mpbarrett Posted January 14, 2015 Share Posted January 14, 2015 I have recently changed the engine in my Herald from a 1500 to a less oil leaky 1500 but with a stage 2 head (think its been gas flowed a bit but have never understood what stage 2 actually means..). It has a tubular manifold into a straight pipe with a back box. This is the same as the previous engine. Its running twin SU's.The engine is fine nice smooth tick over with no nasty noises. But I am getting lots of vibration thru the car from about 1700 to 2300 rpm, bad enough to make the car uncomfortable to drive. Don't think its anything in the engine but am not sure if its coming from the exhaust, maybe it just hitting a natural resonance or whether something else is going on? Did start to wonder if the fly wheel was loose but nothing changes if the I use the clutch.Any suggestion welcome. BTW the exhaust is very noisy and I probably need to fit a centre box to the exhaust but am unsure whats best for a 1500 Herald.cheersmike Quote Link to comment Share on other sites More sharing options...
ferny Posted January 14, 2015 Share Posted January 14, 2015 Did you take the engine and gearbox out together? Obvious suggestion is that the propshaft is out of balance to the rest of the system now. Or that the gearbox and/or engine mounts are iffy. Quote Link to comment Share on other sites More sharing options...
Billus99 Posted January 14, 2015 Share Posted January 14, 2015 Possible, but prop shaft vibration goes with vehicle speed, not engine revs Quote Link to comment Share on other sites More sharing options...
Richard B Posted January 15, 2015 Share Posted January 15, 2015 Find a clear road, get up to speed and put the car in neutral. while coasting does the vibration stay? Quote Link to comment Share on other sites More sharing options...
mpbarrett Posted January 15, 2015 Author Share Posted January 15, 2015 Richard_B wrote:Find a clear road, get up to speed and put the car in neutral. while coasting does the vibration stay?Yes its not the drive train, if I put it into neutral and drop the revs the vibration geos away, comes back when the rev get to 1700.thanks for the suggestions, keep them coming!cheersmike Quote Link to comment Share on other sites More sharing options...
RobPearce Posted January 15, 2015 Share Posted January 15, 2015 The 1500 Herald I used to own developed a truly ghastly vibration at certain engine speed (higher than yours, I think) which was down to the dynamo fan having shed half its blades. Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted January 15, 2015 Share Posted January 15, 2015 Things along the line of what Rob is suggesting are certainly good candidates. What flywheel is fitted? Are engine and gearbox mounts ok and nothing touching the chassis? Is the exhaust arrangement the same as you had before?Nick Quote Link to comment Share on other sites More sharing options...
Alex Posted January 15, 2015 Share Posted January 15, 2015 Don't suppose it has the 1500 viscous fan fitted? Quote Link to comment Share on other sites More sharing options...
Mark Hammond Posted January 15, 2015 Share Posted January 15, 2015 Disconnect the fan belt to isolate the generator and the water pump, then run it. Those cheap and nasty Indian built water pumps, they don't last.....Mark Quote Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 15, 2015 Share Posted January 15, 2015 If its not something making contact with the chassis one other obscure vibration creatoris the clutch disc damper springs ,, has the clutch disc been changed or its off the old engine??pete Quote Link to comment Share on other sites More sharing options...
mpbarrett Posted January 15, 2015 Author Share Posted January 15, 2015 Great, thanks for all the suggestions.I did disconnect the fan belt but it made no difference to the vibration.It has a new clutch (plate and pressure plate). Operating the clutch makes no difference to the vibration.The exhaust is essentially the same but I have put in a new short section with a boss for a wide band sensor, which is in the pipe. I finally have everything to inject it... once I get rid of the vibration...I think it is to do with the exhaust I am going to try clamping the exhaust half way down the pipe (change the pipe resonance ) and see if it effects the vibration. Will try it over the weekend, was going to do tomorrow but have decided to go down to London Model Engineering and drawl over the models and toys instead of playing cars :)cheersmike Quote Link to comment Share on other sites More sharing options...
Richard B Posted January 15, 2015 Share Posted January 15, 2015 The exhaust should have a clamp from the enging/gearbox joint.Does sound to me like it could be touching the chassis somewhere. Make sue you have 1/2" clearance on the whole exhaust run.Worn mounts allowing the engine & exhaust to move?It's not a wheel barrow exhaust is it? :X Quote Link to comment Share on other sites More sharing options...
mpbarrett Posted January 16, 2015 Author Share Posted January 16, 2015 Richard_B wrote:The exhaust should have a clamp from the enging/gearbox joint.Does sound to me like it could be touching the chassis somewhere. Make sue you have 1/2" clearance on the whole exhaust run.Worn mounts allowing the engine & exhaust to move?It's not a wheel barrow exhaust is it? :Xnot a wheel barrow had one on my gt6 horrid thing...The herald has a tubular exhaust manifold in to a large pipe to a single read box that might be from a vittesse. The exhaust is only supported at the rear box (rubber mountings at both ends of the rear box.Will try putting a fixing between the exhaust and the engine/gearbox.Think it is clear of the chassis but will check.It has new engine mounts but looking yesterday they do seem to deformed a lot. I think I have a pair of nos so might fit those instead.cheersmike Quote Link to comment Share on other sites More sharing options...
mpbarrett Posted January 17, 2015 Author Share Posted January 17, 2015 Fixed!one of the new engine mounts had come unbonded, it looked slightly lower than it should be but when i took it off it came competely apart. looking at the metal part you can see that it was only bonded over about 30% of the area so I guess it was weak and came apart.Not sure where it came from (had it in my stock of parts) otherwise I would sent it back to the supplier.thanks for all the helpful suggestion.mike Quote Link to comment Share on other sites More sharing options...
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