Packard Forum Index » V-8 (1955-56)

The BTV has not been repaired recently that I know of. I did just have the brake light switch replaced. There was an issue where the MC was almost out of brake fluid when the switch was replaced.

I guess that I've got some work to do this winter, re brakes. I'll keep working on finding the best solution for me.

Bob

To my knowledge there is nothing modern that will just bolt in. The space the BTV occupies is very limited which rules out almost everything vacuum operated. Those units that will fit are a bit too weak and located at the end of the pedal, makes it impossible to get the correct mechanical advantage without doing something along the lines Craig has done. Any use of vacuum units in that case without pedal mods requires it to be located further up on the firewall as several have done but also indicates immediately to the purist that the car is no longer stock.

There are a couple of posters who have mentioned using the Electroboost unit from ABS. I believe that is all ABS would recommend as a replacement also. It is an expensive way to go but apparently either will fit in the space or can be hidden well under the floorboard using a different pedal. The additional boost unit can be hidden out of sight & can be adjusted so any mechanical problem is overcome while power is present. Unfortunately unless I missed them, there have been no pictures of installs posted & I don't believe anyone has posted much on the operation. To that end, I would want to know if in original location and something happened to the electrical system and brakes were needed, is the mechanical advantage enough to have decent brakes.

"There was an issue where the MC was almost out of brake fluid when the switch was replaced"

If there is no sign of leakage on the floor where the car sets or on the frame then most likely the fluid was sucked out of the master cylinder and into the power unit of the BTV.

When u remove the BTV pour out any fluid in the power unit for an approximate measurement and report back please.

The disk brake conversion is probably not needed in you case. Even with a disk brake conversion u will still need to convert the BTV to something else.

Why not do it one step ata time. Either have the BTV rebuilt by a COMPETENT BTV REBUILDER or convert to a modern master and power unit. It's your choice.

MY RECOMENDATION is the same as Craigs. Convert to a MODERN unit. Tha'ts what i did. At this point i do NOT recommend ANY BTV whether newly rebuilt or otherwise. The BTV has become much too controversial. Arguments (pro and con) over the BTV have raged for pages and pages over the last 10-12 years.

I agree with you about the BTV being something that I want to get away from. I am going to take this a step at a time and do it right.

I have a question about the brake pedal travel ratio, my 56 Executive, and the MC/booster mentioned in the Packard Panther rebuild site. If I install the same MC/booster (drilling the new holes for the booster unit) will I need to modify the brake pedal mount to achieve the desired higher pedal ratio?

Bob

Yes. As Craig found, the 1:1 in the Packard requires extreme effort in a master designed for 3 or 4:1. The BTV is not a master cylinder in the conventional sense. It uses a long stroke with a narrow rod that never touches the cylinder walls to displace or squeeze the fluid out whereas the modern units use a short stroke and larger surface area to push the equivalent volume ahead of the piston.

To achieve the desired longer pedal stroke, could I add spacers to the brake pedal mounts?

The cylinder itself is the limiting factor. It can only move so far and you still have the force issue. At 1:1 you only get as much pressure as you can push with your foot whereas at the greater ratio you get your foot force plus the lever advantage but in a shorter distance. That limited distance is why the larger surface area is needed for the same volume. It becomes a trade off with the lever advantage getting the nod.

The booster/MC manufacturers specify (not recommend) 3 or 4 to 1 pedal leverage for a reason. I tried to use 1:1 with the MP booster and my Pat would not even slow down no matter how hard I pressed!

The releveraged pedal shown on my website works beautifully. Some have complained beforehand about the different pedal position, but not so much after they have driven it. Your muscle memory learns the new position pretty quickly whether or not you left or right foot brake.

If you want an original pedal position and 3-4:1 ratio, you must go to a firewall mount booster/MC like PackardV8 (Honda), Turbopacman (Ford) or YesterdaysRadio.

Craig

Craig,

Do you have the dimensions of the brake pedal brackets and the measurements for the new holes to be made in the pedal arm?
I think that yours is probably the best solution. It seems to be one with the least amount of metal work. It also leaves the changes as unobtrusive as possible.
I could leave the two brake pedal mounts unattached to the firewall. This would mean that only two holes be made to the brake pedal arm.
One thing though, in the final pictured brake pedal assy, what is attached to the top 'rod' via a clamp?

Start at post #3 and see pics that follow in the thread below. This about the eziest, cheapest fasterst and cleanest way to convert:

packardinfo.com/xoops/html/modules/newbb ... orum=3&post_id=29815#forumpost29815