my gear sets to pieces? (diffs/ t-case)

It's not rocket science I'm sure. But after the driveline service guy was under my truck for 10 minutes measuring angles and came out talking about how my IFS was worn out...I just shook my head in pure, amazed disbelief. Then pointed out to him the solid front axle under which he'd just spent said 10 minutes. He was as amazed at that as I was to his IFS comment.

Are there any knowledgeable AND honest mechs in Colo Springs?? I have yet to find them. Please point me to them if you know one.

Is there an actual problem you are trying to solve or are you just looking for answers to questions?

 

[LandLocked93]

Is there an actual problem you are trying to solve or are you just looking for answers to questions?

Yes. It is horrendous vibes and clatter that appeared immediately following a transmission rebuild.
They can only be shut up by pumping the shaft yokes and u-joints full every 30 miles. This has since led to the shaft end caps blowing out. I've since learned the angles are out by 3.5 degrees. The tranny mount was not replaced.

The answers above pretty much cover next months projects - finish the suspension bush replacements. Check the angles again and go from there. Might have to add motor mounts and tranny mount after that. Maybe not.

Prob try a knuckle job too. Not because of this issue, just a hunch 'Smitty' is ready for it (very little history is known on the vehicle/I'm too cheap for a carfox repart).

Plus the front diff "fluid" is sea green. And quite thick. I feel like that means a PO used the wrong grease in the birfs and the inner axle seals are shot, allowing that grease into the diff to mix with the diff fluid. I was concerned about draining and refilling the diff because I wasn't sure how much would end up in the birfs. And as I understand it, diff fluid in the birfs is worse than birf grease in the diff. And all that is definitely a diff thread altogether.

 

[LandLocked93]

You want to shoot for as close to stick angles as possible when in your standard trim.
You want it to be 95% correct for 90% of your use.

PS @nukegoat will confirm, your head gasket is the cause of all your drive line woes

Copy on the guidelines. Great info again.
I knew that head gasket looked crooked!

 

[shocktower]

Yes. It is horrendous vibes and clatter that appeared immediately following a transmission rebuild.
They can only be shut up by pumping the shaft yokes and u-joints full every 30 miles. This has since led to the shaft end caps blowing out. I've since learned the angles are out by 3.5 degrees. The tranny mount was not replaced.

The answers above pretty much cover next months projects - finish the suspension bush replacements. Check the angles again and go from there. Might have to add motor mounts and tranny mount after that. Maybe not.

Prob try a knuckle job too. Not because of this issue, just a hunch 'Smitty' is ready for it (very little history is known on the vehicle/I'm too cheap for a carfox repart). Plus the front diff "fluid" is sea green.

So pumping grease in your uni's gives you the Placebo affect, I would get some new Matsubas from @cruiseroutfit and go from there, make sure you have not spit a weight on your drive shaft, also make sure your slip joint is not over greased that will put a hydraulic load on the Uni and giving you a grinding sound, and then if you cannot fix this your tranny guy probably screwed something up probably the planitary gears.

 

[Bear80]

Is there an actual problem you are trying to solve or are you just looking for answers to questions?

DITTO

Yes. It is horrendous vibes and clatter that appeared immediately following a transmission rebuild.

I would look at THIS as the root cause. Something was not assembled correctly, internally or when the drive shafts went back on. Did the shop pull the shafts by the slip yokes and not get them properly phased? - That would be my first, no brainier, course of action.

They can only be shut up by pumping the shaft yokes and u-joints full every 30 miles. This has since led to the shaft end caps blowing out.

All I can say is holly chit...you ran the risk of cracking your t-case by pumping the shaft that full, good god, at least the caps blew out first.

To properly identify the culprit, why don't you grease just ONE u-joint at a time and test for improvement and likewise for the slip yoke?

I've since learned the angles are out by 3.5 degrees. The tranny mount was not replaced.

What do you mean by "out by??" The rear t-case flange is about 3* upward facing, is that where you got 3.5*? Matching the angles to each u-joint - that's what matters. Both u-joints need to be within 2* of each other. The transmission/engine mounts are not like German cars that can collapse and cause a significant change in the driveline angle.

Finally, this may help you: Pirate4x4.Com - Extreme Four Wheel Drive

 

[LandLocked93]

So pumping grease in your uni's gives you the Placebo affect, I would get some new Matsubas from @cruiseroutfit and go from there, make sure you have not spit a weight on your drive shaft, also make sure your slip joint is not over greased that will put a hydraulic load on the Uni and giving you a grinding sound, and then if you cannot fix this your tranny guy probably screwed something up probably the planitary gears.

Yes, well, in troubleshooting, I stopped filling both the u/j and the yoke at the same time, and just filled the u/j's by themselves to try to nail down the issue. This has helped to quiet the grinding sounds. But the clatter is still there under engine braking (above 40mph). Slight tip-in on the throttle shuts up the clatter. Then it returns under engine braking (lift throttle). Driveline guys thought the u/j's felt fine, although one is tighter than the other to move through its range of motion.

I'm still baselining the truck, so what you suggest to do when the time comes to dig into the shafts specifically sounds perfectly doable. I did the dizzy oil seal today to find that the source of the oil is actually coming up the shaft and into the dizzy. Not the head/o-ring seal that most folk do. :\ Ah discovery is great, yeah? And this project was hunting a pinging issue with oil seeping out the dizzy itself.

Thanks for the advice. Great stuff!

 

[LandLocked93]

Loving it @Bear80

Did the shop pull the shafts by the slip yokes and not get them properly phased? - That would be my first, no brainier, course of action.

Great question. Put it this way - the tranny shop resorted to the canned answer for everything, "Coincidental failure. We think it's your t-case. We can rebuild it for $1200." There's not enough space on this thread to share the whole story of the debacle that was my experience at this shop. It's been 20 months since the event. They would deny any and all knowledge at this point. I can say that the driveline folk did in fact put both pieces of the front shaft together, in phase, in front of me at the counter because I told them they came apart in my hands when I took it off - which is true. It made a satisfying 'thoomp' sound when it separated. And because the end caps are blown, the two halves will separate simply by gravity.

All I can say is holly chit...you ran the risk of cracking your t-case by pumping the shaft that full, good god, at least the caps blew out first.

Thanks for the heads-up. Had no idea. Have come to learn that watching the t-case slide rearwards with every pump of the grease gun is not part of regular maintenance.

What do you mean by "out by??" The rear t-case flange is about 3* upward facing, is that where you got 3.5*? Matching the angles to each u-joint - that's what matters. Both u-joints need to be within 2* of each other. The transmission/engine mounts are not like German cars that can collapse and cause a significant change in the driveline angle.

"Out by" were the words used by the drive line guy. I thought they were pertinent. The angle was taken from the front axle flange to front t-case flange *presumably. I didn't watch him do it. At first he said it was 8 degrees "out". Then said he thought "that is alot", and went to confer with a coworker to make sure he was doing it right. He returned (alone), laid under the truck, took the measurements and reported "3.5 degrees out". And then, "Your independent front suspension is worn out", etc.

Perhaps he simply meant there is a 3.5 degree difference between the two flanges, where you state there should only be 2 degrees? I'm hoping that difference will be rectified with the last 12 suspension bushings replaced - 4 of 6 front lca, 4 rear uca and panhards. Just waiting on the 4 front lca's to hit my front door. Plus the build out weight.

If not, this thread is GOLD to chase the gremlins down!

Finally, this may help you: Pirate4x4.Com - Extreme Four Wheel Drive

Awesome! Thanks so much for all the help. Happy Trails!

 

[nukegoat]

What is the phasing of your driveshaft?

 

[LandLocked93]

What is the phasing of your driveshaft?

No idea.

But you know I do not know. lol

When I said, "...put them together, in front of me...", it suggested I knew what they were doing. I did not.
Ok, so I called this drive line place to have them look at my OEM shaft and a shaft I got from a pik'n'pull. I think you know that part.
I also told them the shaft had separated and I didn't know how to get it back together. They said no prob bring it on down.
I dealt with two dudes when I got there. One older, one younger. We talked for 10 minutes or so, some with both dudes preseant, some with just one. Then some with just the other. Then the last couple with both again. During that time, the younger noticed the shaft was not in phase, took it apart, and put it back together. The older dude was not present to see this.
Later, when both dudes were there, the older says to me, "It looks like you got it back together in phase." I tell him no, the younger guy did that. He say's, "oh, ok.".

So that's why I just simply said, "...they put it together in front of me, in phase...", as if I knew whiskey tango foxtrot.
It's just shorter.

But to your end, no, I still have no idea if it's in phase or not. lol