Disc Brake Conversion For '68 W300

[adam]

I would like to replace the stock drum brakes on my truck with discs. Helitool makes a set. Has any one installed this conversion before? Any feedback would be helpful. When I contacted Ray at Helitool he indicated I would have to use M715 Hubs in place of my W300 hubs. Has any one modified their W300 hubs to accept Ray's kit? How difficult was it to modify the hubs?
Are the other options? I will not replace my axle with a modern unit.

Thanks in advance for your input.
Feel free to call if you can't condense your response to something that can be easily typed.
-Adam
530.520.4293
In southern CA

[adam]

I was so anxious to ask the question- I missed the fact that this should be posted below-feel free to move.

[Aaron S]

I did this exact conversion on my 68 and it was not too bad, there were a couple of issues though. Apparently some of these trucks have slightly different rear spring set ups, on mine we had to drill offset mounting holes in the caliper bracket in order to set the bracket at an angle which would allow the caliper to mount without hitting the spring. You may or may not encounter this issue. Not a big deal.

I sent Ray the rear hubs which he machined and installed the rotor flanges on. He does great work, you will not be dissappointed. Depending on the rotors you get you may have to have them turned a few thousandths to get everything to fit just right.

On the front I have the NOS M715 hubs that Ray supplied. They fit right onto the spindle, no sweat, but they require different races, bearings, seals, wheel studs, and lug nuts. All of this should be available from your local parts house.

The big hitch with the M715 front hubs is that you will not be able to run your factory 16 inch split ring wheels. The wheel will fit right on and look fine, then when you spin the wheel the valve stem will hit the caliper, you will cuss loudly and go in search of some M715 rims which are almost identical but have about a half inch difference in backspacing which allows the valve stem to clear the caliper. Or if you are better capitalised than me you may be calling Stockton Wheels and having some tubless rims built.

Even if your truck has factory power brakes you will probably want to install a better booster and master cylinder (I will be doing this as soon as I'm finished building the motor and my truck is running again). With the factory set up the truck will seem to be stopping much better with your initial push on the pedal, however pushing harder will not slow you down any faster which can lead to an accelerated heart rate in certain situations.

If there is something I left out feel free to ask, I will be happy to help you out to the best of my ability.

[adam]

Aaron, thanks for the information. Does the valve stem interfere on all wheels, or just the rear. I have a spacer on the rear-so I'm only running singles. Would you mind sending pictures of the interference & the front hubs.
Thanks again-Adam 530.520.4293

[Aaron S]

The valve stem only hits the caliper on the front, because of the M715 front hubs. When I encountered this problem I asked Ray about the possibility of placing a half inch or so spacer behind the front wheel to provide the necessary clearance. His response was that due to the shear forces involved mounting the wheel farther out on the studs with use of a spacer would be absolutely unsafe and quite foolish to even attempt.

I cannot send you pictures of the valve stem hitting the caliper because I no longer possess my factory rims. I traded them to a friend for a set of M715 rims which solved the problem. I may be able to get you pictures of the front hubs, the truck is at my friends shop where we are doing the motor. I will try to remember to take my camera next time I make it over there.

My truck is single rear wheel also. Do you have the factory single rear hubs or are you running some sort of spacer on a dual wheel hub? If the truck was a dually when you got it, are you still running the dually rims?

[adam]

My truck has been SRW as long as I've had it. I had assumed it was a DRW when new & some one converted it to SRW by adding a spacer to the rear hub. My parts book shows unique p/n's for rims and front hubs depending on SRW or DRW, but the rear hub/drum is the same p/n regardless of application. It seems that of the valve stem would interfere with the caliper, it would do so no matter what hub I was using.

I've taken pictures of the spacer & the how the valve stem exits the rim-but I seem to be unable to post them, perhaps someone can explain the process to me. Or I can email them directly to you.

Thanks again,
Adam
awkilgore_at_hotmail.com

[Aaron S]

Valve stem clearance should not be a problem on the rear axle, only on the front. However, single and dual rear wheel hubs are most definitely different, the rest of the axle is the same either way. That is to say, whether single or dual, you will have the same axle housing, brake drums, and brake location on the housing. Only the hub is changed to mount the wheels farther inboard on dual applications or farther outboard for single applications. Because of the inboard location of the brakes on the axle, many people will assume that these trucks began life with duals even when they are a factory single and what appears to be a spacer coming off of the brake drum is actually the hub. The point of all this rambling on is that whichever hubs you have will make a difference in your conversion if Ray is still doing them the same way we did mine, which is to use M715 hubs on the front axle and your W300 hubs on the rear axle, all modified with rotor flanges. If you have the correct single rear wheel hubs you are good to go.

If Ray has told you that you must replace both front and rear hubs with those from an M715 then I am entering uncharted territory.

[Bradf]

I was wondering if you have the brake drums left over from your conversion, I'm looking for drums for a 1963 sweptline with 6 bolt hubs

thanks Brad
905-650-9168

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