Topic: Brakes with bigger tires

[sharpxmen]

Hi all,
Any pointers on how to restore braking power with bigger tires. I put 33s on my Jeep and the difference is significant. I read somewhere of a brake boost pump that uses powersteering pressure to get more braking but it goes for about $800. Not sure about a bigger boost pump as there isn't much room left between the current one and the TB elbow that goes to the airfilter. Any suggestions would be much appreciated. Thank you.
(95YJ, 2.5L, 3.5'' lift, 33x12.5x15 BFGs MT, TCase 1'' lowering kit, cold air intake, 4.0TB)

[Jeffy]

You could do this a number of ways.  Simple things like getting better brake pads and shoes would be a start.  Next would be to install a larger master cylinder.  E350 or Grand Marquis, MC work for swaps.  This will increase the pressure to the brakes.  Upgrading the brakes themselves to larger ones will also help.  Grand Cherokee two-pot calipers will work with some modifications.   You can also go with drilled and slotted rotors.  For the rear, a disc brake conversion.  I believe the Teraflex kit is one of the cheapest at $500.

You could also adapt larger drums but you will need to redrill the backing plates to accept the D35 flange bolt pattern.  The next level up would be to install hydroboost.  This gets rid of your vacuum booster and replaces it with a hydraulic setup.  These work extremely well.  The down side is if the engine isn't running, expect one good stop.  After that you won't have much brakes.

Another thing.  I noticed you have a cold air intake.  What kind is it?  Intake pressure is what the brake booster runs on.  With a CIA, you end up increasing the CFM but that causes the PSI to drop.  The lowers the available vacuum for the booster and results in poor brakes.  You might try to put the stock setup back on and see if that changes anything, before spending money on other things.

[wrangler387]

O no jeffy double posted... motion for ban  :P
I thought you could use the grand cherokee rear disk brake set-up? I've also heard mixed reviews on installing a larger brake master without going to larger piston calipers also. What modifactions need to be done in order to use the two piston calipers? I would like to upgrade my set-up waaaaaaay down the road  

[MA2LA]

the grand brake swap works pretty good and is easy.

[wrangler387]

^ which one are you refering to? front or rear? and you have any links or info on how to do the swaps?

[Jeffy]

You can swap the front AND rear brakes over.  You'll probably want to swap masters also.  The front's are a lot better then the single pot Wrangler brakes.  The rears should bolt right up.

Honestly, the biggest bang for the buck would be hydroboost.  I'd like to eventully convert mine over to that but it's not cheap either.

[wrangler387]

What all is involved with installing the front two piston calipers? I'd definately upgrade my MC if i upgrade the front calipers and add rear disk brakes.

[sharpxmen]

Thanks all, that helps. I guess I will have to do some research on Grand Cherooke brakes - would these bolt right on? Or there are some mods involved - if i can find one at a wrecker i can probably get most of the stuff off of it and try it out.
The hydro booster upgrade - saw that but it is pricey - if any of you know discount/budget ones please post a link - that would be really helpful.

Another thing.  I noticed you have a cold air intake.  What kind is it?  Intake pressure is what the brake booster runs on.  With a CIA, you end up increasing the CFM but that causes the PSI to drop.  The lowers the available vacuum for the booster and results in poor brakes.  You might try to put the stock setup back on and see if that changes anything, before spending money on other things.

It's a home made one - just a conical APC with a 3'' OD pipe between the factory hose and the filter + 2 x 1/4'' NPT fittings for the breather and gas vapors - cost $40 bucks, best bang for the buck i have ever done on my YJ (along with the 4.0TB which i forgot to mention). I don't think it would make a difference even without the filter as far as braking goes - the vac booster charges with the throttle closed: that goes to about 28mmHg vacuum while using the engine brake and somewhere around 20 when idle - if you floor it goes close to zero (that would be the vac created by the air-filter). I got a vacuum/boost indicator (i have a S/C in the works so i jumped the gun and install the gauge ahead of time).

Thanks again for all feedback on this - this forum rocks  :)

[ratherbejeeping]

The WJ swap involves getting the knuckles and welding a spacer on, redrilling the pattern in the rotors or sourcing others ( I run Sport Trac with my hub kit), a new drag link at the least (it's cross over steering), and either grinding the calipers to clear (you want the earlier ones) or 16" wheels. the mounting hole for the brake lines is a lot lower too and took new lines in my case.

pics of my set up
http://pg.photos.yahoo.com/ph/ratherbejeeping/album?.dir=2c79&.src=ph&store=&prodid=&.done=http%3a//photos.yahoo.com/ph//my_photos

Totally worth it

[ratherbejeeping]

Almost forgot, there's another option.  Dual diaphragm brake booster about doubles your clamping force and it's a lot cheaper then hydroboost or the WJ swap.  (I did both)