Coromal F400

Submitted: Saturday, Aug 17, 2013 at 16:19
ThreadID: 103892 Views:4186 Replies:4 FollowUps:4
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This morning we went to the local Coromal dealer on the off chance they had some pop-up campers in there.

They had this immaculate 2 year old F400 in there, which wifey and I liked the look of very much.

I realise the Coromals have independent suspension on them and the Jaycos are beam axle, but the Jayco comes with shockies, the Coromal does not.

I discussed this with the salesman as I considered it to be a black mark for something of this weight (just over 1T) that is meant to be off-road capable (i.e. unsealed roads).

He said to me that it is not an issue because the IRS is one of the best in the business and shockies arent needed because the IRS does the job just fine on the dirt. He showed me the large new off road Coromal caravans that have the same suspension set up and no shockies. It appears to be a type of semi-trailing arm IRS.

I am not convinced as in my opinion suspension and shock absorbers do different things. I.e. shock absorbers are exactly as the name implies, to absorb vibration and impact from travelling over bumpy road surfaces whereas the suspension itself is meant to "suspend" the vehicle from the road.

Am I on the right track here? I am not that bent out of shape about having shockies or not, but I feel that one is better than the other. Our little camper trailer, which is little more than an Oztrail 6 tent on a European made Erde box trailer, has independent suspension AND shockies.

We won't be going full on off road, because our tow car is an AWD Ford Territory, so we won't be dragging it where the car can't go.
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Reply By: Erad - Saturday, Aug 17, 2013 at 18:21

Saturday, Aug 17, 2013 at 18:21
I am surprised that the Coromal does not have shockies. Does it have coil springs? If so, it must use shock absorbers, because the van would bounce around uncontrollably. Jayco us leaf springs and you get inter-leaf friction which damps out (mostly) the bouncing as you drive along. Our 13 yr old Jayco van has no shockies, and it rides OK for most of the time. Sometimes we get a bouncing motion established, but most times it damps out the bumps fairly quickly.

With coil springs, there is no interleaf friction and if you hit a bump, it will just go boing boing boing boing because there is nothing to damp out the initial deflection caused when you hit the bump. The Coromal has independant suspension, but unless it uses leaf springs it must have shock absorbers, or else it would bounce all over the road and be unsafe.
AnswerID: 516587

Follow Up By: Road Warrior - Saturday, Aug 17, 2013 at 19:11

Saturday, Aug 17, 2013 at 19:11
Erad I was surprised as well. But yes it has leaf springs.
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FollowupID: 795950

Reply By: Ross M - Saturday, Aug 17, 2013 at 18:57

Saturday, Aug 17, 2013 at 18:57
Road Warrior

How many axles has it got? If it has "I"ndependent "R"ear "S"uspension, then that would only be on the rear axle by definition. So what has the front axle got?

The salesman said "is one of the best in the business". Hmm.
If that was so they would be frequently mentioned and referred to, as being just that.
I haven't heard any mention or the brilliance of it until now. It may be OK though, just doubting the claim. Sounds like Saleman Uncontrolled Speak to me. ie, no jaw shock absorber to dampen the oscillations.

If trailing arm type, lots of them around, would require shock absorbers for good control of the unsprung weight. The salesman may not know about that factor.
If it has a leaf spring attached that will sort of slow it down but having shocks is better, as mentioned.

I think your understanding of the difference of springs and shocks far outweighs the salesman's limited understanding or what he is prepared to admit to.

Have a real good look at the suspension to see if there is substantial bushes which are the pivot points for the arms. Some Coromals, I had an earlier one, was billy cart quality although an independent A arm was used and pivoted in the centre of the caravan.
It bent easily and wheels were out of alignment.
I don't think Coromal are renowned for their suspension design.

As a test, get the salesman to draw the suspension on a piece of paper, that will test his intimate knowledge of it's features and ability.

Cheers
Ross M




AnswerID: 516590

Follow Up By: Road Warrior - Saturday, Aug 17, 2013 at 19:19

Saturday, Aug 17, 2013 at 19:19
Yes Ross I think what I got was typical salesman speak i.e. if you don't quite know, make something up anyway and hope they don't know. The unit is a single axle but has leaf springs. Upon closer inspection it does not appear to be a trailing arm setup like a car, more a wishbone/a-arm design that pivots from near the centre of the van much like you described. I will have to have a much closer look next weekend (if it is still there that is).

On another note, I have managed to squeeze another 90mm of clearance out of my garage by reprogramming the door to make it open higher. Which may come in handy if I buy this Coromal because it has Jayco roof racks fitted to it and I don't know how much height it will add to the F400's 1840mm closed height but I'm tipping it will be close to 100mm...
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FollowupID: 795952

Follow Up By: Ross M - Saturday, Aug 17, 2013 at 21:15

Saturday, Aug 17, 2013 at 21:15
Road Warrior
Sound like the same as I had, maybe a bit more substantial.
I found it just cambered out when unladen and went negative when under load. Not a heavy load by any means. Wore the insides of the tyres and did that until I took corrective action to make the spring work as it was poorly designed to do.
Bodywork ok, SUS suspension.

I dropped the wheel into a pot hole and it unexpectedly bent the axle as I drove through. A bigger than average hole, but it was enough.

By what you have said, as long as the suspension can be made to ride at a correct wheel camber while loaded travelling then the action of the suspension does work ok and would do your task quite well.

I would check the alignment of the wheels ie toe in or out before purchase using a straight edge to a fixed point on the ground for and aft of each wheel so you can measure between and detect that all is well with the axles or they are out of alignment.

If pivot bushes are worn then it may show toe out where it shouldn't have any.
Smart thinkin' and doin' with the roller door action, that will help and may be a good solution for the height problem.

You can always deflate the tyres so they are squashy to get the "footprint" you need to get under the door. Any soft sand there?

Cheers
Ross M
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FollowupID: 795959

Follow Up By: Road Warrior - Sunday, Aug 18, 2013 at 19:24

Sunday, Aug 18, 2013 at 19:24
Yep, when we go back I will be checking the tyres out to see if there is any adverse effects of incorrect camber. But I doubt it given the age and usage of this particular unit plus nothing jumped out at me when I was looking at it.

Here is a good pic of the suspension.



As for the clearance yes I will deflate the tyres if I have to but I'm heartened by the fact that I have squeezed a bit more by raising the garage door a bit more (can go a little bit more too I think) which may just make the grade. No soft sand either side though, no.
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FollowupID: 796024

Reply By: Rockape - Sunday, Aug 18, 2013 at 06:36

Sunday, Aug 18, 2013 at 06:36
I think it has the same Coromal suspension as the road vans, maybe beefed up more.

I have a Coromal poptop that I have towed over 100,000 k and the suspension has been excellent. No adverse tyre wear and it just does the mumbo with no fuss at all.

It is a very simple suspension, but I don't believe it would be any good for proper off road.
I really think the F400 is a dirt road unit and not an off road one. Dirt roads and sometimes maintained tracks would be no problem at all.
AnswerID: 516607

Reply By: Member - PJR (NSW) - Sunday, Aug 18, 2013 at 09:52

Sunday, Aug 18, 2013 at 09:52
This reminds me of the "Hydrolastic" suspension that the orignal Minis had.

Could a shock absorber function be built into the trailing arm? Physically it is possible.

Phil
AnswerID: 516613

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