spankrjs's Biloxi, MS '83 Scrambler

FLCJ8

Legacy Registered User
City
Palm Bay
State
FL
Even with the spacer, the stock length rear brake line is pulled tight at max droop. I need to install a longer rear brake line.

View attachment 67287
When I built my suspension I used a "L" bracket bolted to the axle and the "T" brake line fitting bolted to the "L" with the brake line to the frame pointing up.
More than enough length. Not sure if it's an option for you. :shrug:
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
When I built my suspension I used a "L" bracket bolted to the axle and the "T" brake line fitting bolted to the "L" with the brake line to the frame pointing up.
More than enough length. Not sure if it's an option for you. :shrug:
That should work, and keep me from having to bleed brakes :thumbsup:
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
I have been driving this one the past few weeks, still very happy with the ride quality, nice and smooth.

One problem - I finally got it out on the interstate, and when it got up to around 65-70 mph, slight vibration from the rear end. I checked the rear pinion/Dana 300 output angles before the lift, they were both at 4 degrees, or pretty close to it (Dana 300 4 degrees down, rear pinion 4 degrees up).

After the lift, Dana 300, 5 degrees down, rear pinion 9 degrees up. I should have figured this would happen, the new shackles are much longer then stock.

IMG_20181201_093257851.jpg

According to the FSM, you should strive for the following (regular driveshaft, NOT CV shaft):

IMG_20181201_093250884.jpg

No problem, I have some steel shims left over from other pinion angle/caster angle projects. So, took it all apart, pulled out the center pins from the leaf springs, and a problem. I drilled all my shims center pin holes out to 3/8". IIRC, the Superlift and Rubicon Express springs use 3/8" center pins. The BDS springs use a 5/16 center pin. So, I ordered some new RE steel shims. They come with a 5/16 center pin hole. I also had to get some longer center pins, the BDS ones are too short to add a shim to the pack. Added bonus, the shims came pre-painted black, woo-hoo!!!!1

IMG_20181204_174112513.jpg


So, I added the shims, fat end toward the rear of the vehicle, to roll the pinion down 4 degrees. Put it all back together, got it back on the ground. nice and level, rechecked my angles:

IMG_20181204_193529453.jpg

So, according to the angle finder and the FSM, I should be good to go, I need to test drive to confirm.

I am going to assume that the longer front shackles have knocked the caster out of whack, too. I will probably get the alignment checked, unless I can accurately check the caster angle with my angle finder some how, before I add shims. On my other two Scramblers, with RE 4.5" lifts, that have longer front shackles, I had to shim the fronts to get the caster correct. So, more shims to come.

I also bought myself a Christmas present, and used it early:

IMG_20181130_203147949.jpg

A Dewalt 899 impact, and some impact sockets. All the years of working on these things, I have never had any type of impact, air or electric. This thing is cool. Works perfect for me. It easily took the lug nuts/u-bolt nuts, shock nuts off, no problem. Added bonus, no compressor or air hose to worry about, and since it has a battery, I can take it anywhere.

That's it for now, till I mess with shimming the front end :wave:
 

LetchcoreCJ7

Legacy Registered User
City
Nashville
State
TN
I have that impact it’s a great. I have snap on too and that one is as good. I don’t touch a bolt with a wrench unless I have to.
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
The rear end shims helped some, but I still have some vibration from the rear. Did some more math:

Driveshaft angle = 15 degrees
Pinion U-Joint operating angle = 10 degrees (15 degree ds angle - 5 degree pinion angle)
Dana 300 operating angle = 9 degrees (15 degree ds angle - 6 degree Dana 300 angle)

Random "internet knowledge"

"No more then 12 degree driveshaft angle with single u-joints one each end"
"No more then 15 degree driveshaft angle with single u-joints one each end"

33" long drive shaft divided by 10 = no more then 3.3 degree u-joint operating angle (I'm at 10 degrees)

(20,168/tire diameter) x gear ratio = driveshaft RPM at 60 mph
(20168/30) x 3.31 = 2,225 RPM at 60 mph
2,225 x 1.25 = 2,781 RPM at 75 mph

2,000 MAX RPM for u-joint at 8.67 degrees
2,500 MAX RPM for u-joint at 7 degrees
I'm at 10 degrees

It operates smooth up to about 60 mph, then it starts vibrating some. It's not terrible, minimal, but I don't like it. I had no vibration prior to the new springs.

One other thing I have noticed - my rear driveshaft has extended out about 1" more then before. I don't have any play at the slip joint, but maybe that is causing the vibration? I have another rear drive shaft, it measures 31-1/8" collapsed, that I had built for my Red Scrambler after I put the 4.5" RE lift on it. I might swap it on to see if the vibration goes away. I bet not.

So, unfortunately, looks like I might be heading toward a CV rear drive shaft on this one too, which seems crazy with a 2.5" lift on a Scrambler :shrug:

Going to go back and review my other two Scrambler threads and look at some of those drive shaft angles. I ended up with CV's on both of those.
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
I know I have a CV in the back of my Red Scrambler, but no info on my thread about it :shrug: I'm either losing my mind or never put any information on the thread about it :shrug:

On the Tan Scrambler, 4.5" RE lift/700R4/Dana 300/AMC 20, I had the following before the CV install:

Dana 300 = 5 degrees down
Pinion = 5 degrees up
Driveshaft = 15 degrees
Driveshaft length = 28-1/4"

This one vibrated with the 10 degree u-joint operating angles.

After the CV install:

Driveshaft angle = 12 degrees
Pinion angle = 10 degrees up (11 degrees would be better)
No vibration

I just cant wrap my head around the fact I have the same u-joint operating angles on a Scrambler with a 2" lift, I can see it on the 4.5" lift, but the angle finder doesn't lie :shrug:
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
Swapped in a slightly longer rear driveshaft and test drove it Friday night. I still have the vibration. It is perfectly smooth until 55 MPH, then it starts to slightly vibrate. The vibrations get worse as speed increases.

Ordered a CV Yoke/CV driveshaft this morning, and a slightly longer front driveshaft, too. Always something :wave:
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
Picked up and installed a new CV driveshaft/yoke for the rear, and a new longer front driveshaft yesterday:

1.jpg

The existing/stock front driveshaft might have been OK, but it only had like 1" more outward travel, better safe then sorry. The front driveshaft was made with same size tubing as the rear shaft, so slightly larger OD then a stock shaft. No clearance problems on this applications (258/T5/Dana 300/2.5" lift).

With the rear shaft, you have to change the Dana 300 yoke from the stock non-CV type to the CV type.

I flipped around the 4" shims I installed on the rear leaf springs (fat end toward front now), just to see if this would get me close.

My angles now:

10-11 degrees UP on the pinion
12-13 degrees DOWN on the driveshaft

So, the pinion is running 1-3 degrees DOWN from the driveshaft, 1 degree preferred. It is hard to make out the exact degree with my angle finder, but I am going to guess it is closer to a 2-3 DOWN angle.

Test drive confirmed the angle is still not correct. The vibration doesn't start now until around 65 MPH, so I am getting closer. I will swap in some 6 degree shims next, see what I get.

I am measuring the pinion u-joint angle on an actual u-joint cap. The rear end housing/yoke do not have a machined surface that runs the exact same angle as the u-joint. Bit of a pain, but the most accurate way to measure the pinion u-joint angle :twocents: I can also tell by looking that I have a bit more then the recommended 1 degree downward angle. With a one degree difference, the pinion yoke/driveshaft yoke would almost be parallel, and they are not.

Hopefully the 6 degree shims get it right :fingerscrossed:

A quick not about the shims - you can't necessarily go by what they are advertised as. An example:

Pinion angle, no shims - 9 degrees UP
Pinion angle, 4 degree shim, fat end to back - 5 degrees UP (9-4=5) WORKS OUT
Pinion angle, 4 degree shim, fat end to front - 10-11 degrees UP (9+4=13) DOESN'T WORK OUT

Also, when you change the pinion angle, you change the driveshaft angle some, too.

My driveshaft angle was at 15 degrees, with the pinion UP 5 degrees
My driveshaft angle is now 12-13 degrees with the pinion UP 10-11 degrees (CV shaft)

I am "scared" a 6 degree shim is going to make the pinion u-joint angle match perfectly with the driveshaft angle:crazy: That would be perfect with a linked rear end, but with leaf springs, you want the pinion a degree down to compensate for slight axle wind up. Or so they say......................

On my red Scrambler, with a CV shaft, I have zero vibration. I need to check the angles on it, and match
On my Tan Scrambler, with a CV shaft, slight vibration at exactly 60 MPH only, slower or faster then exact 60, no vibration.

IF I some how end up with the pinion u-joint/driveshaft angle exactly equal, I will probably slightly lift the engine/transmission to give it a slight misalignment. Lifting the power train will increase the driveshaft angle.

The vibration I have is slight, not super bad, just aggravating. Mainly feel it in the seat/floor boards, not audible. I know it should be running super smooth, so i will keep working at it.

That't it for now:wave:
 

FLCJ8

Legacy Registered User
City
Palm Bay
State
FL
I am "scared" a 6 degree shim is going to make the pinion u-joint angle match perfectly with the driveshaft angle:crazy: That would be perfect with a linked rear end, but with leaf springs, you want the pinion a degree down to compensate for slight axle wind up. Or so they say......................

That't it for now:wave:
Here's some interesting info, with a method for checking spring wrap.
https://www.quadratec.com/jeep_knowledgebase/article-3.htm

You may have already seen this.
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
Here's some interesting info, with a method for checking spring wrap.
https://www.quadratec.com/jeep_knowledgebase/article-3.htm

You may have already seen this.
Yep, tried that Sunday morning :thumbsup:

Scrambler in Low Range
Scrambler in First Gear
Front Wheels blocked
Brake pedal pushed down all the way
Come off clutch slowly until the power train starts to load up

Observations:

NO upward pinion movement UNTIL immediately before both rear wheels break free and spin. Not until this critical moment is their any spring wrap. Once the wheels spin, pinion returns to normal angle. And when I say moment, I mean a second before the rear tires spin. I would think this is a worse case scenario, Max torque and vehicle held stationary. So, I would assume I do not have any spring wrap above 65 mph, 30" tires, 3.31 gears, T5, 258 with MPI :shrug:
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
I was going to swap out the rear degree wedges, but the pinion u-joint angle is "perfect" how it is :shrug:

Rear Pinion, 11-12 degrees:

IMG_20181216_081159488.jpg


Driveshaft angle, 12-13 degrees:

IMG_20181216_081306129.jpg

What it looks like:

IMG_20181216_081621768.jpg


So, maybe my vibration is from an unbalanced tire/wheel? IIRC, I had no vibrations at all before the lift. I could swap in 2.5 degree wedges to drop the pinion angle down another 1.5 degrees, but that would too much :shrug:

Not feeling like messing with the rear end anymore, I decided to mess with the front end.

I was pretty sure the lift/longer shackles screwed up the caster on the front end. Steering was still tight, but felt vague, and little "return to center". So, quick alignment check:

IMG_20181216_095824490.jpg

Caster at 2 degrees, should be at 6 degrees:

IMG_20181216_095854658.jpg

So, I installed some 4 degree steel shims up front, fat end toward the front. That should fix that.

One other interesting thing - the toe is out. The guy started to adjust it, then realized I was just getting the "free alignment check", and stopped. But, after I installed the front 4 degree wedges, and the half fixed alignment, a little less vibration, unless I am imagining things....

I might go back and get the alignment checked and the tires re-balanced before I mess with anything else. The toe was probably thrown out, passenger tire toed in, from the lift, which put more of an angle on the drag link (pitman arm to passenger front knuckle tube) which effectively shortened it.

I checked all the motor mount, bell housing, transmission, and transfer case attaching bolts, all tight. The transmission mount bolts were a hair bit loose, but no other obvious issues found.

Vibration is evident above 60 mph, while under power, or coasting.
I can shift out of third gear at 55 mph, no vibration.

Does not seem to be power train/drive line dependent, since it also vibrates while coasting. The only constant is the tires are turning :shrug:
 

CJ8LVR

Legacy Registered User
SOA Board Member
City
Madison
State
AL
Chasing vibrations is not fun. I've been dealing with some in mine for a while now. I'm now leaning toward a wheel or tire out of balance.
Like you, I'm good up until just above 65mph or so. With my engine, gearing, tires, etc, I can and usually do cruise on long trips even towing a trailer at or above 70 so I'm hoping a tire change and possible wheel change fixes it for me.

One other thing worth noting, in working with Jim Reel with Reel Drivelines, he recommends the rear pinion be down about 4 or so degrees from pointing directly at the back of the transfer case. When under throttle, it rotates up and into alignment but regular cruising that little bit of misalignment works the needle bearings in the rear u-joint which is good for it. I'm running a double cardan joint on the front end of my rear driveshaft and a flange on the back of the Dana 300 from Novak Conversions. The flange is shorter and much stronger than a yoke and I'm also running 1350 joints now in there. Any who, maybe that helps, maybe not.
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
Chasing vibrations is not fun. I've been dealing with some in mine for a while now. I'm now leaning toward a wheel or tire out of balance.
Like you, I'm good up until just above 65mph or so. With my engine, gearing, tires, etc, I can and usually do cruise on long trips even towing a trailer at or above 70 so I'm hoping a tire change and possible wheel change fixes it for me.

One other thing worth noting, in working with Jim Reel with Reel Drivelines, he recommends the rear pinion be down about 4 or so degrees from pointing directly at the back of the transfer case. When under throttle, it rotates up and into alignment but regular cruising that little bit of misalignment works the needle bearings in the rear u-joint which is good for it. I'm running a double cardan joint on the front end of my rear driveshaft and a flange on the back of the Dana 300 from Novak Conversions. The flange is shorter and much stronger than a yoke and I'm also running 1350 joints now in there. Any who, maybe that helps, maybe not.
I'm thinking it is a tire/alignment issue, need to get the tires re-balanced before anything else, cheap and easy :thumbsup:

If that doesn't work, I can swap in some 2.5 degree shims in the rear, drop the pinion another 1.5 degrees :shrug:
 

Belizeit

CJ-8 Member
CJ-8.com Member
City
River Ridge
State
La
Luckily I have never had to deal with any real vibration. I would get the wheels and tires checked like you said. I just got some used wheels sand blasted and painted and new tires mounted. Only 1 needed extra amounts of weights but I have not had any problems with vibrations.
 

spankrjs

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Biloxi
State
MS
Luckily I have never had to deal with any real vibration. I would get the wheels and tires checked like you said. I just got some used wheels sand blasted and painted and new tires mounted. Only 1 needed extra amounts of weights but I have not had any problems with vibrations.
Hopefully just a tire issue, but I think I will be resetting the pinion angle, again :banghead:
 

MrBeep

CJ-8 Vendor Supporter
CJ-8.com Vendor
City
Dillsboro
State
IN
I chased a vibration at 60-65 mph in my Black 83 Scrambler for 2 over two years. Daily driver, 360/T-18/300. Finally pulled axle and found passenger side outer axle bearing had just a tad bit of play in it. new bearing cured it. :shrug:
 
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