Timing Chain Tensioners - SOCTFL Investigation

[Guest]

Dear Members

One of the next items that seemed popular on the recent forum vote was the timing chain tensioners.

In order to just understand the issues here could those who voted for it provide us with the following information

1) Why are you changing them?

2) If you are changing them as a matter of course ( ie a certain mileage is reached ) are you seeing any wear or deteriation in the old tensioners and if so exactly where ? Pictures would help.

3) Has anyone been able to source these recently, if so where from and were you happy with the quality.

We look forward to your comments.

Regards

SOCTFL

[Bob Heritage]

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One thing about the new tensioners, can you enlighten us to the advantages of the oilway coming out before the tensioner instead through the centre as originals were. The theory is probably to pre-oil the pad but does this work as an advantage or just cheaper to manufacture?

[NickA]

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Thought Rolon was the only company manufacturingtensioners? so the suppliers are all supplying the same product?

I'm very happy with my Renold ones though; in a nice BL box as well!!

I swapped mine as I didn't like the location of the oil hole as mentioned by Bob and the resulting lack of oil flow to the chains. Didn't leave them inlong enough to see how they wore.

[alan_thomas]

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I am unable to confirm what I am about to say but someone may be able to help out here.

Its true the remanufactured tensioners have the hole in a different place than the Stag 'Renolds' originals but, having played with TR7 motors for a long time before owning my Stag I believe the original Triumph designed tensioner for the TR7 had the hole in the same place as the remanufactured ones. ie Triumph found the repositioned oil hole was an improvement on their original design and cutin a change on their later motors. The remanufacturers simply copied the later design.

As I say my TR7 stuff has long gone but maybe someone can confirm this. Anyone seen the tensioners from the Saab slant 4?

- Alan

[StagnJag]

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If I remember correctly, the base plates for the re manufactured tensioners are currently missing the 'hook' on the end that prevents the tensioner from coming all the way out when the chain stretches and reaches the end of its life.

Rgds

Dave

[Ian Durrant]

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The last set of tensioners I bought, the body was missing the dowel that locates it on the engine block and the oil hole was really really tiny. So tiny compared to an original renold that I could easily see it getting blocked and additionally not supplying enough oil to keep the tensioner well damped or the chain well oiled. I threw them in the bin and reused my old tensioners.

[SOCTFL]

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Bob Heritage wrote:

One thing about the new tensioners, can you enlighten us to the advantages of the oilway coming out before the tensioner instead through the centre as originals were. The theory is probably to pre-oil the pad but does this work as an advantage or just cheaper to manufacture?

To be honest we are not sure why the design was changed, however it is believed that one design has a bigger hole to feed the oil through than the other and the bigger hole is much less likely to block than the smaller one. Apart from this we can see little difference or benefit betweenthetwo.

Hopefully we will get some furtherfeedback from members on this issue in this thread.

Regards

SOCTFL

[Ian Durrant]

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Surely a smaller hole means 1) less oil can pass to oil the chains and the rubber foot and 2) however tight the tensioner piston is in the bore if it is not to seize it must also leak some of the oil. In the currently available tensioners the oil hole that transfers oil from the engine block gallery is so small, it cannot possibly supply enough oil to keep the bore filled to act as the damper the chains need as far as i can see.

If triumphs later design also had this miniscule hole then maybe its enough, but honestly I cannot see that as being the case.

Next bit added.

here is some video on youtube

http://www.youtube.com/watch?v=rfcLGNo1wx8

and

http://www.youtube.com/watch?v=FxJuGzelPN4&NR=1

these appear to me to be the new style tensioners. firstly note the tensioner was originally blocked and secondly, despite the slight increase in damping that can be observered, also note just how much oil pours out through the piston to bore clearance. surely that tiny transfer hole is not filling the bore and therefore not damping as much. The point is the bore piston clearance even if small, is much much more of an area than the almost microscopic oil feed hole.

Triumph would have tested any mods, so if the later tensioners were identical in design to the currently available, then all is probably well, but if they weren't you can be pretty sure nobody has properly tested the ones we have supplied now!

[NickA]

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Ian Durrant wrote:

<snip>
Triumph would have tested any mods, so if the later tensioners were identical in design to the currently available, then all is probably well, but if they weren't you can be pretty sure nobody has properly tested the ones we have supplied now!

Interesting Videos

Does anyone have a factory supplied tensioner with the alternate oil hole? I remember buying a tensioner for my TR7 in the early 80's and it still had the hole in the slipper face.

[marshman]

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The two videos were posted by me when I was having problems with knocking noises and oil pressure being too high.

The tensioners were indeed Rolon ones. The oilfeed hole to the tensioner on the left hand chain was blocked - not the hole in the piston. When I examined both tensioners and a new pair (again Rolon) I was disturbed to find a largevariation in the hole sizes. The holes in the pistons were consistant but the feed hole was not - some were really tiny whilst others were larger.I drilled out the holes to around 1mm in both tensioners. Unfortunately I could not drill the piston hole as they appear to be hardened.

The second video shows that there is adequate oil flow to the chains and to me the movement is well damped. The original tensioners had done around 10,000miles and showed no signs of wear other than a shallow indentation in the pad.

The only issue appears to be the small and variable size of the feed hole.The exit hole being at the side or in the pad makes no difference in my opinion - either way there is plenty of oil getting on the chain.

If fitting new tensioners I would make sure that the feed hole is at least 1mm in diameter, if not then drill it out to this size. There is little you can do about the hole in the piston.

It would be interesting to see a similar video of the original style tensioners in action if anyone has theirs apart at some stage.

Roger

[flying farmer]

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I am in the process of fitting the timing gear to my spare engine using a pair of iwis chains and the original renolds tensioners as they are hardly worn.

Guess what, the oil holes are in the stem of the tensioners just like the new repro ones. I guess that clears up the arguement of where the holes were in renolds tensioners, but as to which of the two designs came first I have no idea:?

Neil

[marshman]

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Hi Neil,

Thats insteresting. What size are the holes? both the feed hole into the main body and the hole in the piston side.

both holes seem to vary in size in the Rolon tensioners I have - i have actually looked at a total of 6 different tensioners.

Roger

[Stagdad]

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I've done a mix of renolds holder and rolon pison because i liked the peg for the oilway on the renold but my rubber feet were worn so i used the rolon ones.the fit seemed to be spot on.Hope i wont regret it.

Cheers Steve

[Bob Heritage]

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Stagdad wrote:

I've done a mix of renolds holder and rolon pison because i liked the peg for the oilway on the renold but my rubber feet were worn so i used the rolon ones.the fit seemed to be spot on.Hope i wont regret it.

Cheers Steve

Done the same

[confrench]

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I agree with you,however dont forget the input hole should be of a size that restricts oilflow so as to maintain oil pressure in the main oil gallery.I once fitted a Saab high pressure pump and although the oil pressure stayed high{50lbs]the shoes onthe tensioners soon had deep grooves in them.When you start from cold the pressure would push the pistons out of the tensioners to the next notch and not go back.The lesson was learnt.These engines run on a lot lower oil pressure than you would think,hence they never fitted a pressure gauge,but a clock instead!