Car D.I.Y.

[Drago]

Convince me of any positives of a wet belt on a vehicle....
Take your time,no rush.

Slightly more compact external dimensions, quieter, reduced intertial losses over a chain, and the biggie - significant reduction in frictional losses and consequential marked improvement in economy and emissions,.

In an ideal world theyre fantastic.

Sadly, we don't live in an ideal world - we live in one in whcih the likes of Ford and PSA/Stellantis are allowed to design engines.

 

[Adam4868]

In an ideal world theyre fantastic

I rest my case....

 

[Drago]

I rest my case....

But that wasn't the question you asked.

You asked for positives, I was happy to supply them. And that's fair list.

 

[Profpointy]

But that wasn't the question you asked.

You asked for positives, I was happy to supply them. And that's fair list.

I though chains were more efficient than belts, which is why the latter haven't caught on for pedal bikes

 

[Adam4868]

But that wasn't the question you asked.

You asked for positives, I was happy to supply them. And that's fair list.

Except the supposed positives you supplied are far outweighed by the negatives.

 

[Drago]

Except the supposed positives you supplied are far outweighed by the negatives.

But tht wasn't the question you asked. Had you asked for list of negatives I'd have been happy to oblige.

I though chains were more efficient than belts, which is why the latter haven't caught on for pedal bikes

Chains have less frictional losses than a dry belt, but th inertial losses from the extra mass typically well negate that.

 

[CXRAndy]

When an early repair costs nearly 1k negating the savings in efficiency. Then it's a pointless design. Stick with external dry belt or chains.

 

[Drago]

The problem is manufacturers are facing ever tighter emissions targets. Tactics like wet belts are a kind of desperation measure as they chase ever more elusive marginal gains. There'll come a point where no matter what they do it won't be practical, and wet belts are a step along that path.

I guess its one of the indicators of the begining of the end for ICE.

 

[CXRAndy]

Here is the video for the job on PureTech Citroen engines. Mine is 1.2 non turbo, but looks very similar. Seems used car dealers are staying clear of these wet belt vehicles or low valuations to cover costs of repair

View: https://youtu.be/yNVooBE9vhA?si=Ufr6glb_K-zhFbOP

 

[Drago]

Known affectionately as PukeTech,

 

[Profpointy]

Well not DIY, but my veteran Saab is going in for its MOT and 230,000 mile service next week.

However it's just started pissing out a load of oil, so I think I'll need to get it towed back to the menders in Bristol as the drive back might be a bit of a stretch. Last time this happened I was going on holiday and persevered the last few miles kyboshong the engine in the process. Let's try and avoid a repeat performance. I have a psychological target of get to the quarter million miles mark, which is about another year

Well that didn't go as well as I'd
hoped. I put another half gallon of oil in intending to limp back to my dads with a view of "recovery" to Bristol in a few days, but the auxilliary belt has gone: power steering, alternator and most crucially water pump, so had to give up. Truck due in an hour so hey ho. Hopefully fixable, but have to think about cost, as I'm not sure it's worth shelling out a lot more than a grand this time, albeit I can do without the grief of car shopping at the moment, and I do like the car

 

[Profpointy]

Chains have less frictional losses than a dry belt, but th inertial losses from the extra mass typically well negate that.

With something like a car the inertial losses would only matter when your accelerating so would be quite small in "normal" driving as opposed to perhaps racing. Cars already have quite heavy flywheels after all.

... unless I've misremembered my physics or otherwise goofed in my thinking

 

[Drago]

And the accelerating of that mass is where the biggest economy gain is to be had. Once it's already moving it's not suc a problem.

Lightening the valve train has pleasant benefits for acceleration too.

 

[Profpointy]

And the accelerating of that mass is where the biggest economy gain is to be had. Once it's already moving it's not suc a problem.

Lightening the valve train has pleasant benefits for acceleration too.

The valves themselves and any springs sure, as they are constantly accelerating and decelerating with their momentum having to be overcome on every cycle; the rotational components somewhat less so, though I do realise flywheels in particular are lighter on race oriented cars to allow a more rapid pick up. But even so, the inertia (or angular inertia if that is even a thing) will be dwarfed by the ton or so of the car. (sloppily mixing my units / dimensions)

 

[Drago]

Indeed, the mass of th car itself is a different scale. Nefettheles, manufacturers work their too, lighter materials, etc, although that gets offset somewhat by greater expectations for equipment and safety which make and marginal gains in the engine even more valuabl3,

When you're chasing those marginal gains, as manufacturers are now being forced to do now mainy in the pursuit of emissions cleanliness, you play every card in the deck, even if it's a weak hand.