Fiat rear bump-stop advice wanted for a light van...

[Bertilak]

First, I know zillions of members swear by air-bag assisters, and that you can diy them for £300, and they might, or might not, be perfect: however that is not what I need to know... (not this year anyway)

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Our van is a 3.5T MWB PVC. I haven't weighted it, but comparing with how we used to run the T5, I'd be surprised if we ever run at over 2.8T.

The rear suspension is teeth rattlingly crashing, (I don't need stiffer suspension from air etc!), but I've noticed the Spring Assisters aka Bump Stops have deteriorated on the bottom convolution. (c100K miles) . I'm thinking some of the crash is when the spring suddenly hits the (effectively) shortened assister rubber.
Briefly looking round the 'bay it appears I can change them for £30-40, which sounds like a no-brainer.
Question 1: Is this logic reasonable?
Question 2: Are these worth having? I'm sure I can buy them for a lot more from Fiat too... But does the difference reflect OE greed or a superior part?

There are also 3 styles, with different lengths quoted. (135, 150 & 165, where the 165 looks like a 150 with a spacer). None of the factors selling them offer any sense to which fit which model; logical as weight varies across each wheelbase.
Question 3: Have any funsters any experience of which would suit best?

Any other advice? ideally experience based! (e.g. springs from a SWB 3.0T, Dual leaf springs, light springs and airbags, new dampers etc)

Thanks, Harry

 

[1967bowesj]

Rear semi air won’t make your suspension harder unless you over inflate it!
A well balanced rear suspension can be had by adjusting the pressure so it absorbs the sudden impact of the springs rising when going over a bump or a hole.
I would fit them rather than just new bump stops.

 

[Phill D]

At 100k miles have you considered that your shocks may be shot.
Or at least weakened.

 

[BouncyBoatFolk]

At 100k miles have you considered that your shocks may be shot.

And, or springs.
You could take the decreasing tyre pressure route, [ lots of reading before you do so] or self fit the air bags, which give the van a better and safer ride .
Mike.

 

[donkey]

I always ask the same question when I see posts about rock solid suspension.
What tyres and tyre pressures are you running?

Geoff

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[Bertilak]

Yes, clearly thought of both springs and shocks, and being dare I say, Italian.
Shocks haven't leaked... but the oil could have degraded.
Do Sevel springs they actually deform in use? ( I'm relatively new to these vans, I don't know...)
I doubt the spring rate changes , though the active height may. In which case I'm on the hard bit of the stop sooner... ouch! Anyone have any specs for free camber on new springs?
I know that in the olden-days valve springs used to give, and then stay there indefinitely, out of original spec. These days they achieve that in the factory, so they never fade in use. I don't know about suspension or leaf springs though.

 

[2GB Racing]

If it passed its MOT ok I would still consider changing the dampers and bump stops but only for the correct ones for the chassis, not that expensive try Europarts for starters

 

[Phill D]

If the springs and shocks are fine then fitting longer bump stops is likely to increase the rate a the banging.
As has been mentioned by others, tyre pressures!

 

[Badknee]

At 100k your springs could have sag, shocks be tired without leaking.
Get underneath and measure the gap where the bump stop goes, check tyre pressures, or fit air.

 

[ManTheVan]

Also, how old are the tyres. If they‘re all stiff and hard they’ll be less yielding. As Otter Spotter ssys above, what sort of pressure are you running the rears at? We keep ours at approx 4.5bar when loaded. The semi air made a massive difference, as did changing from rock hard old tyres to a decent set of Michelin Cross-Climates, which have been working superbly together to give us a lovely stable, smooth and quiet ride.

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[Bertilak]

Tyres are still commercial ones it came with 215/70-15 109/107 which I've been pumping up to the bottom of the recommended band c60psi. One looses a bit (!) and is much nicer c 40psi... ie less crashy, but with suspect roadholding.
It's never been out of use so they wont be ancient, or had a chance to harden. 100K in nearly 7 years...

 

[IRHP]

If you don't want to go with semi air consider sumo springs

 

[Guigsy]

My previous 5.4m PVC was on the light chassis. It was low at the back and riding on the assistors all the time. They were pretty much destroyed. Larger road imperfections had me checking to see if anything had fallen off.

I DIY'd semi air. Increased the ride height a bit. Decreased roll on corners. Didn't do much for normal road rubble. But big hits were considerably less painful.

 

[RustyRuss]

I fitted semi air suspension to our coach built Autotrail Apache. Truly outstanding! Cost about £200 fitted, but the difference in ride and noise, vibration and harshness is worth every penny. In addition you can jack up the rear end when trying to get level on a sloping pitch. We run at around 2.5-3 Bar. Best addition to our MoHo other than solar panels.

Cheers!
Russ

 

[TheBig1]

I would be speaking to Jones springs about uprating the rear springs to prevent bottoming out. You have to remember that a motorhome drives round constantly under load unlike the base van. Those springs are designed to take varying loads over a couple of years. A motorhome lasts a much longer life than a builder's van but things like suspension tend to deform and wear out way before the body starts deteriorating

Sevel vans from the factory are very rough suspension and only get worse over time unless upgraded