How strong is the D2 chassis?

[Hendrik]

Hi All
As some of you might know, my D2 got written off recently after I hit a washout on Fraser Island, where I bent both front and rear axles, the front being bent the worse, the rear only minor. The chassis also has a slight deformation in it from the impact. So this makes me wonder just how strong is the D2 Chassis? I hit the washout pretty hard, the car was airborne for a while so chassis damage was expected. But what intrests me more, is how the chassis behaves in normal offroad driving conditions.
If say one side the axle (front or rear) flexes up against the bump stop, and the other is down obviously. Lets assume you have lockers, and you keep driving over the obstacle with one side of the axle against the bump stop, some deflection in the chassis is sure to occur. But if this process is repeated by going offroad regularly, can you get to a point of reaching the ultimate tensile strength of the steel in the chassis and causing permanant plastic deformation? And another question, is the D2 chassis made with mild steel, or something more high tensile?

It would be interesting to hear your thoughts on this.

[Slunnie]

The chassis wont achieve plastic deformation with extreme articulation, even when fully loaded and beyond. Impact loads are significantly greater than static or gradually applied loads.

I'm not definate, but I suspect the D2 chassis is made of something slightly better than mild steel although nothing flash.

[Hendrik]

Hi Slunnie, was waiting for your input, always great to read.
So the chassis structure would have been designed never to reach plastic deformation, but would surely it would reach the yield strength where deformation starts to occur?
What I am getting at, with articulation, the chassis would reach its yield strength, but would extreme repeditive articulation (I'm talking everyday flexing) start taking its toll on the chassis. You mentioned a while ago, the front body mounts seam to be a bit weak on the early D2's and do seam to bend.

[Slunnie]

Hi Slunnie, was waiting for your input, always great to read.
So the chassis structure would have been designed never to reach plastic deformation, but would surely it would reach the yield strength where deformation starts to occur?
What I am getting at, with articulation, the chassis would reach its yield strength, but would extreme repeditive articulation (I'm talking everyday flexing) start taking its toll on the chassis. You mentioned a while ago, the front body mounts seam to be a bit weak on the early D2's and do seam to bend.
Gday Hendrik,

There may be some mix up with the definition of yield here, but plastic deformation (ie permanent deformation) occurs after max yield strength has been reached. Where deformation starts to occur, but before plastic deformation occurs is called elastic deformation. Elastic deformation (flexing without permanent bending) is starts to happen as soon as you place a load on the chassis (or anything for that matter). A chassis isn't a totally rigid structure but will to a minor extend flex around in all directions while you are just driving. If you put your fingers over the gap between the door and body in a car and drive it over uneven ground you will feel the door gap change as the body flexs. When you totally articulate the chassis and suspension you are nowhere near the point of plastic deformation, but if you impact on the chassis such as landing it after being airborne then you run a good risk of bending or twisting it as the force is significantly greater than just driving it and articulating.

The repetitive cycling of loads through the chassis is called fatigue and as the loads increase the number of cycles reduces before a failure of some descript occurs. Fatigue failures in the chassis as far as I'm aware won't show up as a bend - a bend is usually indicative of a big force like an impact. Fatigue will typically show up as cracks though and in the areas that are most highly stressed. If you drive it everyday on the road, then you will probably never see cracks in the chassis. If you regularly offroad it then the D2 will be prone to cracks in a couple of places:

In front of the Panhard mount / steering box mount - there is a weld kit to reinforce this part.
The PS body mount behind the front wheel - this was reinforced in the D2a. These crack, they don't bend.
Tops of the B-pillars - this is just a poor engineering design in my opinion and you just live with it.

[Hendrik]

Thanks for the explaintion Slunnie. I did have my wording mixed up, forgot what about elastic deformation completely, my brain is in holiday mode from Uni.

My car was airborne for an instant, and the back end on the LHS came down hard on the rear bar and hence the rail bent up slightly also causing a crease in the roof just near the turret. The fact that it was airborne as you mentioned did cause the deformation you mentioned before.
It all makes a lot more sense now :D

[Slunnie]

Thanks for the explaintion Slunnie. I did have my wording mixed up, forgot what about elastic deformation completely, my brain is in holiday mode from Uni.

My car was airborne for an instant, and the back end on the LHS came down hard on the rear bar and hence the rail bent up slightly also causing a crease in the roof just near the turret. The fact that it was airborne as you mentioned did cause the deformation you mentioned before.
It all makes a lot more sense now :D
How big was the hit?

There has been the odd bent D2 chassis. Your bend usually happens at the spring turret at the rear, but that usually when landing it with a trailer on the back rather than landing on the rear bar!

[Hendrik]

Well I didn't have a trailer, but it bent exactly where you say, at the spring turret. One side is bent more than the other, about a 7-10mm difference in height I'd say. But you can clearly see the marks where it hit. The hit was large, the front diff is bent and both front alloy wheels buckeled. I didn't hit it with great speed, approx 40km/hr but the drop off and step up was huge.

I will take a few pictures off of it tomorow and post them up, I bought the wreck back off the insurance company.

[Rosscoe68]

you parting it out ?
i am in brisbane in a few weeks and looking for some odds and ends off a D2

[Redback]

I have cracked my chassis 2 times now, bent both front trailing arms and both front body mounts on all ocassions there was some sort of hard impact involved, and with me I had the camper on, the first being a washout on the road from Cunnamulla to the Dig tree, that was massive:o 2ft wide and about a foot deep at around 80 to 90ks with the camper on, my D2 has towed a camper on and off road for around 180,000ks and 5yrs on some pretty rough roads, hitting some pretty big washouts and potholes, not to mention corrigations.

When fully articulated, I can still open all 5 doors:D

Baz.

[cal415]

I have pics of a bent chassis, bent on both rails just near the gearbox mounts, including pics of how it happened... not mine and i wont mention any names, i can post them if the owner of the d2 gives me permission :)

[Hendrik]

Well its not as weak as I thought. I did extensive measuring of the chassis today, using the dimensions provided in RAVE and came to the conclusion that the rear left hand side is only bent down a mere 2mm. This is way less than I expected, which means I might as well have a go at fixing it. I don't have anything to lose really, so I will fix the front diff and take it for a drive and see what its like. I have done a thorough inspection of the damage so far its only the front diff thats damaged and the chassis, you can see where the chassis is damaged just near the rare spring turret.
If its crap to drive or if i find some other catastrophic damage elsewhere I will part it out. It has been classed as a repairable write off on the grounds that it would have been too expensive to fix for what the vehicle is worth. They quoted $3200 for the diff housing alone, not including the axles, cv's, steering knuckles etc...stupid prices for those too.

[Slunnie]

Well its not as weak as I thought. I did extensive measuring of the chassis today, using the dimensions provided in RAVE and came to the conclusion that the rear left hand side is only bent down a mere 2mm. This is way less than I expected, which means I might as well have a go at fixing it. I don't have anything to lose really, so I will fix the front diff and take it for a drive and see what its like. I have done a thorough inspection of the damage so far its only the front diff thats damaged and the chassis, you can see where the chassis is damaged just near the rare spring turret.
If its crap to drive or if i find some other catastrophic damage elsewhere I will part it out. It has been classed as a repairable write off on the grounds that it would have been too expensive to fix for what the vehicle is worth. They quoted $3200 for the diff housing alone, not including the axles, cv's, steering knuckles etc...stupid prices for those too.
2mm is probably still within the manufacturing tolerance. They move around heaps with welding. For the front diff, I would contact Bundalene on here and see if he has one that he can send to you - it'll be way cheaper than $3200!!!

[Hendrik]

Yeh thats what I was thinking, so I think it will be fixable. I've found a diff in Brisbane for pretty cheap and in good nic too. The radius arms are still dead straight both front and rear, but the bushes on the rear axles are shot, will definatly have to replace them, hopefully with ones that allow for a bit more flex. Thinking about fitting a cranked watts link at the same time too, but I need to drive the thing first to see what its like.

[cal415]

Its a shame you need to retain the ABS etc, it would be cool to see a heavily moded d2 running patrol/toyota etc diff and some big rubber...

[Slunnie]

Its a shame you need to retain the ABS etc, it would be cool to see a heavily moded d2 running patrol/toyota etc diff and some big rubber...
I think that has been done in the US. I'm pretty sure a D2 was fitted with LC80 axles and the ABS sensors were connected up.

[Hendrik]

Personally I am not a fan of diff converstions (unless your gonna go portals), what is wrong with fitting Ashcroft or MD axles etc, a lot less stuffing around with engineering etc.

Theres is a guy on Pirate4x4 who did a mog conversion on written off d2 that he turned into a soft top. He has never updated the thread but I think it would have come out sweet.

[stig0000]

oi hendo wana use our big angle grinder, UTE TIME:D:D

[Hendrik]

No need to mate, I took it for a drive just before and it drives straighter than the day it came off the showroom floor. So happy with it :D

Now to put all my mods back in, rerego, inspection by QLD transport and then its time to hit the tracks again.

[Cannon]

that's good news:)

good luck

[Hendrik]

Thanks.
Been sorting out a few niggly things on it. Have to remove the rear carpet as I had a leaking 10L water bottle on the last trip and it has all soaked into the carpet. Will have all new transfer case seals, diff pinion seals and diff axle seals in the front too. Lots of work to do still. Will update my member rides thread soon.

[that_kid]

i think a cranked watts is a bit of an overkill at the moment as mine runs the same suspension setup without sway bars n there is still a few mm of travel there it doesnt bind surprisingly.

as for dif conversions, if you put a LR centre next to a GQ patrol centre the rover one is dwarfed. Plus the cost and availablity of replacement parts for the patrol difs is much better and they are overall much stronger. I would love to chuck some GU difs under my disco!

good to hear the car drives straight!

[Hendrik]

i think a cranked watts is a bit of an overkill at the moment as mine runs the same suspension setup without sway bars n there is still a few mm of travel there it doesnt bind surprisingly.

as for dif conversions, if you put a LR centre next to a GQ patrol centre the rover one is dwarfed. Plus the cost and availablity of replacement parts for the patrol difs is much better and they are overall much stronger. I would love to chuck some GU difs under my disco!

good to hear the car drives straight!

Thats because the Lovell shocks are the limiting factor in your flex and preventing the watts link from binding up. Going by the pics you posted up in another thread, it doesn't seam like you are getting any more flex with the sway bars out in the rear that what I get with sway bars. In the front it has made a big difference, I'm definatly getting those disconnects from the US.

[Redback]

Thats because the Lovell shocks are the limiting factor in your flex and preventing the watts link from binding up. Going by the pics you posted up in another thread, it doesn't seam like you are getting any more flex with the sway bars out in the rear that what I get with sway bars. In the front it has made a big difference, I'm definatly getting those disconnects from the US.

It's true, you don't get anymore rear travel in the rear with the swaybars removed, in the front you will, because of the shear size of the front swaybar, it's also true about the Lovells, they bind before full travel.

I have re-installed my rear swaybar and will re-install the front once I get the disconnects.

Join the D2au site and ask the guys on there, a lot of good info about D2s from guys that have been there and done that, Slunnie is on there too, along with Tombie and many other D2 owners from here.

Baz.

[that_kid]

im not to keen on the disconnects so much as they only allow one side to disconnect and not fold the sway bar up out of the way completely,

you are right about the lovells, i am somewhat dissapointed about it BUT you live and learn,

bilstein 7100's will soon replace them :)

[DiscoDan]

i think a cranked watts is a bit of an overkill at the moment as mine runs the same suspension setup without sway bars n there is still a few mm of travel there it doesnt bind surprisingly.

as for dif conversions, if you put a LR centre next to a GQ patrol centre the rover one is dwarfed. Plus the cost and availablity of replacement parts for the patrol difs is much better and they are overall much stronger. I would love to chuck some GU difs under my disco!

good to hear the car drives straight!

I agree with the size difference however a Patrol with 33 inch tyres has the same clearance as a disco with 31's. making the standard stronger will help more in giving more clearance.

[TJS-70Y]

The other thing is with a diff swap to nissans is that it will never ever drive as nicely as a rover diffed vehicle. It would take a LOT of money to make it close.

Thomas