I had no problems with 18s but i just put a set of 20s on my toyota and I need to re notch the rear and the firewall but also my brake booster and the clutch master cylinder (not sure if that is the correct name) because of it being manual is in the way by alot. can anyone please give me a detailed way to maybe relocate this or do away with it please. maybe pictures of yours. thanksss
Sounds like fun. You can use a 78-83 Toyota 4WD brake booster. They are considerably smaller, and I was able to get a core exchange for my OEM one at Pep Boys. Saved $45. Or you can use a pre-fabricated under dash unit like this one: http://www.kugelkomponents.com/products/brakesystem_reverse90.php
As for the clutch master, you can either move it up, in, or re-configure it to work inside the truck under the dash. If you are doing a full show engine compartment, you might want to move it inside like this one: http://www.yotascene.com/forums/viewtopic.php?f=31&t=3988
Or this one: http://www.yotascene.com/forums/post49288.html?hilit=clutch%20master#p49288. This is not a mod for novices.
There are also pre-fabricated underdash set ups for clutches too. It is easier to move the clutch master in, but its not as clean looking. I've also seen guys move it into the cowl area.
On my first yota build I pushed the clutch into the cowl and recessed it 1.5" or so. I read an 85ish clutch master is smaller. I also have a 85 yota booster. Considerably smaller.
im guessing you need to call a shop to help you out. this is your brakes. your life depends on it. and im not being a jerk, but if you cant figure it out on your own, youll need some expert help there.
you can run a booster off a geo metro which has about a 7 inch diameter. the clutch master can be recessed inward or flipped around to the inside of the truck ( lots of fabrication on that). believe minitruckin did an article on it recently.
i ran geo metro booster. besides making a plate for it to mount to on the firewall since the holes were close to the original but off just a little bit, i had to have the plunger inside i believe lengthened because i wasnt getting enough pressure when i hit the brakes, but i had someone figure that part out.
im runnin the Geo booster right now, as well as raised and recessed the slutch master cyl.....the cylinder I used was off a 86 4wd cause it was about an inch shorter....
for the Geo booster, I just plated and redrilled the mounting holes, and lengthened the plunger rod like mentioned before...works fine if done properly