Steve Rupp
Observer
expeditionswest said:
Except I don't think it would be the "lower cost method" though. I believe it would have to do more with an engineering aspect.
Land Rover Discovery Suspensions: Caster
- Thread starter david despain
- Start date
Except I don't think it would be the "lower cost method" though. I believe it would have to do more with an engineering aspect.
Steve Rupp
Observer
Mike_rupp said:
Mike Atlantic British has a complete set of replacement poly bushings for the rover suspensions. The radius arm bushing looks just like the one from Inland Rovers. It's possible that they build that arm to the exact same bushing specs and the factory arm. The OEM bushing might even fit into that radius arm.
H
Hank
Guest
I doubt it. The LR bushings are a really weird size. I have a feeling that the Inland Rovers mounts are standard DOM tubing, and they've sourced the correct size bushing to fill the hole. When I built a set of rear trailing arms, I found the LR bushing to be an odd size, and the DOM had to be machined down a bit so the bushings would fit.
Keith may know. I think he uses the same bushings in his rear links.
Scott Brady
Founder
I have been saying that the swivel ball option is a good one all along
However, I am still researching if in fact the arm only / DDC for a 1.5-2" lifted Disco is a bad one from a pure design / engineering perspective (as functionally, it is currently working as I would expect). Fortunately I know several chassis engineers, and am awaiting their feedback... I will share the results with all of you, good or bad.
Steve Rupp
Observer
Scott I don't think anybody is saying that your setup won't give you positive castor and a vibe free driveshaft. Who knows really what the long term effects will be by using a DDC driveshaft in your case. It might prove to work flawlessly for years. I just think it wouldn't be the way an engineer would design it.
R_Lefebvre
Expedition Leader
I'd like to take a step back on this discussion and make it maybe a bit more relevant to most in this forum: D2, with an OME lift. What are the feelings on caster and driveshaft angle? And what driveshaft does the D2 have anyway. I haven't looked, and it's too cold to bother crawling underneath it right now. I think I saw it mentioned here that it's a DC shaft.
I'm running the OME lift, and I do detect that some steering center feel has been lost, but it's not too bad. However, when I have my dirt bike mounted on one of those motorcycle racks that plugs into the hitch reciever, the back end sags a bit and the front end lifts, and I do feel that it starts to get a little spooky. It's not too bad, but I have to pay more attention, and I wouldn't want my wife driving.
What options do we have for getting caster back?
I like the sound of the redrilled swivel balls as it seems like the most proper solution, but I know I don't have swivel ball housings so... do we have something equivalent that could be done?
I don't feel any drivetrain vibrations, so hopefully the driveshaft angles are fine.
Lastly, is it just me, or does it seem like the DDC provides too many degrees of freedom to the center section of the driveshaft? Seems like it's virtually unrestrained in all 6 degrees of freedom. It probably spins true if everything is perfect, but it would seem like if anything happened at all, the smallest bend or anything that put it out of balance, it could enter into a pretty violent running condition where the center section could orbit around the axis it should be simply rotating about.
I'm running the OME lift, and I do detect that some steering center feel has been lost, but it's not too bad. However, when I have my dirt bike mounted on one of those motorcycle racks that plugs into the hitch reciever, the back end sags a bit and the front end lifts, and I do feel that it starts to get a little spooky. It's not too bad, but I have to pay more attention, and I wouldn't want my wife driving.
What options do we have for getting caster back?
I like the sound of the redrilled swivel balls as it seems like the most proper solution, but I know I don't have swivel ball housings so... do we have something equivalent that could be done?
I don't feel any drivetrain vibrations, so hopefully the driveshaft angles are fine.
Lastly, is it just me, or does it seem like the DDC provides too many degrees of freedom to the center section of the driveshaft? Seems like it's virtually unrestrained in all 6 degrees of freedom. It probably spins true if everything is perfect, but it would seem like if anything happened at all, the smallest bend or anything that put it out of balance, it could enter into a pretty violent running condition where the center section could orbit around the axis it should be simply rotating about.
ntsqd
Heretic Car Camper
I'm reading this for my own education. By accident more than anything else I'm a toyota driver, but I like to see what sorts of challenges and solutions folks driving other brands come up against. Somewhere, sometime it very likely will be related to something that I'm doing and I'll have a canned solution just waiting for the opportunity to be used.
That said, I'm seriously lacking on LR-speak. What are the "Swivel balls"? Are they literally the ball-shaped axle housing features that the Birfields/CVJ's/(insert favorite name here) live inside of?
A DDC driveshaft gives me pause. I realize that each Double Cardan Joint has (or better!) a ball and socket between the U-Joints that makes the assembly behave and bend as one joint, but somehow one at each end of a driveshaft seems wrong. Perhaps only because it is an unusual creature?
Lifted Early Broncos have, I believe, a similar problem to that under discussion. The radius arm rotates the Caster in the wrong direction as the lift increases. The pinion angle stays fixed relative to the radius arm. At least until some aftermarket bushings come along. There are 4 bushings in the shape of a "V" laid on it side. The aftermarket bushings add an angle between the inner and outer surfaces. Provided that you put them in correctly you can gain back some Caster at the expense of pinion angle.
The most ideal solution is to cut the 'C' brackets that the knuckles steer from off the housing and rotate them to the correct Caster angle, then weld them back in place.
Like-wise, I've read of LC owners cutting the Birfield cavities (for want of a better term) loose from the housing and doing the same rotation and re-weld deal.
I'm assuming that "re-drilling the swivel balls" is accomplishing something similar with an entirely different method?
That said, I'm seriously lacking on LR-speak. What are the "Swivel balls"? Are they literally the ball-shaped axle housing features that the Birfields/CVJ's/(insert favorite name here) live inside of?
A DDC driveshaft gives me pause. I realize that each Double Cardan Joint has (or better!) a ball and socket between the U-Joints that makes the assembly behave and bend as one joint, but somehow one at each end of a driveshaft seems wrong. Perhaps only because it is an unusual creature?
Lifted Early Broncos have, I believe, a similar problem to that under discussion. The radius arm rotates the Caster in the wrong direction as the lift increases. The pinion angle stays fixed relative to the radius arm. At least until some aftermarket bushings come along. There are 4 bushings in the shape of a "V" laid on it side. The aftermarket bushings add an angle between the inner and outer surfaces. Provided that you put them in correctly you can gain back some Caster at the expense of pinion angle.
The most ideal solution is to cut the 'C' brackets that the knuckles steer from off the housing and rotate them to the correct Caster angle, then weld them back in place.
Like-wise, I've read of LC owners cutting the Birfield cavities (for want of a better term) loose from the housing and doing the same rotation and re-weld deal.
I'm assuming that "re-drilling the swivel balls" is accomplishing something similar with an entirely different method?
Steve Rupp
Observer
Yes the swivel balls are the same thing as the "birfield cavities" on the toyotas. The one thing the LR axles have over Toyota axles in my opinion is the fact that the swivels are on a flange. This makes it nice for a few reasons. Instead of grinding the weld from the housing to change the castor, you can simply pull the swivels off and re drill the holes. The other thing that makes it nice is the fact that they can be easily removed to throw on a press for replacing the bearing races. I forget how the swivel seal works on the suzuki and toyota axles but by being able to remove the swivel it allows for a one piece seal and backing plate.
Rob, there really aren't many options for correcting pinion angle and castor together on the D2's which is why you rarely see one lifted more than 2 to 3 inches. I have done many 2" lifts on D2's and the driveshaft/castor angles haven't been harmed to the point that the truck acts funny. Luckily the D2 comes from the factory with a DC front shaft. As far as towing your dirt bike goes, you're actually much better off with it sagging a tad as you gain some castor back. The odd handling is most likely caused by the short wheelbase. IMO the 2" lift is ideal for the D2. Actually a 2" to 3" lift is ideal for all Discoveries. There is no reason to go taller for expedition travel.
Rob, there really aren't many options for correcting pinion angle and castor together on the D2's which is why you rarely see one lifted more than 2 to 3 inches. I have done many 2" lifts on D2's and the driveshaft/castor angles haven't been harmed to the point that the truck acts funny. Luckily the D2 comes from the factory with a DC front shaft. As far as towing your dirt bike goes, you're actually much better off with it sagging a tad as you gain some castor back. The odd handling is most likely caused by the short wheelbase. IMO the 2" lift is ideal for the D2. Actually a 2" to 3" lift is ideal for all Discoveries. There is no reason to go taller for expedition travel.
R_Lefebvre
Expedition Leader
Huh, so here's one case where a D2 came better from the factory than the D1. Other than the fact that the CV's need to be replaced with greasable units... I'm all set.
For the bike, I'm not towing it on the trailer, I use one of those hitch mounted racks. The bike sits crosswise with it's full weight (plus the 50lbs rack) about 24" behind the rear bumper. The rear sags, but more importantly, the front lifts. I understand that the change in pitch of the truck would help caster, but the net result is, it does feel a little spooky. I had originally chalked it up to the reduction in weight on the front axle. Maybe it is the (lack of) weight on the front axle that is the real culprit.
How could I tell if I'm in "death wobble" territory, before finding out the hard way?
For the bike, I'm not towing it on the trailer, I use one of those hitch mounted racks. The bike sits crosswise with it's full weight (plus the 50lbs rack) about 24" behind the rear bumper. The rear sags, but more importantly, the front lifts. I understand that the change in pitch of the truck would help caster, but the net result is, it does feel a little spooky. I had originally chalked it up to the reduction in weight on the front axle. Maybe it is the (lack of) weight on the front axle that is the real culprit.
How could I tell if I'm in "death wobble" territory, before finding out the hard way?
ntsqd
Heretic Car Camper
Thanks for the explanation! I've done the knuckle re-seal job on a yota and I don't recall the details either. There's a felt wiper and a rubber wiper followed by 2 steel thin plates, but I don't recall if the felt & rubber are split or not.
Given that option of re-drilling the swivel balls I don't see why one wouldn't do it unless the rotation required didn't clear the exising holes. Would be really cool if they were available undrilled.
R_, some adjustable rate springs (i.e. air springs) would push the tail up and the nose down thereby shifting some weight back onto the front. Short of something like that or hanging all of your riding gear, extra bike fuel, etc. on the front, or both, I think you'll have to live with it.
Given that option of re-drilling the swivel balls I don't see why one wouldn't do it unless the rotation required didn't clear the exising holes. Would be really cool if they were available undrilled.
R_, some adjustable rate springs (i.e. air springs) would push the tail up and the nose down thereby shifting some weight back onto the front. Short of something like that or hanging all of your riding gear, extra bike fuel, etc. on the front, or both, I think you'll have to live with it.
Lars70
Observer
Interesting reading. I'm also an outsider; I happen to own an early Bronco as referred to by ntsqd. Same issues as the Disco though: coil springs and radius arms. Longer springs to increase lift decrease caster. Enough lift and the caster (which in the case of poorly manufactured Dana 44s from the early 70's was usually less than spec in the first place) goes to zero. The usual fix, bushings that rotate the housing back relative to the radius arms (that would be clockwise if on the left side of the vehicle looking to the right), also has the effect of rotating the pinion down. Since the Broncos came stock with a double cardan driveshaft, that puts the front u-joint out of alignment. Most Bronco owners don't notice, likely because (a) their trucks vibrate so much already that a little more isn't noticed and/or (b) they never drive fast enough with 4wd engaged to get the driveshaft humming.
Another issue with the early Bronco, which may not be a problem with the Discovery, is that by rotating the pinion down, the driveshaft is at a steeper angle at any given ride height. A lifted Bronco at full droop can bind the front u-joint. Get a little air off a jump with 4wd engaged and oops! There goes the front driveline. Even if the u-joint doesn't bind at full droop, the potential is there to get close enough to shorten its life dramatically. A DC driveshaft can confer an advantage here. Mind the lubrication on the DC joint though, or they don't live very long.
I dealt with mine 5 years ago by cutting the inner knuckles off the Dana 44, rotating them back and welding them back in place (a thanks out to ntsqd for tooling ideas on that job). And at the same time eliminating the caster correcting but pinion uncorrecting bushings and going back to stock. The re-clockable swivel ball on the disco front end is neat, and a lot less work than I went through.
Another issue with the early Bronco, which may not be a problem with the Discovery, is that by rotating the pinion down, the driveshaft is at a steeper angle at any given ride height. A lifted Bronco at full droop can bind the front u-joint. Get a little air off a jump with 4wd engaged and oops! There goes the front driveline. Even if the u-joint doesn't bind at full droop, the potential is there to get close enough to shorten its life dramatically. A DC driveshaft can confer an advantage here. Mind the lubrication on the DC joint though, or they don't live very long.
I dealt with mine 5 years ago by cutting the inner knuckles off the Dana 44, rotating them back and welding them back in place (a thanks out to ntsqd for tooling ideas on that job). And at the same time eliminating the caster correcting but pinion uncorrecting bushings and going back to stock. The re-clockable swivel ball on the disco front end is neat, and a lot less work than I went through.
michaelgroves
Explorer
That's pretty much the crux of the problem in general! If the pinion angle weren't a problem, then the simplest solution for any lift would be to fit radius arms that retain the optimum caster. But the lift offsets the pinion further (vertically) from the transfer case output shaft, and makes the propshaft angle steeper.
It seems to me that there is some (low) level of lift where the steeper angle doesn't matter, some greater amount of lift where it would be adequate to use a modified propshaft that can cope with the greater angle, and a yet greater amount of lift where it's not possible to operate a reliable shaft at that angle. In this last case, it would be necessary to point the pinion upwards to make the angle acceptable, and then solve the resulting caster problem by redrilling (or cutting and welding) the swivel pin housings.