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shock mount mods

Posted: Thu Nov 20, 2008 4:13 pm
by waandy
ok iv seen the commodore/hiace shock setup but i dnt wana reduce my uptravel as i am finally sorted with this aspect. my question is.....
is it possible to cut off the old shock mount and make another 50mm higher? and has anyone done this or similar before?

Posted: Thu Nov 20, 2008 4:39 pm
by hobzees4wdshop
Yeah mate pretty easy to do. I know some guys that have cut it off completely and replaced it with a section of shs 50x50x3mm. Cut the angle you want off the chassis, then cut and fold and reweld for pin mount at top then weld to chassis and brace. I think Built4Thrashing has used this method. Bit of work though.

Might be easier to pick up some F-truck mounts which are cheap and longer but have an eye terminal at the top rather than pin. Otherwise I'd look at Hilux, Bundy shock mounts might be long enough.

cheers.

Posted: Thu Nov 20, 2008 5:41 pm
by Kitika
Image

Here's the ones I've made up. You'll probably have to use 25x25x2 or close to that because of the lack of space in the wheel well (depending on tyre size, rim offset or spacers). And it'd be just as easy to weld it or make them bolt up if you don't want to weld them to your chassis.
Also after this pic was taken I've moved the mount to an even more vertical position and cut the outer sleeve off the shock because of tyre clearance issues.

Posted: Thu Nov 20, 2008 7:31 pm
by Gwagensteve
I have seen some botched jobs of moving the stock mount up, I'd start from scratch. The stock mount is thin, not that strong anyway (I've seen a number broken) and hard to extend without looking hacky as it's a complex shape and tapers.

You'll want to doubling plate the chassis where the mount is welded on - the chassis is only 2.5mm thick, and ideally mount to both the face and top of the chassis- as you increase the height, you'll really increase the leverage on the chassis.

Not knocking Kitika's mount, but I did a mount like this once and it broke off, although it probably has more to do with crappy FCAW welds and hasty construction.

Here's how I've done a few:

Image


These work well (they're designed for N76 shocks and bumpstop spacing, but the length isn't the issue, it's an example of the construction) But with big tyres and reasonable backspacing, the tyres will catch he mount due to its width. These JUST clear the inner guards.

The next version I'm building currently is much taller as the shock mounts on top of the axle. They run the same shock, but angle them in more at the top so although the shock mount is higher, it's over the top of the chassis so there's lots more tyre room. Of course, it's well through the inner guard and with the top mount 11" above the chassis, we think we'll need a cross brace to take some load off the chassis. You shouldn't need to go that high.

Steve.

Posted: Thu Nov 20, 2008 9:02 pm
by VR Rodeo
Gwagensteve wrote:
You'll want to doubling plate the chassis where the mount is welded on - the chassis is only 2.5mm thick, and ideally mount to both the face and top of the chassis- as you increase the height, you'll really increase the leverage on the chassis.

Not knocking Kitika's mount, but I did a mount like this once and it broke off, although it probably has more to do with crappy FCAW welds and hasty construction.

Steve.
Excuse my ignorance Steve, but I dont see how there is going to be that greater force/leverage on the mount over stock. If the shock is the right extended length then it shouldn't pull on the mount, and if it has the right compressed length or bumpstop setup then it shouldn't push on it to any great extent, should it ? There will be 'some' twisting when the axle moves but most of that will be soaked up by the bushes wouldn't it ??

Posted: Thu Nov 20, 2008 10:05 pm
by GRPABT1
Gwagensteve wrote:
The next version I'm building currently is much taller as the shock mounts on top of the axle. They run the same shock, but angle them in more at the top so although the shock mount is higher, it's over the top of the chassis so there's lots more tyre room. Of course, it's well through the inner guard and with the top mount 11" above the chassis, we think we'll need a cross brace to take some load off the chassis. You shouldn't need to go that high.

Steve.
I'd like to see pics of the beast in question once you're done.

Posted: Thu Nov 20, 2008 10:39 pm
by PJ.zook
VR Rodeo wrote:
Gwagensteve wrote:
You'll want to doubling plate the chassis where the mount is welded on - the chassis is only 2.5mm thick, and ideally mount to both the face and top of the chassis- as you increase the height, you'll really increase the leverage on the chassis.

Not knocking Kitika's mount, but I did a mount like this once and it broke off, although it probably has more to do with crappy FCAW welds and hasty construction.

Steve.
Excuse my ignorance Steve, but I dont see how there is going to be that greater force/leverage on the mount over stock. If the shock is the right extended length then it shouldn't pull on the mount, and if it has the right compressed length or bumpstop setup then it shouldn't push on it to any great extent, should it ? There will be 'some' twisting when the axle moves but most of that will be soaked up by the bushes wouldn't it ??
Have you ever tried extending or retracting a shock with youre hands? You will find you will have to apply quite a bit of force to do it. Now just imagine youre suspension compressing or extending the shock in a matter of milliseconds as the suspension moves, that is a hell of a lot of force to be exerted on the mount. Plus the longer the mount is from where it attatches to the chassis to where it attatches to the shock, the more leverage is applied.
To be honest without knocking, im amazed the first shock mount pictured has held up. Although i have seen with my own eyes a truck engine last a few hundred thousand kilometers without main bearing lubrication other than splash feed, so it is conceivable.

Posted: Fri Nov 21, 2008 5:52 am
by cj
GRPABT1 wrote:
Gwagensteve wrote:
The next version I'm building currently is much taller as the shock mounts on top of the axle. They run the same shock, but angle them in more at the top so although the shock mount is higher, it's over the top of the chassis so there's lots more tyre room. Of course, it's well through the inner guard and with the top mount 11" above the chassis, we think we'll need a cross brace to take some load off the chassis. You shouldn't need to go that high.

Steve.
I'd like to see pics of the beast in question once you're done.
Maybe ;)

Posted: Fri Nov 21, 2008 6:34 am
by Gwagensteve
VR Rodeo wrote: Excuse my ignorance Steve, but I dont see how there is going to be that greater force/leverage on the mount over stock. If the shock is the right extended length then it shouldn't pull on the mount, and if it has the right compressed length or bumpstop setup then it shouldn't push on it to any great extent, should it ? There will be 'some' twisting when the axle moves but most of that will be soaked up by the bushes wouldn't it ??
It's not the force the shock is putting into the mount, it's the force the mount is putting into the chassis. the taller the mount, the more leverage the mount can put into the chassis, even if the force at the shock is the same.

Hope that makes sense.

Steve.

Posted: Fri Nov 21, 2008 1:33 pm
by Guy
I have a 10 cm lever, I apply a load of 20Kgs to the end of it (or the stock mount)
I now have a 30cm lever and i apply a load of 20Kgs to it (extended mount)

The longer lever is going to exert significantly more leverage against it's base (chassis rail) even though the load at the top end is the same.

Posted: Fri Nov 21, 2008 4:36 pm
by get it up there
I reinforced the mounting points with some flat bar (welded onto the chassis), cause as someone said before, the chassis are thin and weak! I got this set up from low range off road
Image

Posted: Fri Nov 21, 2008 8:56 pm
by VR Rodeo
Gwagensteve wrote: It's not the force the shock is putting into the mount, it's the force the mount is putting into the chassis. the taller the mount, the more leverage the mount can put into the chassis, even if the force at the shock is the same.

Hope that makes sense.

Steve.
Cheers guys, I understand how levers work just didn't think there would be a great deal of difference between stock and raised 3 - 4 inches ;)

Posted: Fri Nov 21, 2008 9:08 pm
by hyzook
As has been said plating the chassis is esential. I have had these in for 2.5 years and after some hard work they are fine. I kept the mounts far apart on the rail to spread the load and the tube was welded heavily to the plates (which mount on two planes) on the bench, then after it cooled I then did stitch welds to the rail.
I have had to cut a hoop shape out of the inner guards to fit them but if done neat enough the hoop will fill the hole.
Image

Posted: Fri Nov 21, 2008 9:41 pm
by Kitika
I like hyzook's mounts because they look to be quite inboarded and wouldn't foul on the tyres etc and be very strong.
I did mine the way i did because of the simplicity of design and i believe they'd be just as strong or stronger than the cheesy stock mounts. Also i wanted to whip something up fast so i could back on the road after doing a RUF :roll:
They seem to have held up pretty good to the abuse so far and hope they do for along while yet!

Posted: Sat Nov 22, 2008 8:36 am
by lump_a_charcoal
love_mud wrote:I have a 10 cm lever, I apply a load of 20Kgs to the end of it (or the stock mount)
I now have a 30cm lever and i apply a load of 20Kgs to it (extended mount)

The longer lever is going to exert significantly more leverage against it's base (chassis rail) even though the load at the top end is the same.
Where can I buy this lever? It sounds perfect for my car...