Suspension woes

Submitted: Friday, Feb 24, 2006 at 12:48
ThreadID: 31111 Views:2179 Replies:8 FollowUps:8
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Morning all,
A question for all you suspension guru's (anyone actually),
The problem I have is that our Terracan has a double bounce that seems to be coming from the front end. The terracan has a torsion bar front end and live axle rear. We had the Trek and Tow fitted and it had the double bounce, we got the original refitted after some to and fro with Hyundai(& got our money back too), the double bounce was still there, but not as bad as when the TnT was fitted. Went to ARB for the OME kit and had it installed, but the double bounce is still there. The torsion bars have never been replaced as no-one makes aftermarket ones. Is it correct to assume that because the torsion bars are original and we have fitted better dampers all round that this will occur. (the OME kit is still in/on the truck)
Has anyone had this trouble on their 4wd(regardless of make)
Any help would be greatly appreciated.
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Reply By: Mav1 - Friday, Feb 24, 2006 at 13:44

Friday, Feb 24, 2006 at 13:44
You could also try here if you haven't already:
Which is a Terracan forum
AnswerID: 156868

Follow Up By: Member - greg S (QLD) - Friday, Feb 24, 2006 at 18:36

Friday, Feb 24, 2006 at 18:36
Already reg'd on that forum, and talking to the guy's there, it seems only us and maybe a couple of others?? that have the same problem, all the others are pretty happy with their Terracan.

FollowupID: 411065

Reply By: Member - Paul P (Bris) - Friday, Feb 24, 2006 at 13:52

Friday, Feb 24, 2006 at 13:52

Does this occurre with weight in/on the rear of the vehicle or the vehicle lightly loaded? In any case a suggestion would be to go back to the original springs in the rear (leave the shockies as is) and see if this fixes the problem. If it does I would suggest a set of PolyAirs for the rear to handle the towing etc.


AnswerID: 156872

Follow Up By: Member - greg S (QLD) - Friday, Feb 24, 2006 at 19:06

Friday, Feb 24, 2006 at 19:06
Paul P,
This occurs with or without a load on board. You can drive down the road/ highway that is nice and smooth, no probs, but when you hit a resurfaced bit of road( the lip that is always there where they join),or any holes or hollows, the front does a double bounce. At first you think okay I can get used to this, but after 3-400km's it becomes a bit much. This has happened since new. On really uneven surfaces you don't notice it as much, but then it bump steers. Which it has done since new.
With the change out of the rear springs, thanks for the idea, I will get in and do that.
Other than the susp the vehicle is great, plenty of grunt for what we need, for now anyway. When we pick up our new/second hand camper it might need a boost, especially for Fraser Is.
Do you have PolyAirs in the back of yours and if so what pressure do you run them at when towing.


FollowupID: 411074

Follow Up By: Member - Paul P (Bris) - Friday, Feb 24, 2006 at 19:21

Friday, Feb 24, 2006 at 19:21

Also check your ride heights are within speck at the front. Torsion bars can sag or be faulty/incorrectly set from factory.

PolyAirs. Pump to MAX prior to loading (use a hand pump or 12 volt pump only). Once loaded let down until vehicle is level (trailer attached as well). I run 12-14 psi in the Nissan fully loaded and with the trailer attached. You need to keep air in them when empty also ( I keep about 5psi).

I run standard springs and OME shocks


FollowupID: 411080

Follow Up By: Member - greg S (QLD) - Friday, Feb 24, 2006 at 19:33

Friday, Feb 24, 2006 at 19:33
Hi Paul,
Hyundai gave me the specs for the front, so I went out and adjusted them to this spec, and it still did the double bounce thing.
When we picked up our truck for the first time the boys had it on the four post hoist and it had a lean of around 15mm to the right(looking from behind). They adjusted about two thirds of this out, but couldn't get it all.
Do PolyAir have an incab kit to pump up their airbags and what did you pay for your setup.



FollowupID: 411083

Follow Up By: Member - Paul P (Bris) - Friday, Feb 24, 2006 at 19:50

Friday, Feb 24, 2006 at 19:50

No in car adjustment for the PolyAirs. Once mine are set they have been fine. (I had a set for 9 years on a 4 runner with no problems prior to the Nissan) On a recent 20,000k towing holiday no adjustment was required. (Obviously correct fitting is the key). From memory mine cost around the $4-500.00 dollar mark supplied and fitted.

See this site as well Airbag Man.

Mine were supplied and fitted by my favourite ARB shop at Cleveland


FollowupID: 411086

Follow Up By: Member - greg S (QLD) - Friday, Feb 24, 2006 at 20:05

Friday, Feb 24, 2006 at 20:05
Thanks paul

FollowupID: 411089

Reply By: Hero - Friday, Feb 24, 2006 at 16:39

Friday, Feb 24, 2006 at 16:39
Ironman are about to release their uprate torsion bars in a few weeks.
AnswerID: 156885

Follow Up By: Member - greg S (QLD) - Friday, Feb 24, 2006 at 19:07

Friday, Feb 24, 2006 at 19:07
Thanks Hero,
I'll give them a buzz.

FollowupID: 411075

Reply By: Member - Collyn R (WA) - Friday, Feb 24, 2006 at 20:01

Friday, Feb 24, 2006 at 20:01
Suspension was my main interest when I was with GM reaeewsto

Would define what you mean by 'double bounce'. Is it accompanied by any steering wheel feedback or ongoing shake?
Collyn Rivers

AnswerID: 156917

Reply By: Member - greg S (QLD) - Friday, Feb 24, 2006 at 20:24

Friday, Feb 24, 2006 at 20:24
By double bounce I mean that when we go over bumps/ speed bumps etc the front end seems to want to continue to go up and down. It's like the damper is not doing it's job. When we had the Trek and Tow kit in, we used to pick up our daughter from school and had to go over speed bumps, when we did this it felt like the front end was going to cave in under you. The wheels would drop back down to the road with a big thud, even going slow. The edelbrock dampers fitted with the TnT kit have a oil bypass system in them to allow the damper to return to the road quicker, which is fine, but they kept going up and down.
Now we have the OME kit in it is still there, though not as bad, but still, you feel it through the seats.When going over speed bumps now it is a lot better and you don't get that feeling that the front end is going to collapse.

AnswerID: 156921

Reply By: arthurking83 - Saturday, Feb 25, 2006 at 17:17

Saturday, Feb 25, 2006 at 17:17
Hi Greg,

I don't have a Terracan, and my only experience with "double bounce" was with a few cars, that
a) had faulty shockers...(in your case they have been replaced, but you would notice the "dead shocker"
b) a cracked spring on the rear of my Rangie.

My regular everyday vehicle is now a Rodeo, and it 'almost' exhibited pogo-ing effect, and lots of steering pull(even after an alignment!)

On it's only ever service at a Holden dealer, I asked if they could align and re-set the torsion bars (I know know how easy it is to do!!), and it raised the car by 50mm (:o and it felt much more steady.

either you got dud OME shockers (unlikely) or you need the tortion bars re-checked/replaced.
If you are up for an easy job, all you need, is some patience, a large socket(easier than a ring spanner), and a good small ruler something about 4-6 inch.
Wind up the tortion bars, the large nut will be obvious, and make sure the bump stop clearance on both fronts is the same (after a test drive or severe bounce test.....a couple of your heaviest freinds boncing the front end up and down!!! :))
Note: you can easily wind it up too much , so take care.
AnswerID: 157022

Follow Up By: Member - greg S (QLD) - Saturday, Feb 25, 2006 at 20:38

Saturday, Feb 25, 2006 at 20:38
Hi arthurking83,
Thank you for the info.
First of all I will get it back to ARB to see if the correct dampers were put in, if all ok then I will change the rear springs back to original and see if that makes a difference, and if it doesn't then I will have a chat to my Hyundai dealer to see when they can have a look at it.
I've adjusted the torsion bars so that the gap is correct and it made no difference at all, so I'm not to sure what is going on.

FollowupID: 411229

Reply By: fourstall2000 - Tuesday, Feb 28, 2006 at 08:47

Tuesday, Feb 28, 2006 at 08:47
Regardless of spring or torsion bar weights or tension the shocks have to control the rig,obviously yours are not.
I would certainly go back to ARB as something is drastically wrong with the shock valving to suit your vehicle.
AnswerID: 157466

Reply By: Member - MrBitchi (QLD) - Tuesday, Feb 28, 2006 at 09:00

Tuesday, Feb 28, 2006 at 09:00
I'd go for the shockies. Had simiar symptoms in a Commodore I had once, stupidly fitted Pedders struts, three sets of struts later finally chucked them out and fitted Munroes, I think. Problem solvered... :-)
AnswerID: 157468

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