24 replies to this topic

[Captain Vimes]

Since fitting the tubby back box on my car the clamp holding the u-bend to the box keeps coming loose. I've tried a band clamp and a u-clamp with the same results. When it's tight, I get a horrible vibration through the whole car between 2-2.5K rpm. Once it's worked loose again the vibration (mostly) disappears. So just clamping it tighter doesn't appear to be the solution.. I've added poly inserts to the engine mounts to reduce engine movement and also tried with/without the post-cat hanger connected with the same results. Anyone else experienced similar? Any suggestions? Ideally I'd like to mount the box with a bit more 'give' to dampen the vibration.

[Zoobeef]

Yep, I used the uBend clamp you pointed too on fbook and it's come loose, I assume it's stretched from big crap steel or something. Will try and modify it or get an OEM one once I'm home 

[Captain Vimes]

Do you get a vibration through the car as well? It's always done it since I fitted the tubby box but don't understand why it would be different to the NA box?

[Zoobeef]

IM not sure on vibration as it's striped to fudge.

I got flagged on a drive by at Bedford (na engine tubby backbox) then noticed just after that my backbox was free to move. It doesn't go any tighter so reckon it's stretched. 

[chris_uk]

Try putting a load of exhaust paste in the join trn use a propper big band clamp and if that doesnt work.. Welding is your only option.

[smiley]

I've added poly inserts to the engine mounts to reduce engine movement and also tried with/without the post-cat hanger connected with the same results.  

 

Funny. My situation got better after adding the postcat hanger.

I don't have rubber on my precat hanger though.

 

[Captain Vimes]

Thanks, will try again with a new clamp, some paste and strengthen the cat hanger. Good to hear I'm not the only one.

[Captain Vimes]

IM not sure on vibration as it's striped to fudge. I got flagged on a drive by at Bedford (na engine tubby backbox) then noticed just after that my backbox was free to move. It doesn't go any tighter so reckon it's stretched. 

Despite the movement it seems to keep a good seal add the u pipe goes so far into the main box, so if be surprised if it contributed any extra noise.. Oem clamp looks like the way to go though.

[Chris P Duck]

Have the same but no vibration issue. Tubby backbox on a SC and it keeps working loose. Tried quite a few different types of clamps and tightened it to the point things are getting close to shearing but it always ends up loose again. Can't see any evidence of it leaking though.

[Captain Vimes]

When I say vibration, it's a drone through the car where the engine vibration is being transferred to the chassis via the exhaust. I think the solution might be to mount the box using something with more 'give' than the oem rubber blocks. Are the oem turbo mounts any different to the NA ones?

[Zoobeef]

Ordered an OEM one. I have a tubby u bend and backbox but it's the same number for both.

It turned up but it's massive. Going by the numbers on it it's a 70mm clamp. In the right GM packet etc. How can they get that so wrong??

[Captain Vimes]

OK - saves me ordering from Vauxhall!

 

I think the fundamental issue is that the box is mounted too solidly. It needs to be able to move around a bit more so the stress isn't put on the clamp to stop the movement. Replacing the solid rubber blocks with something like this should do the trick:

 

http://www.amazon.co...st mount rubber

 

(Note - I have only spent 5 minutes googling for the kind of thing I'm looking for and in no way recommend the above part)

[Zoobeef]

They shouldn't come loose anyway as they normally don't. You're getting extra vibration though so I can see why it's an issue. The OEM band are Norma heavy duty ones so I've just ordered a 55-59mm one. The old one seems to be 56mm at full closed so hopefully tat will do it and not stretch. We shall see.

[Captain Vimes]

Thanks. Will be interested to know if the 55-59mm band clamps well!

[D-DAWG83]

Il keep an eye on mine, as recently fitted a Milltek turbo back box and U bent. My post cat hanger had fallen off, but got a new pre cat hanger, as the original one had failed, that was with a NA Milltek. I have a full turbo Milltek now, with Piper manifold. When i get it back il have a good look

[adamvx220]

Zoo beef were did u get your clamp from.in the end was it straight from vauxhall I'm. Having the same issue thanks ad

[Zoobeef]

The one from autovaux was way too big, and expensive.

So I just got a cheap ebay one. Just monitoring it at th minute although I've not used the car for a while.

[Captain Vimes]

I've added 2 of the cheap u clamps from Halfords and had no problems since.

[adamvx220]

Thanks for the replies I'll nip down halfords tommorow

[Ali87]

Mine comes loose since fitting vse. It's a pain in the hoop. Have tightens the original and added a big jubilee job. Thinking about getting a few spots of weld on there too