OK, time for an update...
I have only just found out as I tried to replace the last Jaguar unit I had by me which I recently sent out to Geoff Sparkes in New Zealand, how much the trade price for the Jaguar ones has risen by over the last few years; put it like this, with Robsport charging £72.00 for them, they're not making a lot of profit!!!
The Rolon slipper pad failure is now affecting MGA/B/C owners and basically anything that uses 'B' series engines; one MG forum has even referenced this thread, so quality tensioners are now in demand. It has been the case for a while that some Jag specialists have superseded the EAC3629 part number and will supply Rolon rubbish instead.
The New Zealand connection continues as I've been conversing with Bob Wyber over recent months having sent various parts out to him in Dunedin, and during their lockdown Bob has been doing some sterling research into alternatives, so my thanks to Bob for sharing his knowledge with me, which I'll now share with the forum plus a bit more.
The OE MGA/B/C timing chain tensioner is very similar to 'ours', but it too is now copied by 'Made in India' Rolon and is no better quality with many slipper pad failures being reported. Bob found a UK supplier who had a quantity of new old stock, boxed OE 'British Leyland' made in the UK slipper pads for the MG tensioner, which I have now acquired. They differ from the Triumph and Jaguar parts in that where ours have a 'push to release' function post installation which applies the spring tension, the MG version relies on an allen key to rotate the plunger inside the slipper pad shaft post installation to release the tension; this relies on the chassis casting of the tensioner having a co-axial hole so the allen key can be inserted. The hole is tapped to receive a blanking bolt to prevent the oil pressure escaping in use. Other than this hole and bolt the chassis seems identical to Triumph OE with the correct bolt hole spacings to mount to our engine block and with a locating dowel on the back face through which the oil feed runs. The dowel does seem to be a 'gnat's cock' width too big to fit into the hole on a Sprint block, but the only block I have to hand to test it on at the moment is one that has been sitting in my back garden for the last 20 years as an ornament, so it may be the hole in it is contaminated or oxidised...but even if there is a compatibility issue, opening up the hole in the block for the 5 mm or so the dowel protrudes isn't going to be difficult, or alternatively grind the dowel off. The BMC slipper pad has the hole in the rubber to directly lubricate the chain which has been missing on some aftermarket versions.
Anyway, to cut to the chase, there is no known problem with the chassis component of the Rolon brand tensioners, just the slipper pads. Therefore, sourcing a BMC Rolon tensioner, discarding the slipper pad and replacing it with one of the NOS OE slipper pads I've acquired will give a reliable tensioner combination which isn't going to fall apart. I've bought a couple of the Rolon tensioners (with hole and bolt variety) to do just that, and am looking into sources for economic supply of more.
Shortly, I hope to be able to provide costings for supply of a tensioner and OE BMC slipper pad combination, or if you are lucky enough to have the type of chassis with hole and bolt already, I'll be able to supply a quality slipper pad on its own. No doubt some of you are equipped and competent to drill and tap the 'blind' type of chassis also.
Anyway, pictures, as they say are the equivalent to a thousand words:
This is the BMC style tensioner, note the bolt on the back face of the chassis and the dowel on the mating face:
This is the new old stock OE slipper pad:
This is the NOS BMC slipper pad (top on first photo', bottom on second) next to a Jag slipper pad to show the fundamental difference between the two; there is a very slight difference in the curvature of the rubber profile, but in my opinion this is not significant:
This is the NOS BMC slipper pad (LHS) next to the Rolon rubbish variety; note how the NOS BMC one envelops the edges of the metal pad, whereas the Rolon one just sits on top of it:
So, whilst stocks last (should be a while, I might even be able to let MG owners have one or two!) we now have an economic solution to the Sprint timing chain dilemma.
) does the hole in the shaft drop oil onto the chain Before it gets to the pad due to the angle of the chain relative to the pad? Ive not got enough here to mock one up yet.
