Interesting, do you have any pictures of that? I assume you mean a solid rubber piece or is it a hydraulic bumpstop like some of the trophy trucks run? If it's a solid rubber piece where is it mounted?
Bump stops hitting springs
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It's the frame mounted bump stop that's used on 93 (and maybe 94?) trucks. They used both the cone inside the spring and one on the frame. Just like the rear axle.
Interesting, I just found out I am having the same issue with FOR 3.5" springs and no spacers since I put on the castor plates. I wonder how difficult it would be to make the castor plates so they move the axle forward slightly to give the springs more clearance at the bumpstop. I guess adding the frame mounted bumpstop would be easier for those of us with the plates already installed but perhaps a redesign of the plates would help. Just thinking out loud.
there's already a caster plate design that avoids this and other issues from hinging the axle at the rear bushing.
I'd be happy to make more but nobody has asked for them.
I'd be happy to make more but nobody has asked for them.
*Partial hijack*
I did not catch the orginal thread on the castor plates you designed but I just finished reading it. Hugely informative and strong work sir. I am very suprised that no one has asked for them. The benefits might be missed by the average Joe on the street but I would think they would be very attractive to those of us on this forum that are so addicted to and perfecting our 80's. Thanks for sharing.
*End Partial hijack*
I don't have phot shop or the ability to use it so hopefully my lame description will make sense.
From the center of the hub to fender without flare is 23 1/2" on USDS and 23 5/8" on USPS. My springs are advertised as 3.5". They are bowed toward the front same as are others in this thread but mine are contacting the metal bell or bucket that the urethane bumpstop is mounted in and slightly on the bottom edge of the bumpstop itself. At static height there is only 5/16" between the two. (Picture 1) They also appear to be bowed in toward centerline of the truck slightly and I am wondering if others have this problem as well. I measured the clearance from the frame bracket that the frame mounted bumpstop pad attaches to to the outside edge of the coil at 3/4" USDS and 5/8" USPS. (Picture 2) Could someone get a comparative measurement? The top of the coil wrap does not end like the OME's do it just ends abruptly. If you stand facing the front wheel well the upper end of coil is in the 6 oclock position if you were to look down on the top of the spring. (Picture 3) I am thinking this may cause the slight inward bow of the coils spring.
No one?
Definitely looks like lifting the 80s w/ the stock arms is pulling the bumpstops into the springs. It seems that the axle would line back up w/ the bumpstops by putting longer arms on. I know, the price of that substantially changes the cost of lifting the 80.
They were made for J spring heights...and I need an excuse to get the new hotness arms 
I don't think it's that but the fact that the caster plates move the axle back on the arm. It's do to the fact that the plates hinge on the rear bushing. I'd bet if the plates were removed the contact would not happen.
Mine did the same thing after I went to the Slee 4" kit.
Everything is w/in spec.
Called Christo, & he told me I could grind them. I have the bumpstop extensions removed right now, still trying to make a decision.
FYI, I have had no rubbing w/ this setup. (No severe articulation situations yet)
Everything is w/in spec.
Called Christo, & he told me I could grind them. I have the bumpstop extensions removed right now, still trying to make a decision.
FYI, I have had no rubbing w/ this setup. (No severe articulation situations yet)
I'm still thinking your plates might be the best thing for me. Just waiting for XXXR to finish his caster correction bit to see his results since his truck has very similar caster readings to mine.
I've had that problem on mine as well after going with the 6 inch springs. I readjusted the panhard to better center the axle under the rig and it helped. For me the problem is that the bumpstop extensions just lower the bumpstop to the point that the axle movement side to side will hit it. I've contemplated moving over to the other type of stops but that will require some work ;p
I always know when I hit the bumpstop when I hear that twang after nearly bottoming out. The other solution would be to drive slower of dips.
Of course I don't know how the 2nd gen arms might have effected this issue. Like I said after adjusting the panhard it barely happens.
I always know when I hit the bumpstop when I hear that twang after nearly bottoming out. The other solution would be to drive slower of dips.
Of course I don't know how the 2nd gen arms might have effected this issue. Like I said after adjusting the panhard it barely happens.
I originally made 3 sets of plates. The first set went into my truck. The second set went into Montana Cruiser's truck (there is a write up). And the third set should be installed in a few weeks. If all three truck's results are the same then I'll make them available in limited quantities.
Right now it looks like a 3.5"-4.5" caster solution which will demand a DC shaft. Out side that lift area will result with the respective caster error.
I think you nailed it right on the head. I had no rubbing of the bumpstops (not lowered) with the OME heavies with OME cc bushings, no rubbing with the 3.5" FOR springs, factory bumpstops and the OME cc bushings. The rubbing only started for me when I put on the castor plates. I will be very interested in how the readings come back on the third rig with your plates. How much do you plan on your plates costing, and what ball park time frame do you think they will be available? I know alot of variables.
Could you please clarify whether you mean 3.5-4.5 inches or degrees. Thanks
that would be in inches of lift.
When I got done with my caster plate design it became apparent that the real focus was on aligning for a DC shaft to minimize drive line vibrations. With that approach in mind, the amount of lift that would fall within the Toyota specs as far as caster is concerned would be 3.5"- 4.5" of lift.
Since I only have one 80 to work with I rely on others to help me ensure the design is compatible across the line. Once this third set is installed and I can confirm with reasonable certainty that others will get similar results I'll make them available.
That's assuming the truck was within caster spec of 2*-4* before the lift, correct? I do not know what mine was prior to the lift, but it must have already been light in caster since it is now still around 0*- 0.6* with the OME CC bushings. And I only have the OME 2.5" lift. Given what you say above, it'll be interesting to see what my driveline does after getting the caster back into spec. I'm figuring that if I pull the OME CC bushings, and replace them with Toyota stock bushings, and use your plates, I might need upwards of 5*-6* of caster correction to get back to spec. Does that make sense at all?
Yes that makes sense.
So far my plates have been installed at 7* of correction. This was to align for a DC shaft. So what we did was measure the front u-joint drive angle and then correct for a DC shaft.
It's not how people typically look at this sort of thing. Most times they look at caster and then work out the vibrations later. Here, I'm working out the vibrations first and then looking at caster.
Once the drive angles are correct, caster is easily adjusted by changing the height of the truck with either weight, shims or springs.
I think I understand what you're saying. This is a case where the truck in question already has driveline vibrations _and_ caster issues, right? So, the CV shaft is to get rid of the vibrations and then the front set up needs adjusted to make the CV shaft work efficiently and properly within its specs, hence the application of caster plates.
Since I don't have any noticeable driveline vibrations right now, I'm assuming I would go about addressing my truck in the traditional manner of caster first and then see if the driveline suffers. But I could also see how that could run in circles--fix caster, get vibrations, fix vibrations, adjust caster again. I feel like I'm asking a ton of questions but I want to make sure my train of thought isn't derailed and this caster thing seems like a heckuva gremlin.
My apologies for this thread hijack--I can start or continue another thread if necessary.
You have it almost right. The main point of correcting the castor is to have proper steering geometry not so much to change the driveshaft angle and remove vibrations, that is the job of the DC driveshaft itself. If you imagine a horizontal plane that the steering knuckles and tie rod move in that plane wants to be rotated approx 3* up in the front IIRC, that is your castor. This helps return the steering to center and keeps it from being too twitchy and unstable. The more that steering plane is rotated down and eventually back toward the rear but under the centerline of the axle the worse the symptoms will get untill the rig is undriveable at anything more than a crawl.
As you lift an 80 series the axle is rotated on this same plane by the radius arms bringing the castor down from it's intended position and makes the steering more twitchy and can make the rig very unstable, especially at speed and/or with evasive maneuvers. The connection with the castor correction and the driveline vibes is the more you rotate the axle to get the castor within specs to optimize steering characteristics you change the angle of the driveshaft, especially on the axle end of the front driveshaft. Driveshafts with two ujoints like our factory units are designed to run with the same angle at both ends. If they are uneven then you get driveline vibration. The DC driveshaft spreads the combined angle change of the entire driveshaft over three ujoints instead of two and helps equalize all ujoint angles to prevent driveline vibes.
Thanks, SloMo--the additional explanation of what exactly causes the driveline vibrations helps--inequality between u-joint angles on the driveshaft, which can be caused by lift and caster correction. It's helpful to see the front end as a system versus a group of disparate parts--everything is kinda dependent on everything else.
So, if I correct my caster and end up with driveline vibrations, I may have to opt for a DC driveshaft as a possible solution while maintaining my corrected caster. Of course, none of this is definite until it is seen how the truck ends up after step one--caster correction.