9" drum hub drill to BBP?

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Furious65

Furious65

C-body Guy
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Can the 9" drum hub be drilled to BBP? I tried searching but couldn't locate the info. Thanks.
 
People have enough concern drilling drum rear axles to install BBP studs. I haven't heard of anyone wanting to install BBP studs in a front hub. Usually, they go BBP because they changed to 73+ disk hubs (thus need to BBP the rear). I don't know that 9" drum hubs have a smaller diameter where the studs sit than 10" drum hubs. They do use smaller wheel bearings.
 
I think I read on here about a disc brake kit(LBP)conversion for the 9 inch drum spindles.Try searching in the Brakes forum.
 
Unless you're building a drag race only car, throw those 9 inch drums in the scrap pile. They may have worked in the late sixties, but will not stop you fast enough when the soccer mom in front of you slams on her four wheel discs because her kids are fighting over the DVD remote control. Lots of better options available now. From the cheap Scarebird kit all the way up to Wilwood kits.
 
BrianT said:
Unless you're building a drag race only car, throw those 9 inch drums in the scrap pile. They may have worked in the late sixties, but will not stop you fast enough when the soccer mom in front of you slams on her four wheel discs because her kids are fighting over the DVD remote control. Lots of better options available now. From the cheap Scarebird kit all the way up to Wilwood kits.
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X2
There is a reason for the 9X3 drum brakes being found on slant 6 a-body only. You can buy modern, more aggressive brake linings today.
Actually, you don't have a choice since the OEM asbestos was outlawed.
Those will just wear the drums faster. Have you searched for new drums lately ? Good luck with that.
 
I plan to ditch the drums. The info I'm seeking concerns the Scarebird front disc conversion for the 9" drum spindles. The rotors are already bbp so it would be nice to just drop them, and future replacements, on without redrilling them for the sbp and have more wheel choices.
 
Furious65 said:
I plan to ditch the drums. The info I'm seeking concerns the Scarebird front disc conversion for the 9" drum spindles. The rotors are already bbp so it would be nice to just drop them, and future replacements, on without redrilling them for the sbp and have more wheel choices.
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I might be wrong but I think the rotors used by Scarebird are a GM bolt pattern ( 5 on 5, or something metric ). If so you would be re-drilling rotors and your hubs to 5 on 4.5 chry lbp
 
Yes it can be done as there is enough meat to do it for the front. I agree about not wanting to do so as there are many better options out there. ''IF'' you do it yourself, what I did was get the 4 to 4 1/2 adapter to use as a templet. I found some at a swap meet for a $1 each.Remove the studs from the 4 1/2 and bolt the adapter to the hub.Drill and tap the hole for the 1/2'' screw in studs from the aftermarket such as Moroso.
 
RedFish said:
I might be wrong but I think the rotors used by Scarebird are a GM bolt pattern ( 5 on 5, or something metric ). If so you would be re-drilling rotors and your hubs to 5 on 4.5 chry lbp
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Their setup uses Toyota Previa rotors which have the 5 on 4.5" bolt pattern. That is why I was asking as it would be the most affordable and easy way to convert to disc and bbp. I was just worrying about the 9" hub having enough material to safely be drilled to the larger bolt pattern.

I have spoke with another member, 66Dvert, that has done what I was hoping and says it works with no problem. So, I have the answer to my question. Yes, the 9" drum hub can be drilled for the 4.5" bolt pattern using screw in studs to work with the Scarebird disc brake conversion.

Thanks everyone for the info!
 
I have used the scarebird version of the adapters on a 9" hub,10"hub A-body and B-body cars . with the screw in studs (2"long worked for me on the previa rotors) there is enough meat left on the hub. (well unless you doing wheel stands daily, then I'd change them to larger ones.) but that was because I'd rather drill the hubs once and be able to take off the shelf parts and put on the car with no waiting. I know that I'll be changing to an 8.25 LBP rear end so I can have a lot more rim choices.

I have never seen a spindle break on a 9" hub but have seen the little lower ball joint bolts break from a snow slide into a curb. I went grade 8 and larger bolt size on my 9" ball joint hub setup and yeah you have to drill the holes out to accept the new bolts.
with scarebird adapter without drilling
View attachment DSCF2791.jpg


test fit rotor
View attachment DSCF2790.jpg


rotor on and drilled 5 on 4.5 (stock pattern for the previa rotors)
View attachment DSCF2966.jpg


! had to search for a picture of the drilled ones. It's been sitting in the garage for too long darn humidity get's in and flash rusts everything unless it's painted. #@!@#$%$ there is plenty of meat left of you use screw in studs, but it might be a bit tight if you use the knurled ones since the hole can be as big as 11/16th. the rotor is centered using an adapter ring so the rotor has a snug fit to help with the clamping force. I looked at the rotor and it's close to 1/2" thick in that area. so if you use a rim that's hub centric and it fit's tight there is a lot less chance of damaging your studs/hub/rim.
View attachment WP_20130917_002.jpg


I helped a buddy do his 9" hubs for his 440 engine'd 64 dart. with the fully tubbed rear end upgraded to a hefty 8 3/4 with really sticky tires he does yank the front wheels off the ground at almost every pass he makes at Milan dragway. he hasn't broken a spindle or (they are grade 8 bolts) lower ball joint bolts yet. he's got about 60 total passes on the car so far. he did have to re-weld he sub frame connectors twice through:glasses7:
 
would doubt the previa actually uses a SAE bolt pattern (4.5 in) but it is so close, so as a metric equivalent it works.
1 in = 25.4 mm so 4 in = 101.6 mm
1 / 2 in = 12.7 mm
101.6 mm + 12.7 mm = 114.3 mm
the previa rotors are most likely 115 mm bolt circle

Noticed this when i used Spirit / Shadow balonies to mount up to and roll around an early A valiant tub - they fit!! (100 mm bc is very close to 4 in)
 
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