grinding when pulling off

Mr Quoter-vator Joined: 16 Feb 2004 Posts: 7405

put my decat back on tonight...went to take it for a spin....and noticed when pullin off hard theres a nasty grinding/rumbling vibration in first!! i cant see how its related to the decat that must be coincidence surely but it wasnt makin the noise before

it whenever its under a lot of load i.e. pullin off and especially a hill start...it feels bad, it sounds like grinding gears but softer....not full on crunching.

the feeling/noise can be described as driving with no tyres...really hard metallic rumbing noise.....once moving its ok.....floorin it in second is ok altho it does feel a bit more "unsecure" than normal...just seems to be under load like gettin the car moving from standstill.

was thinking a knackered shaft but cant understand the grinding vibration when pulling off...as in...imagign doin a hill start, u rev and bring the clutch up...and its as the clutch starts to engage its starts to rumble...and even when fully engaged...if u give it some it will still grumble...but the initial pulling off before things start to get moving makes me think it may not be a shaft?

suppose it may well be my turn to have a fecked box tho...everyone else seems to have it...

cheers

JB

Forum Moderator Joined: 18 Feb 2004 Posts: 7432

is it your exhaust vibrating against something? ie when you put the engine under load, it moves a bit and the exhaust touches.

I used to get this because of my bodged exhaust hanger (i had it held up too high)

Would make sense since the only thing youve changed is a part of your exhaust

Level 5 User Joined: 18 Jun 2004 Posts: 114

get under and check the flange isnt rubbing against a heat sheild or something.

Mr Quoter-vator Joined: 16 Feb 2004 Posts: 7405

it doesnt have that kind of noise...no knocking metal on metal like....much more of a deep vibration than knockin....i did look and it is well clear....the decat is obviously much smaller than the cat and it is sitting nicely where the cat goes in mid air.

i know its too coincidental but i cannot see how its related...

i have since just gone out and jacked up each frt wheel in turn and just spun them with my hand...they spin freely...

Mr Quoter-vator Joined: 16 Feb 2004 Posts: 7405

ok the more i think about it the more sense it makes that it MUST be the exhaust...for gods sake...that would be just tooooo much of a coincidence....if it is then it must be the downpipe has been pulled backwards and not returned to its original position....

its sounds like someone tryin to get thru the bulkhead with a hammer drill with i boot it in first....will try wiglling zorst in the morning

u can see how optimistic i am in my trusty steed and that it will never let me down....lol

Site Subscriber Joined: 24 Apr 2004 Posts: 318

hmmm - sounds very similar to mine, I did have a new zorst fitted but it was about a month or so before I first noticed the noise so I think it's something different.

I only get it when accelerating hard in 1st, worse on hill starts under load etc as you say JB, fine in other gears and normal driving. It's worse when it's very wet, does it in all gears - water getting in somewhere?

been doing it for about 3 months and not got any worse (or better) so decided to leave it - can't afford a big repair so would rather not know it's about to go bang!

Mr Quoter-vator Joined: 16 Feb 2004 Posts: 7405

well it is my exhaust..but cant see how....i put a lever from the top down behind the manifold and heatshield and wiggled it....made a bit of a diff but came back after a while....so will get under and have more of a look...

its bloody weird tho cos this decta has been on before...all i did was swap the cat for the mot....so why its done this now i dont know....bloody thing.

Site Subscriber Joined: 24 Apr 2004 Posts: 318

hmmm - well I'm changing my starter motor tomorrow so will look at my zorst then - although in my case not sure why it's worse when it's wet

Mr Quoter-vator Joined: 16 Feb 2004 Posts: 7405

sorted...seems the decat isnt particularly straight...put it on one way and it draws the downpipe too close to the rack...hence the contact when pulling off....rotated it thru 180 and its fine again. thank the lord!