PrinceValorum
New member
My stock brakes were already warped or warped immediately after I got the truck. I've never towed more than a utility trailer and I was at stock weight when they warped, too. No way I'd go without the TBU for a built rig, but my truck is also extremely heavy.
Unfortunately I've been dealing with the soft/extended travel on the first pump and then a firm pedal on the 2nd or 3rd issue for a while as well. It hasn't yet caused me any issues, but having to press the pedal 60-80% of the way to the floor, it's not exactly confidence inspiring, at least until the brakes do kick in.
I went with the 199mm setup over the 231mm as I figured it would result in a more balanced setup overall vs having huge in the front and drums in the rear. I remember reading ages ago that an unbalanced setup like this resulted in worse overall braking performance, aka longer stopping distances, in the context of track cars. If the stock balanced brake system results in the front tires accounting for 75% of the stopping effort, just due to weight transfer/physics, and you add big old brakes to the front that now cause the front tires to do 90% of the braking, you have a less effective brake system, since the rears are under utilized.
After reading this thread I'm now wondering if it isn't also the proportion of the new volume F/R vs stock.
This is obviously hypothetical (and conjecture, as I don't have experience tuning brake systems), but if the stock setup has an equal 1 volume unit [VU] required for the front calipers and 1 VU required for the rear drums, and the TBU results in something like 2 VU front / 1 VU rear, then I think this would be part of the problem. Without something else added to the system like a proportioning valve to send the new increased volume percentage to the front, the system sends an equal 1:1 to the front and rears, causing the rears to fill first and the fronts to be short the increased volume amount. Without increasing the volume of the MC I'm curious how adding/adjusting a proportioning valve would affect this issue.
I'm in the same boat. I read through the first thread a few weeks ago, and there was no real consensus. A page linked in that thread does have this chart, but there is no direct upgrade path, as far as I can tell. The booster seems to need replaced as well if you want to try one of the Land Cruiser flavors. The FJ45 does have a 1 1/8" bore according to the chart, but it came with drums front/rear. There does seem to be an option on the T100 to get a 1 1/16" bore, and it came with disk/drums from the factory like ours, but also requires a different booster. I find it extremely odd that the Tundra from '99-'14 came with a smaller bore MC than the 3rd gen 4R.
Unfortunately I've been dealing with the soft/extended travel on the first pump and then a firm pedal on the 2nd or 3rd issue for a while as well. It hasn't yet caused me any issues, but having to press the pedal 60-80% of the way to the floor, it's not exactly confidence inspiring, at least until the brakes do kick in.
I went with the 199mm setup over the 231mm as I figured it would result in a more balanced setup overall vs having huge in the front and drums in the rear. I remember reading ages ago that an unbalanced setup like this resulted in worse overall braking performance, aka longer stopping distances, in the context of track cars. If the stock balanced brake system results in the front tires accounting for 75% of the stopping effort, just due to weight transfer/physics, and you add big old brakes to the front that now cause the front tires to do 90% of the braking, you have a less effective brake system, since the rears are under utilized.
After reading this thread I'm now wondering if it isn't also the proportion of the new volume F/R vs stock.
This is obviously hypothetical (and conjecture, as I don't have experience tuning brake systems), but if the stock setup has an equal 1 volume unit [VU] required for the front calipers and 1 VU required for the rear drums, and the TBU results in something like 2 VU front / 1 VU rear, then I think this would be part of the problem. Without something else added to the system like a proportioning valve to send the new increased volume percentage to the front, the system sends an equal 1:1 to the front and rears, causing the rears to fill first and the fronts to be short the increased volume amount. Without increasing the volume of the MC I'm curious how adding/adjusting a proportioning valve would affect this issue.
I'm in the same boat. I read through the first thread a few weeks ago, and there was no real consensus. A page linked in that thread does have this chart, but there is no direct upgrade path, as far as I can tell. The booster seems to need replaced as well if you want to try one of the Land Cruiser flavors. The FJ45 does have a 1 1/8" bore according to the chart, but it came with drums front/rear. There does seem to be an option on the T100 to get a 1 1/16" bore, and it came with disk/drums from the factory like ours, but also requires a different booster. I find it extremely odd that the Tundra from '99-'14 came with a smaller bore MC than the 3rd gen 4R.
