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Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
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| | | | Joined: Jan 2008 Posts: 4 New Guy | | New Guy Joined: Jan 2008 Posts: 4 | Hello, Has anyone done a front disc brake conversion on a 40 1/2 ton? I have an original with 6 lug wheels. I see the conversion sets for sale but they only have 5 lug for a 1940. What else is avaliable? What kind of master cylinder would I need? Proportional valve? Any help would be appreciated. Thanks Gerry | | | | | Joined: Dec 2004 Posts: 1,897 Shop Shark | | Shop Shark Joined: Dec 2004 Posts: 1,897 | Get a drop axle from Sid for a 41-54. Then find a set of hubs from a 52-59, and use the kit they sell for the 41-59. Of course you are on your own when it comes to mounting the MC. I got the clutch and brake pedal set from a 1.5 ton 1941 GMC. This pedal setup allows the use of a frame mounted MC.
John | | | | | Joined: Jul 2002 Posts: 166 'Bolter | | 'Bolter Joined: Jul 2002 Posts: 166 | Not to hijack a thread, but will this also work on a 37? | | | | | Joined: Dec 2004 Posts: 1,897 Shop Shark | | Shop Shark Joined: Dec 2004 Posts: 1,897 | I believe it would work, however...
The 41-54 axles have larger king pins. This is desirable.
The width of the axles may vary slightly.
the 41-54 axles should bolt in exactly like the 1929-1940 axles, but measuring the spring spacing should be done as a check. | | | | | Joined: Jul 2002 Posts: 166 'Bolter | | 'Bolter Joined: Jul 2002 Posts: 166 | Thanks!! I will measure the spring spacing. | | | | | Joined: Aug 2006 Posts: 129 Shop Shark | | Shop Shark Joined: Aug 2006 Posts: 129 | I have converted my '39 to discs with the stock straight axle. I am also using a 2002 4WD Blazer rear axle with rear discs. I originally intended to go with 5 lug 4-3/4" bolt circle wheels, but could not find anything that would work with the stock hubcaps and look right. I sent my front and rear 5-lug rotors and the rear axles to Moser Engineering in Indiana and had them weld up and re-drill for the stock 6-lug pattern. Now I can use my stock 16" wheels with the disc brakes. | | | | | Joined: Feb 2000 Posts: 5,199 'Bolter | | 'Bolter Joined: Feb 2000 Posts: 5,199 | My 37 has the newer axle with bigger king pins and it was a bolt in swap. Fact I didn't know it was there till I ordered a disk brake kit for a '37 and it didn't fit. The spindles of the newer axle have a larger inner bearing. Then when I replaced the king pins, I figured out it was the bigger axle.
I went with Master Power brakes and use 4 3/4 bolt pattern all around.
What are you guys using for a master cylinder?
I have a Mustang unit with 7/8 bore I think, its takes a lot of effort to stop, but it will stop right now if need be. I am thinking smaller bore for more pressure along with more travel.
Joe | | |
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