Information request: Hub to flare measurements and castor degree number on a stock height 80 (1 Viewer)

[Beej]

Hey folks,

I see lots of hub to flare measurements and a good couple of castor numbers but cant seem to find both together for the same rig on stock springs.

What Id like to do is use these numbers to calculate a stock height hub to flare measurement with 3* of castor. If we can say that stock height with 3* of castor is X then we can better predict issues that might pop up from a taller lift height. (Just to be clear anyone with a stock height 80 can provide the data and we can use a formula to guess at what the hub to flare measurements would be if there were 3* of castor. Be great if someone had a stock 80 with 3* of castor but not necessary.)

Ive also read that the first 1" of lift require 1.7* of correction, the second 1" needs 1.75* and the third 1" needs 1.83* and with all these choices around for plates and bushings and bearings, i think it'd be nice to be able to play around with configurations without having to go to the alignment shop first.

Of course, no measurement will be perfect for all 80s but it'd be great to dial in that baseline stock figure.

Thanks in advance for any replies.

-- Beej

 

[inkpot]

I think the FSM states about 4 degrees is stock. Small variations will result from wear and/or load. The calculations have been done before but it seems like there are always exceptions poppin up.

 

[Beej]

Spec is 2-4* and of course people have their own preference. I chose 3* because its the middle.

With the matched stock castor and hub to flare data, you could really target any castor you wanted. All the castor correction solutions correct a fixed amount of castor but they are sold as correcting for a certain amount of lift. Its apples and oranges. Castor is non-linear. That coupled with the fact that lifts result in different heights for different trucks means we need a way to measure actual lift so we can measure actual castor needs.

Again, all of this trouble sort of goes away with a trip to the alignment shop but considering how many threads there are for castor and lift needs and driveline issues, having an agreed upon standard would be great.

 

[LandCruiserPhil]

22.5 hub to flare measurement using caster plates from Slee or Metal Tech will put you at 4°. The closer to 4° of caster you get the happier you will be going down the road. Although 2° of caster is within spec on a lifted truck with big tires 2° is for those that never driven one with 4° of caster. @Delta VS can make you beautiful arms to meet any caster needs you may have. After the first of the year Im thinking about using some Delta custom arms and going to 5° of caster.

 

[Beej]

@LandCruiserPhil isnt it true though that that "extra" caster will cause driveline issues?

Thats how we come to have all of these 2.5 inch lift options. Angles is the culprit, not lift.

 

[LandCruiserPhil]

@LandCruiserPhil isnt it true though that that "extra" caster will cause driveline issues?

Thats how we come to have all of these 2.5 inch lift options. Angles is the culprit, not lift.

Smart guys have no driveline issues with any lift at any speed
I run 5° on our LX470 and it drives like a dream.

 

[Delta VS]

, having an agreed upon standard would be great.

Our preferred method is measuring to the center of each bolt on each end of the panhard. That is a spot that will be the same on every rig, regardless of flares, no flares, w or w/o bodylift, body damage (known or something a previous owner fixed), etc.

 

[Beej]

Our preferred method is measuring to the center of each bolt on each end of the panhard. That is a spot that will be the same on every rig, regardless of flares, no flares, w or w/o bodylift, body damage (known or something a previous owner fixed), etc.

Thats sounds like a good option! Still need that measurement and a matching caster figure. Be awesome if you guys had one.

If anyone with a rig with stock springs is willing to take the height measurements then ride over to the alignment shop, and post up a pic of the print out, ill send you the $20 for the check.

 

[landtank]

Again, all of this trouble sort of goes away with a trip to the alignment shop but considering how many threads there are for castor and lift needs and driveline issues, having an agreed upon standard would be great.

Don't hold your breath.

 

[Delta VS]

Don't hold your breath.

always a relevant XKCD: xkcd: Standards

 

[Beej]

Don't hold your breath.

Lol, i know you've probably wanted this for years, landtank. No one, certainly no individual, has made more of a contribution in this area than you.

The situation is getting worse though. It used to be we were wrong about how much caster is needed for each inch of lift but the products were sold by how much caster they corrected. 3* bushings on a 2" lift isnt enough but at least you know its 3* (assuming that was actually a correct figure).

Now vendors arent including the caster correction figures; theyre just saying what lift its for. Even with your plates, though the caster figures are readily available on Mud with a bit of searching, the product page lacks the correction degree figure. And at 5*, the 2.5" plates correct for 2.85" of lift.

I think mudders know that we're in good hands with Landtank products; i question the other offerings. i want the actual caster figures.

 

[Beej]

always a relevant XKCD: xkcd: Standards

Lol I now trust DeltaVS as well since XKCD is the nerdiest comic ever.

I still want the caster figures though.

 

[Delta VS]

Lol, i know you've probably wanted this for years, landtank. No one, certainly no individual, has made more of a contribution in this area than you.

The situation is getting worse though. It used to be we were wrong about how much caster is needed for each inch of lift but the products were sold by how much caster they corrected. 3* bushings on a 2" lift isnt enough but at least you know its 3* (assuming that was actually a correct figure).

Now vendors arent including the caster correction figures; theyre just saying what lift its for. Even with your plates, though the caster figures are readily available on Mud with a bit of searching, the product page lacks the correction degree figure. And at 5*, the 2.5" plates correct for 2.85" of lift.

I think mudders know that we're in good hands with Landtank products; i question the other offerings. i want the actual caster figures.

Easy there...

As stated, we are working on a complete table showing all the stuff. Until then, we've put this together:

These are carefully measured stock arms at various lift heights and the associated change in caster angle. As far as we can tell, the stock arm in the "ideal" situation, gives a caster of 3*. We will compile everything and publish. We have a tire shop nearby and have been putting different arms on the same rig and getting the caster measured for real, and are about to start taking different rigs to the same shop to come up with a way to measure caster without having to go to a shop, just using a cheap digital HF angle finder.

 

[Delta VS]

Lol I now trust DeltaVS as well since XKCD is the nerdiest comic ever.

I still want the caster figures though.

What we are going to be able to contribute directly:

91 with OME 2.5
91 with ICON "3"
94 with stock springs
95 with stock springs

Also have a set of 850J springs that will be swapped in and measured. Need some more springs sitting around the shop to fill out the table with...

 

[Beej]

Easy there...

As stated, we are working on a complete table showing all the stuff. Until then, we've put this together:

View attachment 1816810

These are carefully measured stock arms at various lift heights and the associated change in caster angle. As far as we can tell, the stock arm in the "ideal" situation, gives a caster of 3*. We will compile everything and publish. We have a tire shop nearby and have been putting different arms on the same rig and getting the caster measured for real, and are about to start taking different rigs to the same shop to come up with a way to measure caster without having to go to a shop, just using a cheap digital HF angle finder.

Commendable!

There at least one school of Cruiserhead that pays close attention to suspension geometry and those guys (im not including myself since i dont know enough yet) have to work quite hard and spend a lot of money to produce the best configurations that the rest of us go and copy and well, I appreciate those people; inwant their job to be easier.

 

[Delta VS]

BTW, uploaded the wrong (old) image before, have edited post but I don't think anybody gets notified when a post is edited. This way everybody on the post who may have been paying attention will now know the image is different.

 

[Delta VS]

@Beej looking for feedback on that graphic as well, does it make sense?

 

[Beej]

With the context you provided, it makes sense.

The context needs to indicate that these are the resulting caster measurements from the lift heights shown on stock arms.

If you could find a way to include the deltas, 3-(-.52)=3.52, while still keeping the graphic nice and clean, thatd be cool but not necessary. The way it is is illustrative of what actually occurs so that is best imo.

In addition to Rick, @Pin_Head was one that got me started down this road. If hes still around here, he may have something to add.