Tensioners Mechanical or Hydraulic?

[996tt_Stevo]

For Race Car, max RPM 7700... Can't decide what to go with

[Grady Clay]

I used mechanical for my race car.

However, care must be forefront.
My engines were only used for 25 hours of at-speed laps (8300 every shift – 8700 on occasion).
They were also dyno run-in for a couple of hours prior to install and racing.
This allowed re-torque of the heads and rocker arm shafts, adjust the valves (935 rockers), install the rocker arm shaft retainer hardware AND re-adjust the solid tensioners.

I was VERY careful to pre-heat the engine (propane ‘torpedo’) and care during warm-up.
The engines were never started other than for racing (not driving around paddock, in trailer, etc.)

Today, I would use the ‘Turbo’ tensioners with the wide-spaced idler arm.
Simply rebuild them with a new seal kit at every rebuild.

The ‘Carrera’ tensioners have more opportunity for leaks and are no more reliable.

Best,
Grady

[996tt_Stevo]

Thanks Grady... you wouldn't happen to know if that's Part No

930 105 053 00 or 930 105 058 03

[ajwans]

I think we're talking about 3 different things here.

1. Most of Grady's post pertains to solid tensioners, these are manually adjustable
billet parts which are set with the chain box covers off and should be checked
regularly as they cannot self-adjust as the chains stretch with use.





2. Turbo tensioners. These are also known as 930 tensioners although earlier
versions of these exist since the first 911. These are oil filled but not oil fed.
There are quite a few variations of these, you can't fully rely on the casting
number to be sure you are getting the right version. The one Grady recommends
has a narrower arm where the stud goes through to accomodate the wider
idler arm. This is important, the failure mode of these tensioners is related
to idler arm binding on the stud because of the lateral force the tensioner places
on the idler arm. Get or make the wide idler arm. Rebuild kit is 911-105-901-01.

Pelican Parts - Product Information: 930-105-053-00-M260

3. Hydraulic tensioners. These are also known as Carrera tensioners as they were
first indroduced with the 3.2 Carrera I believe. These require the cam oil line
with the extra branch to constantly feed oil into the tensioner. Not rebuildable
AFAIK.

Pelican Parts - Product Information: 930-105-058-03-M260

andy

[996tt_Stevo]

Yip, I get all that, but can't exactly decide which one to go with.

[996tt_Stevo]

Any others out there care to comment

[al lkosmal]

I've always gone with the non-pressure fed tensioners with lock collars. I've had a tensioner fail, but the lock collars prevented it from total collapse and massive destruction.........I trust this combo.

Regards,
al

[chris_seven]

Originally Posted by 996tt_Stevo

Any others out there care to comment

Steve,

I think it is a simple balance of risk.

The more complex the system the more it must tend to fail under race conditions.

I would not use Hydraulic Tensioners at high rpm as I am not totally convinced that they are completely reliable or that they don't have some float at high rpm.

The conventional spring loaded tensioner - Turbo Type with Turbo Idler Arms seem reliable but springs have been known to break which may be due to some resonance but as has been stated you can fit chain savers to eliminate the problem. These parts will eliminate rattle on start up but to some extent may mask chain wear.

The 'solid' tensioner is simple and reliable. It does need some experience to set correctly when cold and will certainly rattle as the engine warms but it shouldn't fail.

With a well maintained Race engine I would favour the solid follower.

I think on race engines chain stretch is a bit of a worry rather than a practical reality and adjusting the chain annually should be enough. (Do chains really stretch or is it wear at the pins that makes them longer? and if is wear then on race engines perhaps they should be changed more often?)

I think a new chain does increase in length when it first runs due to all the pins settling. I believe it then stabilizes and is good for a reasonable length of time.

[996tt_Stevo]

Originally Posted by chris_seven

Steve,

I think it is a simple balance of risk.

The more complex the system the more it must tend to fail under race conditions.

I would not use Hydraulic Tensioners at high rpm as I am not totally convinced that they are completely reliable or that they don't have some float at high rpm.

The conventional spring loaded tensioner - Turbo Type with Turbo Idler Arms seem reliable but springs have been known to break which may be due to some resonance but as has been stated you can fit chain savers to eliminate the problem. These parts will eliminate rattle on start up but to some extent may mask chain wear.

The 'solid' tensioner is simple and reliable. It does need some experience to set correctly when cold and will certainly rattle as the engine warms but it shouldn't fail.

With a well maintained Race engine I would favour the solid follower.

I think on race engines chain stretch is a bit of a worry rather than a practical reality and adjusting the chain annually should be enough. (Do chains really stretch or is it wear at the pins that makes them longer? and if is wear then on race engines perhaps they should be changed more often?)

I think a new chain does increase in length when it first runs due to all the pins settling. I believe it then stabilizes and is good for a reasonable length of time.

Fantastic Chris... Thanks for your input

[aws]

I started using mechanical tensioners on my race engines in 1973 and have never had a failure. I do have several caveats, however. I have always run the engines in on a run stand and then do a leak down, inspect all plugs, adjust valves, torque heads, recheck rocker shaft torque and check cam timing and chain tension. New timing chains stretch substantially and I would not use them on a race engine for that reason unless I absolutely had to. Adjusting the initial chain tension on the bench is critical----I think Henry has a method for doing that, I have always done it by feel. I have not found any adjustment problems with mechanical tensions when using a 25-30 hour overhaul interval.
I have used mechanicals on the street on my own equipment and have found that a 10,000 mile interval for chain adjustment seems to be adequate. My opinion is the late Carrera style tensioners are really the best answer for street use. If you are going to use the late style tensioners on a race engine you should use the spacer kit that Jerry Woods developed and sells on the Smart Racing website.

aws

[996tt_Stevo]

The ones pictured above are JB Racing are they not?... I can't see any pics of the Jerry Wood Tensioners... anyone have any pics?... are they similar to JB Racing ones?

[ajwans]

Originally Posted by 996tt_Stevo

The ones pictured above are JB Racing are they not?... I can't see any pics of the Jerry Wood Tensioners... anyone have any pics?... are they similar to JB Racing ones?

Yes, that's right, JB Racing. Should have added the attribution.

Here's the Jerry Woods spacer kit for pressure fed tensioners:



It's listed on the Smart Racing website under 'engine'.

andy

[neilca]

I run the mechanical tensioners. I haven't had to adjust mine yet. I checked the tension after two races and decided to leave them alone.

[996tt_Stevo]

Neil... what ones did you go for?

[996tt_Stevo]

Originally Posted by ajwans

Yes, that's right, JB Racing. Should have added the attribution.

Here's the Jerry Woods spacer kit for pressure fed tensioners:



It's listed on the Smart Racing website under 'engine'.

andy

I'm lost!... are they not to adapt what you already run?... these look like rollers to me not what JB Racing have

[Flieger]

They fit inside the cylinder of the oil-pressure-fed tensioners to provide a stop to keep them from collapsing all the way in the case of loss of oil pressure. They have to be short enough to allow the piston to move and the spring and damping oil to do their thing and keep the chain in check. You cannot use the safety collars on the pressure-fed tensioners, only the plain oil-filled ones.

[996tt_Stevo]

Thanks for that, I noticed that on another thread, but I am right that these are nothing to do with Solid Mechanical Tensioners, that is a completely different product, yes?!!

[Flieger]

Yes, this is an upgrade for the Carrera oil pressure-fed tensioners, not the solid metal ones.

[neilca]

I made some mechanical tensioners for my 2.0 by pulling the guts out of a hydraulic tensioner and machining an insert that had a bolt in it for adjustment. I bought an old style, looks kinda triangular off ebay for my 2.4. I am not sure who made them.

[H-viken]

Originally Posted by ajwans

Yes, that's right, JB Racing. Should have added the attribution.

Here's the Jerry Woods spacer kit for pressure fed tensioners:



It's listed on the Smart Racing website under 'engine'.

andy

Lifting an old thread - Are these, or other alternatives, still available?

Cheers!

Johan