TTORA Forum banner

1 - 20 of 22 Posts

·
Registered
Joined
·
363 Posts
Discussion Starter #1 (Edited)
Been a while since I've posted, but here goes,

I recently had a Diamond axle and 4 Wheel Underground 3 link SAS kit installed. Still working out the bugs but the rear driveline vibes are out of control.

Prior to the install, my Inch Worm 4.7 Lefty and OEM 8.4 rear w/ ARB 5.29 equipped locker was flawless, all worked great.

The guy that did the work didn't get the T-case output flange angle as he installed a temporary cross member. I drove it home and man, what a ride that was. My dentist loves me at the moment.

Does anybody with a stock regular cab Prerunner w/ 2.7 & auto trans know what the OEM output flange angle should be?

Thanks in advance.
 

·
Registered
Joined
·
363 Posts
Discussion Starter #3
Scuba... still diggin' going through your build!

At bit of history:

When I had the A340F trans rebuilt, the Inch Worm T-case was installed, the drive shaft was built to fit. At that point, I had zero issues. All of this while retaining the OEM cross member.

Now, the 3 link brackets take place of the complete OEM cross member.

As I've attempted to replicate the new self made cross member, I am struggling with the correct angle on the output flange. The motor mounts haven't change nor has the rear axle.

If I had the OEM t-case angle numbers, I can build to that and all should be good.

Am I missing something?

Thanks for the reply.
 

·
Registered
Joined
·
1,657 Posts
I agree with what Scuba said.

After removing the old cross member and placing a temporary one, how much do you think that changed the tcase's output angle realistically speaking? What did you do for your rear suspension? What kind of springs? How is it set up? (longer aftermarket shackles, blocks, shims to correct pinion angle, etc)
 

·
Registered
Joined
·
363 Posts
Discussion Starter #5
OK... thanks for the replies first of all.
2nd, here is a bit of history which will bring you to where I am today:

2.5 years, I had an A340F trans rebuilt and at the same time, an Inch Worm 4.7 Lefty installed along with the trans. No front driveshaft installed. The rear driveshaft was built to order and off I went, zero issues.

The rear has a Deaver 8 pack set of leafs which was on prior to the trans & T-case install. Again, no issues, before or after.

All has been affected by the removal of the OEM trans cross member as the rear has not changed.

One change worthy of note, I am now using the trans mount location on the T-case instead of the adapter between the T-case and trans.

Do you think there is where the change could be?

Thanks for tuning in.
 

·
NorCal Chapter Pres
Joined
·
12,210 Posts
If you changed the height at all of the tcase and trans, it will change the angle of the output, and it will change the angle of the driveline, and throw off the u joint angles.

What's probably happening is the rear pinion angle is not equal to the rear tcase output.

Just put a shim on the leaf pack to get the angles back to canceling out and you're okay (this is assuming you're not running a cv shaft, which in this case, the rear pinion angle is set to 0)

Sent from my SM-G920V using Tapatalk
 

·
STITCH - Come and Take it!
Joined
·
9,051 Posts
Richie, do you have any photos of the 4Wheel Underground system?
 

·
Registered
Joined
·
363 Posts
Discussion Starter #8
Richie, do you have any photos of the 4Wheel Underground system?
I have quite a few photos. What in particular do you want to see?

Phil,
The drive shaft has a Cardan just after the output flange on the T-case. Also, it has a slip joint too. The rear pinion angle has never been changed.

Thanks for the replies.
 

·
NorCal Chapter Pres
Joined
·
12,210 Posts
So your ujoint operating angle needs to be 0 degrees. By raising or lowering the tcase height, you also change the pinion end operating angle.

Because you have a cv, the rear ujoint angle needs to be 0. You measure this by measuring the pining flange angle, and subtracting it from the angle of the driveline. It should equal 90.

Another problem is the u joints could be out of phase. If the rear slip was taken off and not slipped back exactly the ssme, it's out of phase.

https://youtu.be/gmV4qwLfOMY

Watch the video. It will explain why angles are so important. Since you have a cv, you are essentially working with just 1 ujoint, so having the operating angle at 0 is critical.

Sent from my SM-G920V using Tapatalk
 

·
Registered
Joined
·
363 Posts
Discussion Starter #10
Phil,

Thanks for the link. Very informative. I will make the adjustments tomorrow.

Tejas,
I will post some pics shortly.

Thanks for the replies.
 

·
Registered
Joined
·
363 Posts
Discussion Starter #11
Here are the usual 3 link pics... no different than the many others but... this one is mine. I never thought the day would come.
 

Attachments

·
Registered
Joined
·
363 Posts
Discussion Starter #12
Here are some with the CO's in place. I need to replace several brake lines and remove the entire ABS system. The module takes up the space where my ARB 'twin' compressor will soon reside. The shock tower on the PS is now where it once was.

Many little things to correct but it's getting closer.
 

Attachments

·
NorCal Chapter Pres
Joined
·
12,210 Posts
I also forgot to add. With leafs on the rear and no trac bar, the pinion will rotate up under load. If you point the pinion downwards from 0 by 1 or 2 degrees, when you're moving and under power, the pinion will rotate up to a 0 degree working angle

Sent from my SM-G920V using Tapatalk
 

·
Registered
Joined
·
363 Posts
Discussion Starter #14
... I forgot to add, the current frame height is @ 20".

I will make the adjustments tomorrow and set it @ 21".

Thanks for tuning in.
 

·
Registered
Joined
·
8,951 Posts
Sound like they've got you on a good track.
One thing I'll add.. Make sure the slip joint on the rear shaft isn't too far extended at ride height. I once added an axle relocation plate to push my axle back 3/4" or 1" (don't remember which) to center the rear end in the wheel well. After roughly 30k miles, it wore out the slip joint splines because it was too far extended.
 

·
Registered
Joined
·
363 Posts
Discussion Starter #16
Sound like they've got you on a good track.
One thing I'll add.. Make sure the slip joint on the rear shaft isn't too far extended at ride height. I once added an axle relocation plate to push my axle back 3/4" or 1" (don't remember which) to center the rear end in the wheel well. After roughly 30k miles, it wore out the slip joint splines because it was too far extended.
Good point, thanks.

I'll have this remedied later this morning.

Thanks for the tips guys.
 

·
Registered
Joined
·
363 Posts
Discussion Starter #17
So your ujoint operating angle needs to be 0 degrees. By raising or lowering the tcase height, you also change the pinion end operating angle.

Because you have a cv, the rear ujoint angle needs to be 0. You measure this by measuring the pining flange angle, and subtracting it from the angle of the driveline. It should equal 90.

Another problem is the u joints could be out of phase. If the rear slip was taken off and not slipped back exactly the ssme, it's out of phase.

https://youtu.be/gmV4qwLfOMY

Watch the video. It will explain why angles are so important. Since you have a cv, you are essentially working with just 1 ujoint, so having the operating angle at 0 is critical.

Sent from my SM-G920V using Tapatalk
Phil,
My driveshaft angle is 13 degrees and my pinion flange is 77, totaling 90, is that what you meant?

The T-case flange is close to 90 degrees now. It still vibrates. I have 5/16" spacers on each side of the cross member.

Do those numbers work or am I missing something?

Thanks.
 

·
NorCal Chapter Pres
Joined
·
12,210 Posts
Doh, yeah you're okay there.

So you have a carrier bearing support or is it a one piece with a cv at the tcase end?

I'd check that the u joints are in phase. Even one tooth off on the slip yoke will throw the u joints out of alignment and they will not be in phase. It will vibrate horribly with the u joints out of phase

Sent from my SM-G920V using Tapatalk
 

·
Registered
Joined
·
363 Posts
Discussion Starter #19
No carrier bearing, one piece w/ slip.

The u-joints appear to be in phase. I didn't measure or check it but I may just do that now.

Thanks.
 

·
Registered
Joined
·
363 Posts
Discussion Starter #20
So an update is in order:

In attempting to find the correct cross member angle, I used washers to incrementally find the sweet spot. I was getting burned out on this so I took it to MIT in El Cajon.

Turns out, I was one washer off on each side of the cross member and this entire time trying to figure this out, junked the rear bearing in the Lefty.

All sorted now. No vibe sso I'm good to go on this.

Question for the 3 link guys... when I back up from a parking spot, I get a loud popping noise. When I begin going forward, It repeats itself. Annoying for sure.

I've checked everything underneath and found the panhard bar does hit the upper link bracket that is welded to the axle. As it is on HEIMS, it does pivot quite a bit. Do you think that may be the sound I'm hearing? I can't prove it which is why I ask.

I'm thinking I will install either a Teflon washer or steel between the HEIM in the inside of the bracket to keep it from rolling back & forth.

Any thoughts?

Thanks.
 
1 - 20 of 22 Posts
Top