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Bump stops

little fella

Silverstone
Joined
22 May 2020
Messages
145
I'm fitting koni active dampers and eibach springs -30mm.

Question is do i need to cut my new bumpstops down or leave them.

There is about 3" between bottom of bumpstop and damper.

Cheers
Carl
 
I fitted the same Konis recently with standard springs and didn't have to alter the bump stops in any way, sorry i don't know if lower springs would be different.

There's some photos on my instagram page db996gb if fancy a look.
 
On the VW's I've had in the past they had almost identical bumpstops and when I fitted lowering springs they were slightly squashed with the car just sat there, and they were soon destroyed by driving. I used to cut one of the sections off.

Don't know if the same applies to the 996 but I'm sure there will be someone on here who can tell you,after all I'm sure you're not the first person ever to fit some lowering springs to a 996!

I wonder if Center Gravity would tell you?

Mac
 
I'm fitting koni active dampers and eibach springs -30mm.

Question is do i need to cut my new bumpstops down or leave them.

There is about 3" between bottom of bumpstop and damper.

Cheers
Carl
Carl, what did you end up doing with your bumpstops? It seems the Eibachs/Koni Special Actives would ride better with shorter bumpstops(?)...
 
At -30 you'll be riding on the bumpstops pretty much all the time. You'll have to trim them a bit and see how you get on.

Trimming bump stops makes them firmer as springs. Porsche, in fact, call them additional springs. This in itself will have an effect.
 
I posted this in the other thread about Koni and H&R the other day.

Well worth reading that thread for more tips if going with Konis and shorter springs.


I had the standard bump stops, they also do them for the x74, which would be better with the shorter springs, the standard ones just looked too long, they took up half of the shaft nearly once under load.

Hence, when taking my stuff apart to put the hose and the support ring back in, I decided to cut the bottom of the bump stop off.


This photo shows the two bumps at the bottom (should be the top)...

View attachment 102165


However, when I went to do the other side I realised that the garage had put the offside one in, the one I had just shortened, upside down. Doh!

But I have driven it loads in anger and there is a dip near me that bottomed out my car on older OEM dampers that still doesn't hit the bump stops with it how it is.

This is the shorter one...
View attachment 102166

Part number 99634398009
 
Carl, what did you end up doing with your bumpstops? It seems the Eibachs/Koni Special Actives would ride better with shorter bumpstops(?)...
I cut them down in the end and i went with vogtland springs as the eibachs lowered the car more than the -30mm stated by eibach
 
I just did my front bump stops last fall as the old ones were totally shot. I have M030 suspension, so I opted for the shorter bump stops Porsche offers. I ended up with going with aftermarket ones, I think from Schaffler and they have been flawless so far.
 
I did my front bump stops and top mounts last week! It's a C4S.

I used the standard bump stops and top mounts. These are listed for the C4S despite having the factory lowered suspension.

The shorter ones are for the IX74 option.
 
Yeah, shorter ones are more for IX74 and for those using H&R or Eibach etc.

Can't see there being an issue using them with M030 though, if the dampers are good you shouldn't hit them anyway, and if you do your dampers are already gone I would guess?
 
Mine is X74 with H&R lowering springs and Koni special actives, I also drive on horrifically bumpy B roads in Suffolk. I have the standard length bump stops and don't feel amy restrictions unless doing stupid speed over said bumps, I'm not sure if reducing the size of the bump stops would not simply reduce the efficiency of what they are there for.

There is no doubt that a properly set up set of decent coilovers would be far better and a set of Bilstein B8s would be more in tune with the reduced height but good coilovers are much more expensive and every report I have seen has stated the B8s as being way too harsh for British B roads.
 
I'm the same as you, Konis and H&R, I have been in loads of different set ups on these and for me, this just works so well as a road car.
Not sure the coil overs are better, everytime I get in a car with Ohlins, KW or Bilstein it feels far too firm, a bit fidgety at the back as soon as the road is not super smooth, which, being in Norfolk is 90% of the time.

Hold on....

Not sure what you mean yours is X74? Surely the X74 is the X74 dampers, Springs and bump stops, which you have now swapped? Or do you mean you have the standard X74 bump stops.
 
Got ya.

I'm running quite aggressive negative camber at the rear with quite excessive toe in.

However, at the front I am running virtually no camber at all, and no toe in.

This has worked really well, with the Konis and H&R, far less fidgety at the front, feels very planted, nice steering feel, and the back is super grippy.

You could mark all three top mount bolts, slide the dampers as far out as they go and then see what you think. You can go back if you don't like it if all are marked.
 
I had standard bump stops fitted when I had the Koni SA and H&R springs out on. It was nearly 5 years ago, I would think the advice now is to go with the M030 bump stops if you’re fitting lowering springs whatever dampers you’re using.
 

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