79 series suspension concerns

Submitted: Saturday, Jan 18, 2014 at 13:53
ThreadID: 105853 Views:2616 Replies:5 FollowUps:6
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Hi I have a 2013 79 series tray back with a Concept canopy (alloy) on a recent trip from Brisbane to Ballina towing a 4mt tinny and loaded with camping gear I found that when driving on the Concrete sections of the M1 my truck bucked and bounced so bad I could not drive over 75-80ks as it was very uncomfortable. This morning I drove to the GoldCoast again to see if it was better without the boat on the back and found it no better ,it only seems to do this on the concrete sections and not on the hot mix so I was wondering if any one else has had similar problems and what I could do to fix it, thanks
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Reply By: Member - Rosco from way back - Saturday, Jan 18, 2014 at 14:52

Saturday, Jan 18, 2014 at 14:52
G'day Craig

We have a similar setup and whilst I didn't notice a difference between concrete and AC, I can say that in my opinion the OE suspension is abysmal crap. We have a similar canopy (about 300kg) and at 500kg under GVM it was like a dog with worms.

You'll get no joy from Mr T. Even if they change the springs it'll be back to the same in no time. Any chance your shocks have prematurely failed? No weeping?
I wasn't at all happy about having to spend about $3K on a complete front/rear change of springs and shocks. I went with Sax incl a 2" lift and to say it has transformed the vehicle is an understatement. Happy so far after a fully loaded trip to the Kimberley towing about 2 tonne + a much better ride all round.
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Reply By: Member -Pinko (NSW) - Saturday, Jan 18, 2014 at 15:07

Saturday, Jan 18, 2014 at 15:07
Hi Craig 2H
I have a 2007 model with an alloy canopy, drawers, under tray water 60 litres, up 4 jerries fuel, 3 jerries water.
Travel outback roads mainly but transit the road you mention frequently.
I had the same problem that felt like the seat hitting me in the back.
Fitted air bags and that was ok for 18 months untill the leafs sagged more.
I fitted 150kg. dobinson coils on the front.Winch steel b/bar second battery.
Rear leafs replaced with SAX 3SDS leaf springs. No air bags.
Now rides as comfortable as a car loaded or unloaded.
We tow an ultimate camper.
Living is a journey,it depends on where you go !
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Follow Up By: Craig H2 - Saturday, Jan 18, 2014 at 19:35

Saturday, Jan 18, 2014 at 19:35
Thanks for your feed back, as it only has 6000ks on it I might have a talk to Toyota and see if they will do any thing but I doubt it as they haven't been very helpful previously any way I will keep you posted.
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Reply By: Member Andys Adventures - Saturday, Jan 18, 2014 at 20:34

Saturday, Jan 18, 2014 at 20:34
Hi Craig,
Concrete roads are built with a bump rate of at least 16 to 18 bumps a km also contraction joins are on an angle so one wheel at a time goes on to the next slab. your suspension might be a bit hard. Have you tried letting down the tyres a bit 30psi might help.

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Follow Up By: Dennis Ellery - Sunday, Jan 19, 2014 at 16:55

Sunday, Jan 19, 2014 at 16:55
Hi Andy,
I haven’t noticed those bumps.
Excuse my ignorance, but why are concrete roads built with bumps every 50 or 60 meters?
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Follow Up By: Member - Rosco from way back - Sunday, Jan 19, 2014 at 17:53

Sunday, Jan 19, 2014 at 17:53
Construction joints Dennis.

It's where they stop the pour and then start again.
Plus concrete shrinks so pouring in short lengths helps overcome this problem.
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Follow Up By: Dennis Ellery - Sunday, Jan 19, 2014 at 18:01

Sunday, Jan 19, 2014 at 18:01
I should have guessed that - my grey matter must be slowing down.
Don't know whether its old age or a miss spent youth.
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Follow Up By: Member Andys Adventures - Sunday, Jan 19, 2014 at 18:26

Sunday, Jan 19, 2014 at 18:26
Construction Joins are at the end of each pour, and a normal pour will be around 800M record is 1,235M their is a contraction joint every 4m cut on an angle so only one wheel hits it at a time. the bump rate is their to keep you awake. So Rosco short lengths are for driveways not freeways.
Slip form concrete roads have been used since 1983 first one is at Wyong NSW. But it was layed by a suburban paver and could only lay a max 7.4M wide, hence the big crack up the middle of the inside lane. They now use hwy pavers laying 11.4M wide in one go.
The bump rate changes when the road has more bends in it per Km but on average on a straight road it is 16 to 18 per Km you do not notice it but the rise and fall is around 10mm.

Did the concrete sawing(cutting the contraction joints) on the first one at Wyong and last one was at Tarcutta. And many more in between.

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Follow Up By: Member - Rosco from way back - Sunday, Jan 19, 2014 at 20:02

Sunday, Jan 19, 2014 at 20:02
Quite correct Andy. I kept in simple, rather than go into it in more detail.
The reason for the contraction joints every 4 or so metres is because of shrinkage as mentioned above. Shrinkage strain varies considerably due to a vast number of factors which I won't go into, however if we take an average we would adopt perhaps about 500E-6 mm/mm, hence an unrestrained slab 10 metres long would reduce in length by 5mm, resulting in a rather nasty gap. With joints every 4 metres we reduce this to in the order of 2mm which can be easily handled.
The above only skims the surface of concrete technology, but as I said, I wanted to keep it simple.
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Reply By: The Bantam - Saturday, Jan 18, 2014 at 23:29

Saturday, Jan 18, 2014 at 23:29
The first thing you should do.....as sort of mentioned above...is get a load V pressure table for the tyres you are running....then weigh the thing axle by axle and apply the appropriate tyre pressures.

Toyota utes carry more or less the whole payload on the rear axle, you need to vary the tyre pressure to suit the load carried.

when I picked up my 2wd hilux from the used car dealer, the tyres where pumped up to 50PSI all round.... unladen it rode like a dray.....inflating to recommended pressures...down arround 28PSI all round unladen made a big difference.....fully loaded arround 60psi is required in the rears, but the fronts remain the same.

As people have mentioned,
The toyota shockies are not real flash even when they are in good nick, and they don't last long.

Again because the utes carry the whole payload on the rear axle, unladen the springs are very stiff......this give the shockies a hard time.....the suspension deflects over bumps and there is a tendancy to rebound fast and hard.

replacing the shockies in both my 2wd and 4wd made a huge difference....especially unladen.

Toyotoa utes need good shockies and are very hard on shockies.

The other thing is weight.

All these toyota utes ride a hell of a lot better with some weight in them....both in the tray and in the cab.

One reason lots of cockies run fairly heavy steel trays is because they are heavier and make the utes ride better unladen.
100Kg in the back can make all the difference..I recon 200Kg is good.

I noticed that both my utes ride a hell of a lot better with a pasenger in the cab....the weight gives the cab rubber suspension something to work on.

I have moved a couple of heavy items into the cab....my drag chains and pully blocks and a couple of other things sit behind or under the seats...this extra 20 or 30 odd KG weight makes a difference especially when traveling alone.

I understand the toyota factory springs are not the cleveerest......no doubt a better set of aftermarket springs woul help......but try the other things first.

BTW.....whatever you tray post us back and let us know how it went.

AnswerID: 524730

Reply By: bigcol - Monday, Jan 27, 2014 at 23:00

Monday, Jan 27, 2014 at 23:00
I am constantly driving over the concrete section between Reedy Creek and the Old Burleigh Town exit.
I drive a Triton dual cab and tow a work trailer that weighs around 1.2T.
It bounces around. My BT50 did it as well. So did the D22 Navara before that.

It's speed related. The concrete section between the M1 and Bermuda street is worse.
If I do less than the speed limit it's all over the place. If I do right on the limit it goes away.
The bounce is related to the speed. When the car launches it's coming down in a hollow and then compressing the springs and then launching again.
Try a different speed and it will probably go away or be not as bad
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