Flywheel Bolts and Crank Spigot

[JC]

As a natural follow-on to my previous query on choice of replacement clutch ...

I took off the flywheel yesterday to get it skimmed - and I've a couple of queries

1. I presume it's good practice to replace the 10 flywheel bolts? I remember being told that these can stretch - or it that a spurious Old Wives Tale?

2. The crank spigot is now staring at me!! I'm assuming it would be also good practice to replace this? Is this going to be easy to replace, or do I need a specialist puller?

Cheers, John C

[christopher storey]

I think the bolt stretch is an old wives tale ( all bolts stretch under tension) but for the cost entailed it can do no harm to replace them with ( I presume) grade 8 setscrews C 4855

Do you mean the spigot bearing ( the phosphor bronze bush )? The usual way of getting this out is to put a suitable threaded bar or tap into it and then grip the other end with eg a stillson or self clamping wrench and gently tap the wrench in the outwards direction

[mgcjag]

Hi John an easy way to get the spigot bearing out is to stuff the hole with very wet tissue paper ...place a rod/bolt as close to hole size as poss on the paper and whack with a hammer.....the hydraulic pressure created in crushing the wet tissue forces the bearing out.....Steve

[Series1 Stu]

Or use a grease gun and pump grease into the hole and it will push the spigot bearing out. Piece of cake and no risk of damage. Don't forget to soak the replacement in oil for at least 24 hours.

As for the bolt stretch, it is a thing. There are many instances where bolts are fitted and tightened just beyond their yield strength but below their ultimate tensile strength. It is to ensure that the joint will maintain its clamping force through the loading cycles it endures.This is why bolts and studs are sometimes supposed to be replaced after being disassembled. Your service manual will advise where this is necessary. I'm not sure whether this is the case with flywheel mounting bolts but there can be no harm in doing so. I would expect T grade screws would be used here, which is the British grade approximate equivalent to US Grade 8.

Regards

Regards

[PeterCrespin]

As for the bolt stretch, it is a thing. There are many instances where bolts are fitted and tightened just beyond their yield strength but below their ultimate tensile strength. It is to ensure that the joint will maintain its clamping force through the loading cycles it endures.

Sorry, but there are no torque to yield bolts on any stock E-Type and certainly not short, fat, steel to steel joint fasteners like flywheel bolts. That's precisely why they used lock tabs, because it's not practical to rely solely on stretch for such a chunky short bolt.

Jaguar only introduced torque to yield on the all-alloy sixes in the mid 1980s, where long, thin fasteners holding alloy castings are a classic use for that tech.

The issue with flywheel bolts is to be sure to use the fractionally longer manual flywheel bolts if doing an auto to manual conversion. For the rest, for a normal street engine if the flywheel threads are undamaged I normally inspect and reuse the bolts with blue Loctite as well as fresh tab washer.

[abowie]

if the flywheel threads are undamaged I normally inspect and reuse the bolts with blue Loctite as well as fresh tab washer.

I agree with Peter. We never replace the flywheel bolts.

[angelw]

Stuart Wrote:

Or use a grease gun and pump grease into the hole and it will push the spigot bearing out. Piece of cake and no risk of damage. Don't forget to soak the replacement in oil for at least 24 hours.

Hello Stuart,
How would that work? There has to be some means of containing the grease and forcing it to act on the bottom end of the spigot bush to push it out. Simply pumping grease into the bore would require a component of the grease outlet to be a neat fit in the bore and then you would be fighting the pressure to keep it in place and for the bush to be pushed out. The grease will seek the easiest route out and if that happens to be past the nozzle, or if the nozzle is a neat fit in the bore of the bush, you have to be stronger than the grip of the bush in the fly wheel.

On occasions, the bush can be quite loose and then it would be possible with just the use of a grease gun alone. But mostly its a good interference fit and will require a solution as suggested by Steve with the wet tissue paper; bread instead of tissue paper also works and I've used grease in the same way as with the wet tissue paper, but never with just a grease gun.

The hydraulic method can be hit and miss if the bush is tight, but the never fail method is to cut a thread in the bore of the bush with a suitable tap and then use a bolt to either jack it out of the fly wheel, or in conjunction with a slide hammer to pull the bush out.

Regards,

Bill

[steve3.8]

I've tried removing a spigot bush by grease and hammering a made to size pin ,would not budge -- so tapped and used a draw bolt.
Even though the flywheel is potentially spinning at 5000 rpm five inches from your ankle a new lockplate + original bolts in good order are fine - the 10 flywheel bolts are backed up by the 2 dowels that provide a direct fit/drive.The only replacement bolts i would trust would be ARP - Rob Beere and not unbranded from the usual suppliers.

Edit- John , it's preferable to get your flywheel ground not turned .

[Series1 Stu]

Sorry, but there are no torque to yield bolts on any stock E-Type and certainly not short, fat, steel to steel joint fasteners like flywheel bolts. That's precisely why they used lock tabs, because it's not practical to rely solely on stretch for such a chunky short bolt.

If you read carefully what I said you will realise that I was correcting Christopher's assertion that torque to yield is an old wife's tale. I also said that there is no harm in changing the bolts because you never know what abuse they may have had in the past. By all means re-use bolts if you know they haven't been overtightened, most applications are designed for re-use. Everything we do is designed for re-use to avoid the need for carry-on-board spares.

Regards

[Series1 Stu]

Hello Stuart,
How would that work? There has to be some means of containing the grease and forcing it to act on the bottom end of the spigot bush to push it out. Simply pumping grease into the bore would require a component of the grease outlet to be a neat fit in the bore and then you would be fighting the pressure to keep it in place and for the bush to be pushed out. The grease will seek the easiest route out and if that happens to be past the nozzle, or if the nozzle is a neat fit in the bore of the bush, you have to be stronger than the grip of the bush in the fly wheel.

Regards,

Bill

What can I say? It worked for me. It was a long time ago and it was a tip I got from Derek Watson when I converted to the T5 gearbox. The radius of the grease gun nozzle seated against the spigot bush hole and provided enough of a seal to jack the bush out.

I guess I just got lucky.

Regards

[PeterCrespin]

If you read carefully what I said you will realise that I was correcting Christopher's assertion that torque to yield is an old wife's tale. I also said that there is no harm in changing the bolts because you never know what abuse they may have had in the past.

Rather than talk to excess or snap, I will yield to your somewhat elastic argument if you twist my arm.

[Series1 Stu]

Rather than talk to excess or snap, I will yield to your somewhat elastic argument if you twist my arm.

The stress is too much to bear. I'll wrench myself away now.



Regards

[MarekH]

Grease in the spigot bush hole works a treat. The key thing is that the dowel you whack is (very nearly) exactly the same diameter as the hole it goes into. The grease can't get out, so the bush has to come out as the hydraulic force from the whack exceeds the friction holding the bush in the flywheel. It's a very neat trick.

kind regards
Marek

[Dawnpatrol]

Hi John,
I also agree with Peter, in fact so much so I'll happily accept your olds ones and recycle them for you
At about 7-8 quid each it's an unnecessary expensive if not obviously damaged.
More importantly, you will foreever worry that the next person in your position will know it's not matching numbers without the Bees markings on the head
Regards,
Michael

[JC]

Thanks again for the comments, advice and humour!!

For those interested, I employed the wet tissue extraction approach - with some considerable scepticism!! I was flabbergasted when with lightish taps of a hefty lump hammer, the spigot moved!! I needed to reload the tissue when the spigot was halfway out, but then out it came with a few more taps!!!

Cheers, John C

[mgcjag]

were here to help. ...great it worked for you.....one of the simple E type jobs Steve