[seanzook06]

was browsing a few older threads on shocks, and I am looking at running ome n76, however I cant find anywhere in australia that sells them, and old man emu doesnt seem to have any prices online, the other thing I have noticed is all the american websites list the n76 shock absorber as fitment for 40 series landcruisers , is this the same shock as the one referenced on az (e.g https://www.auszookers.com/forum/viewto ... 37&t=54402) would love some help please

[Brenno]

I bought direct from ARB for $175 each. They are a good shock but they are long and have a large upper body. The bottom bush is too large for the standard lower shock pin on a Sierra so I sleeved mine. It will require completely new upper and lower mounts.

[seanzook06]

Shock mounts aren't a problem, making a full custom suspension setup anyway, just wanted to know a rough price guide, and a place to get them from, thanks

[Gwagensteve]

N76 is N76. As you've found they are a lifted rear land cruiser fitment but they were actually developed for off road racing in the early 1980's. In the US they were also used as a lifted TJ shock where they must have been hilariously too soft.

As Brenno points out, they're bulky and very long. Depending on the other parameters of your suspension you might find them impractically long (i.e they still have 100mm or more of travel left in them when the suspension is fully drooped. This can accelerate spring damage in a leaf sprung application and of course will result in the springs falling out in a coil application. If you're designing everything from scratch it might be wroth going to soft valved 5125 Bilsteins which are much easier to package and available in more manageable lengths.

[seanzook06]

still going with a leaf sprung setup, would inboarding the shocks make the extra length more managable

[Gwagensteve]

Inboarding makes the problem worse, and makes the shocks less effective. The more they're laid over, the less the shaft moves relative to the axle. If the shocks are load over at, say, 45˚, when the wheel moves 100mm, the shock only moves 71mm, so the shock is effectively 30% softer compared to vertical. Then, a 11" travel shock laid over at 45˚ actually moves through 15" vertically, which makes the problem even worse.

Add to that that the more the top of the rear shocks are moved inboard, the closer they are to the car's roll centre. This means the shocks barely move at all on articulation. in extreme cases, the drooped shock can actually start to compress again the more the axle articulates as the axle rolls off to the side.

N76 were a great choice when they were A)$100 each and B)There weren't soft valved Bilstein 5125's available.

Whilst I agree with buying shocks a bit over length to allow for changes in spring etc down the track, going waay over length has more drawbacks than advantages.

[Brenno]

I must say I do love the n76 and coil combo in my ute, it's such a pleasure to drive. I would likely have gone a shorter bilstein 5125 for ease of packaging but during covid I couldn't get them which is when I was building mine.

[seanzook06]

What price are these Bilstein 5125s and where can you get them from, wanting to get maximum droop, I would prefer to at least use the lower shock mounts, but I don't care if I have to modify the top mount, or run an additional crossmember to inboard

[Gwagensteve]

Wanting to get "maximum droop" doesn't have anything to do with the shocks. In the leaf cars I setup with OME springs, rears up front and slightly extended shackles, there was still near 100mm of unused shock travel at full droop. Leaf sierra's just can't use 11" of travel, especially on the rear where the motion ratio is low.

If you flex your car up and measure how much actual shock travel you need, I bet it's not over 8" front or rear.

to give you an idea of how impractical N76's are, (and the compromises we were willing to make to run a shock that was correctly valved for a Sierra, here's some installs from way back in the sands of time:

Here is the most travel I've ever been able to use on an N76 - basically all 11".



This was because we moved the lower shock mount up onto the top of the axlehousing to get it as far out as possible. This was deliberate - the further outboard the lower mounts are, the better the shocks are at stabilising the vehicle and fighting body roll. However, it led to huge front shock towers:

You can see how high they are in the engine bay here:



And that was in a car with a 2" body lift AND 2" bump stop spacers. with neither of those things those towers would be 4" higher in the engine bay.

This car could also use full travel in the rear, but that was with springs that were something crazy like 10" longer than stock and extremely long shackles,



The top shock mounts were hard up under the tray.

Here's a more conventional installation in the front:



and it did use stock lower mounts, but because of the bulk of the shock, any axle wrap would cause the axle to hit the shock.

Here's the rear mounts on the same car, which came though the floor 2", again, on a car with a 2" body lift and 2" bump stop spacing. So, with neither bump stop spacing or body lift, the shock would be 6" through the floor of the car. Yes, you could lay it over at which point it would be basically useless.



Here's the N76 mounts I built when I coiled the rear of my car. Obviously, this isn't practical for a full bodied car and the shocks were only OK like this because the car was radius arm. When I swapped the rear to 3 link the shocks did not provide enough damping in that position and the car was very unstable.



to give you some reference on relative lengths, here's a comparison:



From top to bottom:

Stock sierra front
Stock sierra rear
Rancho 99010 (10" travel, generic soft valving)
N76
OME 80 series front (not recommending it, just there for comparison)

and here:



Left: 12" travel 5125
Right: N76

you can see the bulk difference. Also, note that because they're a monotube, the Bilsteins mount body up, which means only the shaft is down at axle level which really improves packaging issues.

Two drawbacks for 5125's, both associated with them being monotube:

They aren't very efficient lengthwise - i.e a 10" travel monotube is longer compressed than a 10" travel twin tube, foam cell or remote reservoir shock. That's because there's a floating piston in the end of the shock that separates the gas and the oil.

Also, because they're monotube (i.e single wall) if you dent the body, they'll jam up. The body is cromo and much thicker than on a twin tube shock, but it's something to be aware of.

5125's are available from low range offroad, shock warehouse and lots of other places on line. I've also seen them on amazon with free shipping if you're an amazon prime member. Price is around USD $100 each + shipping so depending on how you get them here they're line ball with N76's.

Check part # listings, not everyone carries every valving configuration in every length. if the car is leaf sprung you want the 170/60 valving

Here is the full part # listing: https://www.shockwarehouse.com/site/bilstein_5125.cfm

Happy to provide more assistance with your setup and what you want to achieve, but my advice is don't go overlength with shocks - it creates a tonne of work for no gain.

[seanzook06]

So an 8 inch travel 5125 with 170/60 valving would be good, rest of the setup will include ome springs in the rear, and standard rears in the front, would this be good for all four corners of the car

[Gwagensteve]

I can't really be that prescriptive - you'll need to set the car up in the normal way for RUF - derate the spring you want to run in the front to a single leaf, and then fully cycle the suspension through both vertical travel and flex and check for length, taking into account desired ride height and bump stop location.

It's likely you won't cycle the rear more than a standard aftermarket leaf sierra shock can accomodate, and trying to is a bit futile - maybe you'll pick up 20mm of travel or so but messing with all your mounts etc to do that is a lot of work for 20mm. the rear of sierras doesn't like to flex anyway due to high roll stiffness and that's not really a problem because it keeps the car stable when climbing and forces the front to work which keeps the car low and settled on the obstacle.

If you want to run bump stop spacing in the rear for tyre clearance, there is a case to move the shackle hanger forwards and run a slightly longer shackle - this will gain significant droop and may require a longer shock.

Likewise with the front, desired tyre size, guard work and steering rod clearance will potentially influence bump stop spacing, which will determine shackle hanger location, chassis extension length, top shock mount location and what length of shock is best for the application. You'll be building new front upper mounts anyway as OME N76 and 5125 are eye top rather than pin. Over the years we progressively have run less and less extension with less bump stop spacer to run the cars lower. We've moved towards less bumpstop spacing and less lift with more guard cut in order to run flatter springs with a lower rate Consider too that the compressed side bump stop acts as a fulcrum in a leaf sprung car - the more the drooped wheel can droop, the higher the compressed wheel gets in the guard. Likewise, building a car at full compression with (customary) 1" of shock shaft left at full compression will typically see the shocks bottom out at full flex.

Here's an extreme case:

I have 2" between my bumstop and axle at ride height and 12" travel shocks. to leave 1" of unused shaft travel at full flex (in order to prevent shock damage) I have 6" of shaft showing at ride height.



There's a number of reasons for that - my bottom shock mounts are extremely outbaorded ( on top of the steering knuckles) for packaging and stability reasons, I have lots of flexibility and my bump stops are inboard and not spaced down at all. Whilst it's easy to look at my car and think it's not relevant because of coils/links etc, go back to the silver/grey car I posted photos of - it was using all of an 11" travel N76 because of the outboard lower mounts.

So, as I've said, I can't be prescriptive - there are lots of choices you have to make about how much work you want to do and how you want the car to sit.

Yes, the same valving will work front and rear because you'll have fairly close spring rates front to rear and a sierra packed with normal recovery gear and tools, esky etc is pretty balanced front to rear weight wise.

[seanzook06]

I am wanting to run as low a ride height as possible with 33 inch tyres, but I still want the most travel possible within reason, in the front at the moment I already have 2 inches between the axle and bumpstop, my leaf springs are already flat. In the rear I Will be removing leaves from the 2 inch ome springs, until springs are roughly flat, I will be doing a fair bit of guard trimming to fit 33s, is that enough info to figure out bumpstop spacing?

[Gwagensteve]

Sorry I missed the question in this last post.

No, you actually have to measure and flex to work out how you juggle the parameters. you can run any tyre size a Sierra axle can support at no lift you're willing to trim enough, but that's a lot of work and you may have other constraints based on where you position the axle etc.

For instance, not everyone is willing to move the accelerator to accomodate a massive firewall cut, or pinch the nose of the car for headlight clearance. I can't decide for you how much work you're willing to do or what skills you have, like welding sierra body panel. If you ran tall 33's with no bumpstop spacing or body lift and full wheel travel, I'd expect the guard cut to be a similar size to mine above.

I can say if you're going to run heavily derated rear spring in the front, I'd strongly recommend packaging a panhard rod to get steering lock back. This alone might dictate some bumpstop spacing.