Post 4" Lift Woes - Violent Braking & Rumbling

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Herk
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Re: Post 4" Lift Woes - Violent Braking & Rumbling

Post by Herk »

First thing I see is the rear driveshaft angles look terrible. Compared to the transfer output angle, the differential looks like it's almost in line with the shaft. Mismatched angles will cause vibration and driveline failure. You'll never get the front close to right without totally messing up the caster angle. The higher the lift, the worse this gets.

Is the vibration when you brake felt in the steering or the brake pedal? If you feel it in the pedal, the drums are warped. If it's the steering, I would start with the wheel bearings and work my way in to the knuckle bearings. Loose wheel bearings or incorrect knuckle bearing preload will cause all sorts of grief. Lifting just makes it all worse. Also the angle of the drag link is not ideal. A drop pitman arm will help with that. Any slop at all in the tie rod ends will also cause problems.

SJTD
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Re: Post 4" Lift Woes - Violent Braking & Rumbling

Post by SJTD »

Got out the calculator. I figger raising the the thing 4" in effect shortened the shaft about 5/32"ish so I now doubt it's binding but that would move the balls partially out of the indentations they pounded into groves they run in when the cross is flat but they would prolly be in them at bottom and out at the top when the cross when the cross is vertical. Rumble, rumble...

Similar to brinelling in a regular u-joint only worse.

Maybe.
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kjandb
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Re: Post 4

Post by kjandb »

Alright, finally getting around to the driveshaft.

I'm having a hard time finding the right output yoke. 10 spline d20. I'm assuming I need the felt seal too - anything else I should replace? This look right?:

https://teamgrandwagoneer.com/dana-20-q ... 1963-1979/


And help me understand ujoint compatibility. Does the rear Axle (d44) yoke style need to match the tcase? Both 1310 for example. Pics are below for current style, no clue what the teamgrandwagoneer.com style is.

Tcase:
Image
Image
D44:
Image
Image

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'71 Wagoneer - 4" BJ's Leaf Lift - early 360 - Avocado Mist ???
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sierrablue
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Re: Post 4" Lift Woes - Violent Braking & Rumbling

Post by sierrablue »

Mine has 1310 on all of the yokes. Makes it way easier to find u joints but there's nothing saying it HAS to match.
'71 Wagoneer (DD)
-B350 (HEI, iron 4-barrel, Edelbrock 1406), TH400, D20
-'74 D44 front (nonpower discs)
-custom headliner
-Front shoulder belts (rears eventually)

viewtopic.php?t=23070

There are 2 major differences between new Wranglers and FSJs. FSJs are meant to be both utilitarian and capable, not just capable. FSJs are also rarely initially recognized as Jeeps by the average American.
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Stuka
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Re: Post 4" Lift Woes - Violent Braking & Rumbling

Post by Stuka »

They don’t have to both be 1310, but it is advised to keep vibrations to a minimum.

They do not have to use the same yokes. One could be a flange mount and one be a yoke.
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sierrablue
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Re: Post 4" Lift Woes - Violent Braking & Rumbling

Post by sierrablue »

I do suggest you get a yoke with closed ends, it it's a 1310. Can't tell you how many times before I got new bolts that the straps vibrated the tiniest little bit loose, and it started vibrating horribly. It's fixed now but still.
'71 Wagoneer (DD)
-B350 (HEI, iron 4-barrel, Edelbrock 1406), TH400, D20
-'74 D44 front (nonpower discs)
-custom headliner
-Front shoulder belts (rears eventually)

viewtopic.php?t=23070

There are 2 major differences between new Wranglers and FSJs. FSJs are meant to be both utilitarian and capable, not just capable. FSJs are also rarely initially recognized as Jeeps by the average American.

Srdayflyer
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Re: Post 4" Lift Woes - Violent Braking & Rumbling

Post by Srdayflyer »

you DEFINATELY need to address the pitman arm angle you need a drop as much as you lift, your gonna have steering issues amd magnified DEATH WOBBLE.

sierrablue
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Re: Post 4" Lift Woes - Violent Braking & Rumbling

Post by sierrablue »

Srdayflyer wrote: Sun Mar 05, 2023 3:34 pm you DEFINATELY need to address the pitman arm angle you need a drop as much as you lift, your gonna have steering issues amd magnified DEATH WOBBLE.
How will this induce death wobble? It has new leaf springs, so the only bushings that could be causing problems would be in the shackles. Death wobble is caused by loose joints, not by goofy steering setups. It may amplify it but it being a stiffly leaf sprung setup, death wobble seems unlikely. Theoretically possible, but unlikely. And it could really only amplify it if the suspension was moving up and down rapidly at the same time, which I don't think is possible with a 4k lb Jeep on springs that stiff.

Srdayflyer is right about the steering issues though--you want the drag link and the tie rod to sit pretty much level at ride height, as with no track bar these Jeeps will have some bump steer, guaranteed. If you set it so it's level though, it will always jog left, so you know what it's gonna do.
'71 Wagoneer (DD)
-B350 (HEI, iron 4-barrel, Edelbrock 1406), TH400, D20
-'74 D44 front (nonpower discs)
-custom headliner
-Front shoulder belts (rears eventually)

viewtopic.php?t=23070

There are 2 major differences between new Wranglers and FSJs. FSJs are meant to be both utilitarian and capable, not just capable. FSJs are also rarely initially recognized as Jeeps by the average American.
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kjandb
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Re: Post 4" Lift Woes - Violent Braking & Rumbling

Post by kjandb »

Just received new yokes and driveshaft from Tom Wood's. I told them what I have and it was delivered to my door in 2 days.

The tcase yoke is different enough than my old yoke, and the yoke pictured in the TSM, that I'm hesitant to install it. The new yoke doesn't have the lip going around the housing or a felt seal.

Do I need a different yoke? Or add a seal?

I'm sure Tom Wood's will be able to help too, I just didn't work wait til Monday. ImageImageImageImage

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Yeller
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Re: Post 4" Lift Woes - Violent Braking & Rumbling

Post by Yeller »

You do not need the dust shield or the felt seal. install the new parts with a new seal without the other parts and it will work well
The bus I ride is so short it is a yellow Smart Car full of squirrels, monkeys and clowns.

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sierrablue
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Re: Post 4" Lift Woes - Violent Braking & Rumbling

Post by sierrablue »

^what Yeller said

I don't have a dust shield or anything on my '71--well the front output yoke on the D20 does, but nothing on the D44s.
'71 Wagoneer (DD)
-B350 (HEI, iron 4-barrel, Edelbrock 1406), TH400, D20
-'74 D44 front (nonpower discs)
-custom headliner
-Front shoulder belts (rears eventually)

viewtopic.php?t=23070

There are 2 major differences between new Wranglers and FSJs. FSJs are meant to be both utilitarian and capable, not just capable. FSJs are also rarely initially recognized as Jeeps by the average American.

sansabarJ
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Re: Post 4" Lift Woes - Violent Braking & Rumbling

Post by sansabarJ »

I've done many lifts on the 4x4s ,Jeeps Scouts Travelalls and the like . All require the same upgrades once lifted ,IE: longer driveshaft front and rear , extended brake lines , caster wedges on front spring perches to get back the correct caster . Lifts throw a big wrench into any lifted vehicle. Once lifted, the driveshafts are usually at or near t the limit of (extended ) travel . The driveline angles are off ,and will be incorrect . Pitman arm and draglink will be as shown here with this wagoneer at steep angle .
All these items now require rework to perform at acceptable levels.

The Dana 20 can use the new Yoke as shown , install it and torque the nut to specs . The driveshaft need to be redone to install a standard slipyoke with a 1310 joint . Measure the distance between your ujoint cap " center " at Tcase yoke to the differential ujoint yoke cap center .This gives the driveline shop Tom Woods the correct length driveshshaft you will need . This applies to both the front and rear driveshafts. Once youve got the proper length driveshafts installed , you can address the U joint angles . I recommend a digital angle finder from Amazon . The angle finder has a magnetic base so you can get accurate measurements. You want no more than 3 degrees difference in your angle from Tcase to differential . More then 3 the vibrations result . I recommend looking at driveline angle videos to help with your drivelines. Don't try to make your old driveshafts work because they won't properly. The trunnion output joint setup binds and cannot be made to work period . A trunnion setup cannot , as has been said here on this thread , accept this much lift AKA driveshaft angle , a 2inch lift may be marginal also for a trunnion . Caster : the front differential at this high of lift requires the caster angle to be corrected . Degree shims can be successfully used on some lifts depending on the amount of the lift . However the driveshaft angle at front differential can be too steep and cause the U joint to bind . This issue requires more fabrication to the front knuckles . This we can leave out of the discussion at this point unless there's an issue . The rumbling on deceleration IS a result of the incorrect rear driveshaft angle . Yes the trunnion added to this but the rear angles MUST be resolved . Tom Woods shop is very good and dedicated to resolving issues . Always use SPICER u joints or similar high quality joints with lubrication capability . Leave the solid joints for the hardcore 4x4 folks running extreme angles etc . Incorrect caster causes a lot of squirrely handling , steering and a not good driving experience overall . The lift moves the steering box "OFF CENTER" which immediately causes loosness feel in steering . Your tires are not tracking straight down the road . You will note that the steering wheel is now not straight. The drag link may be able to be adjusted out enough ( has the adjuster sleeve ) to recenter steering box back to center of travel and this moves the steering wheel back to the correct position it was before the lift . A. Caution here is drag link may be too short in length requiring a new one be fabricated. Or purchased to correct the issues discussed here . Now , a drop Pitman arm is definately going to be required on this lift as this will ease the angle of draglink including allowing adjusting it . I will recommend installing the drop arm FIRST , then address the drag link if necessary to resolve steering . I will agree with the others on the shackles . They " should " angle toward the front and not the rear as they are .They can Pop back inverted as you've had said as suspension moves . If the springs do not settle enough to move your shackles back into proper position , another look at the spring pack to decided how to lessen the lift amount . I'll add my post along with the other guys here to address the problems . All lifts just require a lot of extras to get it right and enjoy it , not hate it .


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kjandb
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Re: Post 4" Lift Woes - Violent Braking & Rumbling

Post by kjandb »

Thanks for the detailed post sansabarJ.

I started at the rear driveshaft, since that trunion style wasn't going to work either way. Let's hope the front driveshaft will work with the new angles. I used a digital angle finder and sent them to Tom Woods - they recommended a single joint at each end instead of CV. Hoping I won't need shims. Pic below.

I took your advise, and others, and went ahead and ordered a new drop pitman. And once I have it moving again I'll put more time to the shackle angles and see if I can get it out and flex a bit.
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Yeller
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Re: Post 4" Lift Woes - Violent Braking & Rumbling

Post by Yeller »

Those driveshaft angles are very livable.
The bus I ride is so short it is a yellow Smart Car full of squirrels, monkeys and clowns.

1970 J2500 Resto Mod
https://www.fsjnetwork.com/forum/viewt ... 12&t=21395

1974 Bronco “Broncno”
https://classicbroncos.com/forums/threa ... st-3411909
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kjandb
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Re: Post 4" Lift Woes - Violent Braking & Rumbling

Post by kjandb »

New driveshaft and yokes are working great. Installed the drop pitman too. Thanks for all the help. Now onto my shackles....

I contacted BJ's and they agreed the angle is terrible. They recommended loosening both shackle bolts, get it off the ground, attach ratchet strap and keep tension, then lower it down to pull them forward. I tried it several times and maybe gained a quarter inch in the right direction. Then after flexing it (jumping up and down on bumper and a short drive) I think they settled back into the same position as when I started.

BJ's is now suggesting upgrading to longer shackles to fix the problem: https://bjsoffroad.com/shackles-heavy-duty-1-inch-lift/

My questions are:
1) Is this a safety concern with this angle or just poor ride quality
2) Are the longer shackles going to fix my issue and is it worth it? Apparently they'll take some modifying to fit my '71
3) Anything else I should try? Will time/miles fix it?

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tgreese
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Re: Post 4" Lift Woes - Violent Braking & Rumbling

Post by tgreese »

Aren't BJ's springs made by Deaver in Santa Ana CA? If so, I would give them a call. Longer shackles on the front will change your caster angle (reduce it) and be more mmm wobbly for lack of a better term?
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Re: Post 4" Lift Woes - Violent Braking & Rumbling

Post by akguy09 »

I can't see how a longer shackle will fix a bad angle
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Stuka
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Re: Post 4" Lift Woes - Violent Braking & Rumbling

Post by Stuka »

Longer shackles will not resolve the issue, they will make it worse. Longer shackles are a good idea if the shackle angle is too far forward. But if its too far back, a longer shackle will result having them point farther back than they do now.

To me, either the springs need to be broken in a LOT so they sag some, which will make them longer and fix the shackle angle. Or, the main leaf is just too short and needs to be replaced. The other leaves are all likely fine.
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Scotty54
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Re: Post 4" Lift Woes - Violent Braking & Rumbling

Post by Scotty54 »

I second Tim's suggestion - call Deaver. They are very helpful. They have a Jeep guy who knows FSJ's. (714) 542-3703
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akguy09
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Re: Post 4" Lift Woes - Violent Braking & Rumbling

Post by akguy09 »

Are the springs on backwards? I can't remember when I put my new 4" springs on in November if they were longer one way. I do remember there was a front orientation though.
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