paul jacobs Posted May 2, 2007 Share Posted May 2, 2007 I've just lifted my Duratec up with about half an inch of spacers under the engine mounts and on top of the rubber, I've checked all around to see if it's touching anything on the chassis and it doesn't seem to be, yet I'm getting a really strong and nasty vibration period between 1500 - 3000, after that there is no sign of it, it spins as smoothly as a nut up to the red line. I'm going to drop the engine back down again to see if it goes, but in the meatime, does anyone have any other ideas which I can try? Paul J. Loud pipes save lives, but quiet ones save your hearing. Link to comment Share on other sites More sharing options...
Jason Plato Posted May 2, 2007 Share Posted May 2, 2007 oil filler cap on bonnet   Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted May 2, 2007 Share Posted May 2, 2007 U/Js on propshaft can cause a nasty vibration if the gearbox outlet isn't perfectly square and parallel to the flange on the diff. ****************** And you run and you run to catch up with the sun, but it's sinking... And racing around to come up behind you again. photos Link to comment Share on other sites More sharing options...
Tony C Posted May 2, 2007 Share Posted May 2, 2007 1/2"  You did fit longer bolts. I only used two large diameter washers, but longer bolts too; to get the entire mounting thread length engaged with the bolt. BRG Brooklands SV 2.0L Ammo Duratec 😬 It seems that perfection is achieved not when there is nothing more to add, but when there is nothing more to take away. (Antoine de Saint-Exupery) Link to comment Share on other sites More sharing options...
paul jacobs Posted May 2, 2007 Author Share Posted May 2, 2007 Thanks Tony , yes I did fit longer bolts, they were so much longer in fact that I had to put a spacer under the head so they didn't bottom out  There is plenty of room above the oil filler cap [well about 3/16" anyway], good point about the Propshaft U/J, but if I knock it into neutral and coast, with the engine at tickover, the vibration goes, so I think it is something to do with the engine  Paul J. Loud pipes save lives, but quiet ones save your hearing. Link to comment Share on other sites More sharing options...
Manxseven Posted May 2, 2007 Share Posted May 2, 2007 Does it do it when revving it up on the drive eg: not moving.   Caterham Fireblade here Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted May 2, 2007 Share Posted May 2, 2007 If you have lifted engine - surely the centreline of the drive train is going to be stepped, as the gearbox outlet wont be lined up with the diff ?? I'll still put money on this one !! ****************** And you run and you run to catch up with the sun, but it's sinking... And racing around to come up behind you again. photos Link to comment Share on other sites More sharing options...
paul jacobs Posted May 2, 2007 Author Share Posted May 2, 2007 Yes, I can replicate it when reving up when stationary, so this being the case, it should rule out the propshaft angle, but then with this sort of thing, nothing can be ruled out, so I will look carefully at the angles that I've now created. Paul J. Loud pipes save lives, but quiet ones save your hearing. Link to comment Share on other sites More sharing options...
Rob Walker Posted May 2, 2007 Share Posted May 2, 2007 I have lifted my 2L engine by 7mm. I took particular note of its effect on prop angle and noted that the gearbox output shaft hardly moved and was actually improving the prop alignment. Its not your exhaust catching something when its hot and expanded? Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted May 2, 2007 Share Posted May 2, 2007 If you can replicate it by revving when stationary - did you change anything when moving the engine ? Sounds like something is out of balance - flywheel, clutch, etc ?? Or is one cylinder not firing between those revs ? ****************** And you run and you run to catch up with the sun, but it's sinking... And racing around to come up behind you again. photos Link to comment Share on other sites More sharing options...
Manxseven Posted May 2, 2007 Share Posted May 2, 2007 *arrowup* that being the case ,I'd wedge the throttle open at the required revs and stick me hand around the engine bay (mind the wirring bits ) and feel for the vibration 😳. Does it do it with the bonnet off?   Caterham Fireblade here Link to comment Share on other sites More sharing options...
DaveMorris Posted May 2, 2007 Share Posted May 2, 2007 Could something be touching the steering column ? Dave X-flow(er) powered Link to comment Share on other sites More sharing options...
Big Brother Posted May 2, 2007 Share Posted May 2, 2007 Exhaust touching the sideskin? Steve  SE7EN-UP! -----Ever noticed that the word enviromentalist contains the word mentalist!----- Link to comment Share on other sites More sharing options...
paul jacobs Posted May 2, 2007 Author Share Posted May 2, 2007 All good guesses, it could have been any of those excellent suggestions.....but wasn't. If you look back at my 2nd post, in answer to Tony, I said that as I had used longer bolts, I'd put spacers under the head of the bolt to stop them bottoming out, well it seems that one of the spacers wasn't quite long enough, and the bolt was tightened down against the chassis, effectively doing away with the rubber engine mount  Whilst I haven't had a chance to start it tonight, I have cut the bolt down and made sure that there is no chance of it contacting the chassis when fully tightened down now. I'll try it tomorrow night, fingers crossed that it was the problem : amateur dabblers eh?  Paul J. Loud pipes save lives, but quiet ones save your hearing. Link to comment Share on other sites More sharing options...
Manxseven Posted May 2, 2007 Share Posted May 2, 2007 Nah .. get out there now and rev it up to check 😬 😳 😬 😬 Caterham Fireblade here Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted May 2, 2007 Share Posted May 2, 2007 ooh - the neighbours would just love that !!  ****************** And you run and you run to catch up with the sun, but it's sinking... And racing around to come up behind you again. photos Link to comment Share on other sites More sharing options...
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