Land Rover Discovery Suspensions: Caster

[michaelgroves]

Ask yourself this question when thinking of this debate.

How would Land Rover have designed it if they wanted to mass produce the vehicle with a 1.5" lift?

Would they use a DDC shaft or change the location of the mounting holes on the swivel ball?

Where are all you guys coming from, and why are you all missing my point? I'm not saying that the modified swivel is a bad way of doing things - it's almost certainly the best way for most situations. I'm sure Land Rover would do it that way. I get it, and I understand why it's a very very good method.

But I'm asking what the drawbacks would be, if for some reason I want to keep my swivels standard. Under those circumstances, what are my options? It's a simple question, so don't keep answering, "it's best to modify the swivels". If you can't think of any other ways of doing it, or show why it can't be done, that's ok, just don't answer!

 

[michaelgroves]

Sorry, I wasn't speaking to you directly, but the readership at large.

LOL, ok, and it was a fair comment too. I plead the 5am excuse for my quick trigger finger!

(So far, though, I don't think anyone has suggested that the swivel modification method isn't at the top of the list for consideration when doing a lift.)

 

[Mike_rupp]

Michael, assuming that you want to leave the swivel housings alone, IMHO the best way to tackle the problem is to use radius arms to correct the pinion angle with a DC shaft to have a vibe free front. The sole drawback to this is that the caster won't be ideal, however, when the radius arms correct for pinion they also correct the caster, but just not quite enough.

I'm running a 3" lift and use this setup. The caster is not perfect, but it is manageable. I will definitely add drilled swivels at some point, though.

Scott, I did some browsing on the Inland Rovers site. In your discussions with them, did they mention why they cost $1,100 more than the Rovertym radius arms? Is there any reason to justify the cost difference? Do they out perform the Rovertym arms in any manner?

 

[michaelgroves]

Michael, assuming that you want to leave the swivel housings alone, IMHO the best way to tackle the problem is to use radius arms to correct the pinion angle with a DC shaft to have a vibe free front. The sole drawback to this is that the caster won't be ideal, however, when the radius arms correct for pinion they also correct the caster, but just not quite enough.

I'm running a 3" lift and use this setup. The caster is not perfect, but it is manageable. I will definitely add drilled swivels at some point, though.

Thanks, Mike.

When you say use radius arms to correct the pinion angle, in what sense do you mean "correct"? Pointed upwards towards the transfer output flange, or kept facing back in the same orientation as originally? (The latter approach would be better for caster, the former would be better for propshaft angle).

Another question: are different spec. radius arms available for each lift height? (2", 3", 5" etc.)

 

[Mike_rupp]

The point I was trying to make is that when the radius arms correct the pinion angle they rotate the axle housing backwards and the caster improves. It doesn't go back to stock.

 

[Steve Rupp]

Another question: are different spec. radius arms available for each lift height? (2", 3", 5" etc.)

The great thing about Rovertym is that they will correct the radius arms for whatever you want. The Inland Rover's arms, while they are super cool looking, they have one single option... correcting castor for "2" to 4" lifted trucks". If I call up rovertym and say I have a certain lift and i want to correct this problem they will do it. They have been doing it long enough that you don't need to give them measurements. You just tell them what lift you have and what you want to do and they'll make an arm that'll work for your application.

 

[I Leak Oil]

A big part of what makes Land Rovers special is the fact that they can drive across the country, spend a weak off road and then drive back across the country without issues.

Shhhh....don't say that too loud. The toyota guys might stop thinking we break down every 10 feet!:Mechanic:
Just kidding...kinda...
Jason T.

 

[Mike_rupp]

Scott, I have another question about those radius arms. I looked a little closer at those radius arms last night and noticed that the bushings clearly aren't factory bushings. They appear to be polyurethane.

What was the thought process that was behind these bushings? Being in the plastics & synthetic rubber industry my whole career, I wouldn't expect that polyurethane would be the best choice for a radius arm bushing that experiences a radical amount of compression. Polyurethane is a good material, but doesn't compress and recover in the same manner as rubber. Rubber is very good at compressing and being deformed into weird shapes and then returning back. It doesn't have the ultimate stiffness of polyurethane. Polyurethane will resist deformation better, which will give a stiffer, tighter ride. Their big downside is that when they fail (all bushings fail eventually), they break apart potentially giving you a bushing that isn't a bushing anymore. When rubber fails, it tears & splits, but somewhat remains intact. Since I've owned my Discovery, I've replaced every bushing on the truck at least once and all of the failures were along the line of how I just described.

Is there anything about those bushings that Inland Rovers perceives as a benefit compared to the LR bushings? Are they easier to fit into the radius arm? Clearly, that is not a job that can be done in the field with a LR bushing.

 

[Scott Brady]

Scott was here making it sound like he is testing something new

I am not testing a new method, but a new product from Inland Rovers for an old method.

Clear as mud, huh

 

[Scott Brady]

Ask yourself this question when thinking of this debate.

How would Land Rover have designed it if they wanted to mass produce the vehicle with a 1.5" lift?

Would they use a DDC shaft or change the location of the mounting holes on the swivel ball?

Very good point. They would take the lower cost method and change the mounting holes on the swivel ball.

 

[Scott Brady]

Scott, I have another question about those radius arms. I looked a little closer at those radius arms last night and noticed that the bushings clearly aren't factory bushings. They appear to be polyurethane.

Generally, I am not a fan of polyurethane, and typically prefer a factory rubber bushing for many reasons, including compliance, durability and noise.

The bushings were one of my early concerns with these arms, especially the potential loss of articulation due to the poly bushings. Gordon advised that his testing did not result in a loss of articulation. Being one to test and validate things for myself (have you noticed that ), once installed, I validated the ROM for the arms. With the shocks connected, the arms allowed articulation to the end of the shock compression and extension stroke. With the shock removed, it allowed about another 1-1 1/4" of extension (droop), but no measurable increase in compression. So the arms allow full compression and extension with the standard OME shock. I do not intend to fit longer shocks, so the articulation of my Disco is not limited by the new arms. (note: I do not run anti-sway bars on either end)

My second concern with poly bushings is noise. I have found a synthetic grease that has worked very well for me in the past, when I had to use poly bushings in the Tacoma. It is called SuperLube. For about two years, and 40,000 miles (including Arctic conditions), the poly bushings in my Deaver springs did not squeak or fail. So far, the bushings do not squeak, and have not needed to be serviced, but it has only been a few months. Again, time will tell.

The rear arms also have poly bushings, and I applied the same SuperLube to them. If they start to squeak, I will swap back to stock rubber bushings.

Is there anything about those bushings that Inland Rovers perceives as a benefit compared to the LR bushings?

Are they easier to fit into the radius arm? Clearly, that is not a job that can be done in the field with a LR bushing.[/QUOTE]

I did not ask Gordon that question, but I expect the answer is ease of fitment, reduced cost and potentially improved handling precision, but that would require validation. The poly bushings front and rear has improved attenuation and the truck has a very solid, predictable and precise transition at speed in corners, lane changes, etc. However, I want to make it clear that I do not attribute this to only the poly bushings, as my ENTIRE suspension and steering system was changed at one time. It is certainly a combination of everything.

Are they easier to fit into the radius arm? Clearly, that is not a job that can be done in the field with a LR bushing.

Absolutely. The bushings (after heavy greasing) slid into the arms with light motivation from a rubber mallet. They can be removed with a wide flathead screwdriver. I expect servicing will be very simple.

In my experience, the quality and durability of poly bushing has improved noticeably over the past decade, and combined with the SuperLube I am using, I am hopeful these bushings will be reliable and quiet.

With your experience in the plastics and poly world, have you seen improvements in the materials used?

 

[Scott Brady]

Scott, I did some browsing on the Inland Rovers site. In your discussions with them, did they mention why they cost $1,100 more than the Rovertym radius arms? Is there any reason to justify the cost difference? Do they out perform the Rovertym arms in any manner?

I expect it is because the Inland Rover arms are all-new, and the Rovertym arms use a factory arm as a core. It looks like the Rovertym arms are heated and then bent to the desired correction, then reinforced.

The Inland Rover arms are nicely constructed, with skid plates added to the bottom of the arm and reinforcing gussets on the sides. The weld quality is notable.

Rovertym Arms:

Note: The factory Rover arms have a reputation for strength, being solid cast steel. It looks like Rovertym does the offset to a core, reinforces the arm and then finishes the arm with new paint. A quality solution for sure.

 

[Mike_rupp]

Scott, the materials themselves have improved ever so slightly over the years. What has improved is engineers specifying better materials for the applications and designing better parts. In a nutshell, when traditional companies started using plastic, the engineers designed parts that followed design characteristics of metal. An example would be to design a part with a sharp 90 degree transition instead of having a radius. Mold that part using a crystalline polymer and you have a weak spot. 20 years ago, it was commonplace that plastic parts being produced had to use more expensive, higher performance materials simply because of design flaws.

That's why I'd trust an engineer at an automotive company to a greater extent than a small aftermarket parts company, as a general rule.

At least with these radius arms, they did take a new approach. I'm not sure I'd use them, but at least they have presented something new to the market. I haven't seen any aftermarket radius arms that use bushings that can be installed in the field.

My understanding is that the Rovertym radius arms are cut and then welded rather than being heated and bent.

 

[michaelgroves]

Very good point. They would take the lower cost method and change the mounting holes on the swivel ball.

And they'd use a DC shaft

 

[I Leak Oil]

Now I'm feeln' love...Kuhmbayah my lord kuhmbayah....
Jason T.