Technical Cut bumper stops a little - can it make a difference?

[Jonathanhusbil]

Hi,

I have a Fiat Ducato MultiJet 2008 rebuilt into campervan. It weights about 2850kg. Originally is about 2200kg.

I was dissatisfied with the suspension. I have replaced all parts (both shocks front and back, enforced coil springs in front <2000kg, and helper coil springs from MAD suspension system in the rear 350-750kg).

I am happy with everything, it takes potholes very good and stability is great. However, i noticed some bouncing from the back on lower speeds... It's not completely smoth.

I figured this is due to the rear helper coil springs being possibly too stiff. Usually campervans that weight closer to 3,5ton mount these. One indication of this being the case is that the ride got more comfortable lowering from 4,5 bar to 4,1 on the rear tires.

On my van it looked like this, more or less, after fitting them (see the first picture on the link). The bumper stop almost touches the place, maybe 2cm away from it:

Monterat & Klart hjälpfjädring bak - LastaTungt.se - Fjädringssatser till transportbilar

Snabb och proffsig installation utav dina köpta hjälpfjädrar bak från MAD Suspension Systems. Monteringen utförs i Enköping. Vi lämnar bra garantier.

lastatungt.se

I figured that it might make the rear suspension less stiff if i cut the bump stops a little bit (the top/thinnest part) So i cut them this much, see attached pictures.

After this, i went on a test trip. The suspension seems worse now, but i'm not sure... On low speeds, on high speeds it's still very good. Is that possible by cutting this much? As you can see i can bend what i cut with the finger... Or is it impossible and just placebo?

If it's possible, i'd like to attach the parts i cut to the bump stops again...Is this possible, perhaps with super glue? I regret i touched anything, unfortunately, as it was useless.

 

[bugsymike]

Hi,

I have a Fiat Ducato MultiJet 2008 rebuilt into campervan. It weights about 2850kg. Originally is about 2200kg.

I was dissatisfied with the suspension. I have replaced all parts (both shocks front and back, enforced coil springs in front <2000kg, and helper coil springs from MAD suspension system in the rear 350-750kg).

I am happy with everything, it takes potholes very good and stability is great. However, i noticed some bouncing from the back on lower speeds... It's not completely smoth.

I figured this is due to the rear helper coil springs being possibly too stiff. Usually campervans that weight closer to 3,5ton mount these. One indication of this being the case is that the ride got more comfortable lowering from 4,5 bar to 4,1 on the rear tires.

On my van it looked like this, more or less, after fitting them (see the first picture on the link). The bumper stop almost touches the place, maybe 2cm away from it:

Monterat & Klart hjälpfjädring bak - LastaTungt.se - Fjädringssatser till transportbilar

Snabb och proffsig installation utav dina köpta hjälpfjädrar bak från MAD Suspension Systems. Monteringen utförs i Enköping. Vi lämnar bra garantier.

lastatungt.se

I figured that it might make the rear suspension less stiff if i cut the bump stops a little bit (the top/thinnest part) So i cut them this much, see attached pictures.

After this, i went on a test trip. The suspension seems worse now, but i'm not sure... On low speeds, on high speeds it's still very good. Is that possible by cutting this much? As you can see i can bend what i cut with the finger... Or is it impossible and just placebo?

If it's possible, i'd like to attach the parts i cut to the bump stops again...Is this possible, perhaps with super glue? I regret i touched anything, unfortunately, as it was useless.

The yellow looks like progressive bump stops that touch early but gradually take more of the weight as loading increases, so it would have been OK with them fairly close to the stops.
Is it possible the rear shocks are not very effective?
Is there more problem on bends than over bumps in a straight line as rear anti roll bars are more important with camper vans due to more of the extra weight carried is higher up causing vehicle to roll more on bends.

 

[Jonathanhusbil]

The yellow looks like progressive bump stops that touch early but gradually take more of the weight as loading increases, so it would have been OK with them fairly close to the stops.
Is it possible the rear shocks are not very effective?
Is there more problem on bends than over bumps in a straight line as rear anti roll bars are more important with camper vans due to more of the extra weight carried is higher up causing vehicle to roll more on bends.

Thanks for the reply. So if they are progressive bump stops that touch early but gradually take more weight as loading increases - does it matter if i cut this part? I mean, i can obviosly squeeze it with my fingers somewhat - can that really have made a difference and that's why i'm experiencing worse ride quality after cutting it? Or must it only be placebo?

No problems att all in bends... it doesn't body roll/bend much at all.. Straight line asfalt with some minor bumps in low speed is when i notice it being bouncy. In higher speeds, potholes and gravel roads the suspension is perfect.

I'll attach a picture of how it looks now, after i cut part of the bumper stop, on my vehicle. Is it possible to glue back the missing piece with super glue, would it last? Or useless?

When it comes to the rear shocks... I replaced them about 100.000km ago (that's the only 'older' thing on the suspension, but they work as good as they ever have, no leakage or anything) They are AL-KO 204683.

 

[bugsymike]

Thanks for the reply. So if they are progressive bump stops that touch early but gradually take more weight as loading increases - does it matter if i cut this part? I mean, i can obviosly squeeze it with my fingers somewhat - can that really have made a difference and that's why i'm experiencing worse ride quality after cutting it? Or must it only be placebo?

No problems att all in bends... it doesn't body roll/bend much at all.. Straight line asfalt with some minor bumps in low speed is when i notice it being bouncy. In higher speeds, potholes and gravel roads the suspension is perfect.

I'll attach a picture of how it looks now, after i cut part of the bumper stop, on my vehicle. Is it possible to glue back the missing piece with super glue, would it last? Or useless?

When it comes to the rear shocks... I replaced them about 100.000km ago (that's the only 'older' thing on the suspension, but they work as good as they ever have, no leakage or anything) They are AL-KO 204683.

Yes as you say re progressive, the other type are hard and only take the weight when fully laden , so no give/flexibility.
If happy through the bends, not swaying from side to side then rear anti roll bars OK.
Firmer rear shocks will help I feel.
You could try gluing the cut off bits back, if it doesn't work then replace with new same type.
The springs take the weight, the shock absorbers stop the bounce.
Just for a laugh disconnect the shock absorbers and give the van a rock, you will see what I mean.
Are your tyres the correct load rating, softer side walls and a heavier van are not a good idea.
Worn shock absorbers often do not visible leak oil.
Camper vans with heavy weight higher up in vehicle put more strain on shock absorbers than a work van with heavy weight sat on the floor.

 

[Jonathanhusbil]

Yes as you say re progressive, the other type are hard and only take the weight when fully laden , so no give/flexibility.
If happy through the bends, not swaying from side to side then rear anti roll bars OK.
Firmer rear shocks will help I feel.
You could try gluing the cut off bits back, if it doesn't work then replace with new same type.
The springs take the weight, the shock absorbers stop the bounce.
Just for a laugh disconnect the shock absorbers and give the van a rock, you will see what I mean.
Are your tyres the correct load rating, softer side walls and a heavier van are not a good idea.
Worn shock absorbers often do not visible leak oil.
Camper vans with heavy weight higher up in vehicle put more strain on shock absorbers than a work van with heavy weight sat on the floor.

Thanks for the reply.

But is it necessary to replace the bump stops? I mean, since they seem to be progressive and the bit i cut off is quite soft (possible to bend with hand) can it really make a difference if its there or not? or is there some function of the bump stops that i'm missing? That the piece i cut off could carry more weight than what it seems.

 

[Jockstrap]

Sorry but you've mucked up .

There is a big difference between bump stops and progressive spring assists.

Have a look at SumoSprings. The yellow is probably too light for your load. The spring assists, as against a bump stop should sit partially compressed.

I replaced on my Ducato 2 years ago. Raised the rear 2cm from Fiat standards. You tube has a good video.

 

[Jonathanhusbil]

Sorry but you've mucked up .

There is a big difference between bump stops and progressive spring assists.

Have a look at SumoSprings. The yellow is probably too light for your load. The spring assists, as against a bump stop should sit partially compressed.

I replaced on my Ducato 2 years ago. Raised the rear 2cm from Fiat standards. You tube has a good video.

I installed helper coil springs instead of sumosprings, it's the same thing they take the load from the spring leafs.

By the way, i have difficult to believe that the shocks are bad when i think about it, i replaced them less than 100.000km ago (it was the first thing i replaced when noticing problems with the suspension). I know how bad shock absorbers act like, they usually hit through or bounce right after a pothole several times... In my case, they never hit through and never bounche when driving fast on a severe bump... The only thing is that the van seems very sensitive at low speeds, then it bounces a some.

 

[bugsymike]

Thanks for the reply.

But is it necessary to replace the bump stops? I mean, since they seem to be progressive and the bit i cut off is quite soft (possible to bend with hand) can it really make a difference if its there or not? or is there some function of the bump stops that i'm missing? That the piece i cut off could carry more weight than what it seems.

They are designed like that for a reason, to gradually take up more load.

 

[Jockstrap]

I think you should take a moment to reconsider.

Hitting potholes is not a good idea. A loaded or empty van behaves differently especially if you drive fast over bumps and you alter tyre pressures.

Good luck .