Need some advice on the brakes again. Best place to put the master because of a lot of reasons is at the rear of the cab. I can access it there by moving the seat up, but the length of the rod from the pedal to the master would need to be 35-36 inches !!!! What's some opinions on that ? And if the length would work, how big should the tube/rod be ? 1/2" round tube ? 1/2" square ? Or bigger ? The car is the same old 39 Plymouth pickup . Main reason to consider this location is that if I put it in front of the seat, I've got to have a raised door for access, that would stick up about an inch above the floor, and foot room is already tight. Thanks in advance for reading and letting me know what you all think.
In the drag cars we'd have very long pushrods and made them from 5/8ths chromemoly tube with 'weldnuts' in each end to thread 3/8ths rods to return to factory size, at midpoint we'd add a loop the tube would pass thru as a retainer to the rod couldn't possibly drop out. The loop is loose fit, like a big eyebolt, but we'd make then kinda fancy.
Thanks for that idea ! I thought that something bigger than 1/2 would be best ! And the loop is a great idea ! Thanks again !
oj has it right. However, I'd use 5/8 or 3/4" mild steel seamless tube with an .090 or 0.120 wall, as it will be easier to acquire. With luck, you'll be able to find a "drop" of the needed length at your friendly local steel warehouse or racing chassis fab shop. You might also find a thicker wall tube that could be threaded, rather than welding threaded nuts on the ends. The safety loop is important. vic
The length would not be as much a problem as the diameter. After you have your mounting point established measure the length needed and pick a rod or tube stiff enough to resist bending. The loop to support the middle sounds like a good idea but not something as tight a fit as a Heim joint. There has to be a loose enough fit to allow the arc motion of the rod.
Plenty of chassis suppliers back there so for 3' of cm tubing and 2 threaded ends, you are in at under $25. 5/8 would be the absolute minimum for that length, but would go with 3/4 x .058 wall for a safety margin and the fact that most threaded ends are made for that wall tubing.
Thanks much for the suggestions ! I can get started making this work in the morning ! Appreciate all the input from everyone !
Wicks Aircraft or Aircraft Spruce can sell you any diameter , thickness & length of 4130 chromoly tube suitable for a push rod. 4130 chromoly is super strong & is commonly used by aircraft home builders. Same material used for NASCAR roll cages. Best is to TIG or Oxyacetylene gas weld chromoly. If there is a choice stay away from Chinese tube & go with American or German. https://www.aircraftspruce.ca/catalog/mepages/4130tubing_un1.php http://aircraftproducts.wicksaircra...gles/4130-round-tubing?&pagenum=2&pagesize=50 Glenn
I used 5/8" steel rod about 22" long to put my brake pedal bracket where it needed to be and the booster/master cylinder on the crossmember of my '29 AA, just under the seat. It forces me to install a remote filler for the m/c, but at least I have room now to put it all together.
kyotb8, a linear bearing is used to allow a shaft to run back and forth. It will allow your MC pushrod to travel from your brake pedal to the master cylinder with some support. Go on to the McMaster Carr website and enter Linear bearing and you will see what it is.
It is a tube (the outer race), lined with ball bearing in a special cage. The shape of the race allows the bearings to move in a loop. This facilitates something moving through the bearing, in a straight line.
You can use a mounted tube, with a Delrin sleeve inside of it, too. I have done than. Seems to work fine.
If I remember the push rod is around 3 foot long. Hope it helps. I used a bit of tube to 'contain' the rod. The pedal end of the rod will move in an arc (unless you put more joints in it) so you cant have a fixed support point along its length, unless it can also move up and down.
Yes have and am considering that ! Might be easier, but just like the idea of not seeing the master ... I'm thinking ...
I have underfloor pedals on my 27 going to a 66 Chevy pickup truck dual master cylinder (one side brakes the other side clutch) I made pushrods that are about a foot long out of round tubing with bungs welded into each end. On one side I have rod ends that go to the pedals and on the other side I have a cut off bolt that I am using as the pushrod into the master cylinder. That way, I can turn the rods out of the threaded bungs for adjustment. Been that way for over 25 years with a very stiff clutch and no problems. Don