Brake options for my 109' IIA hybrid electric - Defender Source
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  #1  
Old July 29th, 2013, 02:43 PM
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Charles Galpin
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Brake options for my 109' IIA hybrid electric

I'm looking for input and ideas on what approach to take for the brakes on my 109" IIA hybrid electric.

Note - this project has some very specific restrictions and requirements and its not about me not being happy with the stock series brakes. My 88" IIA works fine with it's stock brakes.

What I have is a real mutt. I am starting with:

- 109" IIA body on a defender 110 chassis
- 1994 RRC LWB axles and disk brakes, although I have NAS D90 front rotors/calipers for the front to get rid of the dual lines
- Expect it to be in the 3500lb range
- have stock 109 brake MC/pedal/tower etc if usable
- NO VACUUM
- NO POWER STEERING

In theory the hydraulic brakes will get light use as the first line of braking will be regen, but for redundancy I want the brakes to work well without any regen.

I do not need to stay with stock or land rover parts. But, I would like to use new parts for this because I value my life and really don''t want to put trust in junkyard parts.

So, the two main options I can think of are going with a vacuum assisted booster, or hydroboost which would also give me power steering.

1. Vacuum assisted booster with electric vacuum pump. I assume the means a series III pedal tower/MC? Any other options? I think this means cutting my fender to make it fit too (and maybe bulkhead even)? I assume if I cut the fender the cut depth is not visible with the hood closed. If not, I think this is a non-starter for me as I want it to look stock from the outside.

2. Hydroboost with an electric hydraulic pump. Assuming I can get a beefy enough pump, this would allow me to run power steering as well if I want, but this looks to be a pretty expensive option and it's not clear what kits fit. It has the benefit of minimal clearance needed for the master cylinder so no fender cutting.

Thoughts? My primary goal is to pick a route and make any bulkhead and frame mods needed before galvy.

tia,
charles
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  #2  
Old July 29th, 2013, 02:53 PM
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Adam
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With the proper master cylinder setup, you wont need any kind of boost. At 3500lbs, you're in the same weight category as a lot of classic sports cars and with much bigger rotors and calipers.

Do some research on manual braking systems, you can probably find a calculator out there that, if you know all the piston sizes in your system, will tell you what size master cylinder to use.

Then get the appropriate one from Wilwood or similar. Fabbing it in would be even simpler than adding any kind of boost system.
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  #3  
Old July 29th, 2013, 05:47 PM
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Robert Davis
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Quote:
Originally Posted by cgalpin View Post
I'm looking for input and ideas on what approach to take for the brakes on my 109" IIA hybrid electric.
- have stock 109 brake MC/pedal/tower etc if usable
- NO VACUUM
- NO POWER STEERING
Run a vacuum pump off the rear drive flange with a 1 gallon reservoir and you'll have the vacuum needed for the brakes.
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  #4  
Old July 29th, 2013, 05:49 PM
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Adam
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Until you're in traffic or on a trail and using the brakes more than you are actually moving.

Since the whole vehicle is based off electrical power it would make sense to limit the amount of ancillary draw on the system. Go manual brakes and keep the manual steering, save all of your reserve energy for propulsion and range.
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Old July 29th, 2013, 10:52 PM
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Quote:
Originally Posted by transientmechanic View Post
Until you're in traffic or on a trail and using the brakes more than you are actually moving.
There will be less need for power brakes in a scenario whereby the brakes are being excessively used at low speeds to run out the vacuum reserve and in that scenario the driver is no worse off then if there were only manual braking.

The power brakes will be needed at high speeds when there is more than enough vacuum with a pump that runs off the drive flange. At high speeds the manual brakes you suggest are much much much less effective.

Power brakes are clearly the best braking option for this scenario.
Automotive manufactures would not have added vacuum boost to manual braking systems if it didn't significantly improve stopping power!

The only challenge will be to have a check valve to operate when the vehicle is in reverse and a pump that will rotate backwards without any negative effects. I may have one in the shop that will work that I meant to show Charles when he came by a few weeks ago, but was distracted fitting a transfer case at the time.
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Uncle "Richard" Douglas has a Land Rover with big wheels that never gets stuck... until he breaks something so it won't go. Uncle Douglas always breaks something. - Anna Crowther at the Conclave 2012 (AKA Carburetor Neck)

"What's with this death wobble, Uncle Douglas, I can't keep it in 1 lane?"
UD: "Just Power through it man!"
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  #6  
Old July 30th, 2013, 07:10 AM
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Bill Adams
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Here's a thought:

Remote mount the brake MC and booster so you don't have to cut the wing. Use your 2A tower with a clutch master and push the MC with a clutch slave. It'll just add a short hydraulic run to the system.
Run the booster with an electric vac pump from Jegs. Maybe add a vac reservoir made from 4 or 6 inch PVC pipe.
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  #7  
Old July 30th, 2013, 07:54 AM
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If done carefully cutting the wing isn't a big deal, since that's basically what the SIII wing is, and won't show with the bonnet down. Or just use a SIII wing top.
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  #8  
Old July 30th, 2013, 09:44 AM
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Charles is understandably reluctant to hack up an unobtanium 2A wing. It can be done tastefully, and that requires a bit of old school hammer and dolly work. What you have to do is cut out the profile of the cutaway into two pieces of 3/4 plywood (I'm actually going to double that up so I have an inch and a half thickness). Rough out the cut on the wing leaving about a 1/2 inch that will be used to form the lip. Sandwich the aluminum between the two wooden guide blocks. Clamp tight so it won't wiggle. Then using a soft mallet start turning that edge downward. You gotta work it around the tight radii. I think I'm going to go for a 45 degree bend and not a 90. It should be enough to stiffen the cutaway and not look funny.
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  #9  
Old July 30th, 2013, 10:27 AM
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Charles Galpin
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Lots to think about. This was the most useful link I found

http://www.pirate4x4.com/tech/billavista/Brakes/

I am not entirely sold on the idea of going manual but will run the numbers and see if I can make sense of it. With the increased area of the disk brake pistons, and the fixed pedal ratio of the rover brake pedal (without going crazy and changing either of those), I'm down to different master cylinder bore sizes and living with the tradeoffs associated with that. Rovah farm has a bunch of different bore sizes for MCs so it looks like they are easy to get. I am not sure I'll be able to tell how they will feel without having to actually try it though. Like I said, in theory regen should make this more than doable, but I'd hate to be wrong.

My biggest concern is then having to go make a bunch of mods after galvy if I don't like it. I like the idea of a remote booster (or both the mc/booster) but if I go vacuum I'll just use an electric pump Robert - your way says way more complicated.

Are series 3 wing tops/inners in decent shape readily available? I like your plan with the template Bill, but it would look nicer with a series 3 inner/wing top and I could save the 2a one.

So does anyone have a defender brake pedal handy? I measured the series one as well as a defender clutch pedal and they are both 5:1 (9.5:1 7/8") so I assume the defender pedal is the same. It's tricky to measure in the truck, although I can probably verify the 9.5" length easily enough when the truck is here.
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Old July 30th, 2013, 11:55 AM
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Quote:
Originally Posted by o2batsea View Post
Clamp tight so it won't wiggle. Then using a soft mallet start turning that edge downward. You gotta work it around the tight radii. I think I'm going to go for a 45 degree bend and not a 90. It should be enough to stiffen the cutaway and not look funny.

Good idea Bill, but I would do the full 90. If you look at how the SIII is done they reduced the amount of metal at the curve so as to not cause cracking or buckling as it folded. At least that is how I remember it.
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  #11  
Old July 30th, 2013, 12:36 PM
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steve
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Quote:
Originally Posted by transientmechanic View Post
With the proper master cylinder setup, you wont need any kind of boost. At 3500lbs, you're in the same weight category as a lot of classic sports cars and with much bigger rotors and calipers.
I'm running a non-boosted 1in wilwood dual brake MC on my 86" with toyota disk brakes. Stops great but you gotta push and you feel it when the ruck is loaded.
IMO I would be reluctant to do it unassisted on a larger/heavier truck.
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  #12  
Old July 30th, 2013, 12:39 PM
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Charles Galpin
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Steve, roughly how heavy is the 86" and what size pistons and number are we talking on the toyota brakes? If you reduce the bore size of the MC you will get more braking power but it will require more pedal travel (which may not be a bad thing).
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  #13  
Old July 30th, 2013, 02:06 PM
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My vote goes to a corvette manual MC adapted to the series tower and front and rear discs
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  #14  
Old July 30th, 2013, 02:14 PM
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I still support the manual braking system idea. There is no need for the added complexity of an assisted system other than the luxury it provides.

Manual systems have been proven to work on everything from older trucks and 4x4s to 200mph race cars. The technology exists to make it work, and work well.
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