wrenchtech

While replacing some bad brake lines on my '84 pickup I thought it might be a good time to upgrade the master cylinder. I already have a '94 master cylinder (looks like a 1 inch bore model?) sitting around waiting to be installed. While I'm doing that it seems like a good time to upgrade to a dual diaphragm booster. Now deciding which one to use is the question. It looks like there are several different part numbers for V6 4runners, pickups and T100's that all look to be 9-3/4" dual diaphragm models. Are all or any of these a direct swap for my '84. And are there any issues regarding the push-rod length to watch out for? -- Matt

netgodsrdn2

I can't say for sure but I believe they are all bolt in swaps. I have a booster and master from a 94 V6 4runner in my 86 4runner and it was a bolt in thing.

Ron

wrenchtech

I went ahead and picked up a salvaged booster off of a '92 4runner today. So far so good. It bolted right up to the '94 p/u master and to the '84 firewall. I had to tweak the brake lines a little, but it was just a little mild bending with my bare hands. A rusty metal brake line on the rear axle started to leak and prevented me from getting the system bled. Should make quick work of it tomorrow though.

The reason I got fired-up about doing this now is becaus I recently picked up an '89 V6 4runner. The brakes were so much better than in my '84, even though I had upgraded the '84 with Landcruiser front rotors and V6 calipers a while back. I noticed that the 4runner had the bigger booster and I thought "this is something I need to do for the old pickup". I'll report the results when I get it installed and bleed the hydraulics. -- Matt

wrenchtech

A small problem appeared when I went to test drive the truck with the new brake booster. I found that the steering shaft universal joint was rubbing against the booster housing. One of the contact points is circled in red in the picture below (you can see that it's tiny). It is still possible to steer the vehicle fairly easily, but it is a thing that should be fixed. Using an inspection mirror I discovered that it is just the sheetmetal (back)edge of the booster housing that is rubbing and the u-joint has made a nice mark where the interference occurs. I think some careful hammer work could reshape the metal edge enough to get the millimeter or two that would solve the problem. But darn it I hate to have to take the booster off again.

netgodsrdn2

Oh yeah the upgrade to V6 hardware made my 86 stop real well. Huge difference... I didn't have issues with the booster hitting the steering u-joint but from what I remember I think you are right about a little bit of light hammer work doing the trick without any troubles. Good luck.

Ron

wrenchtech

Since I installed the booster, the master and bled the brakes before I discovered the clearance problem I was reluctant to pull it all apart again, so I took a sharp new file (a big half round file) a hand filed the edges of the steering joint. It only took 15 minutes to get enough clearance. Now I have smooth steering and awesome braking power! -- Matt

Junetaco90

Hello I just seen your old post. I’m having issues with my old brake booster on my 84 Toyota pickup 4x4 I decided to replace it but I received 2 bad boosters for the local auto parts shop. I returned it and I know purchased a booster plus the master cylinder from a 94 pickup/4runner. I noticed that’s something that you did. I just wanted to know how that setup is currently holding up. Thank you