Rear shock mounting

[cumminscruiser]

Driving down the road in my TDI Jetta I notice things that I dont see in my cruiser. The rear shock mounting in a full size Chevy truck has the passenger side shock in frount of the axle and the drivers side behind the axle. On a full size Ford both shocks are behind the axle.

Since I will be remounting the shocks in my FJ60, what your opinion of shock placement?

 

[cyclic]

The staggered shocks are to prevent wheel hop. Actually works pretty well. Since you are doing it you may as well do it right. Make sure your bottom shock mount does not hang below the axle. The top mount should be easy to access from under the vehicle. Do not place the shock too close to the exhaust. Use limiting straps if you have a long travel suspension to keep from damaging the shocks. Try to get some that have adjustable valving, makes setting up your trucks ride much easier.

 

[ntsqd]

My first thought was why are you moving them? Not that I think that the OE arrangement is ideal, but moving them looked to be a lot tougher than the front (which I did).

In a perfect world I would want the rears mounted as close to the rear wheels as possible and such that they were perfectly vertical when the suspension was bottomed out. Lots of stuff in the way of doing that in a 60.

 

[cumminscruiser]

Rear shocks

Thanks for reminding to keep the lower mount above the bottom of the axle, I am relocating the mounts becouse of the spring over years ago and I just put the shocks back in and they did not line up and did not use all of the travel... So Im thinking of placing the new shocks in the best possible place and I saw that Ford and Chevy had different ideas. I like placing the shocks to help pervent wheel hop. I will be installing a anti-spring wrap thingie at the axle and that should keep the axle wrap down.

 

[ntsqd]

oh, the SOA might open up some room to maneuver. Everything that I've read on SOA indicates that you need a lot more anti-wrap than splayed shocks are going to offer. If you're of the mindset that every little bit helps I'd say go for it, but my own direction would be to optimize the damping and let something else do the anti-wrap stuff.

 

[dieselcruiserhead]

I was going to say I recall your truck being SOA...

The correct shock is a 12" travel shock that you mount fairly vertical. You can place it below the axle but you get some interferance on technical terrain so it's up to you. I've always fabbed and welded a mount on the axle housing fairly close to the spring perches. I then add some slightly inboarded shock pins to the upper mount and that provides about the idea height for the 12" shocks. 12" match the 14" you can run up front but they have a wider mounting pattern so they actually match quite well...

I'll dig up some photos of my FJ62 housing that was under my FJ55, it is set up this way. I hope it helps! Andre

 

[dieselcruiserhead]

Here you go. This is a IFS mini truck axle in the rear but it is very similar. This is me stuffing 14" travel shocks in the rear - again, not worth it in the slightest and less performance. Excellent articulation though of course but I think you can do just as well with 12" shocks more inward. Both are my old Cummins powered FJ55... It is a near identical scenario with a FJ60 they just use a tube for the upper shock mount similar to a FJ40 rather than a crossmember of a FJ55.

All 4 wheels planted and no locker. It was an excellent daily driver that also off roaded very well...

http://www.expeditionportal.com/forum/showpost.php?p=299404&postcount=22

 

[R_Lefebvre]

Below is a statement from one of the OEM shock tuning engineers. So, consider it the bible.

Picture this: The Ford has the superior “lateral” setup – shocks are outboard of the springs. This helps with skate, which is caused by the axle pivoting around the dif (think one wheel going up while the other goes down, rapidly oscillating). So that's a good thing, and the Ford beats the Chevy handily for that. However, in side view, both lower shock mounts are at the same X position, so the axle is free to pivot/oscillate about that shock mount all it wants with no damping. So axle windup under power, bumps, whatever, is not as controlled as if the shocks were splayed.



The best solution would be to have outboard, splayed shocks, assuming you're sticking with leaf springs (which Chrysler has abandoned for coils on the new Ram).

 

[ntsqd]

At the expense of over-complicating things he's slightly incorrect though I imagine that it was omitted for simplicity's sake.
The axle does have some damping about those mounts, but it is small. The internal friction of the leaf springs will provide a minor amount of damping function to that motion. In a classic leaf spring the damping could be significant though still not large. In later spring designs, ala the "GM 63's", it is even less due to the reduction of internal friction in that type of spring assembly.

Just a minor point that bugged me.....
:sombrero:

 

[R_Lefebvre]

Yeah, we were talking specifically about the shocks and I'm sure he just omitted other minor details for simplicity.

 

[cumminscruiser]

Rear shocks

My rear axle is set up now very simular to your FJ55 but I moved the upper mounts towards the inside just to make the shocks work, one of those temperary jobs that stayed for years. I think I'll use the origional upper mounts and relocate the bottom mounts to look like what you did on the 55. I was not sure if I should put one shock in front of the axle and the other behind or just put both behind the axle.

 

[dieselcruiserhead]

Yes, good question!

I've had both styles on different vehicles I own and don't really notice the difference, if it helps!

 

[Metcalf]

Personally I like my shocks outboard as far as possible and as straight up and down as possible. I think this is the ideal location for a shock to do what it needs to. You have to work around all the common packaging problems like ground clearance, the frame, the body, the tires, etc.

Don't get too caught up in massive amounts of articulation or wheel travel. Its about quality of travel, not how much you have IMOO.

Also don't forget to think about proper bump stops and limiting straps to prevent shock damage.