Suspension sag from bullbar

Suspension sag from bullbar

Postby jerrah on Tue Jul 12, 2016 6:00 pm

Just thought I'd mention how much the stock suspension sagged on my MQ with the TJM outback bar.

40mm. More than I expected!
I guess I better get cracking on that lift kit!

How much sag did you get with your bar work?
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Re: Suspension sag from bullbar

Postby seanyboyrulz on Wed Jul 13, 2016 11:25 am

I didn't wait to find out :lol: Ultimate Suspension pretty much straight after.
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Re: Suspension sag from bullbar

Postby Fatback on Wed Jul 13, 2016 11:27 am

Crikey! :shock:

I'm getting an outback T-13 fitted to my MQ tomorrow, so I'll check if it's a similar drop and report back.
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Re: Suspension sag from bullbar

Postby docta.phipps on Wed Jul 13, 2016 3:31 pm

Does anyone know if you can just up the spring rate to take the extra weight in the front? For those who aren't interested in a lift?

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Re: Suspension sag from bullbar

Postby snakesoup on Wed Jul 13, 2016 4:03 pm

yes you can mate
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Re: Suspension sag from bullbar

Postby Merts on Thu Jul 14, 2016 10:07 am

I also can't say how much the barwork sagged the factory suspension, as the Dobinson gear went in at the same time as most of the barwork.

Mine is sitting about 35 higher at the front and about 20 higher in the rear compared to how it rolled out of the dealership with no load and factory suspension.

That's with barwork all around, fridge, battery, compressor and one of the drawers pretty much full of gear including recovery shackles, tow hitch etc.
GLS MQ Triton, ARB Summit front, rear and side bars, Carryboy canopy and rack, Dobinson heavy duty suspension, Harrop rear E-locker, Drifta drawers and a few other bits and pieces.
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Re: Suspension sag from bullbar

Postby Merts on Thu Jul 14, 2016 10:24 am

BTW, after the front bar, rear bar, canopy and suspension was done, and prior to the drawers, battery, compressor and fridge going in, the rear was sitting about 45mm higher than factory. The ride was still pretty firm and bouncy, and I got a bit of driveline shudder on take-off. Now that it's all complete there is virtually no shudder even in 2H, and the ride is pretty good.

I reckon aiming for 40 or 50mm lift in the rear of any vehicle with a two piece tailshaft is asking for problems. As long as the suspension upgrade means you aren't losing clearance when all your gear is fitted you are getting a good result.
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Re: Suspension sag from bullbar

Postby jerrah on Thu Jul 14, 2016 9:18 pm

Merts wrote:the rear was sitting about 45mm higher than factory.
I guess you've got a good point there. With my front bar and nothing on the back I'm going to have the rear in the air even with the suspension upgraded. Got to wonder how most of these "2" kits" fare with a bullbar.

I'm probably 50% empty and 50% fully loaded with little in between. It's a bit difficult to spec suspension for that range!
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Re: Suspension sag from bullbar

Postby ultimate on Fri Jul 15, 2016 9:43 am

If the aftermarket suspension is setup correctly to match the weight of the vehicle, you will not have an issue. The front coils will support the weight of the bar and hold the desired height. All measurements are based on factory heights so a "30mm" lift may actually raise the vehicle 70mm over your current height. A standard height heavy duty coil will raise the vehicle back to the original height (+/-5mm)

The rear leaf springs are a progressive, two stage design so they handle the fluctuating loads very well. It's a legal and practical requirement to maintain the factory rake (approximately 40mm when unladen). As the rear of the vehicle is loaded, the suspension has room to compress and carry the load without dropping lower than the front.

With a full load, the rear should be slightly higher than, or level with the front. If the rear is lower; you will notice a reduction in braking efficiency and vague steering.
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Re: Suspension sag from bullbar

Postby Thanatos on Fri Jul 15, 2016 5:33 pm

fyi I saw a 15mm drop in the front of mine when the ARB Summit bar went on.
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Re: Suspension sag from bullbar

Postby jerrah on Fri Jul 15, 2016 9:15 pm

Thanatos wrote:fyi I saw a 15mm drop in the front of mine when the ARB Summit bar went on.

I'd guess either your bar is significantly lighter or it will settle a bit lower after some driving... I did my 2nd measurement after about 1000km of when the bar went on.

BTW, I did forget I also fitted my bushskinz bash plates at the same time, although I doubt the difference in weight between the factory plates and aftermarket could be a patch on the weight of the bullbar!
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Re: Suspension sag from bullbar

Postby jerrah on Fri Jul 15, 2016 9:18 pm

ultimate wrote:It's a legal and practical requirement to maintain the factory rake
Thanks for your input in the thread Brendan. Although I do worry about the rumors of shuddering with the rear too high in the air. Might have to go for a lower lift? 30-40mm over stock?
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Re: Suspension sag from bullbar

Postby Thanatos on Fri Jul 15, 2016 10:45 pm

jerrah wrote:
Thanatos wrote:fyi I saw a 15mm drop in the front of mine when the ARB Summit bar went on.

I'd guess either your bar is significantly lighter or it will settle a bit lower after some driving... I did my 2nd measurement after about 1000km of when the bar went on.

BTW, I did forget I also fitted my bushskinz bash plates at the same time, although I doubt the difference in weight between the factory plates and aftermarket could be a patch on the weight of the bullbar!


It weighs about 90-100kg I think, but I did measure that straight away after it went on. Theres too much other stuff fitted on it now for me to get a reliable second meausrement.

A mate of mine recently swapped the genuine bash plates on his MN for a new set that were 4mm thick and he said it dropped nearly 20mm due to that alone.
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Re: Suspension sag from bullbar

Postby Duck on Sat Jul 16, 2016 7:48 am

If you replace the springs replace the shocks as well they work together not independently. Spring holds the weight and shock controls the spring. you
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Re: Suspension sag from bullbar

Postby jerrah on Sat Jul 16, 2016 9:14 am

Duck wrote:If you replace the springs replace the shocks as well
Yeah that's the plan. I understand suspension pretty well from racing cars, but I'm not used to adding a heap of weight to the vehicle then compensating with suspension.

Tempted to swap out the suspension myself but I'll need a wheel alignment regardless.
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Re: Suspension sag from bullbar

Postby ultimate on Sat Jul 16, 2016 9:22 am

jerrah wrote:
ultimate wrote:It's a legal and practical requirement to maintain the factory rake
Thanks for your input in the thread Brendan. Although I do worry about the rumors of shuddering with the rear too high in the air. Might have to go for a lower lift? 30-40mm over stock?


No problem.

The shuddering on the MQ is no different to the ML/MN models with easy select. Fitting a tailshaft spacer or lowering the centre bearing will significantly reduce the vibration to a point where it's hardly noticeable on most vehicles. Limiting the suspension height doesn't always mean you will avoid the shudder. A lot of vehicle with 15-20mm lifts still develop it and need to do the same modifications to reduce it.

jerrah wrote:BTW, I did forget I also fitted my bushskinz bash plates at the same time, although I doubt the difference in weight between the factory plates and aftermarket could be a patch on the weight of the bullbar!


The bushskinz plates actually make a big difference to the front end. They generally add 25-40kg to the front axle weight depending on which plates are fitted. A bullbar + bash plate combo is virtually the same as a bullbar + winch combo.
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Re: Suspension sag from bullbar

Postby L200Shogun on Sat Jul 16, 2016 10:39 am

A thread/post on here with pictures. TJM make a new mount for the center bearing which lowers it.
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Re: Suspension sag from bullbar

Postby Maxiy on Mon Jul 18, 2016 7:26 am

just for those interested.

Mounted up an ARB deluxe steel winch bar yesterday on stock suspension, have so far recorded a sag of 10mm, will see if that changes once i have driven it around for a while
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Re: Suspension sag from bullbar

Postby Fatback on Mon Jul 18, 2016 9:13 am

The TJM bar that was due to be fitted to mine last week was dropped/damaged in transit and the install was pushed back, so I won't be able to check any measurements until the new one comes in.
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Re: Suspension sag from bullbar

Postby Merts on Mon Jul 18, 2016 1:11 pm

ultimate wrote:The shuddering on the MQ is no different to the ML/MN models with easy select. Fitting a tailshaft spacer or lowering the centre bearing will significantly reduce the vibration to a point where it's hardly noticeable on most vehicles. Limiting the suspension height doesn't always mean you will avoid the shudder. A lot of vehicle with 15-20mm lifts still develop it and need to do the same modifications to reduce it.


My MQ has a tailshaft spacer. Even with that, the shudder when the rear was sitting 45mm higher than factory was quite noticeable, especially when in 2H. Now that it's sitting only about 20mm higher than factory the shudder is all but gone.
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Re: Suspension sag from bullbar

Postby Lost1 on Sun Oct 20, 2019 7:29 am

I have a bar, winch and bash plates on the front of mine with HD front springs. The front sits at 585/590 on the front. My rear fit out is similar to Merts. The rear is about level or has some rake loaded (depends on trip duration) and run Dobinson +300 rear springs. Most trips are solo or two up only. If I was taking kids and everything that goes with that I would probably consider airbags to maintain a level ride as +500 springs would be pretty rough unloaded.
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