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Re: Unibody durability off road [Re: AZjeff] #4975374
01/10/19 06:32 PM
01/10/19 06:32 PM
Joined: Aug 2015
Posts: 147
Central NY/Arkansas
avacado11 Offline OP
avacado11  Offline OP

Joined: Aug 2015
Posts: 147
Central NY/Arkansas
Originally Posted by AZjeff
Originally Posted by avacado11

My friend drives down dirt roads and hits ruts hard in his stock Wrangler JK like a baja truck without long travel suspension. I would never drive my Subaru down a trail like that, I don’t want to break or bend any suspension components.



There's no reason you can't drive down that trail in your Subie, just don't do it like you're racing in the Baja 1000. Easing over things isn't going to hurt anything but if you find yourself doing it very much a unibody might not be your best choice. Keeping a vehicle stock and avoiding underbody contact will keep you pretty safe, if it's going to drag don't do it. Find a new line or stack rocks.


I have eased my way thru some ditches with my outback, points where the car was on opposite corners. It was cool to see but I know it’s not good for the unibody. The alignment was still good and no creaks/rattles, but I’m always afraid to blow a ball joint or control arm from hitting a rut too hard, or worse bending the suspension mount points. I can fix scraping with a lift and and skid plates.

I don’t off road my Subaru that much anymore after a ball joint went from hitting a 6” deep rut at 10 mph. But my next car will have to be more durable off road. Wranglers are nice but I’d want something more civilized


2017 Subaru Outback - 0w20 FS - Nitto NT421Q
2014 Lexus IS250 - 0w20 FS - Continental DWS06
2014 BMW i3 - Bridgestone Ecopia
2015 Nissan NV200 - 5W30 FS - Mastercraft Courser HXT
Re: Unibody durability off road [Re: avacado11] #4975482
01/10/19 08:07 PM
01/10/19 08:07 PM
Joined: Nov 2018
Posts: 483
Chicagoland
Skippy722 Offline
Skippy722  Offline

Joined: Nov 2018
Posts: 483
Chicagoland
Originally Posted by avacado11
Originally Posted by Skippy722
Here’s the way I think of it... you either have something so solid it has no give at all, like a really stiff unibody, or you have something that has some give, like a body on frame.

In the case of a stiff unibody, it’s great for on road handling. But stiff isn’t always good. Think like a piece of steel. It only has so much give before it breaks or bends permanently.

Now the body on frame. It’s got some more give to it, more springy. Kinda like a leaf spring. It can tweak a bit and return back to normal.

Now, what I’m describing here are very vague generalities. There are unibody vehicles that off-road great (Jeep Cherokee), and there are BOF vehicles that would fold in half off road.


if both vehicles hit a rut that bottoms out a suspension, which body construction would have a higher threshold in general? A unibody designed with off road in mind(ex. Grand Cherokee that’s trailrated) or a Half ton BOF with off road HD suspension(Silverado z71).

Would a 3/4 ton or 1 ton hold up any better with a even stiffer frame or would that work against it? What about fancy suspensions like Chevy Zr2 or Ford Raptor. I’m assuming that stuff is just for comfort. But would a well designed IFS be a weak point compared to a solid axle?


The BOF, in general, will “survive” a hit like that better than a unibody. As for suspension, it depends what you’re doing. Bombing down a fire trail, out in the desert or something like that? I’ll take IFS. Rock crawling? Solid axle. I’ve always wanted a pre runner... crawling slowly over rocks doesn’t appeal to me. I want to do 110mph flying over stuff lol


2016 Chrysler 300S v6
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Re: Unibody durability off road [Re: Skippy722] #4975491
01/10/19 08:13 PM
01/10/19 08:13 PM
Joined: Mar 2017
Posts: 8,274
...
PimTac Offline
PimTac  Offline

Joined: Mar 2017
Posts: 8,274
...
Originally Posted by Skippy722
Originally Posted by avacado11
Originally Posted by Skippy722
Here’s the way I think of it... you either have something so solid it has no give at all, like a really stiff unibody, or you have something that has some give, like a body on frame.

In the case of a stiff unibody, it’s great for on road handling. But stiff isn’t always good. Think like a piece of steel. It only has so much give before it breaks or bends permanently.

Now the body on frame. It’s got some more give to it, more springy. Kinda like a leaf spring. It can tweak a bit and return back to normal.

Now, what I’m describing here are very vague generalities. There are unibody vehicles that off-road great (Jeep Cherokee), and there are BOF vehicles that would fold in half off road.


if both vehicles hit a rut that bottoms out a suspension, which body construction would have a higher threshold in general? A unibody designed with off road in mind(ex. Grand Cherokee that’s trailrated) or a Half ton BOF with off road HD suspension(Silverado z71).

Would a 3/4 ton or 1 ton hold up any better with a even stiffer frame or would that work against it? What about fancy suspensions like Chevy Zr2 or Ford Raptor. I’m assuming that stuff is just for comfort. But would a well designed IFS be a weak point compared to a solid axle?


The BOF, in general, will “survive” a hit like that better than a unibody. As for suspension, it depends what you’re doing. Bombing down a fire trail, out in the desert or something like that? I’ll take IFS. Rock crawling? Solid axle. I’ve always wanted a pre runner... crawling slowly over rocks doesn’t appeal to me. I want to do 110mph flying over stuff lol



The unibody Mitsubishi Montero/Pajero has participated in the Dakar rally among other for many years. Not exactly crawling.


Cannot see signatures any longer so it doesn’t matter.
Re: Unibody durability off road [Re: nthach] #4975511
01/10/19 08:30 PM
01/10/19 08:30 PM
Joined: Dec 2003
Posts: 822
New England, USA
wings&wheels Offline
wings&wheels  Offline

Joined: Dec 2003
Posts: 822
New England, USA
Originally Posted by nthach
The unibody Pajero didn't do too bad for what it is, and it was weird seeing that Prado without all the luxury stuff, as it's sold in the US as a Lexus. I know, Top Gear but it's a Range Rover being at least used for something else but a mall/soccer cruiser.




I hope Land Rover paid TG well for that ad...I mean episode.

That said, the RR's are decent off road, really good considering what they are. Putting aside the shilling for LR, it is a cool video.


'05 Lotus Elise S/C
'85 Land Rover 90 diesel
'74 Triumph TR6
'74 BMW 2002
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'99 Porsche 996 (Wife's)
'01 Porsche Boxster S (mostly Wife's...)
Piper Pa28-236


Re: Unibody durability off road [Re: avacado11] #4975585
01/10/19 09:51 PM
01/10/19 09:51 PM
Joined: Feb 2013
Posts: 11,357
Phoenix, AZ
Nick1994 Online content
Nick1994  Online Content

Joined: Feb 2013
Posts: 11,357
Phoenix, AZ
No problems.

[Linked Image]

[Linked Image]


2015 Hyundai Sonata 2.4L 92k STP Synthetic HM 10w30 & Wix
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1996 Jeep Cherokee 4.0L 148k Mobil 1 HM 10w40 & Fram Ultra
Re: Unibody durability off road [Re: avacado11] #4975672
01/11/19 12:22 AM
01/11/19 12:22 AM
Joined: Dec 2002
Posts: 42,543
'Stralia
Shannow Online content
Shannow  Online Content

Joined: Dec 2002
Posts: 42,543
'Stralia
This was a bit of a story around town some time ago...two vantage points





Because sometimes the simple things in life...
...simply don't know any better
Re: Unibody durability off road [Re: avacado11] #4975700
01/11/19 01:32 AM
01/11/19 01:32 AM
Joined: May 2012
Posts: 6,162
Fort Lauderdale, FL
DoubleWasp Offline
DoubleWasp  Offline

Joined: May 2012
Posts: 6,162
Fort Lauderdale, FL
A 3/4 or 1-ton is a bad off-roader regardless. Weight and length are not your friends. My WJ in 2WD will run circles around my Rams in 4WD hi or lo in pretty much anything serious.

The stiffer load carrying suspensions do no favors either. Not that my Rams are incompetent. My WJ just does pretty much anything they can do with greater ease.


07 Lincoln Navigator M1 0w-40/FU
68 Charger R/T / Supercharged 440 VR1/DBL7349
07 Ram 3500 4x4 / Cummins 6.7 /DBL7349
17 Maserati GranTurismo Cabrio
Re: Unibody durability off road [Re: avacado11] #4975731
01/11/19 04:15 AM
01/11/19 04:15 AM
Joined: Jul 2003
Posts: 5,081
New Zealand
Silk Online content
Silk  Online Content

Joined: Jul 2003
Posts: 5,081
New Zealand
It pays to have a winch in NZ.



1987 BMW R65 - Aegis SAE30
2005 Nissan Expert - 5W-40 Castrol Magnatec diesel.
1996 Volvo T5 - Penrite HPR15 - 15W-60. Ryco syntec filter.
Re: Unibody durability off road [Re: avacado11] #4975737
01/11/19 05:05 AM
01/11/19 05:05 AM
Joined: Dec 2002
Posts: 42,543
'Stralia
Shannow Online content
Shannow  Online Content

Joined: Dec 2002
Posts: 42,543
'Stralia
My BJ42 had a PTO winch...that was brutal


Because sometimes the simple things in life...
...simply don't know any better
Re: Unibody durability off road [Re: avacado11] #4975792
01/11/19 08:18 AM
01/11/19 08:18 AM
Joined: Feb 2007
Posts: 3,774
Southeast
meep Offline
meep  Offline

Joined: Feb 2007
Posts: 3,774
Southeast
I have no personal experience with the new ones but I punished the subarus I had decades ago and didn't experience unibody issues with them. The GLs were nothing I'd feel confident with in aggressive rough driving but the 97 legacy I had was absolutely stout. The only damage it sustained was from bottoming out on soft parts like the fuel tank. I was young, drove a lot of trails, and didn't dodge potholes during tight corners and it never, ever, had any alignment or chassis-softening problems. As long as ground clearance wasn't an issue, i'd feel more confident in that at speed than a wrangler. In addition, that one was an AWD with limited slip center diff, Not FWD with rear wheel assist. It was by far the most sure-footed vehicle for that kind of driving I've owned, though with limited power and all wheels pulling, it was not one for easy hooning on-road. It was a blast off road until moving past its clearance limits. I had a mild spacer lift on mine.

Due to the continual washing out and repaving of a certain part of back road on my commute, I also jumped it twice per day. After years of continual washout and repaving, it became a woop-dee-doo with a big pit in the middle. You either took it at 2mph or 45. you'd be airborn over the washout so each way. I'm not kidding. Obviously, I had this down to an exact science with the precise speed and line to achieve a landing on the ramped back side for the smoothest approach, but I still did it. Both ways, M-F. The previous honda civic I did this with landed with much more grace, so while I eventually got it right with the subie, it took me a few commutes before dialing it in, so we had a couple of hard landings. At 36,000 it had a recall for the front a-arms. The originals were tack welded while the replacements were fully welded. They replaced mine. I asked about the old units and the alignment. They told me the old units looked fine and the original alignment was still spot-on and none was required.

That said something to me. I know what I'd put that thing through.

Last edited by meep; 01/11/19 08:43 AM.

2018 F150
2015 crv (wifey!)
Re: Unibody durability off road [Re: avacado11] #4975806
01/11/19 08:40 AM
01/11/19 08:40 AM
Joined: Feb 2007
Posts: 3,774
Southeast
meep Offline
meep  Offline

Joined: Feb 2007
Posts: 3,774
Southeast
on the flip side, I went from a jeep ZJ to a WK a few years ago when the WKs were new. Its chassis (WK) did not impress me at all in terms of rigidity. In fact, it flexed or regular roads more than any other car I noticed. Hopping the curb to my driveway at crawl resulted in door and dash creaking. Door creaked on gently rolling pavement. I finally stuck my fingers between the door and roof one day with the window down and could feel the door moving up and down relative to the roof as a matter of driving a 25mph residential road. It was really disappointing and I never really got over it, realizing just how much body flex that JEEP had. And they'd advertised a 50% increase in torsional rigidity when going from WJ to WK. I really wanted to love that WK - it did a lot of things well despite cost cutting. But that was a massive chink in its armor to me.

So maybe it varies by vehicle.

For a lesson in body rigidity trying putting a volvo s60 on 4 jack stands. All cars will flex a little, as the jack stands themselves probably aren't on glass-level concrete, but they'll give a little and settle in. The S60 was less cooperative, usually with one of the four stands not contacting the car. I'd have to shuffle them around for a bit or keep the jack in play above the loose jack stand for stability. Those vehicles are .stiff.

Last edited by meep; 01/11/19 08:44 AM.

2018 F150
2015 crv (wifey!)
Re: Unibody durability off road [Re: avacado11] #4976313
01/11/19 05:34 PM
01/11/19 05:34 PM
Joined: Jul 2003
Posts: 5,081
New Zealand
Silk Online content
Silk  Online Content

Joined: Jul 2003
Posts: 5,081
New Zealand
Same on a hoist (lift), but not often. But everytime on the old BMC 1100/1300 - there was always an arm free when lifting those, zero flex.


1987 BMW R65 - Aegis SAE30
2005 Nissan Expert - 5W-40 Castrol Magnatec diesel.
1996 Volvo T5 - Penrite HPR15 - 15W-60. Ryco syntec filter.
Re: Unibody durability off road [Re: meep] #4976552
01/11/19 10:15 PM
01/11/19 10:15 PM
Joined: Dec 2013
Posts: 414
Kuala Lumpur ,Malaysia
alcyon Offline
alcyon  Offline

Joined: Dec 2013
Posts: 414
Kuala Lumpur ,Malaysia
Originally Posted by meep
In fact, it flexed or regular roads more than any other car I noticed. Hopping the curb to my driveway at crawl resulted in door and dash creaking. Door creaked on gently rolling pavement. I finally stuck my fingers between the door and roof one day with the window down and could feel the door moving up and down relative to the roof as a matter of driving a 25mph residential road.

For a lesson in body rigidity trying putting a volvo s60 on 4 jack stands. All cars will flex a little, as the jack stands themselves probably aren't on glass-level concrete, but they'll give a little and settle in. The S60 was less cooperative, usually with one of the four stands not contacting the car. I'd have to shuffle them around for a bit or keep the jack in play above the loose jack stand for stability. Those vehicles are .stiff.



Thats interesting, as what Shannow said, I faced a smiliar issue with my previous car. I was speeding on the highway once and sudddenly a truck stopped and i had to brake hard, the whole car chattered and after that I heard a tick tick tick sound coming from the dash/windshield at 80kmh and above, i thought it was the speedometer cable, so i slowed down and the sound went away , i sped up it came back, I stopped the car to check in the engine bay thinking perhaps my gearbox is giving trouble, but I dont see anything wrong. So i continued my journey, then a few minutes later, all of a sudden a loud pop, and immediately the windscreen started cracking and the cracks slowly spread all throughout the glass. I know there was no stone hitting the glass, so I surmised it must have been chassis flex. You see, at hard corners or going up inclines with either front wheels, the door ajar warning would come on, indicating that the doors have somehow twisted away from the switches, it must have been chassis flex, That car also had lots of squeaks and rattles over bad roads, but it was a econobox after all.
Now my current car is a luxury car ,though its old it seems to be in better condition than my previous car. But lately I have been getting some vibrations on bad roads and some creaks on braking, that seems to be coming from the pillar trims. It didnt have this sound before so maybe I have put back the trims wrongly after the reverse camera install.
Granted the left door is sagging on the hinges, in this case is the chassis flexing ?The door ajar warning is not coming on and when I take hard smooth pavement high speed corners I dont hear any pops or creaks. This car is much better built than my previous car and the creaks is like only 1/10th of it, but I am still worried. Is my chassis flexing ? Its a 89 toyota soarer, which is basically a Mk3 supra with no targa top.So is it possible my braking creaks are coming from suspension mounts and or the inner trims or sagging doors instead of chassis flex ?


Kyosho Optima Mid SWB, LWB and Lazer ZX
1991 Proton Saga 1.3S SOLD
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