Duncaan

I have a 98GT 5-speed, Im having a vibration in the engine between 1k-2k. Atleast thats when I can feel it. I thought it might be the clutch or the motor mounts. So I replaced the motor mounts with poly mounts, replaced the clutch with a SVE Mongoose clutch. When I replaced the clutch i replaced the pilot bearing and the throw out with ford racing. The vibs are still there. I know its not the tranny cause I feel it sitting still or while driving and with the clutch in or out. Pretty sure car does not have UDP. Any ideas?!

CaptainRon

could be anything without looking at the car in person.... could be something as simple as resonance in the exhaust causing the "vibration", loose or worn body or interior components. does it happened when its in neutral and rev it up a bit or only when its in motion? Just go thru a careful process of elimination and you'll find it eventually...

Duncaan

It had an X pipe with high flow cats on it before I did the clutch and motor mounts. Now it has an H pipe w/o cats. Interior is in great shape. It happends anytime its in that RPM range. Out of gear, in gear, diving. its it in the range of 1-2k I can feel the engine vibrating. so I dont thinks its the body or interior. What about the harmonic balancer? Are they known to go bad in the car? The engine mounts I pulled out were horrible. Couldnt belive the engine was still in the car they were so bad. Just Spent a boat load of money when i did the clutch and motor mounts. so I want to narrow it down and not throw more money at it or my wife will lose it lol.

CaptainRon

Harmonic balancer? possibly but we're starting to guess, right?, start cheap then work your way up..... first chance you get look at the MAF, make sure its clean & in working condition. that can cause vibrations too if not working right... that is something you can do yourself.... other than that, if you want to do it right and be cost effective, take it over to your favorite shop and have them look at it. and make sure its a shop that doesnt charge you just to look at it either..

Duncaan

Alright. It does have Grenatelli 24lb MAFF sensor with cold air calibration with 24lb Ford Racing fuel injectors. This is a noob question but whats the difference between a damper and harmonic balancer?

petrock

Don’t forget to check your transmission mount.

If your harmonic balancer was bad (or the crankshaft was bent) you would see it wobble when the car is idling. Good luck...

Duncaan

Ill check it out and see if it wobble. The tranny mount is good. check it when i pulled the tranny for the clutch install. If the Balancer was bad or the crank shaft bent, wouldnt I feel the vibs thru all RPM's not just in the 1-2k range?

petrock

No. It all depends on the frequency at which the harmonic to produce the shake occurs (http://www.physicsclassroom.com/Class/sound/u11l4d.cfm). Just like when your tire is out of balance, you’ll feel a vibration only a specific speeds.

CaptainRon

like I said, its a process of elimination. Just go thru it one at a time and you'll find the culprit. A harmonic balancer is a dampener. same thing, different terminology. I have heard of them going bad in some sn95 mustangs and +1 on Petrock's comment. It really depends on the resonance or frequency that the vibration can be felt at.

That Grenatelli MAF is a drop in replacement & alone shouldnt cause any problems, unless its just dirty, which i doubt, but you may want to double check and make sure its clean & that your fuel injectors are up to par...

Honestly unless your engine is running different cams or some other hi-po mod your stock factory injectors may be the better choice..

supersnake67

I have the same vibration around 1,800 - 2,000 rpm and thought it was my motor mounts so I put prothane mounts in and it got rid of that 1,800 vibration , but gave me an even worse vibration on take off. So I put the stockers back in. Will buy new rubber mounts soon and hopefully fix the problem. If anyone wants to buy some slightly used poly mounts let me know.