seized brake caliper? (hissing from near back right wheel)

[BahnStormer]

edit: thread title changed as it would appear that we've diagnosed it, but I'm still looking for advice...

I apologise in advance as this is one of those irritating list of fairly vague observations that don't make sense and I don't know where to start looking...

I've heard a hissing from somewhere near the back right wheel a few times over the last few days, it's really intermittent and I THINK it starts under heavy 1st/2nd gear acceleration and I think it only starts when accelerating out of right hand corners, but I'm not certain of those trigger events.

There's no change in the car's ability to accelerate, brake or turn and it only lasts 5-10 seconds, but it definitely continues after I've straightened out and stopped accelerating.

I can't even tell if it is air hissing out or something scraping... the first time it happened, I pulled over and had a look at the back right brakes as I was expecting to see some dried leaves wedges in there, although the sound is a little harsher than that... maybe more like some hard plastic caught against the edge of the unsmoothed brake surface.

Considerations:

I know my rear brakes in particular are pretty heavily worn.

My aircon had previously leaked and I had it re-gassed a couple weeks ago (but that's not running at the time of the issue and still running icy cold if I do turn it on).  Also it does seem to be related to accelerating and braking.

Any ideas / things to check?

I'm guessing this is something catching on the edge of the back right brake, but I can't see anything loose that might be caught there and why is it so intermittent?!?

Am I just making up reasons to get new brakes?! 

[PhilzMR2]

Same issue with mine - pretty sure the handbrake isn't releasing fully. Will be investigating this weekend.

[BahnStormer]

hmmm.... this was a good couple of miles after the handbrake had last been on.... and I'm sure if that happens the car gets a lot more tail happy and I was giving it ample opportunity to get tail happy!

I'll try to keep note of any additional symptoms and also preceding actions on my part...

[K T M Rider]

I can't even tell if it is air hissing out or something scraping... the first time it happened, I pulled over and had a look at the back right brakes as I was expecting to see some dried leaves wedges in there, although the sound is a little harsher than that... maybe more like some hard plastic caught against the edge of the unsmoothed brake surface..........

Any ideas / things to check?

A mate once had this with his AC Cobra - turned out it was the snake complaining about his driving 

Next time after pulling over place your hand against the centre of the wheel and compare to the other side rear wheel to see if you can note any difference in temperature. IF both are coolish, then you can proceed to touch BRIEFLY each of the rear discs - again to see if you can note any temperature difference (or if you prefer you could buy an Infra red thermometer from ebay for well under a tenner  -link below)

https://www.ebay.co.uk/itm/Digital-IR-Infrared-Laser-Thermometer-Temperature-Non-Contact-Handheld-Gun-UK/142759319878?epid=24018110305&hash=item213d1e5946:g:m2QAAOSwLjRa0~zr

Presumably you have alrady checked that the cold tyre pressures are remaining stable ?

[BahnStormer]

...to see if you can note any temperature difference (or if you prefer you could buy an Infra red thermometer

Presumably you have alrady checked that the cold tyre pressures are remaining stable ?

I'll check the pressures, I think they're usually pretty good... and good idea on the thermometer - I used to REALLY be into PC overclocking, so I've got one, I'll try to remember to keep it in the car...

[BahnStormer]

...to see if you can note any temperature difference (or if you prefer you could buy an Infra red thermometer

Presumably you have alrady checked that the cold tyre pressures are remaining stable ?

I'll check the pressures, I think they're usually pretty good... and good idea on the thermometer - I used to REALLY be into PC overclocking, so I've got one, I'll try to remember to keep it in the car...

Still not had a chance to check brake temps as it's REALLY intermittent.... BUT I just checked the leather seats and they're clocking 81C at 3pm this afternoon 

[BahnStormer]

Okay - heard a faint hiss a few times on the drive home today.... pulled over a few minutes later and the comparison was:

outer edge (hottest spot) of the right disc was clocking >150C
back of the right pad was ~80C

outer edge of the left disk was ~80C
back of the left pad ~50C

I ran back to the right to see how fast they were cooling down and the right was still >130C.

Pretty sure it is the back right disc catching / rubbing slightly...

NEXT QUESTION.... any bets if that's just badly worn discs and pads (which I'm about to replace anyway) or if there's a caliper/a.n.other problem!!

Caliper refurbs are on "the list", but then so is a LOT of stuff and they're not within budget at present, but then equally, I don't want to put on new discs and pads... only to have one of them get eaten by a cranky caliper...

Any suggestions on where to get discs, pads and braided hoses fitted around SW London / Sussex / Surrey?

[delhusband]

Brake dust guard loose? (I really have no clue re: things mechanical)

[mikek]

I would think you have a seized caliper. Caliper refurb required.

[BahnStormer]

Brake dust guard loose? (I really have no clue re: things mechanical)

Due to take the wheels off on Saturday, I'll have a look then to be sure.

I would think you have a seized caliper. Caliper refurb required.

Options?
1) Just get a refurbed one or two? I think it was £80 each (at TCB) + fitting.
2) All four? £300 (TCB) + fitting.
3) £550 for a swap with some at BCS, but they do painting and fitting included then... I just need to get a day in Nottingham though

Any other suggestions? I want to put new brakes on it really soon (I have the pads, still awaiting the discs), but that's not going to happen when the caliper is on its way out...

Will it just continue to scrub intermittently (a bit of extra heat) or should I expect this to start getting a lot worse?

[Carolyn]

Could be as simple as sticky sliders and rust-build-up around the pad slots.

A lube and clean-up might well suffice.

[m1tch]

I got mine from here (both rears) as I figure they would probably fail at the MOT - worth noting that you don't need to send back your old calipers like other places which means you will also have another set you can refurbish as a spare if needed:

https://brakeparts.co.uk/shop/Toyota/MR2/00-/MR2%20Sports%20Zzw30%201.8%20Roadster/Rear%20-%20Brake%20Calipers%20and%20Wheel%20Cylinders

[james_ly]

Could be as simple as sticky sliders and rust-build-up around the pad slots.

A lube and clean-up might well suffice.

Sounds like this to me. Worth winding the piston in and out a couple of times, then go and give the brakes a hammering and see if it comes back.

[BahnStormer]

I got mine from here (both rears) as I figure they would probably fail at the MOT - worth noting that you don't need to send back your old calipers like other places which means you will also have another set you can refurbish as a spare if needed:

https://brakeparts.co.uk/shop/Toyota/MR2/00-/MR2%20Sports%20Zzw30%201.8%20Roadster/Rear%20-%20Brake%20Calipers%20and%20Wheel%20Cylinders

Thanks - not heard of Budweg before, but then to be fair I haven't heard of a lot of component manufacturers before unless they're the serious upgrade components (e.g. Brembo, AP, Wilwood)... what are those like? Are they at least OEM quality?

Could be as simple as sticky sliders and rust-build-up around the pad slots.

A lube and clean-up might well suffice.

Thanks - mines only 11yrs old (assuming original) with 60k and very little corrosion on the suspension components, so hopefully this is the case... but that brings me back to the previous question: I'm looking for recommendations on a MR2-sympathetic mechanic in SW London / home counties to put new brakes on and give these calipers a clean and a lube.

[Carolyn]

Floating calipers with the handbrake in the piston are by no means unique to our cars.

Many 10 - 20 year old cars have such brakes (especially Toyota and Honda).

What you need is good local family operated garage that's been in business for ages, and that comes well recommended.  They will doubtless be up to the task.

[BahnStormer]

are these brake specs correct? (I know they had the wrong YS pads listed, so I'm a little concerned about the discs!)

[BahnStormer]

I got mine from here (both rears) as I figure they would probably fail at the MOT - worth noting that you don't need to send back your old calipers like other places which means you will also have another set you can refurbish as a spare if needed:

https://brakeparts.co.uk/shop/Toyota/MR2/00-/MR2%20Sports%20Zzw30%201.8%20Roadster/Rear%20-%20Brake%20Calipers%20and%20Wheel%20Cylinders

Thanks - not heard of Budweg before, but then to be fair I haven't heard of a lot of component manufacturers before unless they're the serious upgrade components (e.g. Brembo, AP, Wilwood)... what are those like? Are they at least OEM quality?

Thanks - mines only 11yrs old (assuming original) with 60k and very little corrosion on the suspension components, so hopefully this is the case... but that brings me back to the previous question: I'm looking for recommendations on a MR2-sympathetic mechanic in SW London / home counties to put new brakes on and give these calipers a clean and a lube.

Looking at £370 for a set of four (Budweg) calipers... does that sound about right? That's to buy 4 new calipers outright, but Budweg aftermarket items...

TCB are: (2x £72.85 + 2x £83.38 ) + VAT = £374.95.... but that's for refurbished OEM units "on exchange".

Feels quite appealing to get the new ones, get them painted and then take all that in for fitting somewhere.... but how would those Budweg ones compare to OEM?

[BahnStormer]

Presumably you have alrady checked that the cold tyre pressures are remaining stable ?

Not sure if it was just the slope I parked it on earlier, but back right tyre might also be losing pressure - if it is this, is it just a side effect of the heat fluctuations due to the rubbing brakes or potentially something different? TBH, whenever a park up on the kerb, I always think the lower tyres are losing air and every time I check them, they're fine. I'll check the pressure once it's all cooled down.

[BahnStormer]

Presumably you have alrady checked that the cold tyre pressures are remaining stable ?

Not sure if it was just the slope I parked it on earlier, but back right tyre might also be losing pressure - if it is this, is it just a side effect of the heat fluctuations due to the rubbing brakes or potentially something different? TBH, whenever a park up on the kerb, I always think the lower tyres are losing air and every time I check them, they're fine. I'll check the pressure once it's all cooled down.

I think this was just me being paranoid... both rear tyres were 31PSI, so 3PSI low, but that was at 6am this morning and I think I last checked them at 3pm when it was >30C (and at a local garage, so looks like I need to double-check their machine readings).

[Carolyn]

Presumably you have alrady checked that the cold tyre pressures are remaining stable ?

Not sure if it was just the slope I parked it on earlier, but back right tyre might also be losing pressure - if it is this, is it just a side effect of the heat fluctuations due to the rubbing brakes or potentially something different? TBH, whenever a park up on the kerb, I always think the lower tyres are losing air and every time I check them, they're fine. I'll check the pressure once it's all cooled down.

I think this was just me being paranoid... both rear tyres were 31PSI, so 3PSI low, but that was at 6am this morning and I think I last checked them at 3pm when it was >30C (and at a local garage, so looks like I need to double-check their machine readings).

31 psi is 1lb low - not 3

[BahnStormer]

31 psi is 1lb low - not 3

(facepalm)

Do you know how much smarter I'd be if I used all the information that I have at my disposal (I have those numbers in the glovebox, a photo of that card in the glovebox AND a txt file in my dropbox, synched to the phone)....

Thanks though - a 1PSI drop isn't worth worrying about then!!

I still need to decide on:
1) buy the Budweg calipers.
2) buy OEM refurbed on exchange.
3) chance my arm with a refurb at a mechanics, but risk ruining new discs and pads.

Given the cost, I'm erring toward #3, but haven't got around to contacting the preferred mechanic yet...

[Carolyn]

Get the sliders lubricated and make sure the pistons aren't stuck and you'll be fine. 

I've done loads of brakes on these now and never had to replace a caliper yet.

[BahnStormer]

Get the sliders lubricated and make sure the pistons aren't stuck and you'll be fine. 

I've done loads of brakes on these now and never had to replace a caliper yet.

Thanks - given your reputation on here ( :notworthy:)... I'll take that to mean they never have to be replaced! So time to check how good that mechanic is!!

[mr2garageswindon]

Don't forget to check the wheel bearing for excessive play. If it has excessive movement when in corners can push the disc against the pads also creating drag and heat.
Not a common problem but I have seen it before.
Most likely knackered caliper though.

[Carolyn]

Get the sliders lubricated and make sure the pistons aren't stuck and you'll be fine. 

I've done loads of brakes on these now and never had to replace a caliper yet.

Thanks - given your reputation on here ( :notworthy:)... I'll take that to mean they never have to be replaced! So time to check how good that mechanic is!!

Never say never!!  But I do think simple service and repair is often overlooked because of all the horror stories from folk who just haven't got to grips with them.