Spring-over on trailer

Submitted: Wednesday, Jan 04, 2006 at 20:22
ThreadID: 29341 Views:3393 Replies:10 FollowUps:8
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I have been working on my 7x4 Off Road Box trailer, fitting it out for this years adventures.

I fitted 265/75/16 tyres to match those on the GQ. All the extras have been built in and the trailer carries all the camping soft stuff and 12 jerry cans for long distance excursions.

Without the fuel and water load there was only about 60mm clearance between the tyre and mudguard.

So I put the axle underneath the springs and have gained 140mm taking my liquid unladen clearance to 200mm. This should give me enough clearance when fully laden.

Does anyone know of any pitfalls or something that I have not thought of? LOL
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Reply By: Member - Roachie (SA) - Wednesday, Jan 04, 2006 at 20:27

Wednesday, Jan 04, 2006 at 20:27
My 8x5 tandem has a spring-over with no troubles (but it's not used off-road). Also, mate of mine recently did a spring-over on his large tandem caravan and all is well there too.
I would think that as long as you've done it properly with good bolts etc, there should be no issues to worry about except the slightly raised centre of gravity.
Cheers mate
Roachie
AnswerID: 146448

Follow Up By: Willem - Wednesday, Jan 04, 2006 at 20:40

Wednesday, Jan 04, 2006 at 20:40
G'day Bill

Thought you were down by the river....or are you?...lol

The trailer is new and I used the original bolts, turning them upside down.

Cheers mate
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FollowupID: 399952

Follow Up By: Member - Roachie (SA) - Wednesday, Jan 04, 2006 at 21:01

Wednesday, Jan 04, 2006 at 21:01
Back home now mate.....only went down on Friday night (stinking hot and temp gauge was running around 110oC for extended periods)....then back on Monday arvo.
Cheers
Roachie
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Follow Up By: Willem - Wednesday, Jan 04, 2006 at 21:10

Wednesday, Jan 04, 2006 at 21:10
As I said to Pesty a while ago......I learnt my lesson a long time ago about going camping at Xmas time.

Much nicer hiding in the cool of the house or the shade of a tree with a cool drink in hand LOL
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Reply By: Lone Wolf - Wednesday, Jan 04, 2006 at 20:40

Wednesday, Jan 04, 2006 at 20:40
I guess the one thing I WOULD be looking at is, is the rate of compression on the springs when FULLY loaded. If they are getting near flat, then extra leaves would be the go, as you would undoubtedly be aware of.

I am sure that there is a ruling for spring over in 4 x 4's, but I don't think it carries through for trailers, so legally, one would think you are okay.

If you are concerned, maybe look at lengthening the spring shackles instead, to five some lift, instead of the spring over, although I think what you have done is fine.

Wolfie
AnswerID: 146452

Follow Up By: Willem - Wednesday, Jan 04, 2006 at 20:49

Wednesday, Jan 04, 2006 at 20:49
Thanks Ian

7 leaf springs and helpers springs as well. Going to fill up all the containers this week to see how everything sits.

Will be fitting shockies as well

Cheers
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FollowupID: 399957

Follow Up By: Member - Roachie (SA) - Wednesday, Jan 04, 2006 at 21:03

Wednesday, Jan 04, 2006 at 21:03
Wolfie raised a good point....maybe a couple of rubber bump stops might be a good idea too.
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FollowupID: 399961

Reply By: Outnabout David (SA) - Wednesday, Jan 04, 2006 at 21:15

Wednesday, Jan 04, 2006 at 21:15
Willem,

Best bet is to ring industrial springs in Adelaide. Unladen or lightly loaded I don't think would matter but fully loaded there may be stesses in the wrong place on the spring with the spring over.
AnswerID: 146456

Follow Up By: Willem - Wednesday, Jan 04, 2006 at 21:44

Wednesday, Jan 04, 2006 at 21:44
Thanks for that, David
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Reply By: Member - Frank - Wednesday, Jan 04, 2006 at 22:04

Wednesday, Jan 04, 2006 at 22:04
good advice wilem industrial truck supplied my springs for the trailer I made (spring over)

if you are doing a lot of twisting your profile is higher and this my cause a main leaf to break (carry spare) I have broken 1 in 6 trips but very rough conditions

normal unders would have bottemed first but tops twist futher a problem but worth it especialy if you ever (god forbid) have to dig it out
AnswerID: 146463

Reply By: cokeaddict - Wednesday, Jan 04, 2006 at 22:07

Wednesday, Jan 04, 2006 at 22:07
Hi Willem,
You have any idea of how much weight it will carry fully loaded mate?

Most common problem i have seen with offroading trailers is the mounting brackets for the springs breaking off. When you call the spring experts, ask them if your set up puts extra strain on the welds around the spring mounts.

Better safe than sorry i say, and im sure you have done the battery welding trick in your travels, not something anyone wants to do if it can be avoided.

Ange
AnswerID: 146464

Reply By: Richard Kovac - Thursday, Jan 05, 2006 at 00:54

Thursday, Jan 05, 2006 at 00:54
Hi Willem

I'm no spring expert just a smart-ass

But the main difference with over and under slung (to me) is the twisting of the axle would be greater with under slung
e.g. draw a spring then the axle under and over, then draw the wheel.
Draw a straight line from the centre of the axle to the bottom of the wheel you will see greater toque will be applied to the spring by the under slung axle (I would say weakening the spring rate) not a problem if you down rate the load.

Don't worry Ive had the same thoughts

By the way thease are MY thought and I'm sticking with them

Regards

Richard

PS have read about this somewhere if I fined it will post it
AnswerID: 146489

Reply By: kesh - Thursday, Jan 05, 2006 at 08:33

Thursday, Jan 05, 2006 at 08:33
Willem.
When the U bolt plate is under the spring (axle over) the tension of the bolts will pull the clamp plate onto the convex shape of the spring and the axle will remain snug against the top concave side. As the spring flexes it will increase tension on the bolts.
When the U bolt plate is on top of the spring (axle under) the bolts cannot pull the plate into the concave shape of the spring and the bolts will be fore ever coming loose as the spring flattens during flexing. Also the axle is going to be held against the convex (rocking) side of the spring which doesnt help when the U bolts loosen.
Vehicles designed for spring over usually have mountings and resilient blocks to suit the dynamic requirements. Plenty of van lifts have come to grief this way.
kesh
AnswerID: 146508

Reply By: Original Banjo (SA) - Thursday, Jan 05, 2006 at 10:01

Thursday, Jan 05, 2006 at 10:01
What a bugger Willem - those comments above on the altered geometry etc for your idea seem to make a lot of sense ! Anyway, when I last dropped into Industrial Springs on Port Rd, to discuss a lift for the boat trailer, it didn't cost a lot. They said my old springs were cactus and sold me some new ones "that will be higher". Can't recall the cost - not much - but they weren't higher ! No worries they said - drop them in and we will adjust them, no charge. Bit difficult from the 'Borough' though. Their best guestimate may be out a bit - might pay to do the job while in Adelaide for a day or two ?
AnswerID: 146522

Reply By: GOB & denny vic member - Thursday, Jan 05, 2006 at 17:57

Thursday, Jan 05, 2006 at 17:57
goodday willem
jeez willem rotflmao when i read the lead in spring over trailer i thought whats willem on that we are not springing over the trailer??????????
then it got serious lololol

steve
AnswerID: 146622

Reply By: Willem - Thursday, Jan 05, 2006 at 21:04

Thursday, Jan 05, 2006 at 21:04
Thanks fellas for your comments and advice.

Today I 'fuelled' and 'watered' the trailer and fully laden it still has 160mm clearance from top of wheel to mudguard.

I have taken note of your twisting concerns. I am also looking at where I could weld extra strength into the trailer.

The bottom plate, which is now at the top, as pulled down flush with the spring.

My other concern is that the U boilts are fastened by Ni-lock nuts. Will they be good enough?

The trailer is brand new. Fully laden as it is now, the trailer is about 30kgs over weight i.e. 780kgs unbraked all up. It will only be fully laden in extreme bush distances and probably not for more that 500km at a time.

I will do some bush testing in the next couple of months over some rough terrain to see how it holds up.

Cheers

AnswerID: 146661

Follow Up By: Richard Kovac - Friday, Jan 06, 2006 at 01:12

Friday, Jan 06, 2006 at 01:12
Willem
i had problem with my CT on last years trip (new in 1983) shocky mount broke off chassis
I fitted the shocks in 1984 never had any problems b4 just damage to shocks

This time i blame over weight on one side

as said above I will be fitting bump stops

as for Ni-lock nuts

I fit standard nuts (ht) then the Ni-lock nuts as lock nuts, then fit garden hose over thread to protect the thread.

I was amazed at the movement of the springs on the last trip I must have never had as must weight in the CT before

I took more notice after the failure

Richard
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FollowupID: 400197

Follow Up By: Willem - Friday, Jan 06, 2006 at 20:39

Friday, Jan 06, 2006 at 20:39
Thanks for those comments Richard, I will fit nuts before the lock nuts.

As I said I will do some testing over the next few months.

I took the trailer over the weighbridge today and it came in at 780kg with a full load on board. Most of the time the trailer will only weigh around 550kg. With shocks and lower tyre pressures and me travellimng at snails pace it should work out OK LOL

Regards
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FollowupID: 400334

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