poor mileage, no other symptoms

[dlb]

alright, i'll try that when the wife is kicking around. the pads appeared fine when i took a look today but i will do a thorough check anyway.

sort of on the same topic, do those two little v-shaped metal springs that clip into the brake pads really retract them from the rotor when not braking? they're so tiny, i can't imagine them being sufficient.

[Petros]

I think those springs are there to reduce the tendency for disk brake pads to squeal badly especially with light brake load. The pads tendency is to do a high frequency vibration in place, which sounds like squeal. I suspect the spring is just there to reduce the squeal by changing their natural frequency.

[dlb]

so if not the springs, what pushes the pads back after you finish braking? this is something i've been wondering for a while.

[Petros]

they do not move much, but I suspect the reduced pressure allows them to retract by vacuum on the brake fluid. Unlike the drum brakes, the calipers have no retraction springs at all. This has been true from the very first disk brakes. Who knows which car had the first disk brakes? Answer: 1947(?) Jaguar. Borrowed brakes off WW2 fighter aircraft.

[ARCHINSTL]

First production car with disc brakes: 1949-50 Crosley Hotshot (I remember when these came out - you think the T4WD's rotors are small? HA!);
First racing car with disc brakes: 1953 Jaguar C-Type (I believe LeMans was its first race, confounding competitors - I recall reading about it at the time; ......Mercedes, Ferrari, and Maserati were amazed at how much further the Jags could dive into the corners than their cars);
First BritMobile with front discs standard: 1956 TR-3;
Next American car with front discs standard: 1963 Avanti.

Note that the 1949-53 Chrysler Imperial used a type of disc brake, but not of a caliper type.
Lanchester made the first caliper type in 1902, and used it for a while, but used copper as the pad material (wrong!).
Tom M.

[takza]

First BritMobile with front discs standard: 1956 TR-3;

My second car and first drivable one was a 56 TR-3 in British Racing Green...car was in decent shape...I just had an uncle lead in the rust spots behind the rear wheels and match the paint. These cars had POOR HEAT...air leaked in around the top of the door windows....sliding plexiglass. Fun...basic sports car...what the Miata wanted to be?

[dlb]

psuedo-update: not much new. checked the calipers and thoroughly and the driver side definitely grips a little tighter than the passenger but it releases as soon as the peddle is let up. i also checked the the same on one of the other tercs just for reference and the difference between ron's driver side wheels spins only marginally less freely than the others i've checked so i'm not sure if that could be causing such a significant drop in mileage. the pads are all wearing equally and i've never noticed any burning brake smells or heat coming from either side. what do you guys think? could the slightly higher drag on the one side still cause the problem?

possibly related to the above, i've noticed that the car has a significant pull to the passenger side on cruising but that's odd because it's the driver side caliper that drags more. i had the alignment done around the spring but something is obviously off so i'll check the alignment using keith's home technique:

https://tercel4wd.com/forums/viewtopic.php?f=7&t=2273&p=35747

thoughts?

[takza]

Last winter I hit some potholes under strong acceleration in 1st...which resulted in a serious toe in issue. I find the string method works about the best.

THE REALITY I've found over doing 3 different vehicles is that they don't stay in alignment for long...I'll be checking mine every 3 months from now on....just aiming for ZERO toe. Easier to do it this way....and the main issue is getting it back near to where it should be...not extreme accuracy.

[Petros]

I would agree, not likely the brakes causing it. Alignment is a possible culprit since you have pull, it needs to be done anyway. Notice any abnormal tire wear? Or not long enough to notice yet?

IF the engine is running good (compression is good, spark plugs and wires all good, etc.), and brakes an alignment are good, how about exhaust: blockage in muffler or cat?

[dlb]

just checked the alignment and it appears to be way out. using keith's method, there is a toe out of just over 1". is it just me or is that extremely out?

i had it aligned at a shop probably about 9-10 months ago but i wasn't happy with it because i then found the car still pulled a bit and the steering wheel was not centered. i talked to them about taking another look at it but then my work schedule prevented me from getting it back in anytime soon and i finally decided i'd live with it. my mileage was good until recently though so maybe something changed in the last several months. i just checked to make sure that the inner tie rods were still locked in place and not unthreading themselves, all is well there.

compression, spark plugs, and wires are all good. i'm glad i checked actually because i moved to a cooler plug in the last year since i found my old ones were were all but melted away. the current ones are a nice light brown. i replaced the exhaust pipe and muffler and removed the cat within the last year so this muffler has never seen a cat. my understanding is that it's usually the cat that gets plugged or can plug the muffler, but mufflers with no cat rarely have problems. i was told a baffle in the muffler can break off but then a rattling sound should be audible as the broken piece bounces around, and there is no rattling so i don't think that's the problem.

i've been looking for vacuum leaks as well and wonder if anyone else with a weber can look and tell me what they have in place of the 'vapor vent to canister' shown in this diagram:



currently this port appears open on my weber since it has no cap or nipple. i've never messed with it before so i have no recollection of what it was like before.

[Petros]

one inch toe-out is WAY too much. should be something like zero to 1/4" toe-in. sounds like you may have whacked something, or perhaps you did some front end work and disturbed the alignment?

The vent is likely just a float bowl vent to atmosphere, I do not think I would leave it open, run it up to the air filter perhaps, or to a tiny air filter of its own.

[dlb]

one inch toe-out is WAY too much. should be something like zero to 1/4" toe-in. sounds like you may have whacked something, or perhaps you did some front end work and disturbed the alignment?

that's what i thought. i haven't touched the front end since i did all the work almost a year ago and don't remember hitting any potholes or curbs but i may have, or my wife might have. i can't tell how much to take in each side so i made an alignment appointment for wednesday at a different place that has done good alignments for my VW van in the past.

The vent is likely just a float bowl vent to atmosphere, I do not think I would leave it open, run it up to the air filter perhaps, or to a tiny air filter of its own.

i wish i knew if there was every anything there to begin with. i just PM'd deejay to ask him and am hoping tom sees this soon as well. if there is no cap or nipple on anyone's, i will assume that this is normal and not worry about it. it seems it should have a brass cap like most of the other ports on the weber though.

[ARCHINSTL]

My Weber DGEV, new in 2008 from Carbs Direct, has no "normal" cap - although it does look like it has an "inverted cap." By that I mean - it has an obvious hole that is plugged with a "closed tube." The PDF on troubleshooting I received (don't recall if from Carbs Direct or Redline) shows a photo of the carb with many items labeled - but nada on the "hole" in question. The installation paper shows the same diagram as you attached, but makes no mention of what to do with it (other than the "optional" tag of the diagram). I'd imagine if it was vented to the atmosphere through a tiny hole instead of the "optional-to-canister" there would be some mention.
Tom M.

[dlb]

that looks the same as mine so guess it's status quo. i was able to slide a thin screwdriver 2-3" into the tube before it stopped. weird.

thanks for looking and taking/posting the pic, tom!

[takza]

As mentioned...you'd be better off just taking the time to learn to set it yourself and then checking it at least every 6 months. I can check and adjust the front on a car/truck in less time than it would take to get it to a place...but I'd also have to make an appointment...wait...and pay $.

that's what i thought. i haven't touched the front end since i did all the work almost a year ago and don't remember hitting any potholes or curbs but i may have, or my wife might have. i can't tell how much to take in each side so i made an alignment appointment for wednesday at a different place that has done good alignments for my VW van in the past.