johny

yes its difficult to see how a modern sealed battery can have an internal gas explosion ignited by an external source like a connection spark....

modern sealed batteries dont contain free acid as its all held in a gel or a glass mat which offers both disadvantages and advantages (eg. no spillage). One failure mode is that the lead connections between the plates inside the battery are gradually eaten away and when that reaches a certain point cant carry the high starting current without overheating which can then start a rapid downward spiral....

Cant see that an external hydrogen explosion would have split the battery case like that - think its more likely to have been a high internal resistance or short inside somewhere that quickly generated a lot of heat during the engine start up causing an rapid expansion of the battery contents.....

hmmm usually the warranty on the free replacement battery is only for long as the original was going to last but in your case dont know how that would work......

ah they were happy days werent they before Health n Safety and Risk Assessments?

When jump starting anything in the future I'll definitely be keeping out of the way!

ha, no in my book a ruptured battery case implies a major occurence and an exploded one a disaster! Where these recent events? If so I think there should be a warning in the engine bay.....

What casing ruptured and acid sprayed out?

As I understand it car batteries internally have ~2v cells connected in parallel and series to give current and voltage respectively. Then if a connection or cell fails you can still have an overall good normal voltage but on starting it drops excessively so giving slow cranking. Of course, as said, it can also be down to poor cable connections/resistance but on modern stuff that is less likely. Many times I have detected the battery deteriorating on my everyday cars by a slowing in start up and then subsequently leave it until it fails completely giving me loads of problems! Theres that advice about making sure youre never exposed to a battery during starting because of the risk of an internal short and explosive release of acid but Ive never known anyone whose experienced it so wonder if its another of the many urban myths......

not a bad idea Paul. Have you ever made a successful battery replacement claim?

In reality I bet the number of warranty claims are miniscule as the manufacturers know pretty well how long the battery is going to last (usually just outside the warranty period), then I believe its got to be complete failure as opposed to just slow engine turn over and finally the owner has to find the original receipt after up to 5 years!

Tanya have it as 031 but it appears that size can come with different outputs. It must be about the biggest that will go in and I did have to extend the battery clamp rods a little although its such a lump its not going anywhere.....

Yes complete bolt removal is the best way to ensure 100% lubrication but note on my MK1 Vitesse the radius arm has to be dropped out of its vertical link bracket to be able to tap the bolt all the way out....

Ive got an Exide EA755 in my standard Vitesse so 75ah and 630A which has been and is brilliant. Its not that it needs that cranking power but more that I can leave it for ages (no power supply for a trickle charger) and its still got enough to spin and push a bit of oil around the engine before firing.

I avoid Halfords because of their prices as it annoys me that you have to wait for a sale or have a trade card to get a good deal. How much of a mark up are they normally making when theres still profit in the lower prices????

yes you must be able to move the bolt along its length not just rotate it to prove that its not rusted into the trunnion sleeve (I believe they now come in SS to prevent this). I dont think I would take the bolt out completely as it'll be hassle to reassemble so instead just tap it through a bit and try to get some lube in. While your there, if not done recently, you could grease the wheel bearings but best done with the drums off to check that excess grease isnt making its way into the brakes....

I think the manufacturer/quality is always important and even more so for classic cars that dont get used frequently. Obviously Bosch, Varta, Yuasa etc are good but also pricey so I prefer Exide (and other makes like Hankook who sell them under their name) for a great price/qualtiy balance....

Out of interest, where do we think diff whines come from: the bearings, the gears or both? With the propshaft now that weve established its a posh 'frictionless' jobbie Im even more doubtful that its the source of the loud knock.....

youre right and I didnt know but it appears that a 'frictionless' prop was fitted for a while before they went to the simpler type. Also if it is worn theres nothing that can be done other than replacement probably using the later more common design. With the diff I think Pete is warning that its quite a complicated item that can be difficult to overhaul successfully and I agree....

eh! loose rollers - are we talking about the sliding joint here? As far as I know theyre all the same (with the exception of the earliest types) having a splined bar on the propshaft end onto which the coupling with its u/j slides. The there's a threaded cap that you do up onto the end of the coupling part to retain it. Theres no rollers and shouldnt be any loose parts unless some of the splines have broken off.......

When I took my prop in for a balance they found it bent! Dont know how that had happened but it needed heat on it to be straightened after which it was successfully balanced....

Pete, do you reckon it could be put back together 180º out and affect the balance? What were the symptoms of the wear in your case and do you think theres any chance with thin strips of shim to pack out the splines?

well Ive had mine apart before and cant see any problem except that perhaps the shaft was balanced assembled so that if the splined shaft is put back differently the balance will be out.....

wow well if its definitely not u/js or the backlash clonk coming from the diff or gearbox gears as you rotate the prop back and forth then its got to be the splines and replacement is the only option. Saying that mine has some play in it (but doesnt give a clonk) and Ive been toying with the idea of making thin strips of steel shim to insert in the splines! Probably wont work or they wont last very long but I do love a good fiddle - as long as its cheap of course......

when you say play do you mean radial or rotational? There will always be some play especially radially and I think it would have to be huge to make a knock so its much more likely to be something else such as a bush/mounting on: suspension, tie arms, leaf spring, differential, gearbox, exhaust etc