Suspension......

[pickle2000]

Hi everyone,
I have currently got a MK1 1.2 Merit and have fitted some Koni adjustable dampers and -60 GMAX springs. The ride is pretty hard - and I love it as it is now loads more sporty, however when going over big bumps or pot holes the suspension makes a very loud bang. I think that this is normal, since the travel has been reduced but don't know if it is damaging the car at all.
Yesterday I was driving along a pretty new road, and it didn't have any surface on it yet...... I was happily driving along and then suddenly the road went from being no surface to having a tarmac surface. But the difference in height between the 2 surfaces was a couple of inches, and travelling over it at about 20mph there was a large thud sound from the front of the car.......
Do other people that have hard suspension have things like this?
Is it damaging to the car/suspension?

Cheers
Pickle
What is causing the actual 'thud'..... is it the suspension topping/bottoming out?

[Ben (lurk75)]

sounds like you could have knocked your sump on the ridge between the 2 surfaces. (very common on road works with exposed drains sticking up and your car being lowered)

Sumps can take quite a wack (beware on Astra GSI engines as these had alloy sumps and crack easier)

An easy way to check is bend down and have a look under the car from the front bumper and see if you can see a dent in front of you.

[pickle2000]

Cheers man, I will take a look later. Not really sure where or what the "sump" is, but I will check for anything that looks like it is dented.

Is this a common problem for everyone with lowered (and uprated) suspension?

[nathanl]

The sump is what holds your oil, you will see it under the car, It is the lowest part of your engine.

[Ben (lurk75)]

its not really a problem with lowered cars its just a pain for people who live on new housing estates where the roads arent finished etc.

They can take quite a hammering but will only last a certain amount of bashing, this is why the rally boys have sump guards etc to help them.

it is a big tank sort of thing thats attached to the bottom of the engine. if youve damaged it badly there will be oil pi**ing out of it! (doubtful)

[pickle2000]

I have just re-read the message and I am not sure but think that you are referring to me "knocking" the bottom of the car on the road......?
I think that the thud sounds come more from the suspension than the actual bottom of the car hitting..... hence hitting a sharp bump in the road, causing the suspension to re-act quickly and make a loud noise.

Hope that I am not going round in circles......

[Ben (lurk75)]

as you said by having your car lowered it will bang when you go over bumps. just check thetops of your struts and make sure all the nuts are done up tight (could be slack)

but just something will have to get used too.

(just check the sump)

[pickle2000]

Yeah, will defo check the underneath just incase....... I don't mind the hardness at all (makes my 1.2 feel a lot more sporty 8) ) and was only really worried incase it was dangerous, but it sounds as though that is the price to pay for lowering your car.

Cheers Lurk, you have been a g8 help.

[ade]

dunno about koni adjustables but when I installed my gmax 60mm dampers n springs I had to cut my bump stops 20mm.

Did you do this (providing you have to with koni's).

If you dont the shortness in the dampers will slam the bump stops into the suspension strut tops making a bang and wearing them out.

That could be the problem...
:?

[Rich Dale]

Ade has said exactly what I was going to say!

It's the suspension "bottoming out" i.e.....reaching it's full limits of travel and hitting the bump-stops.

On my GTE which was on -60mm Pi springs and standard dampers, it would be IMPOSSIBLE for the sump to hit the ground on flat roads.....you'd have to have a high part in the middle of the road where both wheels go either side of it (like a raised pot-hole as mentioned by Lurk75) or a speed-mound.

The GTE did occasionally bottom out and it made a loud bang, but only in very extreme cases........like road works with "Ramps" exactly as in your case.
I never cut down the bump-stops though.

Basically, buy cutting down the bump-stops, you increase the distance that the suspension can travel but be careful if you have large wheels......if they can travel further, they could hit your arches, especially the front ones when cornering hard!

You can also get to the point where all the coils of the spring totally contract (fully compress)....this would make a bang too and would happen if they were too soft for the weight of the car, or if the dampers where not hard enough to cope.

[pickle2000]

I had the suspsension fitted by a garage, and don't think that the bump stops had been cut down at all........ will not cutting the bump stops down begin to damage the car?
Like you rich, it only happens in extreme conditions - i.e. any deep potholes, or roads under construction.

I have currently got 195/45/R15 wheels on at the moment, but the -60mm drop has put the front wheels pretty close to the arches...... and since the wheels are an ET 42 they do stick out more than they should. I think that if the suspension travels any more then it might start fowling on the body work......
So my options are (i think) - get the front arches looked at so that I can get the bump stops shortened allowing me more travel, or put up with it as it is at the moment....... If it is going to be worse in the long run to leave it as it is then I will get it sorted out, but if it isn't going to cause any probs then I will leave it be...... Its just that I don't like the sound of loud bangs, makes me nervous about my pride and joy... :lol: :lol: .......

BTW. would rolling the front arches sort out the wheel problem, or would I need to get them pulled out (flared??) further...?

[ade]

get them reduced - 1... they WILL damage your shocks after a shortish period (impact sends shock through shocks damaging seals) and 2... it may invalidate youir warranty with the shocks (check manufacturers guidelines). My Gmax instructions advised that they MUST be cut down do prevent damage to the shocks and if not the warranty (3 yrs) was null and void.

Like you, my new 15's are a little phat for the arches (although they are correct offset) - I'm going to roll my arches (fronts) - to do this I 1st cleaned all shite off the inside lip on the front arches, made small cuts using a hack saw at 3" intervals and gently pushed them up with my fingers. I tham coveed the inner lip with hamerite (black will do) and once dried covered the lot in seam sealer (grey stripe will do) - one thats dry add some more hammerite to hide sealer. Game over... :D

[Ben (lurk75)]

lol Ade by the time youve painted all that on the arches will be as fat as they were! :lol: :wink: :lol:

[pickle2000]

Cheers guys.......
Alright, I will look into getting the bump stops sorted out......... Do you recommend cutting them down by about 20mm? Just need to check, but will this lower my car further - i.e. another 20mm lower, or will it just allow more travel in the suspension?

Will get my front arches sorted out as well. Do you think that rolling the lip over will give me enough room? Because if I roll the lip back and do need some more room for the wheels on the front, what can I do?

BTW are bump stops different to "bushes" or are they the same thing? Because I have seen uprated bushes that you can get as well.

[ade]

it usually depends on your suspension but if dropping 60mm you should cut bump stops down by 20mm. This will not lower the car further, simply give the piston in the suspensionhousing further to travel before you hear the dreaded bang (which should not stop or be vastly reduced).

Your bushes are not the same as the bump stops. The bump stops live inside the suspension housing - if you take your front wheel off and look at the front suspension strut (inside the spring), there will be a black plastic cover, inside there is where the bump stop lives. The uprated poly bushes are the buts that the suspension arms move upand down on (I think) the standard ones are rubber which on a lowered car wear out faster than poly ones. Poly ones are receommended but not immediately essential - can be buggers to fit (so I've read on here in the past)

As for rolling arches, probably best rolling inwards and striaght up. You'll probably need to make small cuts in the metal to make it roll easier (that way you dont distort the wing arch) - just push the lip straight up so its flat against the inside of the arch, you dont actually roll it
If your wheels are still too big for the arches, then you'll either have to get wider arches, have your wheels skimmed to the correct offset or find a body shop that can do hammer and dolly work onyour existing arches to stretch them (bit extreme but can be done)

Ade