NorCalVP

I am in the process of buying Sequoia axleshafts in hopes to install the rear disk brakes onto my 96 4Runner. I have not physically seen these axleshafts and will have to drive a few hours each way to pick them up. I don't have any doubt's that the rear brakes will fit, except that i have no way to know if the OD of the 4Runner's axleshafts and the OD of the Sequoia's axleshafts are the same.

I know there has been talk of a rear disk swap (with Factory toyota parts), but i don't know if anyone has actually done it. If i can't find the information needed i will buy the axleshafts anyway and try (there's gotta be a chance) to make it work.


Does anyone know?

havic

I hope you're successful in doing this swap. It'll probably make it easier to swap in disc brakes. Keep us posted, maybe you can do a write up if you get it done.

NorCalVP

Since the day i bought this 4Runner, my biggest complaint about it was the spongy brakes, my 84 Tercel has a better brake feel than my 96 4Runner... If i am successful i will fully document everythng with a full writeup, but if i an unsuccessful, then i will destroy all evidence that i even tried...

I am really hoping that this solves my brake problems and gives me a nice firm pedle, and makes this thing stop like i think it should

Albuquerque Jim

I would be more concerned about the length of the axle shafts. Aren't Sequoia's much wider than 3rd gens?

NorCalVP

I won't be using the sequoia axleshafts, i will be removing the brake components from the sequoia axleshafts, and pressing my stock 4Runner shafts into the Sequoia backing plates.

superjoe83

as long as the 4 bolts on the end of the axle tube are the same, your runner has a 8" v6 style housing while the sequoia has the non TRD taco housing, i would assume that they are the same, but its something to check out

NorCalVP

That's the plan, and hopefully that's what i'll find, but i was hoping that someone had first hand knowledge.

NorCalVP

DAMN!!!!

It looks like i found out the information i was looking for. According to Brian at FROR, the bolt pattern on the sequoia axle is different than that on the 3rd Gen 4Runner.

I am going to go crawl under some trucks at the local dealer this weekend and see what i find...

Steve

http://www.pirate4x4.com/forum/showthread.php?t=282670

MTL_4runner

Man I hate the spongy brakes too, I hope someone finally gets a good mod writeup for this!

Gadget

I doubt what you have planned is going to cure your chief complaint about spongy brakes.

The first thing you should do is flush the brakes properly. Then PROPERLY adjust the rear brakes. If that still does not meet your expectations, then replace the brake lines with the stainless steel braided Teflon brake hoses. That will greatly reduce the swelling of the brake lines when the perssure goes up. This will reduce some of that spongy feel you are getting.

Rear disc brakes are not going to do this for you. Overall it is likley going to reduce the total braking power you have now. Disc brakes require much greater line pressure to get the same braking effect. So, if you are not going to GREATLY increase the line pressure to the rear brakes and just put on discs, you will have less braking power.

To make a rear disc conversion work correctly you will need greater line pressure in the rear. You are going to have to install a master cylinder from a truck with rear disc brakes, then you may need some kind of adjustable proportioning valve to get the proper braking bias set up between the front and rear.

I think it is possible that you are going to spend a ton of money, invest a lot of time and end up with an end product that is not going to cure your chief complaint of spongy brakes.

Gadget

havic

Thanks for killing all hope for a better braking system.

Gadget

I would say that all hope is not lost, but you have to go about it the right way or you will make a mess out of it.

Keeping in mind that at best 25% of the braking effort comes from the rear. I am certain that the current rear drums are more then sufficent in providing all the braking force the rear can handle. Pretty much doing a disc conversion back there is going to reduce rotational weight that could yeild more acceration and a higher number on a initial dyno, but will the braking be any better??

If you want better brakes the area to focus on is the front. URD is working on a very nice front brake upgrade that should make a very nice improvement.

Gadget

havic

No wonder the discs warp so much. Heavy truck stopping on two brakes. Why can't the rear disc brakes work if you put better brake lines? Would it almost be the same as having the drums? I think it would be easier to service and look better if the rears had discs. How do the 4th gens regulate the rears?

Gadget

OK I will try again in a slightly different way.

Drum brakes have some mechanical advantage to them. The leading shoe is pulled into the drum by the friction of the shoe against the drum. This helps apply the brakes and results in less line pressure needed to acomplish the needed braking action.

For a disc brake to acomplish the same braking action or force it will need GREATER line pressure. So, if you just bolt up some rear disc brake without increasing the line pressure as needed, then you will have an overall LOSS of braking affect.

This is all MUCH more complicated then just getting some disc brakes to bolt up to the rear axle. You must also get the needed line pressure increased. Once you solve that problem, then you are golden. If you do not, you are going to reduce the overall braking performance of the vehicle.

If you are going to take on this project plan now for a different master cylinder and proportioning valve. Now after you spend all this time and money figuring all this out, you will have to keep in mind you really are not going to increase the overall braking performance since so little of the overall braking action is provided by the rear brakes. Remember when you slam on your brakes, the weight transfers to the front axle and unloads the rear. The the rear brakes had as much braking force as the front they would lock up and you would spin out of control every time you hit the brakes. There is only so much braking force you can use from the rear and there is no indication at all that the rear drums are not already providing all the braking action that can safely be used.

The rear discs on the 4th gen work because the WHOLE system was designed to have and work with rear disc brakes.

Gadget

NorCalVP

Gadget i have some questions for you.

I have owned this 4Runner for almost a year now (and love it) From the test drive i noticed that the brakes were very spongy, I could also feel a little vibration from the brakes. I have since replaced the front rotors and pads, but it seems like my vibration has returned. When i bought it I didn't notice any gear oil in the wheels like i do now (not to say that they weren't leaking before). but would having gear oil in the pads give me these results?

The first thing i did when i brought it home was flush the brake system out (with the motive products power bleader, Thanks for the tip by the way), but that really didn't help. Changed the front brakes next, which got rid of the vib, but the pedal was still squishy. I have never adjusted the rear brakes, since the E-brake has always seemed to have the correct amount of movement when i pull it.

Sometimes it takes someone who really know's what they are talking about to put things into perspective, Thankyou for doing that. This Truck is my Family hauler, and i want it to be as safe as possible. Do you have any other suggestions as to why the braking power of this truck is so poor?


BTW when i power bled the system, I did the front brakes at the calipers, and the rear at the drums, i didn't find a proportioning valve like on my Tacoma, did i maybe miss a bleader?

Steve

ErikB

I believe the proportioning on these vehicles is done in the ABS unit, which poses another problem/hurdle for a rear disk swap.

One possible cause for a spongy brake feeling is that we have a large dual diaphragm booster. If you disconnected your booster or ran a smaller or single diaphragm one, I bet your pedal would feel pretty firm. To some extent, you could compensate for the lack of boost with a smaller diameter master.... so like Gadget is saying, you have to choose everything to match and/or tune it how you want it. Probably the best/easiest way to do that would be to ditch the ABS, choose your master/booster to match your front calipers, and then run a manual prop. valve to tune your rear calipers/drums to lock up just after the fronts.

The rear drums should have plenty "power" available to them as-is to lock up the tires and/or stop the truck, its just a matter of tuning them to work. A manual prop. valve made a big difference on my '86 w/ stock drums. You ever notice how the rear shoes hardly wear at all w/ the stock LSP/BV setup...?

NorCalVP

With this truck i don't think i'd be able to remove the ABS, as my wife isn't too farmiliar with threashold breaking, and is use to the ABS. Wouldn't changing the vacuum line to the booster give me less breaking power? it's not that i just want a firm pedal, i want to be able to stop as good if not better than my car that is more than 20 years old. I have a feeling that when i bought it the rear drums were already oil soaked and not doing their job, causing the front brakes to do all of the work. Hence the warped rotors on the front.

I think i am just going to try to replace the rear seal, get some new shoes, turn the drums, and see if that will firm up my pedal. hopefully it will allow this thing to stop at least as good as my Tercel.

Otherwise

KZN185W

iTrader: (1)

Gadget,

When do you plan to sell your front brake upgrade? Is that for a 3rd gen? What wheel size is needed for it?
Thanks.

ErikB

Don't forget that your 4runner probably weighs nearly twice what your Tercel does...

Sounds like the easiest thing to do for now is just to get what you already have in good working order.

Oh yeah, one other way to get better/more powerful braking would be to run smaller tires. If your Runner came with 31's, some skinny/light little 225's like the low-end models come with would probably improve seat-o-the-pants performance (accleration and braking) and maybe improve gas mileage too. Definitely un-bling though...

4runner4ever

I had the same problem on my '90 4R.
I also had frequent problems with dirt getting into the rear drums and eat my shoes.
So I also searched for a solution with not too much hassle. I ended up using a Landcruiser 80 series Master cylinder and 70 series rear calipers and discs. This however eliminated my handbrake so I ordered a disc parking brake from All Pro and made my own parking brake setup.
So now I am running 5 discs and no drums anymore and I'm very pleased with the results. I also replaced the front drums with a set of Brembo's and mounted a set of new pads.
All in all I now have good stopping power, no rear wheel lock-up and I can lock my front tyres if I want to.

The only thing I needed to fab was the two brackets for the calipers and a new set of brake lines.

Last thing left for me to do is replace the brake lines with SS/teflon ones and get a new set of front calipers. It recently (sometimes) starts to pull to the right when braking hard so I guess after 14 years they are in need of replacement.