Fitting a timing chain tensioner a different way

linearaudio · Post by **linearaudio** » Wed Dec 02, 2009 6:55 pm

Hallo BMC! Thank God you are back. We tried our best to "hold the fort" while you were cruising on your steam powered yacht!

Had to bring this mini-project forward as the water pump gave up last night, so it seemed the right time to fit the chain tensioner while the radiator was out! As I didn't want to remove the front panel/grille, I couldn't see a way of finding sufficient clearance to drill the blind hole required for the tensioner pivot in the moggy backplate. So I did it the other way- countersunk the pivot hole in the back of the tensioner bracket, then drilled into the small end of the tensioner pivot with a 4mm drill, to emulate a hollow rivet. Then fitted the pivot pin from the the front and peened the pivot end into the countersink. So it will need a new pin when the tensioner ultimately wears out, but that should be a few years off!

Post by **bmcecosse** » Wed Dec 02, 2009 7:00 pm

Hmm - are you sure the tensioner doesn't need the pin to be anchored into the backplate to hold it in place ? I think it pivots on the anchored pin ? It's a while since i did this - so can't remember now. I suppose as long as the fixing screws are TIGHT - it will be ok!

linearaudio · Post by **linearaudio** » Wed Dec 02, 2009 7:07 pm

bmcecosse wrote:Hmm - are you sure the tensioner doesn't need the pin to be anchored into the backplate to hold it in place ? I think it pivots on the anchored pin ? It's a while since i did this - so can't remember now. I suppose as long as the fixing screws are TIGHT - it will be ok!

As one of the mounting "holes" is a slot, I was a bit confused about whether the head of the pivot should actually be in a tight hole in the original backplate- if so, why the slot, which acts as a nice fine adjustment of the tensioner. And yes of course the fixing screws are tight

Post by **M25VAN** » Wed Dec 02, 2009 8:16 pm

Excellent work linearaudio.

I've got all the bits to do this conversion but drilling the front plate troubled me as the head of the pivot pin was the same thickness as the plate. Your solution works perfectly making it a true bolt on conversion.
When my house move is over this will be a job at the top of the things to do list.

Post by **bmcecosse** » Wed Dec 02, 2009 10:55 pm

The 'slot' allows you to adjust the force (don't make it too tight!) - the bracket should pivot on the head of the pin in the hole. The original ones I have - taken from engines - the head is only about half the thickness of the mounting plate. But - your way will be fine, I'm sure!

linearaudio · Post by **linearaudio** » Thu Dec 03, 2009 7:11 am

bmcecosse wrote:The 'slot' allows you to adjust the force (don't make it too tight!) - the bracket should pivot on the head of the pin in the hole. The original ones I have - taken from engines - the head is only about half the thickness of the mounting plate. But - your way will be fine, I'm sure!

Can't see how it is meant to pivot when one of the mounting screws is in a hole? Surely it would need both fixings to be slotted in order to pivot around the pin head!

Post by **Declan_Burns** » Tue Dec 15, 2009 7:28 am

Has anybody got a photo of this arrangement which might explain the procedure?

Post by **GeorgeHurst** » Tue Dec 15, 2009 10:58 am

I don't have a photo of the specific arrangement linearaudio mentions but do have a photo of the tensioner set up... (not on minor engine, but shows the principle)
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Post by **Declan_Burns** » Tue Dec 15, 2009 11:16 am

Thank you George.
Regards

linearaudio · Post by **linearaudio** » Fri Dec 18, 2009 3:05 pm

Yes, thanks, George! I was trying to remember what it looked like!
Here is a sketch of what I did, hope it clarifies things a bit:<br>

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Post by **GeorgeHurst** » Fri Dec 18, 2009 6:30 pm

That looks like a nice easy approach LA, forgive my ignorance but could you clarify what 'Peen' means and how one would do it? I presume it means folding the edges back to sit flush in the countersink?

linearaudio · Post by **linearaudio** » Fri Dec 18, 2009 6:57 pm

GeorgeHurst wrote:That looks like a nice easy approach LA, forgive my ignorance but could you clarify what 'Peen' means and how one would do it? I presume it means folding the edges back to sit flush in the countersink?

Broadly, yes! It is the method of deforming the end of a rivet so as to produce a strong mechanical joint. Works OK on ships, so should be alright on a Moggy! If you are unsure of the method, or do not have a suitable hammer/punch/support block, then probably not advisable to attempt it. The alternative way, taking the front panel out of the car in order to mark and drill a clearance hole in the engine front plate is also best not tackled by the faint-hearted!

Post by **bmcecosse** » Fri Dec 18, 2009 7:39 pm

You can very easily drill the blind hole while the plate is on the engine! Takes about 2 minutes - just take care to collect all swarf.

linearaudio · Post by **linearaudio** » Fri Dec 18, 2009 8:16 pm

bmcecosse wrote:You can very easily drill the blind hole while the plate is on the engine! Takes about 2 minutes - just take care to collect all swarf.

I think we are at crossed purposes! When I referred to removing the front panel, I meant the front panel of the car, with the grille in it, to get access for an electric drill, or is my drill is a non-standard length?
Two minutes to drill the hole, 30 minutes to remove the grille assembly with all those fiddly hockey strip nuts

Post by **bmcecosse** » Fri Dec 18, 2009 8:35 pm

Ahh right - I would think with the rad out the way - and using a smallish drill - it could be done in place ? I certainly wouldn't be removing the grille!

linearaudio · Post by **linearaudio** » Fri Dec 18, 2009 8:37 pm

bmcecosse wrote:Ahh right - I would think with the rad out the way - and using a smallish drill - it could be done in place ? I certainly wouldn't be removing the grille!

Nor me- hence the alternative

Even with a stub of a drill bit, I couldn't get a good straight line for the hole- go on just admit my way is better

Post by **bmcecosse** » Fri Dec 18, 2009 8:40 pm

Your way sounds ok to me - but more hassle than if the 'right' way can be done easily.

linearaudio · Post by **linearaudio** » Fri Dec 18, 2009 8:42 pm

bmcecosse wrote:Your way sounds ok to me - but more hassle than if the 'right' way can be done easily.

Grrrrr!

Post by **GeorgeHurst** » Sat Dec 19, 2009 12:10 am

I've had a read up about peening and I think I could manage it, my only problem will be getting the 4x3mm hole in the pivot pin as I have no pillar drill.

I'm keen to find a way of doing this without having to drill the frontplate as I don't reckon I could get any of my drills in to drill the hole without removing the front panel which, having fitted it after respray, was horribly tight and fiddly.

Just to throw something out there... perhaps it could work this way...

- Countersink the rear face of the tensioner bracket
- Use a c/s head bolt of the same diameter as the pivot pin and of a suitable length
- Slot the bolt through the bracket with the head at the rear face of the bracket and bolt the front, trim off excess bolt if necessary to avoid fouling timing cover
- Use angle grinder to make head of bolt flush to bracket rear face

My thinking is that this way one can get the benefits of not having to drill the front plate, but also allow replacement of the tensioner pad (as the bolt would be removable) should it wear out...

linearaudio · Post by **linearaudio** » Sat Dec 19, 2009 9:48 am

I didn't use a pillar drill! Hold the pin in a vice/workmate, centre dot the pin end, and drill with a small drill first (around 2.5-3mm), then open out to 4mm. The dimensions given are not set in stone, rather a guide to the general principle! 3mm depth can be easily guestimated, especially if you have a 3mm dia drill as a visual aid.
The possible problem with using a screw as a pivot would be the action of the threads as a rasp, cutting at the inside diameter of the slipper pivot. However in reality it may work fine, just not "top-drawer" engineering practise! Go for the rivetty idea (second drawer down?), if that goes wrong then fall back on the countersunk screw method, in which case cut the thread just proud of the nut when fitted, and "peen" the thread slightly to prevent the nut escaping. There is sufficient headroom in the case for a nut depth.
Nice lateral thinking, by the way!

Morris Minor Owners Club

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