Ford Straight Axle Disk Brake Conversion HELP!

OK,

I have an axle from a '40 Ford and spindles from a 35. They do swap out. I want to end up with 5 on 5 1/2 bolt pattern. What rotors and calipers should I use. What will my final axle width be?

Thanks

 

Speedway has a kit

 

I doubt that you will find a kit for this spindle combination. Junk the 35 spindles they have a narrow backing plate bolt span and the snout is 1/4" longer. Get a set of 37-41 or 42-48 spindles and any after market kit will just bolt on. It's a $ well spent or a lesson hard learned.

 

Been there, done that. Spadaro is right, start with spindles at least from '37 up. The conversion will go much better.

 

So is it the lack of an available kit or is it that they are just plain inferior? I have a very extensive background doing machine work and welding. I actually enjoy piecing things together and it typically saves me a buck or two. The axle is going to be used in a fender-less 1930 model A sedan with a Lincoln 368 engine.

Thanks again.

Mike

 

based on what **** said its a matter of not having a kit available. Use the rotors and calipers that the Speedway kit uses and build your own caliper brackets and shorten the snout on the spindles. The kids on here need kits to do things like this.

 

That is what I was hoping to hear. I like solving the problems. Coming up with a solution that works and may be different from everyone else. As long as there is not an inherent danger to using this spindle.

Thanks Again!

Mike

 

Guys, There is a kit from Speedway (I think) that uses rotors off of the large Econoline van and has 5 by 5 1/2 bolt pattern. It may be for the square spindles ('42 to '48).

Dave

 

I had good luck with Speedway dics kit but will end up with a wider track unless you play with wheel offset. If the track is wider, the center line of the tire does not intersect with the king pin line and it causes some tire scrub and increases turning effort.

 

Good point! I will look closely at that and try my darnedest to get that line to match the center of the tire. I am planing to run 16x6.0 0n my front and 17x7.0 0n the rear.

Mike

 

I have never seen a 5 on 5 1/2 disc brake set up from Speedway?

 

Somebody ( Speedway? ) sells one for the 1946-1947 Ford 1/2 ton pickup, which uses the same spindles as the 42-48 ford car.

 

ECI in connecticut has the kit for the later spindles and the 5x5 1/2 bolt pattern

 

If you're really keen on engineering your own, take a look at BMW rotors. The pcd is extremely close to 5½", the difference is a mere 0.3mm (.0012") so they can be m***aged to fit. And they come in solid or vented, anything up to almost 15" diameter. Then you'd just have to fabricate caliper brackets.

 

I just finished a disc conversion on my 29 roadster. CE dropped axle and 37/41 spindles, Speedway bracket kit for 5 X 51/2 bolt pattern $99. I used 70/76 chev calipers that I had "in stock" and rotors from a 79/84 Ford pickup. Rotors cost $31 a piece and calipers (if bought) were $30 something. And, the original ford 15's I have clear the calipers quite well.

 

I am planing on going with '35 Ford 16" wires on the front and 17" wires on the rear. Will these clear the calipers?

Mike

 

I have a set of 16" wires off a 35 on my RPU. It has a modified spindle where (back in the 70s) the front of a pinto spindle was welded to the back of the A spindle, thereby converting to later model rotors and disc brakes. Even with these small rotors and setup, the wheels BARELY clear the calipers. I can't speak for the others on here, but I know my own setup.

Also, in my signature, there is a link to my '29 AA pickup build where I converted it to disc brakes using a speedway kit. If you want to check it out, feel free.

And, I heard somewhere a few years ago there was a conversion kit being made for the earlier spindles. I used a pair of '46 Ford pickup spindles.

And as far as what Anteek says, there's alot to be said about going with a pre-made kit. It's been tried, tested, used, and you have some longevity studies and reputation to follow with. Nothing like making up your own stuff and not know how it works, stranding you and your ride on the side of the road somewhere. Even worse, what if the stuff you put together winds up causing you to wind up in oncoming traffic?

There are alot of conversion threads on here, just have to search them out.

Just my input.

 

I'm not sure you could calculate the geometry. If you patterned out the beam axle, knowing the center line of the king pin then you would have to know the exact wheel and exact tire dimensions to tell where the king pin center line, wheel/tire center line intersect on the road. Was just bringing the subject up to let you know what could happen. If the geometry is incorrect, steering effort is greater, especially when parking. Not too noticeable on the highway.

 

Honestly, I will not calculate it. I will model it in Auto CAD. Nearly every part I make for a car starts out as a CAD drawing. Using a drawing helps me avoid costly mistakes from trial and error. Like most things in hot-roding we are only trying to get it in the ball park. I realize it may not be possible to get it exactly back to factory specs with the different hubs and what not.

Thanks!

Mike

 

I don't like to continue to throw water on the fire but even if you have a fancy computer to model every thing out your idea still has issues. Although it has been done Early ford wires will not correctly fit on disc brake hubs. The wire wheel has a multiple support when properly mounted, first at the bolt face of the wire wheel hub and then from the compression mount portion of the wire wheel hub that ****s to the drum. While the hub will bolt up to a 5 x 5.5 disc brake rotor there is nothing to support the flange portion of the wheel.Without this backing the wire wheel spokes are supported by air. In addition the inset of the wheel hub will interfere with the caliper and rub. To get the necessary clearance you will need at least an 1.5" spacer to offset the wheel outward and this screws up the tire scrub, increases the track and places additional load on the outer wheel bearing. If you are set on using wire wheels you will have to search out a newer design wire wheel.

 

Upon further review, I see there are some pretty wide spacers on the Pinto rotors to allow the use of the wire wheels. Even with these wide spacers, I've only got about 1/4 to 3/8 inch of space between the caliper and wheel center hub cover... or whatever you call it.

 

anything is possible...i just did a straight axle conversion on my 55 chevy sedan. picked up an I beam straight axle off of a 1964 ford truck (junk yard 100 bucks) , rebuilt the king pins, stuffed some 1993 rotors (that i had laying around) off of a full size chevy truck. made some 1/8 washers for the rotors, because of the longer snout, kept the smaller outer ford bearings and everything worked out. i also used the calipers from the 93 chevy truck. i was aiming to keep my 5x 4 3/4 bolt pattern but instead i had to go 5 x 5. the 5 1/2 pattern is basically only used for trucks. other than that i was thinking about getting a chevy car rotor machined out to fit the larger truck rear bearing. still thinking about it for the 4 3/4 size chevy pattern. good luck. but speedway does have kits for certain ford stuff and years. anything is possible, somebody designed the stuff at one point to work, now it's just the builder designing his own stuff to work again.

 

I still think I could make it all work but I am slightly changing my direction with the build. I have acquired a 37 ford front tend. 40 drums and 42 up baking plates. Still going to use the old wires. I am going to run an 8BA Flathead with a T5 transmission behind it.

Thanks to all for their help