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 Post subject: Inboard Brakes
PostPosted: November 2, 2018, 7:58 am 
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I have been thinking about a midi bec that is awd, kind of like the R1ot. I know there is a lot going on in this idea, but it made me think about inboard brakes. What if you would mount the brakes on the input of the diffs? Would that work? Is this a horrible idea? I was thinking you would have one rotor and caliper each for both front and rear. I think you could go smaller as the force would be multiplied through the diff. Am I off my rocker? I would love to hear your thoughts, criticisms, etc.

Vince


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 Post subject: Re: Inboard Brakes
PostPosted: November 2, 2018, 10:17 am 
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hotmalevb wrote:
I have been thinking about a midi bec that is awd, kind of like the R1ot. I know there is a lot going on in this idea, but it made me think about inboard brakes. What if you would mount the brakes on the input of the diffs? Would that work? Is this a horrible idea? I was thinking you would have one rotor and caliper each for both front and rear. I think you could go smaller as the force would be multiplied through the diff. Am I off my rocker? I would love to hear your thoughts, criticisms, etc.

Vince



Brakes wok by converting friction into heat, heat dissipation is already bad with two rotors per axle inboard arrangement.
If you reduce the number of rotors, you´d need to increase its size to maintain heat dissipation capacity, therefore you´d have to have very large diameter discs with very heavy calipers to suit.
For a low speed vehicle it would be OK in my opinion.


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 Post subject: Re: Inboard Brakes
PostPosted: November 2, 2018, 6:23 pm 
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Another factor is that if one wheel loses traction at any moment, all braking is lost if an open diff and most of it with limited slip. How much depends on the type. Scary stuff.

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 Post subject: Re: Inboard Brakes
PostPosted: November 2, 2018, 6:55 pm 
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Fairly common for PARKING brakes.
For main brakes, I would say no.

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 Post subject: Re: Inboard Brakes
PostPosted: November 2, 2018, 7:31 pm 
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I don't understand how brake placement on the axles can cause the above.

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 Post subject: Re: Inboard Brakes
PostPosted: November 3, 2018, 5:26 am 
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KB58 wrote:
I don't understand how brake placement on the axles can cause the above.


He's suggesting having brakes on the pinion with no brakes on the axles to save weight and reduce the clamping ability (commensurate with the ratio of the diff) to be adequate for both wheels. I do not fully follow the heating argument but I haven't thought much about it. Just making my own point.

My P32 bread truck has the parking brake drum on the transmission output shaft, so I have to definately chock the far/other wheel(s) in both directions when jacking, to prevent it rolling off.

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 Post subject: Re: Inboard Brakes
PostPosted: March 3, 2019, 3:12 am 
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I've also been thinking about inboard brakes in the rear for my BEC. I have a "Torsen" type diff so I think I could do a single disc mounted to the outer portion of the diff, just like the sprocket will be.

Or I could mount a disc to the output cup of each CVD.

Both methods, I'm a bit worried about getting stuff true.

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 Post subject: Re: Inboard Brakes
PostPosted: March 3, 2019, 4:11 pm 
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Early E-type Jaguars had inboard discs a the rear. Wasn't a great success, and they stopped doing it. It was a SERIOUS PITA to change the pads - to start, remove rear seat, rear carpet, etc., then remove ALL suspension bolts & lower the suspension. And so on...

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 Post subject: Re: Inboard Brakes
PostPosted: March 3, 2019, 6:26 pm 
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"Wasn't a great success" Hmmmmm

For the first 32 years of production of the first generation IRS, the disc brakes were mounted at the inboard ends of the driveshafts in order to minimise unsprung weight at the outboard end.

https://en.wikipedia.org/wiki/Jaguar_in ... suspension

Graham


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 Post subject: Re: Inboard Brakes
PostPosted: March 3, 2019, 9:12 pm 
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It wasn’t a great success from the standpoint of maintenance. I had to replace the rear (inboard) brake pads on an E-type. It was a long, arduous, involved, and expensive (for the owner) job.

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 Post subject: Re: Inboard Brakes
PostPosted: March 3, 2019, 9:16 pm 
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FastG wrote:
For the first 32 years of production of the first generation IRS, the disc brakes were mounted at the inboard ends of the driveshafts in order to minimise unsprung weight at the outboard end.


I can see that if you want to mount the brakes inboard between boot and diff, that would be okay. Unless of course you lost your CV joint, like I have a few times, then you're not gonna have brakes there, then you have a problem.

Can I assume that, due to rotating mass stress and heat you're not gonna mount the disks onto the diff's axles? Or is that your plan?

I also can note that a brake/rotor pad change would indeed probably take a lot longer. And I can't think of any off the shelf stuff that would bolt onto the CV joint

And yes, I considered it back years ago, just take a pumpkin from some unloved IRS car and bolt disks and stuff to that, then bolt the half shaft to whatever was still sticking out.

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 Post subject: Re: Inboard Brakes
PostPosted: March 4, 2019, 1:55 am 
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On my BEC, it would make changing the pad like 2 bolts and done, now the discs on the other hand...

I was thinking about mounting a single disc right to the diff housing (with an adapter plate) or mounting 2 discs on the CVD output cups. I can see if you lose an axle that rear braking would be a problem.

Pretty much the sole reason I am thinking of inboard brakes is for unsprung mass.

Most images I can find are with 2 discs: https://www.google.com/search?q=chain+d ... 60&bih=526

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 Post subject: Re: Inboard Brakes
PostPosted: March 4, 2019, 2:20 am 
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Single disc at the rear is not new.

https://www.reddit.com/r/formula1/comme ... e_mounted/

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 Post subject: Re: Inboard Brakes
PostPosted: March 4, 2019, 9:06 am 
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I believe the Alfa Romeo Alfasud had front inboard brakes on a front wheel drive car. Great car but had VERY bad rust problem. Many people list it as the first hot hatchback.

https://en.wikipedia.org/wiki/Alfa_Romeo_Alfasud

Graham


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 Post subject: Re: Inboard Brakes
PostPosted: March 4, 2019, 12:29 pm 
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Johnsinski wrote:
On my BEC, it would make changing the pad like 2 bolts and done, now the discs on the other hand...

I was thinking about mounting a single disc right to the diff housing (with an adapter plate) or mounting 2 discs on the CVD output cups. I can see if you lose an axle that rear braking would be a problem.

Pretty much the sole reason I am thinking of inboard brakes is for unsprung mass.

Most images I can find are with 2 discs: https://www.google.com/search?q=chain+d ... 60&bih=526


Single disc directly to the chain diff works well with two calipers. The torsen should improve brake balance.

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