stevensa

Last summer I had a timing chain fail in my car. It was a double roller timing chain of some brand "not sure which" but the links say JWis or JW15 on them. With all of the recent threads about harmonics and how harmonic related chain failures usually result in tight links I decided to pull the old one out and take a look at it to inspect the links. All of the links were nice and free and I also noticed that the pin that failed was the master link.

Is the master link a common weak point on aftermarket chains, did I just get a bad/cheap chain? It looks like the master link pin failed from shear forces which then "kinked" the links.

Gering

OP: If you have to replace the Belt Tensioner, I would recommend this one - http://store.katechengines.com/bille...sioner-p2.aspx If you have to replace your Damper, I your recommend this one - http://store.katechengines.com/ati-s...ts-v-p230.aspx If you have to replace your Timing Chain, I would recommend this one - http://store.katechengines.com/c5-r-...chain-p30.aspx

Do you have an after market Damper other then ATI on your car? Have you replaced your Timing Chain?

taken19

I recently had an timing chain break on me. I believe it was Iwis bought from Katech. No tight links either...

When I get home I will check to see if it was the master link that failed and post a pic or two.

stevensa

Thanks for the info. I see that you are in the woodlands, do you go to any track events at at TWS, MSRH, or GSS?


Thanks, what is the Iwis from Katech? Is that what the links on the c5r chain say?

Gering

No Sir, I have not been to any track events yet. When I have time off I like to hit the back roads when I can. I just hit 132,200 miles on the OD today. PM sent.

taken19

[QUOTE=stevensa;1580557193

Thanks, what is the Iwis from Katech? Is that what the links on the c5r chain say?[/QUOTE]

Yes, C5R chain from Katech. Says Jwis on several I the links. I don't see a "master" link as they all look similar, no markings or differences in pin head to tell the difference.

If there really is an issue with these chains, I would like to be involved in persuing resolution as I lost my whole motor because of this.

stevensa

Gotcha. The master link is hard to tell, but the pin head on mine was ever so slightly different. It had more of a dimpled head than the rest of the pins. As stated above, mine was not a c5r chain, it was some type of double roller chain with the same Jwis links. I believe that the c5r chain is heat treated differently which is supposed to make it stronger. the master link pin is what failed on mine though.

Katech_Zach

Did we determine that your car had an ASP underdrive pulley on it?

taken19

Yes we did. All the other symptoms weren't there, such as "sticky" links. I am by no means blaming anybody, just want to make sure it was the pulley and nothing else. Sorry if you thought I was pointing fingers, that was not my intention. If there is a series of broken chains, I would be interested to see if they all had ASP pulleys or if it could have been caused by something else.

Katech_Zach

I'm counting (on the forum and phone calls to me) about 10-12 broken chains of all brands on cars with ASP underdrive pulleys.

RC45

I am interested to know the outcome.

I have had numerous timing chain failures on LSx based engines.

First chain was a double roller on the cammed LS6 with an ASP under drive pulley. Failed on the freeway back in April 2007.

I downshifted to third and at the top of the 3rd the chain just let go.

The result was a trashed LS6.

The second timing chain failure was also a double roller with an ASP under-drive pulley, 3 weeks into then new 580rwhp LS7 at MSR Houston. Car did 1 on track session, was the second track day with the car. 3 laps into the 2nd session the chain let go at 6800rpm on a down shift coming into Sugar & Spice.

Result 15 trashed valves.

3rd time was a Katech supplied C5R chain (with Katech provided chain tensioner/damper) with ASP under-drive pulley that let go on the street as I pulled away from a traffic light - as I throttle up slightly the rear wheels spun up in recently spilled construction dirt/dust and as the motor tagged about 6800rpm it let go. The LS7 was putting out 600rwhp at the time.

Result 12 trashed valves.

In an effort to try mitigate future failures we removed the .720 lift CamZilla cam and installed a GM Stage III road race cam source from Katech along with yet another new C5R chain and tensioner/damper and new less severe valve springs and a milder 565rwhp is the result.

I would love to know the real cause of the chains letting go - all failed at the master link, but I don't believe the chains where the cause of the failure, they where most likely a symptom/result of piston to valve interference.

Perhaps brought on by valve float? I know the question of valve train harmonics did come up during discussions with various folks over the years.

All I know is that failed timing chains have cost me 2 x $3,500 repairs to the LS7 and a complete engine replacement for the trashed LS6.

If it turns out the under drive pulley was to blame I will be a little p1ssed

At the time I asked the first engine builder if its a good thing and the answer was 'never seen any issues'. This was also the answer in late 2008 when the LS7 was repaired by the second engine builder.

I believe that an ASP underdrive pulley is still on the car - should it be tossed in the trash heap?

**edit** went and checked build sheets and called EG for them to check current status (they are NOT the folks that recommended or installed the ASP ) - ASP pulleys the LS7 both times - and the LS6 also had an ASP under drive on it.

taken19

Yes, I remember that. Kinda sucks that I did this to myself a year prior by choosng ASP. That was a $10k mistake - oops. Live and learn i guess. ATI from here on out!

To the OP, we're you running an ASP UD pulley?

Gering

Katech_Zach

It's pretty clear to me that it's the underdrive pulley. Every time I see a timing chain failure online it's the common part. I would put an ATI on that car immediately.

stevensa

Would you be able to take another look and maybe post some good pictures of your chain to help determine if it was the master link that failed?

How long have you been running this new milder setup with the ASP pulley and c5r chain?


Yes, I do have an ASP pulley currently installed on the car. I am trying to determine if the pulley was the cause, or something else before I replace a bunch of parts for no reason. Like I said in the original post, this happened about a year ago. At that time had I known that the ASP pulley could have been the source I would have just changed it out then.

How many calls have you had about broken chains one stock motors, cammed motors with ATI, powerbond, etc?

I am not trying to start a huge argument here, just trying to get soem good data. From what I have found searching a bit, there are also people who have broken chains on stock cars, cars with ati, powerbond, c5r chains, misc double roller chains, etc, etc.

i have also noticed that the ASP pulley was/is a fairly popular choice for a pulley. I am not sure if this is because it was one of the first available, cheaper, or because of misc articles that are popular for cam installs that mention the ASP unit. My car had one on it when I bought it back in 09.

Basically what I am getting at is, if you have 1000 cars with various setups. 700 have ASP pulleys, 200 have powerbond, 80 stock, and 20 ATI and 35 with the ASP break a chain, 10 with the powerbond, 4 with the stock, and 1 with the ATI you would assume that the ASP pulley breaks a lot of chains, however in each case 5% of each type of pulley had a chain failure.

Also I find it interesting that RC45 broke 3 chains at the master link with one setup and the ASP pulley, and then none after going to something more mild. Maybe the ASP pulley has a hard time with more aggressive setups?

Once again, not trying to start arguments, but rather to continue a good discussion. I am alos by no means looking for a "feel good" reason not to change the ASP out, just looking for more info.

taken19

I will post some pics tomorrow or the next day.

travisnd

ATI or stock. Nothing else. I put an ATI on every C5 I track and take the extra step to pin it and us an ARP bolt. Just one less thing to worry about.

stevensa

I thought the stock ones literally fall apart?

travisnd

I've seen them wear out, but they dampen crank harmonics properly and don't cause broken timing chains.

Shaka

You want to feel good, this aught to do it for yeh.

Mmmm. Some further information into damper and cam drive systems for those inclined. I can't emphasize just how important these components are.
In previous posts I mention some of the shakes and vibration orders that are considered in the design of vibration dampers and valve timing/camshaft drives. Timing chains wear and fail for reasons we used to know little about. Not anymore.

The computer models that they use to design engines these days are pretty amazing compared to the slide rule I used in the 60s, unchanged since the turn of the 19th century with 300 year old formulas..

Its only in the late 90s that computer models arrived with proper timing drive design and analysis capability. Kids graduating out of engineering schools today are loaded with information that did not exist even 5 years ago.

Two engines that suffered because of this lack of knowledge was the Roll Royce Merlin and the Jag 4.2 engine when they stroked it from 3.8. That engine can be made reliable today.
6 cylinder engines are notoriously prone to harmonic disintegration.
Packard was the most experienced V12 engine builder at the time of the war (Since 1908) and that is why RR chose them to build the licensed Packard Merlin.

Their experience in vibration damping allowed Packard to build a superior engine. The Allyson was actually even better than that. No computers in the 30s. I digress.

Computers sure changed the world and engine design is in it's infancy as a result. Durability, displacement, mass and thermal efficiency will reach seemingly imposible gains in the next decade.

The modern computer modeling capability can analyze a multitude of engine inputs in order to modify or design cam drive and crankshaft damping systems.

Here are some of the elements that can be analyzed in whole or part. Thisshows the multitude of factors that are considered just in this isolated region of engine design.

There was a time when an engineer designed the whole engine. Now each component requires specialization.

Programs employ investigative systems that optimize gears, shafts, belts and chain configurations. Analysis shows dynamic components of all mode led drive train elements and their effect on damper and timing drives and chains. They are modeled as a 'lumped' mass system or single elements.

It is best to buy engine components that are supplied by a reputable company that employ such computer modeling capability.

It will save you a bundle later even if you think the price of entry is exorbitant.
The dynamic behavior (motions forces and torques) of the various elements of the system is calculated in time domain by a step by step integration.

External loads ( forces and torques) and speed irregularity at one gear, pulley, sprocket or shaft can be considered in isolation or lumped together. The model calculates dynamic deflections, velocities, accelerations, forces and torques in all the timing drive elements.

For gear driven systems the influence on the dynamic behavior by periodically varying meshing stiffness's and/or changing back lashes in the tooth meshes (Because of bending deformation of shafts) can be considered, thus even investigations into noise generating mechanisms like gear rattle can be performed.

The technology in mechanical/acoustical engineering reached its height in the BMW/Rolls Royce engine. The design approach deviated from the 7 series V12 engine and very little is interchangible between the two. There is a SAE paper on it. It is mind boggling for those who are so inclined.

The elements for chain drive systems simulate longitudinal and transversal vibrations and investigate things like:

Polygon effect( (periodical fluctuations in engagement and disengagement reactions in chains.

Relative motion between chain and tooth mesh.

Engagement impacts at guides and sprockets

Influence of torsional and bending vibrations of pulley/ sprockets and corresponding shafts.

Influence of manufacturing tolerances (eccentricity of pulleys sprockets imperfect geometry of tooth meshes.

Shaft elements are represented in the same way as beam elements in infinite element calculations.

There are spring damper mass elements which consider torsional and bending motion of the shafts.

Rivets and beam design are still mainstay engineering subjects.

Radial bearing elements are considered in slide and stiffness and structure dampening as well as the hydrodynamics in the bearings.

Thrust bearings representation considers structure and axial clearance of the hydrodynamic effect in the optimum clearance range which can be represented as viscous damping.

Someone on another thread had his oil analyzed and they found aluminum. The lubricants have a damping effect and analysis of all lubricants should be a regular procedure.
Worn thrust bearings on crankshaft and cams put unbelievable loads on the chain and excessive clearances destroy viscous dampening. There is much to check when replacing these components.
Better have some one who understand engine dynamics. Going racing requires more than a qualified mechanic.

Chain elements are represented as a separate rigid body with elastic elements between the chain and sprocket. The contact with sprocket guides tensioners described as discrete contour points or can be modeled using contours of arcs and lines and so on.

Gear elements are represented by mass and moment of inertia.
The gear meshes are described by backlash, stiffness, damping and geometry data ( Helical angle) with a specific pre processing tool, these parameters can be calculated based on geometric gear parameters.

Things like variation of tooth mesh stiffness during contact and damping in the back lash region is considered.

Changes in flank contact and the according tooth forces and impacts are calculated. You simply can't change the chain alone. The sprockets and chain are matched and sprocket tooth design is as critical as cam lobe design. This is not a bicycle chain.

All this data is essential for proper vibration damper design. Forces, motions and torques of all gear train elements are included in addition to dynamic equivalent tooth forces in gear meshes (for use in calculation of safety factors against bending fatigue and surface deterioration) and impact pulses in the gear meshes( for assessment of radiated noise) This is appart from information gained from engine components I described in a previous post.
.
The next time you lookat your little timing chain, give it it's due respect. did this help?