Quick answers for vexing GQ gearbox problem

Submitted: Thursday, Mar 31, 2005 at 17:48
ThreadID: 21661 Views:1500 Replies:3 FollowUps:3
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G'day all

The gearbox is out of the GQ and the thrust bearing, spigot bearing, rear engine seal and rear gearbox seal have all been replaced. The clutch plate is OK and good for many more k's and does not need replacing.

The problem is that the flywheel is out of round by 2mm and also has two severe scuff marks on it. The workshop manual says replace flywheel if it is out by 0.1mm

A new flywheel is $575.55 ex Adelaide or Melbourne. I am however, taking the flywheel to an engineering shop in a neighbouring town, first thing in the morning, to see if they could face the drive plate to a smaller tolerance.

Has anyone had experience with this sort of problem? If so how did you remedy it without resorting to buying a new flywheel.
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Reply By: brenn dog - Thursday, Mar 31, 2005 at 18:36

Thursday, Mar 31, 2005 at 18:36
Hi willem , I see that you are going along just nice with the clutch remove and replace. It is very common to have that sort of runout on the flywheel, you have to get it machined back to flat again . your local brake shop should be able to machine it for you as it is a brake lathe that they use for flywheels..
AnswerID: 104538

Reply By: Wayne (NSW) - Thursday, Mar 31, 2005 at 18:36

Thursday, Mar 31, 2005 at 18:36

2mm is a lot of run out.I don't that machining the face will help as they will have to machine the back of the flywheel as well.
You might be better off trying to get a second hand one from a wrecker and have that machined.
I think that flywheels have to be ground and not just placed in a lath and faced.

For the flywheel to be out that much I would also be wanting to find out why it has gone out of round.

When you say out of round by 2mm, do you mean the face is not true by 2mm or the flywheel is moving up and down by 2mm?

AnswerID: 104539

Follow Up By: Willem - Thursday, Mar 31, 2005 at 19:46

Thursday, Mar 31, 2005 at 19:46
Sorry I did not explain myself well enough. The flywheel as a wobble so that it is difficult to successfully griund it back on a brake-machining machine. Am taking it to a proper engineering shop tomorrow early and will see what they suggest.
FollowupID: 361892

Reply By: Member - 'Lucy' - Thursday, Mar 31, 2005 at 20:09

Thursday, Mar 31, 2005 at 20:09
Evening Willem.

Mate, I have no idea why it is out of round, however if you told me it was a Borg-Warner product then the connundrum would be instantly solved.

I have had personal experiences with their gearboxs having 'an oil seal surface out of round on the front seal which leaked gallons of oil into a number of replacement clutches until it was diagnosed correctly, and their c r a p flywheels weren't flat, or machined at 90Deg to the centre line as well as full of hard spots.

Solution to the Oil seal surface on the main drive shaft from the gear box to the engine(via the clutch) was to replace this shaft entirely because it is also the 4th gear in the gear box.

Yes! in theory the seal surface could have been machined into round with the drive shaft and an oversize seal fitted, however the cost was going to be triple supplying and fitting a new fourth gear/drive shaft. Which is what I had done. Oil leak solved.

Solution to the Flywheel situation was to take it to an engine reconditioner and have what they call the 'step down' machined deeper and at 90deg to the centre line (ie drive line) and then clutch plate surface of same machine clear of hard spots.

Tip: You can only get this done correctly in a machine shop. I went down the Brake Shop path once and never again. Its not much dearer if you organised it yourself.

Now for your problem: If I am reading this correctly, when you look at your flywheel on the engine, when it rotates it would look like cam rotating and not a perfectly centred disk like it should be.

If this is the case I would respectfully suggest that if it could be corrected then the time and effort spent in doing so will exceed replacing it.

If it was me I would source one from the wreckers, if necessary replace the ring gear or take it off and reverse it like some do.

Extra Tip: If your flywheel is as describe then imagine it rotating at a milliom mile an hour off centre and grabbing that clutch plate in a different off centre position every time it engaged and disengaged. I would suggest that even if the clutch and pressure plate 'look' allright, this may not be the case.

A new clutch kit may be a prudent thought.

Whatever, this may give you an idea or two

AnswerID: 104562

Follow Up By: Willem - Thursday, Mar 31, 2005 at 20:21

Thursday, Mar 31, 2005 at 20:21
Hi Ken

The funny thing is that everything has been working perfectly. No clutch shudder, no noise or anything. The only noise which was audible was the thrust bearing which was stuffed. As stated before to Wayne, the drive plate has a wobble sideways of about 2mm(estimate). The teeth on the flywheel are in perfect condition.

The clutch plate is clean with absolutely no markings on it and evenly worn(It was replaced about 18 months ago by the previous owner) The pressure plate is fine and looks like new.

A mystery!
FollowupID: 361899

Follow Up By: Member - 'Lucy' - Thursday, Mar 31, 2005 at 20:35

Thursday, Mar 31, 2005 at 20:35
Wait and see what the machine shop techo's say and advise.
FollowupID: 361907

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