Hello

Taken my mk xe out on trackday and its quick in straight line but behaves strangely on limit in bends

I think whats happening is that the springs are reaching max compression and bottoming out.

The feeling is like loading up the rear end under weight transfer then a further compressin due to bump a metal grind/connection sound and it will spin you if you're not quick enough.

I get the same noise but only for an instant when i have passenger in car and go over bump, although this has been minimised by setting damper harder.

I guess it sounds like its happening in corners as the damper is not reacting to fast bump as its in roll situation and spring is fully compressed.

Does this sound right?

The car is MK with live axle, with vauxhall xe engine. It weighs roughly 150 KG for each corner. I weight about 100KG in helmet and all gear etc.

What spring rate should i expect ot have on the rear.

I havent checked whats on now yet?

oh yes

see
http://www.locostbuilders.co.uk/viewthread.php?tid=93811
for it doing a standing 1/4

it does seem to sit quite low?

quote:

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Originally posted by phil T5


I havent checked whats on now yet?

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Hi there are various problems with the MK live axle rear end.

1. The springs if running with 1.9 id springs can end up coil bound. This obviously gives the sudden change in spring rate as hitting the bump stop but more visious.

2. The max spring poundage you want is 160lb and no lower that 120lb for road use.

3. the main problem is that they never modded the rear cross member that crosses the rear bulkhead and hits the top of the diff unit in compression and roll. All other manufacturers have raised the crosmember to give clearance but NOT MK. Means you have to run a much higher ride height. This can be exadgerated if running 15" rims and trying to achieve a 4" ride height for example.

5. some times the axle will not be centered in the chassis and when cornering the diff casing will catch the chassis on the inside of the tunnel. It can be centered if it has an adjustable panhard rod but i do not recall MK's having an adjustable one fitted.

6. as others have said make sure you have the correct length dampers and springs fitted. Get someone to check how close you are to the bump stops visually when seated in the car. And also check how much droop is available by lifting the chassis on one side and measure how far the chassis can raise before lifting the wheel/tyre from the ground. Ideally you want close too 1 1/2" travel in compression and droop available.

Cheers matt

Thanks for advice
is there a way of finding out spring pound ratinwithout removing?

are they marked in a standard way somewhere?

Hi if you can see the end of the spring where is has been croped ans flatend some have the poundage marked there. Other wise it have to go into a tester. But if you post up the open lenght of the spring and wire dia. it will be possible to estimate with in a few pounds.

Cheers matt

Thanks

its sounds to me like axle is hitting cross member /frame, will check other things too though

Im thinking this cos of the sound it makes under load cornering but could be wrong

Ive got avo shocks on so first thing is presumably

Check for marks where it may be hitting

Jump up and down on back with a couple of people to see it it connects with cross member

The wind up the ride height so if if it helps

After this check springs

The other thing I could check I guess is marks on the actual coil to see if the coils are contacting each other i.e coil binding is happening

Hi sounds like you have a plan of action.

cheers matt

Having just watched your 1/4 mile vid, it might be worth raising just your driver's side ride height. It looks as if the car has been set level with no weight in it, but then drops when you get in it. Mine does similar, as I too weight about 100 kgs all up. It might look a bit silly and wonky when sat still, but will sit flat when you're driving.

thanks

thats my first step i think

quote:

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Originally posted by phil T5
thanks

thats my first step i think

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