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Vehicle Mechanics and Maintenance

Whatever my current projects are, not meant to be comprehensive.

Quick Washing Your Car

  1. Rinse car with cordless pressure washer.
  2. (optional) Use a bunch of rags (microfiber towels) in a bucket with rinseless fluid. Avoid scratching paint with soiled rag.

Options for pressure washer dispenser bottle:

DIY rinseless wash ingredients:
1 Tbsp Baby Shampoo
1/2 Cup Distilled Vinegar

DIY window cleaner:
1/2 cup distilled white vinegar 10 drops essential oil (optional)

Wash and wax

Travel Without A Spare Tire

AWD Subaru differentials need same size wheels to avoid damage and I'm not sure how long they could be driven on a different size spare. Rather than trying to find a spare for my custom oversized tires, I'll try using tire repair in emergency situations.

Tires can be repaired with plugs. Sidewall repair is difficult, but can be accomplished by vulcanizing rubber and mesh fiber into the sidewall. See How I do a vulcanized tire sidewall repair, by Misfit Toys on YouTube.

“Unlike the vulcanization of a patch to a tire, tire plugs rely on the general pressure of the tire hole pushing on the plug to create a compression seal, rather than a chemical seal.”

However, they do make plugs that are vulcanizing, for use with vulcanizing fluid. See Fix Punctures and Sidewall Gashes with Tech's Permacure Repairs, by Tire Review on YouTube. Less expensive vulcanizing plugs are made by Zerint (TS-4430, TS-4460, and TS-2560).

Practical Tire Aspect Ratio

Racing Cars Do Not Use Low Profile Tires

Roads are not perfectly smooth racing tracks, and even indy or stock-car racing use sidewalls that are 6“ tall. Sidewall flex is desirable for grip.

Indy 500 Racing Tire:
Indy 500 Racing Tire

Stock Car Racing Tire:
Stock Car Racing Tire

The truth is that low profile tires are just bling appreciated by an immature clientele. Low profile tires cause a lot of damage so they are also appreciated by suspension and tire shops.

In the 70s sports cars came with 65 or 70 series tires (like the 240Z, 260Z, and 280Z). People on forums say this is because tire development had yet to evolve to make lower profile tires. I think that's bullshit from people's belief that development is always for the better.

Wider Tires Are More Comfortable Than Narrow Tires

Some people incorrectly assume wider tires give a rougher ride. That's because they continue to use the same pressure on a wider tire that they were using on a stock width tire. The pressure should be less on the wider tire to have the same tire deformation expected by the manufacturers.

Tire Pressure Calculator from

A more comfortable ride can be had by increasing the total volume of a tire.

Increasing the width and keeping the tire height constant, decreases the pressure needed to run the tire. For speed bumps the 2 dimensional vertical deformation is the same for both the wider and narrower tires. At least on speed bumps. On irregular surfaces the wider tire with more volume will be more comfortable.

To be more precise, the narrower tire does have a contact patch that is longitudinally longer, so it may “caterpillar track” over a bump. But the increased volume afforded by the wider tire overshadows what may be a marginal dynamic deformation improvement? I think so.

Tires for 2008 Subaru Impreza

Click to Expand

Spare Tire for 2008 Subaru Impreza

Click to Expand

Engine Sound: Piston Slap or Worn Valve Clearances

My engine has a more faint version of the clanking sound in the YouTube video referenced in this forum thread. Also could be a need for valve clearance adjustment, as can be heard in this video. The sound lasts a minute or two on cold startup, and goes away more quickly if I rev the engine.


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engineering/vehicle-mechanics.txt · Last modified: 2023/11/11 12:51 by marcos