Finished my 40 plymouth rod project two years ago. I bought the Speedway straight axle kit with the 9 1/4" Mustang ll/Pinto rotors with GM Metric calipers. Does not have quite the stopping power I would like. Went to upgrade to 11" rotors with the GM midsize calipers, which I was told would work from Speedway tech guy. After ordering, read in the fine print that calipers hit axle when at full turn unless you have 4-6" dropped axle. There was reviews that people used this combination on the straight axle and was good to go with it. Speedway was very helpful with the problem and said to put it together carefully and if did not work they would return it. Hoping to talk to somebody who used this set-up.
Before the naysayers or mods hit this, this post is not about the MII suspension! If the spindles on the Speedway axle have snouts that take the MII 9-1/4" rotors, then they can take Camaro or Aspen/Volare rotors that are the upgrade brakes on MII kits. Each will work with your calipers. The difference is wheel bolt pattern GM car v. Ford/Mopar. What you are up against is a bracket issue. Your caliper would need to be in a position where it would not hit the axle when turning, and where it would also still have the bleed screw at the top. I think that's about all that could be done here to make it work, but you would need to make them, or get someone to make them for you.
Any chance you could post a picture of any/all involved caliper brackets, and possibly the spindles? I looked at all of their kits, and I cannot make out exactly what you might have. Depending on which kit, and the style of the caliper brackets for the 11" setup, it might be possible to re-drill the bracket holes, and "clock" the bracket to move the calipers. While it is not the most ideal way of bleeding brakes, calipers can be bled with a steel block between the pads, instead of the actual rotor. If that becomes necessary, they are bled off-rotor, and then put back on the bracket. I have had to "rescue" other shop's work by doing this, so I did not have to re-design entire suspension setups. EDIT: I have deduced that the only kits that started with the small Ford rotors were based off of a Chevy spindle. In that case, the caliper bracket is a chunk of flat plain steel. Making another one, one that puts the caliper in a different clocking, is not a huge hurdle.
I think I'll bolt on the parts they send and see what it looks like. Unless the mid size GM calipers are alot bigger than the Metrics, I think it might work. Thanks for all your time and info.
The "pre-Metric" calipers are bigger in all dimensions. See what's up, and write back. There can be a solution here.
I have the same, I swear I ordered the bigger brakes but I guess I didn't check the correct box. I just ran out and snapped these photos, it's just a flat bracket but the holes are close to the edge.
If I were making brackets, I'd look into using the mid 80s Corvette calipers...they look pretty neat.... but I checked the Wilwood box when I ordered my Speedway axle kit. The only problem is they look too modern.
I'd also be interested in the outcome to see about getting bigger brakes on this. I think they use car spindles but I wonder if they are machined to the 47-59 truck spindle specs, I have a 57 truck with their 11 inch disc kit, wonder if anything would swap over.
When I did mine , they had kits for '49-'54 chev , you an modify a stock spindle to their spec or buy new spindles from them that fit their kitted bearings ( its very simple mod) , they also had kits for ford spindles ('37-'41)?? In both instances I remember do mention scrub radius . I have an old paper catalog I can look at to find more info ...
I was just thinking how much, if any a disc brake kit will increase [or decrease] the track width, i.e. scrub.
On the truck kit for my 57 chevy it states that it increases front track width 7/16" per side (7/8" total).
I went thru the same thing. Upgraded to the bigger brake kit and found that the banjo bolt for the hose ended up being a steering stop. Not good. I ended up making new brackets to mount the metric calipers to the bigger rotors.It seemed to help a little bit, but still not as good as my other car with a dropped axle and the bigger calipers. Gary
I doubt the caliper bracket from the truck kit would fit the gasser front axle then, since it's car and would have car bolt hole spacing. I know when you look at their disc kit for their tube axle (t-bucket) with 49-54 car spindles it wants you to machine the spindle to truck tolerances for the disc kit to work.
No need to go through any modifications these days as Speedway sells a specific disc brake kit that's a bolt on for the '55-'59 Chev truck axles. I got the kit about 2 yrs. ago and at the time it only showed as a 4.75" bolt pattern, but their tech told me they also offered them as 4.5" bolt pattern, which is what I wanted. They're 11" rotors and GM calipers.
Wouldn't know , never tried it , stock chev car spindle had to be shortened , threads extended ,minor diameter extended & a spacer welded on that did double duty as something for the seal lip to ride on .
Hi, ended up using the GM 11” rotors and keeping the metric calipers , just had to fabricate up some caliper mounts. Really helped my stopping power. Thanks for the input
The Jalopy Journal
