[forestergump]

Parked on some rough ground the other day, let the dogs out the back, went to shut the hatch and it wouldn't close. Stood there for a few minutes with a puzzled look on my face trying to see if something was jammed in the way. In the end I rolled the car forwards onto a flatter piece of ground and it shut as normal.

I have a strut brace, subframe lock etc etc but I'm amazed the thing bends so much. I think it needs a big X shaped brace across the back. Wouldn't be able to get anything in the back but.....

 

[The Rookie]

The strut brace won't stop the rear lozenging out of shape, as you say an X or half X is needed for that, rear subframe bolts could never have an effect could they? (all they do is stop the subframe moving relative to the floor)

An H-brace under the front is meant to help quite a bit as well, but not your immediate problem.

If you open the Foz hatch you'll see two wedges on springs by the rear lights, they are designed to 'lock' the hatch in place when its closed so it can contribute to body rigidity, my guess is the body was twisted just enough so you were hitting one of those on the end and not running up the wedge as designed.

By the way, try shutting a rear side door with the body jacked on one rear corner......the SF is vbased on the classic body, renowned for not being very stiff, hence the newage body being so much heavier (and stiffer!)

Simon

 

[mykp]

Yeah mine does the same as well.

Thought about a roll cage in the back. but the its bye bye practicality!

Maybe it needs seem welding? :rock:

 

[mdg]

Idea...an X brace which doubles as a dog guard.

 

[mykp]

but where to mount it on the roof.

 

[mdg]

Plenty of metal above the boot windows. Maybe even more where the roof rails attach.

 

[Nich B]

what about where the roof handles are in the rear ?

just bolt in then

 

[funkymonkey1002]

This is the main reason that the mo_boost rear strut brace was such a great design. Horizontal brace with a V braced to the floor, keeps the strut towers from flexing in any direction.

 

[don1952]

This is the main reason that the mo_boost rear strut brace was such a great design. Horizontal brace with a V braced to the floor, keeps the strut towers from flexing in any direction.

http://www.scoobymods.com/mo-boost-forester-quick-t5521.html

 

[Blue Fox]

Just about all unibody vehicles do this. My buddies Jeep Grand Cherokee does it, my other buddies' Cherokee does.....and even that Land Rover I pulled out of the mud over the winter, he couldn't shut his either until he was back on level ground. So it's not just the Foz, it's the nature of the design.

 

[The Rookie]

As has been said, the moboost style V (or half X) rear strut brace with a mount to the rear floor or a small X with a mount to the bottom of each turret would probably be enough.

Simon

 

[forestergump]

The subtle fender braces made a big difference at the front. I believe he's working on a trunk brace now. Maybe that will help.

Otherwise a couple of old scaffold poles running up to the roof somehow....

Seriously though you can do what you like to the suspension but if the body is flexing shocks/bars can't help. The forester rear subframe sits in two big bushes but some of the hotter impreza ones bolt directly up which might stiffen the floor. I suppose you'd get a lot more noise though.

 

[The Rookie]

Doh! That is the rear subframe lock bolts many of us are running as mentioned above, and yes it only replicates what STi impreza's have, no it doesn't increase noise and no it does nothing to stiffen the body.

Simon

 

[peterk]

Just about all unibody vehicles do this. My buddies Jeep Grand Cherokee does it, my other buddies' Cherokee does.....and even that Land Rover I pulled out of the mud over the winter, he couldn't shut his either until he was back on level ground. So it's not just the Foz, it's the nature of the design.

Earlier this week I had mine parked on some very uneven ground. Guess the car was tilted up from the back around 30 degrees and down to the offside 10 to 20 degrees. The offside rear tyre was right up inside the wheel arch and the car was so balanced that it could be rocked with one hand to take the nearside rear off the ground. The tailgate and the driver's door worked perfectly (as did the traction control when reversing out)

 

[BAC5.2]

...hence the newage body being so much heavier (and stiffer!)

Simon

Supposedly, the GD-X chassis was 150% stiffer than the GC-X chassis! I think it might have even been Subaru that published that figure!

It's not so much that the Forester body is "soggy", it's just that the hatch is a critical structural member. Cut the end off of a shoebox, and it'll flop all over the place compared to an intact shoe box.

The proof is in the pudding. Look at skidpad numbers between wagon and sedan versions of a Subaru. They are probably the same.

 

[kernowjon]

Just about all unibody vehicles do this. My buddies Jeep Grand Cherokee does it, my other buddies' Cherokee does.....and even that Land Rover I pulled out of the mud over the winter, he couldn't shut his either until he was back on level ground. So it's not just the Foz, it's the nature of the design.

I think you will find flexibility in the body / chassis is an intrinsic part of the design of off-road vehicles. The whole body / chassis is effectively a shock absorber (not a damper).

This goes right back to the question - which is stronger Cast Iron or Steel?
Cast Iron is stronger and has more rigidity until it is hit so hard it shatters.
Steel is softer and flexs more when it is hit and therefore is harder to break.

Some examples:-
The little Suzuki SJs (a real off the road vehicle) were made of a wierd steel - which was soft as butter - a pig to weld. Land Rovers were a twisty steel ladder chassis and an ally body.

Continuous welds were at one time required then banned for MoTs because they are effectively runs of Cast Iron.

Hope all this contributes to the debate and understanding.

Jon

 

[The Rookie]

Cast iron is about 1/2 as stiff as normal carbon steel......its not stiffer, its just made much thicker!

No-one designs a car body or frame to flex, its just that they can't always make it as stiff as they want without it weighing too much or being too costly!

Simon

 

[mykp]

and dont forget if you make one part of the body shell more rigid then you just move the flexibility some where else. Just look at how much bracing rally cars have in them.

 

[forestergump]

Earlier this week I had mine parked on some very uneven ground. Guess the car was tilted up from the back around 30 degrees and down to the offside 10 to 20 degrees. The offside rear tyre was right up inside the wheel arch and the car was so balanced that it could be rocked with one hand to take the nearside rear off the ground. The tailgate and the driver's door worked perfectly (as did the traction control when reversing out)

Eee it's grim oop north. When are they going to fix t'roads? :shrug:


Do you have traction control on your Forester?