80 series caster problem (1 Viewer)

[stvrn6]

I purchased this project 1997 land cruiser that i just finished working on. I took it on the highway and its very unstable. The steering seems to very jerky. The steering wheel is also not straight either its a few degrees to the right to go straight as well as has a ton of free play.
I'm running Eibach shocks with OME heavy springs front and rear due to extra load. i went to get an alignment to get a base line for my caster and its showing -2 left and -1.9 right. Do i get a 4 degree correction plat or 2? Im just asking since the 4+ correction is recommended for 4+ inch lift and im runnin 2-3 in lift. should i do bushings or plates?
edit: running 315s r17

 

[mudgudgeon]

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What the point of measuring stuff you can’t change?

It can be changed. You choose not to.

No doubt your set up works for your usage. Doesn't make it the right choice for everyone.

I’m pretty sure very few people here has ever driven a rig where caster made it undriveable.

My 4" lifted 80 with no caster correction was absolutely dangerous, unpredictable, unstable at normal road speeds. Caster correction was the single biggest change in trying to correct this. I did a knuckle rotation on this truck.

A Jeep XJ, for example has 7 degrees as optimal factory spec. So why not 2-4?

7⁰ would make the steering a little heavier, and also increases the amount camber changes while turning. The 80 i mentioned above, i set caster at 4⁰ and the change in steering was noticeably heavier. Not unmanageable in anyway, just noticeably different.

Any positive caster angle is better than negative caster. 1⁰ is c better than -1⁰, 3⁰ is better than 1⁰.
The more you increase it, the more it impacts other things.

Almost every significant modification to any car is likely to compromise some aspect of the vehicle's design.
Raising suspension, correcting caster, not correcting caster etc are no different.

Not correcting caster can make the difference between avoiding a collision, avoiding a roll over, or not.

There's no shortage of stories in the Mud archives of lifted 80s wrecking, rolling etc.

Show me a story where someone wrecked their 80 due to minor driveline vibrations?

 

[Marvelicious]

I redirected the point

I’m pretty sure very few people here has ever driven a rig where caster made it undriveable. Caster isn’t an isolated variable that has to be in a black and white spec.

A Jeep XJ, for example has 7 degrees as optimal factory spec. So why not 2-4? For starters, that vehicle doesn’t have radius arms and it also comes factory with a y-linkage steering setup (relay is attached directly to tierod). That means toe changes with suspension compression and there is terrible vulnerability to bump steer. We don’t deal with either of those things.

I converted an XJ to a long arm radius setup with a custom Dana 44 axle and we deliberately set caster at 2 degrees so avoid quick/touchy steering on a big lift at speed. This worked perfectly 5 degrees under factory spec in conjunction with a crossover steering linkage (like what we do with high steer).

Early on, I had a set of customer front coils built and then provided 9” of lift instead of the 6” we spec’d. The truck drove in a Z down the highway, it wasn’t steering feel or touch, the caster situation was so bad in conjunction with the factory steering and control arm linkage that it was unable to drive straight.

Given that you can convert the front 80 series driveshaft to double cardan, which uniquely to the 80 lowers the pinion and increases caster to offset up a 4” lift, you need to get up in the range I have before ‘driveability’ relative to other platforms is rearing its head.

I also take videos. Look at this terrible time I’m having with driveability.



And before we start arguing that caster isn’t about driving in a straight line, here’s canyon driving. Pay attention to the speed signs in the corners vs. the speedo as I run down that Subaru. 38” tires, no sway bars. My speedo is corrected so that’s accurate. Just in case we’re having conceptual interpretation problems, in order to take these vids I’m driving with one hand.

Okay, but we aren't talking about XJs. It's very easy with a few inches of lift to wind up NEGATIVE on an 80 because they started at around 3 degrees. Toyota tends to opt on the quick side for their steering while Jeep expects people to lift them and plans accordingly. I'm with @Broski on 5-6 being great for running big tires. I have done a cut and turn on an axle before and it was time and effort well spent. I'd rather do that again if necessary to correct driveline vibes than have all the weird steering artifacts that bad caster entails.

I'm not sure what a freeway video is supposed to indicate, but most rigs steer fine when you're driving down a road that doesn't need any steering input. If it was wandering there, it would more likely indicate worn parts, not bad caster. I have driven a few rigs that were - in my opinion - dangerous, including a first gen 4runner with some mail order All-Pro springs and a spring-over-axle converted 60. Interestingly, both of those rigs were on their tops within a year of modification... neither owner listened to me when I said that their steering was dangerous. I refrained from saying "I told you so". Come to think of it, the owners who did the mods had both sold the vehicles and it was other people who paid the price.

 

[Marvelicious]

Hey guys, installed panhard bracket from delta and was able to source some dobinson bolt on plates locally for cheap and the truck drives so much better, night and day. But now I have another question. When I went in for an alignment for my initial caster numbers i was running a different set of springs (eibach) but i since changed them to some heavier springs i bought some time ago for added weight. well i changed out the tie rods and draglinks so i took it back for an alignment and my new caster readings are 5 degrees. the OME springs are 2 in and the eibach are 3+in. How worries should i be about having 5 degrees vs 4?
front: ome 2850 rear : ome 2863. I found some 2864s on fb market place for cheap and was planning on getting those since ive added more weight since than.
I could source some 2850j and 2863j and or dobinsons heavy springs if it'll correct my caster.

5 should be great. It'll likely feel a little "heavier" to steer than before, but that's not necessarily a bad thing with larger than stock tires.

 

[Nay]

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It can be changed. You choose not to.

No doubt your set up works for your usage. Doesn't make it the right choice for everyone.


My 4" lifted 80 with no caster correction was absolutely dangerous, unpredictable, unstable at normal road speeds. Caster correction was the single biggest change in trying to correct this. I did a knuckle rotation on this truck.




7⁰ would make the steering a little heavier, and also increases the amount camber changes while turning. The 80 i mentioned above, i set caster at 4⁰ and the change in steering was noticeably heavier. Not unmanageable in anyway, just noticeably different.

Any positive caster angle is better than negative caster. 1⁰ is c better than -1⁰, 3⁰ is better than 1⁰.
The more you increase it, the more it impacts other things.

Almost every significant modification to any car is likely to compromise some aspect of the vehicle's design.
Raising suspension, correcting caster, not correcting caster etc are no different.

Not correcting caster can make the difference between avoiding a collision, avoiding a roll over, or not.

There's no shortage of stories in the Mud archives of lifted 80s wrecking, rolling etc.

Show me a story where someone wrecked their 80 due to minor driveline vibrations?

Lifting is dangerous, period. How dangerous is adding a thousand lbs of ‘overlanding’ weight at a high center of gravity where you struggle to find suspension options that even allow reasonable use offroad without excessive squat, tire lifting, and the endless myriad of poor performing setups we find here in countless “help me” threads? The cardinal rule of the 80 isn’t the Despicable Me minions ooohing about caster every time it flashes in front of them. It’s don’t add weight to a pig because that is the falling domino you can’t stop.

My emphasis is simple: there is no reason to design driveline vibrations into an 80 series build because you can stay in factory caster spec with a properly aligned DC front driveshaft and the sweet spots are 2.5” and 4” of lift. If you are going to either exceed those parameters or pick a no-man’s land lift height that is hard to adjust for pinion angle, then either be prepared to live with a constantly vibrating driveline, have caster as a measurement that simply follows pinion angle (my approach with the correction of the DC driveshaft), swap to a part-time 4WD setup with lockout hubs, or spend the money on a cut and turn.

The angled expansion joint on an interstate bridge around a corner is as good of an indicator of the stabilty of your setup as you will find in regular driving. My 80 handles those better than IFS vehicles I own because the front end is so rigid. For those who live on the Colorado Front Range, that section at the bottom of Floyd Hill on I-70 heading west is such a good example. I don’t even bother slowing down in the 80 and IFS vehicles are all over the place.

I certainly wouldn’t choose a 100 series over an 80 to handle stuff like that and you can keep the 100 stock.

 

[Nay]

Okay, but we aren't talking about XJs. It's very easy with a few inches of lift to wind up NEGATIVE on an 80 because they started at around 3 degrees. Toyota tends to opt on the quick side for their steering while Jeep expects people to lift them and plans accordingly. I'm with @Broski on 5-6 being great for running big tires. I have done a cut and turn on an axle before and it was time and effort well spent. I'd rather do that again if necessary to correct driveline vibes than have all the weird steering artifacts that bad caster entails.

I'm not sure what a freeway video is supposed to indicate, but most rigs steer fine when you're driving down a road that doesn't need any steering input. If it was wandering there, it would more likely indicate worn parts, not bad caster. I have driven a few rigs that were - in my opinion - dangerous, including a first gen 4runner with some mail order All-Pro springs and a spring-over-axle converted 60. Interestingly, both of those rigs were on their tops within a year of modification... neither owner listened to me when I said that their steering was dangerous. I refrained from saying "I told you so". Come to think of it, the owners who did the mods had both sold the vehicles and it was other people who paid the price.

Again, I think what is missing here is that if you convert the broken back (high angle pinion on a stock 80) oriented driveshaft to a double cardan, simply aligning the double cardan shaft to proper pinion angle requires rotation of the pinion down, which increases caster, and that offsets the upward rotation of the pinion when lifting. At my lift height you will have exceeded that correction, but it doesn’t mean you’ve just gone wildly negative on caster. At 4” of lift this simple modification will keep you within factory caster spec. It will not put you outside of caster spec on the high side, which we seem to believe is better even though it is out of spec. Anybody who lifts their 80 (within a range) and doesn’t take advantage of this simple mod and instead chooses driveline vibrations with a stock driveshaft…that’s on you.

The two primary attributes of positive caster are:

1) Improved straight line steering at speed. This is the tension of ‘return to center’. That is exactly what a straight line freeway video shows. The loss of caster tension means wandering, particularly as speed increases or there is road rutting or other elements that create tire pull.

2) Caster relationship to negative camber to maintain maximum tire grip. The second video shows no drama, clean arc handling at 20 mph above recommended speeds through canyon corners. On 38” Patagonia MTs. If you are going to get overly excited about your caster to camber relationship for cornering on a type of tire that specifically sacrifices those attributes…well get on your FSM specs and feel safe.

My experience with the 80 is that there is relatively low sensitivity to caster values, particularly with point 2 above. This isn’t IFS - it’s a rigid located solid front axle with two bushings in close alignment to prevent much if any straight line motion or weird behavior. Many of us favor this setup over IFS on the highway and there is very good reason for it - you will never, ever, for any reason feel that way about a Jeep and that has zero to do with caster.

I’d probably also not want to drive a sprung over 60 that didn’t have a precise aligned panhard correction due to the lack of lateral location precision and inherent bump steer. That has zero to do with anything here.

I run my tires at 30 PSI, despite all the chicken littles who think you have to be at 40+ or your tires will blow. Let’s dig up those threads where big LT load tires needed higher PSI than stock p-metric tires and people thought 45 PSI was about right. Anybody really think caster to camber relationship is going to influence at 38” MT at 30 PSI? One of the best ways to need a lot of caster is to run your big tires like bricks at high PSI so they wander around on the center of the tread.

Your tires are your first linear rate suspension. Get that wildly wrong because of the safety nannies and you’ll chase all kinds of ghosts.

 

[Nay]

This is so fantastic. We’re talking about original straight axles in cars here, but read the whole thing.

https://www.motortrend.com/how-to/0902sr-science-of-straight-axles/

Of course caster doesn’t affect camber on a straight axle, you can only get negative camber by bending the axle. Mopar, Ford, and others spec’d barely positive camber, like 1/4 to 3/4 degrees. And it is noted here that the only purpose of positive caster is to keep the car in a straight line, meaning not wandering.

Our tierod behind the axle that is unaffected by lift (unlike a y-linkage XJ) keeps “toe in turn” (Ackerman Angle) constant. Keeping your wheel offset near stock - I run a 8.5” wheel with stock backspace (effective to the slightly wider wheel) with a 3/4” custom spacer - will matter. Scrub radius is good, Ackerman is good. Caster is fine within standards of straight axle design with a tierod behind the axle, and the truck behaves like it. I run 1/8” toe in, just like is described here. I’ve put 42K on a set of KO2 and then sold them at 7/32’s with zero irregular wear. I manage tire pressure so it drives right instead of focusing on excessive caster to cover up those problems.

Take a look at the chart at the bottom. The recommendations are so in line with my point on tire pressure to deal with over or understeer and a number of other conditions. None of them points to caster as some sort of magic unicorn solve all alignment spec. As long as your rig points down the road, caster doesn’t do anything on a solid axle and how your steering linkage was designed plays into this if you lift the vehicle.

Also, @Broski may like out of spec positive caster, but he has hydro assist. That’s not much of a sample given what hydro will do to steering input. I’ll wait while one of you tells me how caster is super important if you go full hydro and no longer have running steering gear since it’s the key to being safe in your 80.

The 80 is so easy to lift. And BTW, I am Member #1 of NAXJA.

 

[Marvelicious]

LOL, I've honestly lost track of what you're even arguing... now we're at tire pressure. I'm certainly not telling anyone not to run a DC driveshaft if it's needed, but I don't see where that's MORE important than running proper caster. If you're happy with your setup, run it.

The OP was asking about running bushings or plates, because he had a condition commonly referred to as death wobble. Later he asked whether 5 degrees was too much. It sounds like he go things straightened out and he's on the right track. If he's experiencing driveshaft vibes, he hasn't mentioned it. I think we can put it to bed.

 

[Nay]

LOL, I've honestly lost track of what you're even arguing... now we're at tire pressure. I'm certainly not telling anyone not to run a DC driveshaft if it's needed, but I don't see where that's MORE important than running proper caster.

It’s HOW you run proper caster on an 80.

A condition commonly referred to as death wobble is really hard to produce on an 80. There are no basic design elements on an 80 series that create death wobble and perseverating about 1.5 degrees of caster isn’t one of them.

Tell me about a vehicle where you experienced a condition commonly called death wobble and how you solved it. If you did that on an 80, it’s very likely you have no clue what death wobble is.

 

[Marvelicious]

It’s HOW you run proper caster on an 80.

A condition commonly referred to as death wobble is really hard to produce on an 80. There are no basic design elements on an 80 series that create death wobble and perseverating about 1.5 degrees of caster isn’t one of them.

Agree to disagree

Edit to respond to condescending edit: You're in a thread where the whole thing is demonstrated, both problem and solution. I don't know what more to tell you.

 

[Broski]

Ain't nobody got time for all that hog wash !!

 

[Nay]

Agree to disagree

Edit to respond to condescending edit: You're in a thread where the whole thing is demonstrated, both problem and solution. I don't know what more to tell you.

It’s all good by me. I think it’s useful for people assessing both the problem and solution to understand that misaligned pinions create driveline vibrations and a DC shaft conversion will offset much of the caster loss from lifting. I’ve demonstrated with pictures and videos an aligned pinion on a taller lift on an 80 series that doesn’t have death wobble or other alignment problem presentations that would be consistent with the purpose of positive caster.

My response is purely to the idea that this is somehow dangerous and that a better design would be to introduce driveline vibrations in order to add to positive caster so that my vehicle would then somehow be safe. Agree to disagree

 

[Nay]

Ain't nobody got time for all that hog wash !!

I tore my rotator cuff in a mountain bike crash and am recovering in a sling post-op. I have all the time in the world while my new steering box sits and looks at me pretty to talk about why I should introduce driveline vibrations intentionally.

They made FJ Cruisers for this kind of stuff.

 

[AgentOrange]

Or just join the dark side, cut it all off and tune caster and pinion angle individually. At 4*, my Cruiser wanted to wander a decent amount unless the road was glass smooth and occasionally the front wheels would try to shopping cart a bit at speed which was entertaining. I tried every tire pressure between 26 and 40, and toe adjustments in 1/8" increments from a 1/2" out to in. I made the decision to adjust caster to 6* and now my Cruiser decided to behave at freeway speed, even loaded for 8 days of wheeling with the whole family on a 10 hour drive. It is strange how different rigs are compared to each other. My dad has an 80 lifted more than mine and had only old OME caster bushings and his drove straighter than mine until I dialed more things in with the 3 link.

 

[mudgudgeon]

Of course caster doesn’t affect camber on a straight axle

Tell me you don't fully understand a rigid axle without telling me you don't fully understand a rigid axle . . .

 

[mudgudgeon]

A condition commonly referred to as death wobble is really hard to produce on an 80.

BS

 

[Nay]

Man it’s fun to poke around and see how long we’ve been talking about this.

Our dearly departed friend is sorely missed for his common sense perspective. “Setup greatly affects it, type of springs, shocks, tires, etc.” is spot on - that’s the point that what you feel on your rig is not going to be consistent with a very different setup.

 

[Nay]

Tell me you don't fully understand a rigid axle without telling me you don't fully understand a rigid axle . . .

Haha yes, it was a weak moment

 

[mudgudgeon]

Haha yes, it was a weak moment

We'll forgive yah! But only coz of shoulder surgery

I did a chunk of my degree with a busted shoulder and maybe 2-3 hrs of broken sleep each night. No idea how i passed

 

[Nay]

BS

I’d have to just start loosening bolts to get death wobble on my truck. But “not easy”…we have an inner knuckle design, an outer bearing that is easy to keep adjusted, a long panhard that is supported by a frame brace, a separated tierod and drag link, and a very rigid radius arm system. None of these things goes out of alignment on lifting.

Compared to an outer knuckle light duty ball joint system on a 1/4” platform with say a y-link steering and short(ish) panhard…you can look at a truck like that and get death wobble, it’s’ pretty much in the design and you’ll fix it by redesigning the steering and probably the suspension linkage.

When I got out of this XJ (redesigned steering on a custom Dana 44, long arm radius arm conversion) when my family outgrew it and into the 80, my total impression was “the 80 is out of the box what I spent $25K trying to create with the XJ”.

Also, this isn’t really a full measure of caster, but just gut check kinda stuff. Measured on the trunion cap bolts on zero degree garage ground.

 

[Nay]

We'll forgive yah! But only coz of shoulder surgery

I did a chunk of my degree with a busted shoulder and maybe 2-3 hrs of broken sleep each night. No idea how i passed

I’ll take it. I waited 5 weeks before I saw my ortho while still (carefully) riding my bike because I am stubborn and stupid. The tendon tear broke the upper humerus at the attachment point in a disc fracture, tore the labrum above the long bicep tendon and the rotator cuff. Proud owner of a repaired rotator cuff and relocated long bicep tendon so it won’t aggravate the labrum. Sleep…yea…not so much…that’s pushing through during a degree.

I need my once a decade caster conversation on mud apparently to take out my frustration