Heavy "bang/knock" on launch !
31 December 2007, 01:46 PM
#1
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Heavy "bang/knock" on launch !
After a run round the the North Pennines in the snow on Saturday, "us" WYIOC headed home after a fun day out....
Gritters had been out so at the lights near home I tried a 4000 rpm launch !
All I got was a very loud bang from under the car, so swiftly dropped the clutch back in and went for neutral expecting the worst.....
Set-off normally and all appears fine, could it be the engine/g'box mounts ?
Or is my prop-shaft able to "knock" like that ?
Any suggestions, apart from not acting the goat !
DunxC
Gritters had been out so at the lights near home I tried a 4000 rpm launch !
All I got was a very loud bang from under the car, so swiftly dropped the clutch back in and went for neutral expecting the worst.....
Set-off normally and all appears fine, could it be the engine/g'box mounts ?
Or is my prop-shaft able to "knock" like that ?
Any suggestions, apart from not acting the goat !
DunxC
31 December 2007, 04:55 PM
#2
Easy!
The rear diff carrier can move up enough to hit the underside of the floor pan with an alarming bang when you dump the clutch.
There is a fix to this and it is cheap!
Buy a Whiteline rear diff lock kit.
It replaces the 2 large rubber mountings of the transverse crossmember of the rear diff subframe. The mounts are under the B pillar right next to the sills. There is a triangular steel plate to remove, the rubber mounts and then you replace everything back with urethane bushes.
Job done and NO increase in vibrations.
Bad news is you will dump the clutch more and pop something else.
Behave!
Graham.
The rear diff carrier can move up enough to hit the underside of the floor pan with an alarming bang when you dump the clutch.
There is a fix to this and it is cheap!
Buy a Whiteline rear diff lock kit.
It replaces the 2 large rubber mountings of the transverse crossmember of the rear diff subframe. The mounts are under the B pillar right next to the sills. There is a triangular steel plate to remove, the rubber mounts and then you replace everything back with urethane bushes.
Job done and NO increase in vibrations.
Bad news is you will dump the clutch more and pop something else.
Behave!
Graham.
31 December 2007, 05:08 PM
#3
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Hi 911 !
You seem to know ALL the answers, thank god !
I honestly thought I'd broken something, and I was being "gentle"....
Agreed I don't usually bother ! I blame Mike Wood who told me the std clutch is o.k. up to 400 bhp-ish, if not slipped.... so I didn't !
Any other up-grade advice while I tear the rear-end to bits ?
Many thanks, and have a great New Year !
DunxC
You seem to know ALL the answers, thank god !
I honestly thought I'd broken something, and I was being "gentle"....
Agreed I don't usually bother ! I blame Mike Wood who told me the std clutch is o.k. up to 400 bhp-ish, if not slipped.... so I didn't !
Any other up-grade advice while I tear the rear-end to bits ?
Many thanks, and have a great New Year !
DunxC
31 December 2007, 06:15 PM
#4
Afraid so...
If you are up to it, while doing the mod above get the rear diff out of the subframe and the 2 rear mounting studs free of their rubber bushes.
Get the bushes out (bast@rd of a job so be warned) and replace with urethane items, easy to put in.
Finally, buy the Whiteline subframe bolts, very cheap, very easy to install. Sometimes the threaded bungs in the shell are simply rusty so you might struggle, but lots of grease...
All this does is to tie the whole rear diff and fram tight to the shell, stops bumps and bangs when being a holigan and stops the rear frame holding all the suspension from squirming about under 'holigan' tactics.
You can do this all day without drama till the clutch pops!
4000 rpm is for dainty people, try 6000 and lift the leg as fast as you can.
DropShots.com
If you are up to it, while doing the mod above get the rear diff out of the subframe and the 2 rear mounting studs free of their rubber bushes.
Get the bushes out (bast@rd of a job so be warned) and replace with urethane items, easy to put in.
Finally, buy the Whiteline subframe bolts, very cheap, very easy to install. Sometimes the threaded bungs in the shell are simply rusty so you might struggle, but lots of grease...
All this does is to tie the whole rear diff and fram tight to the shell, stops bumps and bangs when being a holigan and stops the rear frame holding all the suspension from squirming about under 'holigan' tactics.
You can do this all day without drama till the clutch pops!
4000 rpm is for dainty people, try 6000 and lift the leg as fast as you can.
DropShots.com
31 December 2007, 08:46 PM
#5
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I pay for my own mods with the scrapings from the plates of others.....
Actually I kick the **** out of my credit card every few months !
Looks like it will get painted up while it's in bits..... as I hate seeing it rusty underneath !
Whiteline adjustable rear arm set and Cusco trailing arms were next, before a change of shocks (6 years old now) to coil-overs.....
Have you heard anything good about CF propshafts ?
DunxC
P.S. nice link.... I run 235 R888's so thought a bit of grit would "lubricate" my launch, no just dug in and THUNK ! Will save it for Elvington ?
Actually I kick the **** out of my credit card every few months !
Looks like it will get painted up while it's in bits..... as I hate seeing it rusty underneath !
Whiteline adjustable rear arm set and Cusco trailing arms were next, before a change of shocks (6 years old now) to coil-overs.....
Have you heard anything good about CF propshafts ?
DunxC
P.S. nice link.... I run 235 R888's so thought a bit of grit would "lubricate" my launch, no just dug in and THUNK ! Will save it for Elvington ?
01 January 2008, 08:30 AM
#6
No, practice before elvington. It is hard to get just the right wheelspin/slip without wasteing the clutch or time.
As for Carbon props:
Spend the money wisely elsewhere. (IMHO).
Happy New Year!
As for Carbon props:
Spend the money wisely elsewhere. (IMHO).
Happy New Year!
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02 January 2008, 06:18 PM
#8
I know someone who fixed his by ramming a folded-up rubber floor mat and wedged it between the shell and the top side of the diff carrier...
It did actually work well.
Cheap mod if you like those methods!
It did actually work well.
Cheap mod if you like those methods!
02 January 2008, 09:01 PM
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Been looking on NASIOC, why are Whiteline bits priced £ vs $ seems very cheap... I know shipping will cost but so unfair !
DunxC
P.S. Looking to "stiffen"my saggy rear now....
DunxC
P.S. Looking to "stiffen"my saggy rear now....
09 January 2008, 10:02 PM
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i had the same problem and have had this fitted. scared the poop out of me when it first happened
thing is, now when i'm in first gear and drive forward a little bit then take my foot of the loud pedal, i get a loud whine from what sounds the rear diff untill i press down the clutch, i also get this through the gears.
it sounds sort of ok on normal driving but i do get a bit of a whine at motorway speeds
do you think the diff is on the way out or is it down to the new kit???
cheers
steve
09 January 2008, 10:33 PM
#11
In my experience this mod did not add anything to the harshness of my car at all.
Remember my car has no rubber anywhere in the chassis and hard mounts on the engine and gearbox too.
All is well.
If the noise increases with speed and not with gear changes it could well be the diff.
Check / refresh oil first and look for bits on the sump plug when out of the diff.
Remember my car has no rubber anywhere in the chassis and hard mounts on the engine and gearbox too.
All is well.
If the noise increases with speed and not with gear changes it could well be the diff.
Check / refresh oil first and look for bits on the sump plug when out of the diff.
10 January 2008, 08:49 AM
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In my experience this mod did not add anything to the harshness of my car at all.
Remember my car has no rubber anywhere in the chassis and hard mounts on the engine and gearbox too.
All is well.
If the noise increases with speed and not with gear changes it could well be the diff.
Check / refresh oil first and look for bits on the sump plug when out of the diff.
Remember my car has no rubber anywhere in the chassis and hard mounts on the engine and gearbox too.
All is well.
If the noise increases with speed and not with gear changes it could well be the diff.
Check / refresh oil first and look for bits on the sump plug when out of the diff.
ok, thanks for that, will have a look at the weekend
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