Better braking

[mountainhick]

Have a brake shudder, and generally the Prev's braking isn't the strongest. I drive a lot of steep mountain roads and mostly with moderate weight loaded up as a mini camper with camping and climbing gear, my wife and two dogs, probably averages an extra 500 or more pounds Thinking of upgrading rotors and pads all around.

I am confused over premium vs slotted, or drilled/slotted rotors and all the different pad types available. Someone at Yahoo also posted a link to closeout parts at Rock: http://www.rockauto.com/RSS/vehiclefeeds.php?carcode=1278176&m=wc&l=en&html=true

Ideas?

[timsrv]

I don't know much about the slotted or drilled rotors. I'm pretty demanding on my brakes (between my cargo trailer and the cargo area I carry about a ton). I think the slotted rotors would cool a little better, but IMO not worth the extra cost. I've always used the cheapest rotors I could find but I use genuine Toyota pads (I believe Toyota's pads are the best). Of course your driving technique is important too. I always downshift on the steep hills and keep safe following distances. I've been driving overloaded Toyota's for over 20 years and have always found their brakes to be adequate. Tim

PS: The ABS models (like mine) have bigger rotors, bigger pads, and dual piston calipers. If you have a non-ABS Previa (smaller front brakes w/single piston calipers), perhaps a simple upgrade could be finding an ABS Previa at the salvage yard and swapping front brakes. If you do this you'll also need to use 15" rims as the 14's won't fit over the bigger calipers & rotors. Tim

[mountainhick]

Thanks Tim,

I have the ABS dual piston version and drum/disk rears.

I took off the fronts yesterday and had them turned. Pads look like semi metallic. There is so much pad I am sure they were replaced at some point, the van has 155K on it.

I guess at this point the shudder is the scariest part of it. I'll put the freshly turned rotors back on this morning and maybe it'll be different today. If ivibration is still there I'll get the rears turned as well and go from there.

[timsrv]

One thing is for sure, the Previa does have a tendency to warp front rotors (barely enough material to hold their shape). I got to the point that I don't let anybody touch it anymore (not even the tire guys). When I need tires I remove the rims and take them in. Several years ago I got new tires and in coming home I noticed I had a new problem.........shuddering while stopping. When I got home I found the lugs had been extremely over tightened. I broke them all loose and torqued to the proper spec, but it didn't completely fix it. Next I had the rotors turned and that did the job, but the shuddering slowly came back. I speculate the over tightening warped them, but since they were not stress relieved, they slowly came back to their original state after lugs were relaxed and rotors were heated (heated from the occasional heavy demands).

Anyhow, my fix was to get new rotors and I've never messed with turning Previa rotors since. When I start to feel a shudder I simply replace them. The cheap ones only cost around $20 - $30 each. I usually just replace them and the calipers every other time I do pads. Tim

[mountainhick]

That's pretty interesting.

Well rotors installed and I just took it for a test drive and no more shudder, so I'll see how long it lasts. I think I will order a set of centrics for the front to have ready when these go. This turning took them to their very minimum.

[timsrv]

These rotors are similar to the Camry rotors of the same era. The design is nice when it comes to replacing, but not so good when it comes to reliability. I remember when I worked for Toyota (back in the early 90's) there was a service campaign to replace rotors in the Camrys because they were all warping (and there were a lot of them). Some days all we did was replace Camry rotors. The Previa never had such a campaign, but the rotors aren't much different. Tim

[TheMAN]

rotor warping always happens because of uneven lug nut tightening, and especially over tightening... most mickey mouse shops just blast the lug nuts on without even torque sticks... they think just because NASCAR does it this way, it's the thing to do!
at minimum, use torque sticks if you're in a hurry... usually within the spec range... but if you want accuracy, always use a torque wrench like I do

my previa rotors have not warped in 10 years now, ever since I took over maintenance.... before we had shops do it, and the rotors quickly warped

one major bad thing about the previa is the slider pin design... it's a tube that goes into the caliper itself, rather than having bore holes and a slider pin that slides in and a bolt that holds the assembly to the bracket... because of this, there's limited amount of free space to for it to keep enough grease to stop it from seizing... it gets worse when most shops use the wrong grease in any car's caliper slider pins.... they use that black "moly" lube that's really meant for anti-squeal shims... that stuff bakes on and dries out, causing the slider pins to seize... best grease for calipers always have been silicone grease.... I've used 3M silicone dielectric grease for years and it does the job

anyhow... slotted rotors helps clean pads more than really offer extra performance... drilled rotors doesn't either... 30 years ago, they were useful when pads tended to "out gas" when hot, and the drilled rotors helped let the gas out instead of causing the pads to not work
there are lots of heated arguments on sports cars forums over this subject, but many like me have yet to see proof that either slotted or drilled rotors are really necessary in today's day and age... what helps the most are good tires and good pads.... don't settle for cheap pads.... if you don't want to buy Toyota OEM, then get Akibono or Advics pads... they are OEM suppliers to many manufacturers

[mountainhick]

Thanks TheMAN,

How about superlube synth grease?

And, yes I use a torque wrench, alway carry one in the van toolbox.

[TheMAN]

the quality of the torque wrench matters too... the more accurate, the better :)

what is "superlube synthetic grease"?

[mountainhick]

http://www.super-lube.com/

[TheMAN]

their dielectric grease will be fine... anything else petroleum based (or synthetic variant of such), no

[Falconi]

has anyone tried to do a rear disc conversion? I think I am about to attempt one tomorrow because I found a couple Previa's with rear disc (no ABS). From the looks of it, everything should work. The only thing I am uncertain about is the proportioning valve. If I need to swap that out or not. My assumption is yes I do, so I'm going to grab one tomorrow as well. I will let you guys know if everything works out!

[TheMAN]

it's not a straight forward swap... you need to swap the entire rear axle assembly... the flanges for the backing plates are different, so the brake parts won't just bolt in... you can reuse your 3rd member and axle shafts to cut costs down, but it's more work
and yes, you do need to swap the proportioning valve

[Falconi]

Thanks THEman, I learned that the hard way today. So i rented a slide hammer from NAPA went back to the junk yard this morning and started to take the the disc brakes off. I went to another Previa and took the drum brakes off and I saw that I needed to swap the entire axle assembly for the reasons you stated. I still might do it, the junk yard quoted me $250 for the entire thing. :)