Technical Lifting front of car on stands and mounts issues?

[dumbledore]

What I am doing at the moment which also seems to be what Heynes manual suggest is to put a jack under the transmission, then lift the front of the car high enough and then put stands under the front jack points. This works well and seems to be a quick way to get the front on stands. My problem is that this approach will put quite a bit of pressure on the engine/gearbox mounts when the car is raised as the mounts will need to support the whole front weight of the car. I am wondering if lifting the car this way can cause damage to the mounts.

 

[fingers99]

It'll be fine.

 

[portland_bill]

I understand your concerns, it just feels wrong to lift the whole car by the engine mounts. Of course, the weight of the engine and gearbox is supported by the jack, so you're only lifting the car by the mounts. This has often been the recommended way, for all my motor trade life, (40 yrs) but I will always avoid it if possible. If the engine mounts are in good condition, there should be no problem, but if they are weak it may lead to failure. However, if they do fail, they were in need of changing anyway, and this is a better way to find out than on the road. Perhaps we should all do this occasionally to test them?

My method is to jack each side up separately, using the point where the subframe attaches to the body, then put a stand under the subframe or suspension arm, depending on the job to be done. Then move to the other side and repeat. Avoid trolley jack under the sills as they tend to crush the sill edges.

 

[fingers99]

How I see it is that the engine mounts are designed to carry the engine and transaxle in tension. That, and fore and aft play is how they wear/fail.

Thus, compressing them doesn't stress them unduly.

Incidentally, the process isn't just recommended by Haynes, but by FIAT.

 

[dumbledore]

Good to know that lifting the car like that is acceptable and the mounts should survive normally. I am experiencing some vibration at the moment that I can only attribute to the mounts. I replaced the rear gearbox one and will replace the front gearbox one next week.

 

[Elxpunto90]

You will find because you have replaced rear mount you will get vibration I have the same problem when I changed mine if you change the others it will still be there

 

[dumbledore]

You will find because you have replaced rear mount you will get vibration I have the same problem when I changed mine if you change the others it will still be there

I do think that mount is related to this vibration. I changed the clutch and had to change the rear mount as I damaged the old one. I am planning to replace the front one. What I am noticing at the moment is that the vibrations are getting less (or I am starting to get used to them !!!), which if true could mean that the new mount may be causing this.

 

[dumbledore]

Replaced today the front gearbox mount. Initially I thought the old one was knackered, but after some close inspection it appeared to be fine no splits. However, I could easily move the center pin with my hands. The replacement mount is definetelly much stiffer. When I started the engine it sounded quiter, but when in drive it seem not to be much different then before. I will need to do some more testing and also let the mount run in a bit. While doing this work I noticed that now I get some leak on the gearbox that appears to come from the top. I assume it has something to do with the fact I had to take off the top cover to sort out my gear change issues I had after I replaced the clutch.

 

[portland_bill]

You have several issues here, they may be better served with separate threads.

Oil leak is possibly the easiest, look for the highest point of the leak. If you can't find it, clean everything and look at it regularly until the source is apparent.

Vibration: May need more detail if help is to be found.
Was the vibration there before the clutch change, or only since?
At what engine speeds?
Under load, or on overrun?
Driving, or just revving the engine in neutral?
Can you feel any vibration through the clutch pedal when, a) lightly touching it, b) with some pressure on it, c) when fully depressed (the clutch pedal, not you), d) at teh bite point?
Any other symptoms.

 

[dumbledore]

Vibration after Clutch change

Here is some question I got from an earlier thread from User: portland bill
----------
Vibration: May need more detail if help is to be found.
Was the vibration there before the clutch change, or only since?
At what engine speeds?
Under load, or on overrun?
Driving, or just revving the engine in neutral?
Can you feel any vibration through the clutch pedal when, a) lightly touching it, b) with some pressure on it, c) when fully depressed (the clutch pedal, not you), d) at teh bite point?
Any other symptoms.
--------
Answers:
1. Vibration appeared after clutch change
2. It usually happens at lower engine speeds.
3. Under load vibrations are more apperent with a lower pitch. On overrun vibration are still there but the pitch is higher frequencies.
4. Vibration are more pronunced when driving. Engine in neutral produces less vibrations.
5. Vibration cannot be felt really through the clutch pedal at any positions.

6. Other: Vibrations can be felt slightly trough the steering though, Vibrations are definetelly worse when engine is cold. Vibration are noticable at town speeds. At Motorway speeds vibration seem to be same as before.
7. Rear gearbox mount replaced, and now front mount replaced as well following the clutch change. Gearbox was droped to replace the clutch, and driveshaft removed from the CV inner boot and not from gearbox.

 

[blu73]

Re: Vibration after Clutch change

threads merged, no need to start a new one, just carry on here...

 

[dumbledore]

After some more thoughts, I am thinking that the cause of vibration may be to do with the new clutch is not balanced correctly as a assembly with the flywheel and as a result it causes excessive vibration. Is there a way to balance the clutch (through the inspection hole)?

 

[portland_bill]

Only way to balance the clutch assembly is to bolt it complete to a specialist machine. The flywheel should be balanced in its own right. The clutch plate and cover should also have been balanced during manufacture.

Vibration after fitting suggests something is damaged or misaligned.

If the gearbox weight is hung on the centreplate, it can bend the plate. (Like bending a piece of paper, it will never recover) The plate will then flex all the time it is running and will quickly disintegrate. Vibration while running can be a symptom.

If the gearbox is not properly aligned with the engine vibration is likely and rapid failure will follow. If the gearbox shaft is parallel to but not in line with the crank, the centreplate will try to run eccentrically. This will quickly tear it to pieces. If the gearbox is at an angle to the crank, the centreplate is made to flex. It will again tear itself apart, but in a different manner.

Alignment is set with dowels or dowel bolts between gearbox and engine backplate, but on some vehicles these can be displaced, or dowel holes damaged, leading to misalignment. (The Honda gearbox used on Maestro, Montego, Rover 200, 400, 600 and 800 series suffered a lot with this.) A damaged, cracked or bent engine backplate can also cause these issues. Often caused by grounding at some time.

If the vibration has only been apparent since the clutch change, this is the most likely cause. It will sadly need removing and carefully inspecting to diagnose the root cause of the problem.