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Lowered Floors - Bottoming Out


LythamBrownie

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LythamBrownie

Morning Collective......  I’ve got standard Westfield Protech shocks, lowered floors and a 6’4” 17st driver 😬.... + I’m normally ‘two’s up’ with my son who thinks he has the god given right to be sat in the passenger seat whenever I want to blatt!!!  I suppose I’ll look back with fond memories in later years!!!....... anyway..... my problem is that I’ve become nervous about driving at speed on bumpy roads due to bottoming out..... it’s not happening all the time.... but it is taking the edge of a spirited drive.... I’ve got the shocks set to the firmest setting, but I know I’m on bog standard shocks and I’ll probably need to spend some cash on new ones, but want them to be right.  I am a road user only, not track.

 

Any thoughts?

 

Thanks in advance.

David

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I had a customer car in for this exact issue (you might know it actually - Andrew with the green bike engined car?) - it was completely solved by fitting longer bump stops.   It's the cheape

Can't harm to consider that a long, soft, progressive bump stop does the same job as a progressive spring for 1/10th the cost.... It's been tested on track, and down that horrible road to Southport,

What are your ride heights set to (chassis rail to floor NOT dropped floor to floor), with you both sat in?   Most run circa 165mm rear and 140mm front, but you can go higher to improve grou

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Ian Kinder (Bagpuss) - Joint Peak District AO

What are your ride heights set to (chassis rail to floor NOT dropped floor to floor), with you both sat in?

 

Most run circa 165mm rear and 140mm front, but you can go higher to improve ground clearance.

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wizzer

I changed my rear springs to 225lb original had 185lb and would bottom out all the time ,made it better to drive as well. 

Tony 

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corsechris

It does sound like somewhat stronger springs are the best way forward. There’s only so much adjustment you can make with a damper before going too far and causing ‘jacking’

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AdamR

I had a customer car in for this exact issue (you might know it actually - Andrew with the green bike engined car?) - it was completely solved by fitting longer bump stops.

 

It's the cheapest and easiest way, and uses a product designed for the job.

 

Skoda Octavia rear bump stops work well, you can cut them down to suit.

 

https://www.ebay.co.uk/itm/Pair-Rear-Bump-Stops-VW-Golf-MK4-Bora-New-Beetle-AUDI-A3-Mk1-Pair/311787595390


This way you can physically prevent the car from hitting the deck no matter how much force is applied.

 

I do the same up front to prevent the sump grounding out.


The damper adjustment you've done so far will be mostly affecting rebound, which may actually harm more than help - packing down like Chris says.

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Adge Cutler- Dorset AO

I’ve got standard springs and shocks on my 250 (lowered floors). They are: Front 350lb x 9”, Rear 195lb x9”. Ride height set at ~140/165.

Quite a bit of two up driving, only once caught the seat studs on some vicious speed humps. Roads where I live on the Somerset levels are quite “wallowy” as well!

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fil46

Fitting longer bump stops will stop the grounding out ,but by the sounds of it you may want to go with heaver springs, your shocks will be fine, Just made the move from 350/185lbs to 400/225lbs , 2 up is no problem now and car sits better on the road when pushing on a bit,

 

What ride height are you set at as you could raise it a bit if you are on the low side

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Dave Eastwood (Gadgetman) - Club Secretary

I would go bump stops first, the problem with too heavier springing too soon, is that the behaviour of the car can be radically different one or two up, but more significantly, if you go too hard, the wheels struggle to remain in touch with the road, and you're reducing grip.

 

An interesting alternative, are the springs damperman has supplied quite a few owners now, which have a progressive rate at the rear.

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Rhett - Joint Black Country AO

I too had this issue and started by switching to harder rear springs, that helped stop it bottoming but overall made the car worse, I've now switched to progressive rate rear springs as supplied by Damperman and it's now much better. 

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AdamR

Can't harm to consider that a long, soft, progressive bump stop does the same job as a progressive spring for 1/10th the cost.... :) It's been tested on track, and down that horrible road to Southport, so we know it works 😄

 

Perhaps not as 'controlled' and 'known' as a proper progressive spring, but if the main reason is to prevent bottom out, it is the first route I would go (and have gone - with good results - in the past).

 

6 grand set of dampers, made to work better with a couple of chopped up 10 quid rubber lumps from an old German family bus:

 

20200811_135912.thumb.jpg.94c2019ec71204a701069930b744aeba.jpg

 

(Same deal on the back, but can't get into the trailer far enough to grab a photo!).

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Quinten

Do you have to dismantle the shock/spring assembly to fit these bump stops?

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AdamR
3 minutes ago, Quinten said:

Do you have to dismantle the shock/spring assembly to fit these bump stops?

 

Yes, shock eye / end needs to come off. Just one locknut, then it screws off.

 

Another thing to add, the Mk1 MX-5 is / was designed out of the factory to run on the bump stops under hard cornering - effectively a progressive spring...

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Quinten

Sorry to thread drift slightly, but if I've got the below dampers from Protech, but can not possibly see what I need to undo?

 

Protech-Front-Shocks-springs.jpg

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AdamR

You can't see the lock nuts on that photo - they are covered up by the black rubber bump stops. Once the locknuts are undone, the top eye (the one without the damping adjuster) screws off.

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Quinten

Thanks Adam.  Not an easy job on my SEW but something to bear in mind for the winter...

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