What are some car-repair jobs you always wished you could do

On Mon, 6 Nov 2017 20:36:45 -0000, "Ian Field"
<gangprobing.alien1@virginmedia.com> wrote:

"TekkieŽ" <Tekkie@comcast.net> wrote in message
news:RM2MB.70895$Q03.48094@fx44.iad...
RS Wood posted for all of us...



What are some car-repair jobs you always wished you could do but have
never
done?

Mine are, in this order of "I wish I could do it" order
1. painting
2. alignment
3. replace/rebuild engine
4. clutch replacement
5. tire mounting and balancing
6. timing belt
7. head gasket and vcg

I've done electrical, brakes, shocks, cooling systems, alternators,
ujoints, pitman/idler arms & tie-rod ends and ball joints, tuneups,
emissions hoses and sensors, exhaust, electrical components, fuel pumps,
and fluids, but not the six things above.

What are some car-repair jobs you always wished you could do but have
never
done?

I have done all except #3.

The worst job I consider is exhaust. I guess that has diminished these
days.

The hardest is being a good diagnostician.

Diagnostics can be challenging when *EVERYTHING* rattles.................

a hand full of loose nuts and bolts thrown into closed body sections
by disgruntled union workers during "job action" was the worst one I
had to deal with - AMC in '72??

A friend found a full can of beer inside e tire that wouldn't balance
- I believe it was a GM in the sixties? Early in the canned beer era,
anyway.

 

[Frank]

On Mon, 06 Nov 2017 04:49:21 +0000, RS Wood wrote:

Frank wrote:

Chains are hardly ideal. Chains wear. The wear changes the pitch
between the links and the links no longer quite fit on the sprockets.
It turns into a self reinforcing cycle. More wear = worse fit, worse
fit = accelerated wear. Eventually the poorly fitting chain will jump
one or more teeth on the crank gear or start breaking the teeth on the
cam gear.

What are our choices?
1. Chain 2. Belt 3. Pushrod

Anything else?

The other effect of chain wear is retarded cam timing. The more worn
links between the crank and cam, the more the camshaft timing gets
retarded. I changed timing sets on conventional OHV engines and that
usually advanced the ignition timing from 5 to 10 degrees, suggesting
that chain wear had retarded the timing by that amount.

From a repair standpoint, how long do each typically last?
1. Chain ?

Depends what you mean by "how long does it typically last?"

Timing sets on OHV engines typically wouldn't totally fail at under
100,000 miles. Most of those sets were used in the days when cars were
junked at about that mileage. Alot of those cars were junked because the
timing set failed.

But I'd guess timing set wear would retard cam timing around 1/2 to 1
degree every 10,000 miles. If we set an arbitrary failure spec of, say 3
degrees, then the set would have gone out at 30 to 60,000 miles. Of
course, the car would run even if the camshaft were retarded more than
this and the driver usually became acclimated to the poorer performance
and gas mileage.

> 2. Belt ?

I don't know. My car requires belt replacement every 100,000 miles or
six years. I replaced the belt at eight years and it looked perfect.
There's no significant timing change as the belt ages, until it fails.
An insignificant number fail before the required maintenance time.

> 3. Pushrod ?

I don't know what you're getting at. Most US pushrod engines drive the
cam with sprockets and a chain. A few used gears. A few antique
motorcycles used tower shafts and bevel gears. Maybe some auto engines?
dunno.

I don't hear anyone talking about pushrods, so, all I see here are that
chains last a *lot* longer in general than do belts, where if either one
broke on an interference engine, expensive things can happen.

Pushrod engines can be interference engines. Not sure what you're
getting at.

But I still prefer belts. Even on a tight package like a Dodge Neon
with the 4 speed auto, the replacement isn't too bad, once you know the
routine.

If the replacement isn't bad, then the belt isn't 'as' bad.

Easiest belt replacement I ever did was on an early Fox body Mustang with
the 2.3 liter 4. Take of the drive belts, take off the timing belt
cover, swap the belts. With some practice and preperation, it would be a
clean, 15 minute job.

Much easier and cleaner than replacing a chain timing set!!

In the general sense though, belts, I posit, are bad news multiplied.
I try not to take things from the marketing-bullshit standpoint.

My take is always from the *why* standpoint.
Why did the automakers go to belts over chains?

My supposition is that they did it to save them money.
No other reason.

Camshaft timing.

The tradoffs are legendary where the owner is the one who loses in the
end calculation.

Belts became important when Overhead cams became important. A worn chain
in a cam in block engine has, off the top of my head, 10 links between
the crank sprocket and the cam sprocket. What about a OHC motor? Say 30
links? 10 worn links might retard cam timing 5 degrees. What about 30
worn links?

Just like FWD cars and tricked-out cars are, to me, nearly worthless.

I love front wheel drive, especially in the snow.

Lots of cars are FWD that never see snow.

In the general sense though, FWD, I posit, is bad news multiplied.
I try not to take things from the marketing-bullshit standpoint.

My take is always from the *why* standpoint.
Why did the automakers go to FWD over RWD?

My supposition is that they did it to save them money.
No other reason.

The tradoffs are legendary where the owner is the one who loses in the
end calculation (particularly since deep snow is still on the road for
what, maybe 10 days out of 365?)

Anyone who mentions snow with FWD is falling directly into marketing
hell.

Bullshit. Here in Chicago, traffic flows much better in the snow than it
did 30 years ago. In fact, I haven't seen a car stuck in the snow in at
least a couple of years.

Stuck RWD cars used to impede rush hour traffic on a routine basis.
Nowadays, I haven't been late to work because of the snow in those two
years.

Or, maybe it's the FIRE OF MARKETING HELL that's taking care of the
snow. Either way, I'll take it.

Just like anyone who mentions belts are "quieter" and "lighter" is
doing.

The sole reason for belts and FWD is to increase manufacturer's profits.
Everything else is marketing bullshit because the tradeoffs are
legendary.

I know. The "donut in a snowy parking lot" crowd is almost extinct.

 

On Tue, 7 Nov 2017 07:59:09 +1100, Xeno <xenolith@optusnet.com.au>
wrote:

On 7/11/2017 6:32 AM, TekkieŽ wrote:
RS Wood posted for all of us...



What are some car-repair jobs you always wished you could do but have never
done?

Mine are, in this order of "I wish I could do it" order
1. painting
2. alignment
3. replace/rebuild engine
4. clutch replacement
5. tire mounting and balancing
6. timing belt
7. head gasket and vcg

I've done electrical, brakes, shocks, cooling systems, alternators,
ujoints, pitman/idler arms & tie-rod ends and ball joints, tuneups,
emissions hoses and sensors, exhaust, electrical components, fuel pumps,
and fluids, but not the six things above.

What are some car-repair jobs you always wished you could do but have never
done?

I have done all except #3.

The worst job I consider is exhaust. I guess that has diminished these days.

The hardest is being a good diagnostician.

That is the easiest providing you have a good understanding of the
underlying systems, possess a good range of diagnostic equipment and,
finally, know how to use it. For judgemental issues, know first what is
*normal*, then you can easily recognise *abnormal*.

Correct. What I taught all my students (and apprentices). The first
step in diagnosis is understanding how it is supposed to work, and
why. Then understand what the results of any malfunstion would be - -
When you see those symptoms, you have a pretty good idea what has gone
bad and where - as well as, very often, WHY.

 

[RS Wood]

Frank wrote:

Bullshit. Here in Chicago, traffic flows much better in the snow than it
did 30 years ago. In fact, I haven't seen a car stuck in the snow in at
least a couple of years.

People who believe in marketing bullshit never follow basic logic.

Here's simple logic (which may be too difficult for you to follow).

1. How many days in a year are you *driving* in *deep* snow?
2. Tell us what percentage that turns out to be.
3. Now, take that percentage and subtract it from one hundred percent.

That's the percentage you're getting the *other* handling out of FWD.

You may not want to answer the question because it's too logical a question
for someone to ask about handling tradeoffs given your extremely carefully
cherry-picked hand-crafted situations versus normal situations.

 

[AMuzi]

On 11/6/2017 6:19 PM, RS Wood wrote:

Xeno wrote:

I only really started learning *after* I completed my apprenticeship -
and I've never stopped learning ever since.

You stop learning only when you're dead.

I learned a LOT in this thread, particularly about WHY engines last
forever, and why exhausts last forever, and why bearings last forever, and
why ball joints last forever.

That's all good.

I didn't learn a thing on rings that I didn't already know though.

I'm all prepared to learn how the metallurgy or shape of rings is different
nowadays versus yesteryear, but I haven't seen any reference that shows
even the slightest improvement over the years.

It might be there, but saying it's there isn't the same as it being there.
Proof in logic is always very simple.

Everything is simple and seems logical when you don't know
what you don't know.

On a 1965 Chevy small block, measurable improvements can be
had with modern ring technology[1]. Here's a big block, but
the principles are the same:

http://www.superchevy.com/how-to/project-cars/sucp-0404-small-block-chevy-piston-rings-danger-mouse-part-twenty/

check out the chart #5/10!
Discussion of materials, coatings, temper, tolerances and
fitting on that page as well.

That's just a specific engine with which I am very familiar.
Web's got thousands of other examples.

[1] Not the only improvement to be had, but you mentioned
classic vs modern rings.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

 

[Frank]

On Mon, 06 Nov 2017 04:48:45 +0000, RS Wood wrote:

Frank wrote:

10W 40 would coke up faster than 10W 30, for what it's worth.

I just mentioned that, but I didn't look for references.
Do we all generally agree that the *spread* is what causes the coking?

No. Synthetics have a natural "spread" that conventional oils don't.
Conventional oils need additives to achieve their spread. I suppose it's
the multigrade additives that coke up the most, not the oil itself.

As I understand it, conventional oils are a mishmash of hydrocarbons
which react more strongly to temperature.

Maybe this doesn't relate exactly, but consider water. The viscosity of
water doesn't change much from freezing point to boiling point. The
molecules are all the same and they're all acting the same.

Ideally, motor oil wouldn't react to temperature. A perfect viscosity
oil would flow the same at a cold startup as it does at normal
temperature. That doesn't happen, but synthetics are much better in that
regard and is why a much wider spread is possible with a synthetic.

0W30 has a spread of 30 5W30 has a spread of 25 10W40 has a spread of 30
30W40 has a spread of 10 <--- this has the lowest coking

If we agree on that concept of coking:spread, then the question is how
much does coking actually matter and under what conditions does coking
matter?

Coking matters to the extent that it plugs filters and oil passages. The
coke is hard and can abrade bearing surfaces.

 

[Xeno]

On 7/11/2017 11:34 AM, Scott Dorsey wrote:

In article <otqu5p$b88$2@solani.org>, RS Wood <rswood@is.invalid> wrote:

If you think rotors warp in street use then you should be able to find a
ton of references to back up your logic.

Rotors warp in street use all the time when the kids at the chain store use
impact wrenches instead of a proper torque wrench to take tires off and
put them back on.

And of COURSE the chain store blames the driver, the tires, the phase
of the moon, for it. "You must be going over potholes too hard."
--scott

That's been a pet peeve of mine for decades. I hate inappropriate use of
air tools - and final torquing nuts with them is one of those peeves.








--

Xeno

 

[Xeno]

On 7/11/2017 11:35 AM, RS Wood wrote:

Xeno wrote:

Which is the most reliable?

Gear by far, chain next, belt last.

Interesting. Makes sense.
Are gears prevalent?

Used to be on cars. Noise was the issue. Phenolic resin gears solved
that issue but then gear longevity was sacrificed to the god of noise.
Used to change a lot of stripped phenolic resin gears back in the 60s
and 70s.

If not, is the main reason the cost?

On larger diesel engines noise isn't a factor and longevity is. Cost is
less of an issue when long life is the requirement.

Or performance with reliability as in this BMW F1 engine

http://www.formula1-dictionary.net/Images/F1engine-timinggears.jpg

Gears become an issue with distance, as is the case with OHC. In that
case you need too many idler gears so a chain or belt is more
efficacious. From memory, the Toyota KZ engines had both gears and then
a belt to the OHC.


--

Xeno

 

[Xeno]

On 7/11/2017 11:45 AM, RS Wood wrote:

Scott Dorsey wrote:

Rotors warp in street use all the time when the kids at the chain store use
impact wrenches instead of a proper torque wrench to take tires off and
put them back on.

And of COURSE the chain store blames the driver, the tires, the phase
of the moon, for it. "You must be going over potholes too hard."

We covered that in the car forums about three decades ago, where you have
to wonder how anyone could say what you just said.

I haven't *looked* at the problem you speak of for more than 30 years, but
let's take it step by step in really big steps here.

1. How many footpounds *can* you torque a lug nut to before the bolt snaps?
2. Let's put *that* amount of torque on ONE of six bolts, shall we.
3. A rotor isn't solid, but let's assume a solid rotor for a moment.
4. How much torque would it take to *bend* a solid rotor?

It is the balance of the torques.

QUESTION FOR YOU THAT WE ASKED 30 YEARS AGO OF OTHERS:
Q: How much torque on one bolt would it take to bend a rotor?

Had it happen on a Mazda I owned. I wasn't happy and complained
bitterly. You can put a lot more torque of a wheel nut than is required.

--

Xeno

 

[Ed Pawlowski]

On 11/6/2017 7:19 PM, RS Wood wrote:

Xeno wrote:

I only really started learning *after* I completed my apprenticeship -
and I've never stopped learning ever since.

You stop learning only when you're dead.

I learned a LOT in this thread, particularly about WHY engines last
forever, and why exhausts last forever, and why bearings last forever, and
why ball joints last forever.

That's all good.

I didn't learn a thing on rings that I didn't already know though.

I'm all prepared to learn how the metallurgy or shape of rings is different
nowadays versus yesteryear, but I haven't seen any reference that shows
even the slightest improvement over the years.

It might be there, but saying it's there isn't the same as it being there.
Proof in logic is always very simple.

You have not looked
http://www.enginelabs.com/engine-tech/mahles-thin-piston-ring-technology-affordable-effective/

http://www.underhoodservice.com/advances-in-piston-ring-technology/
With so many late-model engines running thinner, low-tension moly-faced
ductile iron and steel rings, one might think cast iron rings are fading
into history. They are at the OEM level, but it looks like cast iron
rings will be around for a long, long time in the aftermarket. According
to several ring suppliers, there is still a very strong demand for plain
cast iron rings. The main reason is that cast iron rings cost less than
more durable materials — and they hold up well enough in light-duty
stock rebuilt engines. Even so, plain cast iron rings can’t provide the
durability of a chrome or moly-faced ring set, or a steel or ductile
iron ring set that is engineered for high output, late-model overhead
cam engines.

 

On Tue, 7 Nov 2017 00:55:08 -0000 (UTC), Frank <analogdial@mail.com>
wrote:

On Mon, 06 Nov 2017 04:49:21 +0000, RS Wood wrote:

Frank wrote:

Chains are hardly ideal. Chains wear. The wear changes the pitch
between the links and the links no longer quite fit on the sprockets.
It turns into a self reinforcing cycle. More wear = worse fit, worse
fit = accelerated wear. Eventually the poorly fitting chain will jump
one or more teeth on the crank gear or start breaking the teeth on the
cam gear.

What are our choices?
1. Chain 2. Belt 3. Pushrod

Anything else?

The other effect of chain wear is retarded cam timing. The more worn
links between the crank and cam, the more the camshaft timing gets
retarded. I changed timing sets on conventional OHV engines and that
usually advanced the ignition timing from 5 to 10 degrees, suggesting
that chain wear had retarded the timing by that amount.

From a repair standpoint, how long do each typically last?
1. Chain ?

Depends what you mean by "how long does it typically last?"

Timing sets on OHV engines typically wouldn't totally fail at under
100,000 miles. Most of those sets were used in the days when cars were
junked at about that mileage. Alot of those cars were junked because the
timing set failed.

I replaced a lot of timing chains and spockets on OHV engines
particularly The GMs with the plastic cam sprocket

But I'd guess timing set wear would retard cam timing around 1/2 to 1
degree every 10,000 miles. If we set an arbitrary failure spec of, say 3
degrees, then the set would have gone out at 30 to 60,000 miles. Of
course, the car would run even if the camshaft were retarded more than
this and the driver usually became acclimated to the poorer performance
and gas mileage.

2. Belt ?

I don't know. My car requires belt replacement every 100,000 miles or
six years. I replaced the belt at eight years and it looked perfect.
There's no significant timing change as the belt ages, until it fails.
An insignificant number fail before the required maintenance time.

Except the little Chevy Optima? where virtuallly NONE made it much
bast the recommended change point and many failed well before. Bad
korean belt.

3. Pushrod ?

I don't know what you're getting at. Most US pushrod engines drive the
cam with sprockets and a chain. A few used gears. A few antique
motorcycles used tower shafts and bevel gears. Maybe some auto engines?
dunno.

The early Riley, for one.


I don't hear anyone talking about pushrods, so, all I see here are that
chains last a *lot* longer in general than do belts, where if either one
broke on an interference engine, expensive things can happen.

Pushrod engines can be interference engines. Not sure what you're
getting at.

But I still prefer belts. Even on a tight package like a Dodge Neon
with the 4 speed auto, the replacement isn't too bad, once you know the
routine.

If the replacement isn't bad, then the belt isn't 'as' bad.

Easiest belt replacement I ever did was on an early Fox body Mustang with
the 2.3 liter 4. Take of the drive belts, take off the timing belt
cover, swap the belts. With some practice and preperation, it would be a
..>clean, 15 minute job.

Much easier and cleaner than replacing a chain timing set!!

I replaced the broken timing belt on the side of the road south of
Sydney NS on my '72 Firenza (Vauxhall HC) in less than half an hour
after getting a friend of a friend to pick up the only belt available
west of montreal - which just happened to be hanging on a nail at the
GM dealer in, of all places, Sydney NS - - -

Sometimes it's better to be lucky than good!!!!
2 days later I was in the USA - where NOBODY would have had the part
because the car was never sold there - - -

In the general sense though, belts, I posit, are bad news multiplied.
I try not to take things from the marketing-bullshit standpoint.

My take is always from the *why* standpoint.
Why did the automakers go to belts over chains?

My supposition is that they did it to save them money.
No other reason.

Camshaft timing.


The tradoffs are legendary where the owner is the one who loses in the
end calculation.

Belts became important when Overhead cams became important. A worn chain
in a cam in block engine has, off the top of my head, 10 links between
the crank sprocket and the cam sprocket. What about a OHC motor? Say 30
links? 10 worn links might retard cam timing 5 degrees. What about 30
worn links?




Just like FWD cars and tricked-out cars are, to me, nearly worthless.

I love front wheel drive, especially in the snow.

Lots of cars are FWD that never see snow.

In the general sense though, FWD, I posit, is bad news multiplied.
I try not to take things from the marketing-bullshit standpoint.

My take is always from the *why* standpoint.
Why did the automakers go to FWD over RWD?

My supposition is that they did it to save them money.
No other reason.

The tradoffs are legendary where the owner is the one who loses in the
end calculation (particularly since deep snow is still on the road for
what, maybe 10 days out of 365?)

Anyone who mentions snow with FWD is falling directly into marketing
hell.

Bullshit. Here in Chicago, traffic flows much better in the snow than it
did 30 years ago. In fact, I haven't seen a car stuck in the snow in at
least a couple of years.

Stuck RWD cars used to impede rush hour traffic on a routine basis.
Nowadays, I haven't been late to work because of the snow in those two
years.

Or, maybe it's the FIRE OF MARKETING HELL that's taking care of the
snow. Either way, I'll take it.


Just like anyone who mentions belts are "quieter" and "lighter" is
doing.

The sole reason for belts and FWD is to increase manufacturer's profits.
Everything else is marketing bullshit because the tradeoffs are
legendary.

I know. The "donut in a snowy parking lot" crowd is almost extinct.

 

[Frank]

On Tue, 07 Nov 2017 01:10:20 +0000, RS Wood wrote:

Frank wrote:

Bullshit. Here in Chicago, traffic flows much better in the snow than
it did 30 years ago. In fact, I haven't seen a car stuck in the snow
in at least a couple of years.

People who believe in marketing bullshit never follow basic logic.

Since you've decided how I'm thinking, what's the logic in responding?

Here's simple logic (which may be too difficult for you to follow).

1. How many days in a year are you *driving* in *deep* snow?
2. Tell us what percentage that turns out to be.
3. Now, take that percentage and subtract it from one hundred percent.

OK, let's say it's 1% of the days. I don't want to be needlessly late
on ANY of those days. More than that, the FACT that traffic is now
flowing more smoothly on snowy days makes driving less stressful.

I will say that, last year, I was driving home on a snowy day. Traffic
was light and what traffic there was, was making safe progress. Some
dumbass decided to pass me fast on the right, lost traction on his RWD
vehicle and spun his car across three unoccupied lanes and smacked his
passenger side wheels against the curb on the opposite side of the road.
Pretty uncommon now, but things like that used to happen frequently in
the RWD days. I don't miss it.

That's the percentage you're getting the *other* handling out of FWD.

Fine. It makes driving safer and smoother a few days out of the year.
It is NEVER a detriment to me. For me, there is NO handling downside.

You may not want to answer the question because it's too logical a
question for someone to ask about handling tradeoffs given your
extremely carefully cherry-picked hand-crafted situations versus normal
situations.

For me, there is no trade off. Whatever difference there is, is
positive. I didn't need any marketing bullshit to convince me of the
superiority of FWD. All it took was getting through the winter. And I
like the extra interior room, too.

 

[Frank]

On Mon, 06 Nov 2017 22:08:55 -0500, clare wrote:

I replaced a lot of timing chains and spockets on OHV engines
particularly The GMs with the plastic cam sprocket

Ford used the same sort of cam sprocket and they failed the same, too. I
don't think the timing sets with the cast iron/sintered metal cam
sprockets held up much better. Once timing chain wear starts changing
the pitch, it's setting itself up to jump a tooth on the crank sprocket
even if it can no longer break the teeth on the cam sprocket.

Another problem with timing chains is the metal swarf they'd put in the
oil as they wore.

 

[RS Wood]

Xeno wrote:

> It is the balance of the torques.

Remember, we covered this in detail DECADES ago.

Everyone confuses *runout* with *warp*.

They're not the same thing.

One requires *permanent bending* of the rotor.

You have to do that without snapping the lug bolts.

Two logical questions HAVE to be considered:
1. How much torque *can* you apply?
2. How much torque does it take to *bend* a rotor?

Without logic - it's just politics or religion.

QUESTION FOR YOU THAT WE ASKED 30 YEARS AGO OF OTHERS:
Q: How much torque on one bolt would it take to bend a rotor?

Had it happen on a Mazda I owned. I wasn't happy and complained
bitterly. You can put a lot more torque of a wheel nut than is required.

There is a huge difference between runout and warp.

Are you talking warp?
Or runout?

I'm only talking pure logic here.
Not religion.

 

[RS Wood]

Frank wrote:

Coking matters to the extent that it plugs filters and oil passages. The
coke is hard and can abrade bearing surfaces.

I have seen what amounts to black sand in the outside sleeve of the crazy
BMW dipstick tube which doubles as part of the PCV system but where the
clearance is too small (so people drill holes in it to solve that).

I had to dig out the "black sand" which was pure carbon it seemed but rock
hard and packed in there.

 

[Frank]

On Sun, 05 Nov 2017 14:42:50 +0000, RS Wood wrote:

> What fails rotors the most (by far) is thickness.

Around here, it's the rust that thins the rotors. The braking surfaces
don't rust significantly, but the rust just flakes out of the vent holes.

Replacing rotors every other brake job is about right in the rustbelt.

 

[rbowman]

On 11/6/2017 7:44 PM, Xeno wrote:

On 7/11/2017 11:35 AM, RS Wood wrote:
Xeno wrote:

Which is the most reliable?

Gear by far, chain next, belt last.

Interesting. Makes sense.
Are gears prevalent?

Used to be on cars. Noise was the issue. Phenolic resin gears solved
that issue but then gear longevity was sacrificed to the god of noise.
Used to change a lot of stripped phenolic resin gears back in the 60s
and 70s.

If not, is the main reason the cost?

On larger diesel engines noise isn't a factor and longevity is. Cost is
less of an issue when long life is the requirement.

Or performance with reliability as in this BMW F1 engine

http://www.formula1-dictionary.net/Images/F1engine-timinggears.jpg

Gears become an issue with distance, as is the case with OHC. In that
case you need too many idler gears so a chain or belt is more
efficacious. From memory, the Toyota KZ engines had both gears and then
a belt to the OHC.


http://www.edelbrock.com/automotive/mc/valvetrain/gear-drives.shtml

I don't know how well the retrofits held up. Long life and race engines
don't go together.

 

[Frank]

On Sun, 05 Nov 2017 05:47:02 +0000, RS Wood wrote:

Never once in my life have I found a single person who has *measured*
the warp.

Does eyeballing it count? I bought a used car in which I could see about
1/16" of warp as I rotated the rotor and looked through the top of the
caliper. It was one of those cars with the rotor captured behind the hub
and the shop price for the repair probably contributed to the previous
owners desire to get rid of the car.

 

[Xeno]

On 7/11/2017 2:08 PM, clare@snyder.on.ca wrote:

On Tue, 7 Nov 2017 00:55:08 -0000 (UTC), Frank <analogdial@mail.com
wrote:

On Mon, 06 Nov 2017 04:49:21 +0000, RS Wood wrote:

Frank wrote:

Chains are hardly ideal. Chains wear. The wear changes the pitch
between the links and the links no longer quite fit on the sprockets.
It turns into a self reinforcing cycle. More wear = worse fit, worse
fit = accelerated wear. Eventually the poorly fitting chain will jump
one or more teeth on the crank gear or start breaking the teeth on the
cam gear.

What are our choices?
1. Chain 2. Belt 3. Pushrod

Anything else?

The other effect of chain wear is retarded cam timing. The more worn
links between the crank and cam, the more the camshaft timing gets
retarded. I changed timing sets on conventional OHV engines and that
usually advanced the ignition timing from 5 to 10 degrees, suggesting
that chain wear had retarded the timing by that amount.

From a repair standpoint, how long do each typically last?
1. Chain ?

Depends what you mean by "how long does it typically last?"

Timing sets on OHV engines typically wouldn't totally fail at under
100,000 miles. Most of those sets were used in the days when cars were
junked at about that mileage. Alot of those cars were junked because the
timing set failed.
I replaced a lot of timing chains and spockets on OHV engines
particularly The GMs with the plastic cam sprocket

But I'd guess timing set wear would retard cam timing around 1/2 to 1
degree every 10,000 miles. If we set an arbitrary failure spec of, say 3
degrees, then the set would have gone out at 30 to 60,000 miles. Of
course, the car would run even if the camshaft were retarded more than
this and the driver usually became acclimated to the poorer performance
and gas mileage.

2. Belt ?

I don't know. My car requires belt replacement every 100,000 miles or
six years. I replaced the belt at eight years and it looked perfect.
There's no significant timing change as the belt ages, until it fails.
An insignificant number fail before the required maintenance time.

Except the little Chevy Optima? where virtuallly NONE made it much
bast the recommended change point and many failed well before. Bad
korean belt.

3. Pushrod ?

I don't know what you're getting at. Most US pushrod engines drive the
cam with sprockets and a chain. A few used gears. A few antique
motorcycles used tower shafts and bevel gears. Maybe some auto engines?
dunno.

The early Riley, for one.

Rolls Royce Merlin and Kestrel engines.

http://spitfirespares.co.uk/Merlin%20MK%20XX%20restoration.html

http://www.avrosystems.co.uk/bomber/merlingearsmodded.jpg

Not a chain in sight. ;-)

I had an ashtray made out of the piston of one.

The long head studs made very good pry bars.

The alloy those engines were made from was nothing like the crap alloy
you get now.


<snip>


--

Xeno

 

[Xeno]

On 7/11/2017 3:19 PM, RS Wood wrote:

Xeno wrote:

It is the balance of the torques.

Remember, we covered this in detail DECADES ago.

You did, I didn't. Wasn't here decades ago.

Everyone confuses *runout* with *warp*.

They're not the same thing.

I am well aware of that.

One requires *permanent bending* of the rotor.

That too - and I've seen it, experienced it. YMMV since you haven't been
actively involved in the trade.

You have to do that without snapping the lug bolts.

Two logical questions HAVE to be considered:
1. How much torque *can* you apply?

Quite a lot you will find. Wheel nuts are torqued way below their
maximum capacity but, unfortunately, there are quite a few rock apes out
there in the trade who have no idea of their strength or how to use a
torque wrench.

> 2. How much torque does it take to *bend* a rotor?

That depends on the rotor and the hub it is attached to.

Without logic - it's just politics or religion.

QUESTION FOR YOU THAT WE ASKED 30 YEARS AGO OF OTHERS:
Q: How much torque on one bolt would it take to bend a rotor?

Had it happen on a Mazda I owned. I wasn't happy and complained
bitterly. You can put a lot more torque of a wheel nut than is required.

There is a huge difference between runout and warp.

Are you talking warp?

Warp! Defintely warp. Once the wheel nuts were loosened and correctly
tightened, most warp disappeared but sufficient remained to cause a
slight steering shimmy. And, yes, steering shimmy is the effect you get
from warped discs.

Or runout?

I'm only talking pure logic here.
Not religion.

I'd have said your *logic* comes entirely from book learning and not
from the real world of the trade I spent 50 years involved in.

--

Xeno