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Brake pedals and dual brake MCs for the roadster


mlw

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My 67 roadster is stripped down for paint, a good time to do some brake upgrades. The 67 roadster has a poor pedal ratio(3.8/1 by my calcs), weak firewall, and single brake circuit (no room for a dual circuit MC, carbs). I am hoping to fix all three.

 

Existing pedals:

P1010253r.JPG

 

Existing firewall:

P1010255ar.JPG

I have never liked the way the brace comes down, making a triangular pocket that traps crud. I am considering cutting the rest of it out.

 

New firewall:

P1254233r.JPG

 

I mocked up the firewall piece with a piece of masonite to locale where to put the holes, then tried it flush with the old firewall. But the roadster has a back slant to the firewall, that combined with the slope in the floor, limited pedal travel. So I folded the edge over, and cut back the center vertical edge to get a more vertical orientation. That gave me enough room for the pedal to bottom out. (they are quite adjustable - this is a Tilton 72-607, with the compact 75 series master cylinders).

 

New pedals:

P1254234r.JPG

 

The pedals will bolt to a couple 4 inch pieces of 1x1 tube, with a heavier wall 3/4 square tube running side to side. A short bit of 3/4 tube will be welded to the bottom of the cowl/hood tray. I am planning on welding the 1x1 tubes to the firewall on the bench, with the pedal assembly attached, then tack in the new firewall and 3/4 crosspiece. Then I can remove the pedal assembly and weld it all in.

 

P1254237r.JPG

 

The new firewall is 11 gauge (1/8). Haven't gotten to cleaning up the interior yet. I went with two 5/8 brake master cylinders. Will replace the clutch MC with a matching Tilton when I recover from the first round (: 

 

Michael

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Have been too busy with work, but slowly getting the new firewall welded in. I am not an experience welder, so its not as pretty as it could be, but I am sure that it is solid. I was welding a little hotter, starting on the 1/8 and dragging the puddle down onto the folded edge of the body sheet metal, and jumping around to keep the firewall flat, so it looks a little rough, but will clean up.

 

P3014246r.JPG

 

I never liked the old firewall brace, it made a awkward triangle with the sidewall that collected crap, and was hard to clean - so I cut it out - the new firewall is plenty strong without it.

 

Also pulled the body off the frame, as I have a new transmisson (not really new) - a six speed!, which should be here in a couple weeks, and will need to modify the frame crossing for the new tranny mount, and pulled the front suspension apart to give it a fresh coat of paint, and replace the rubber boots, which I was too poor to do 18 years ago when I pulled it all apart the first time. By now the boots were a gooey mess. Also have new Mike Young comp springs,  Altima vented rotors and Volvo calipers to install.

 

P3014244r.JPG

 

The suspension came apart easily, since I had been there before, and most of the paint I applied 18 years ago still looked good, other than some overspray from priming the body, and a few rust spots on top of the frame. I am going to spray it with a coat of 'zero-rust', and put it back together.

 

I noticed the bolts that hold the upper A arms are drilled for safety wire. I have no idea if this is common, or something I did years ago, or how to wire them. I can see it would not be good for them to come loose, but they thread into the frame and have some large nuts on the backside.

 

P3014248r.JPG

 

So this may be a thread in slow motion, but eventually I'll get there.

Michael

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I did the Volvo swap on my 69 2000. You are going to love it. Stops on a dime and gives you change. No more brake fade either. Pretty easy swap that is well documented on 311s.org.

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I did the Volvo swap on my 69 2000. You are going to love it. Stops on a dime and gives you change. No more brake fade either. Pretty easy swap that is well documented on 311s.org.

 

Don't mean to hijack this thread, but can I ask how you dealt with the issue of the 2 lines entering the caliper...did you get the special junction block fabricated or did you devise another way? Also, what year/model Volvo did your calipers originate from. Thanks!

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Ogre - I am doing Mklotz70's vented Altima rotor and caliper mod, see his thread for caliper info. He sent me a plug for one hole, I am drilling the calipers per his method. I did the unvented volvo caliper mod years ago, and have some leftover junction blocks.

Michael

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67_roadster_altima_rotor_volvo.JPG

 

Front Passenger side, with the Altima vented rotor and Volvo girling calipers. Still a few ends to torque down, (the ones without a cotter pin). Drilling the rotors went fine, you want to start 3/16 to 1/4 up the sidewall of the caliper bore, which is a little tricky, I used a rounded point carbide bit in a die grinder to give myself a dimple to start in.

 

While I am on the subject;

 

A few thoughts on assembling the Datsun Roadster front suspension.

 

I had a bit of a time deciphering left and rights, and I have done this once before - many years ago, I have a good memory, it's just short (:  

From the factory parts manual:

 

frontsuspension-3.jpg

 

Looking at the lower A arm, I assume this view is the passenger side, seen from 3/4 rear.  You can tell from the slot on the leading side of the lower A-arm for the sway bar clip.

Forgive the coffee stains, this is a scan of my vintage 1983 Rallye catalog, which is clearer than the factory parts pdfs. Note the spindle (#1), and the bolt hole just inboard of the #5 spacer. In this view, that should be behind the verticle centerline of the spindle. Also look at the Arm closely, particularly the center bolt hole boss. Now if you look at the Arm itself, the part, the factory illustration would have the side rod going down into the arm, which is wrong,as confirmed in the steering linkage diagram, and doesn't work. That part, in the drawing, is backwards, and upside down.

 

Or to put it another way, parts number 1 and 29 are drawn of the drivers side, seen from the front (which he also does with the sway bar mount below), while the A arm assembly is drawn from the passenger rear.  I have done these sorts of drawings (for a big airplane co, pre CAD), and it pains me to see a drawing as a source of confusion rather than clarity. The trouble is that it almost works to assemble it the way its drawn - spindles swapped left to right, etc, everything almost bolts together, except for a small rub on the caliper attachment plate. (Don't ask me how I know).

Now look at the same here:
http://spriso.com/content/wp-content/gallery/1967-datsun-1600-sr20det/front-end-assembled.jpg
note the arm appears to curve inboard from the center bolt.
and that the top bolt for the caliper adapter is forward of the spindle center line. I am guessing these fellows have it right, more or less (:

And another popular roadster picture source:
front end before, and reassembly:

http://www.mydatsunroadster.com/category/front_end/
http://www.mydatsunroadster.com/images/large/RH_rod_free.jpg

(if you carefully follow his assembly photos, he takes a few tries to get it right too)

Note in the old photo, that the arm curves outward from the center attachment. The arm will bolt on either way, and in the murky recesses of my brain I remember some discussion that turning them in would give a little more lock to lock turn, although examining the part would suggest that the arm is meant to be mounted with the center bolt hole under the arm, and in plan view, curving outboard to the tie rod end (which comes in from below). So I happen to have two right hand arms, rather than a pair (I assume there is a pair, there are two part numbers), but I don't think it will make a bit of difference.  I am guessing my tires will rub before I hit steering lock (:
 

The brakes cleared my 14" Appliance mesh wheels fine, imagine they would clear most. I am curious to get it set back down on the tires and see how much the comp springs lowered it,. although I probably won't see much until I set the body and engine back on it. But I need to get everything buttoned down first, the front suspension is not someplace to forget to tighten something.

 

Next, now that the weather is warming up a bit, I can finish my brake pedal/firewall project and get some epoxy primer on it.

 

Michael

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