Front or back !

[Huzo]

I've got an inkling of what might happen here, but (for once), my question is not loaded and I've only 2 answers that I can think of.
Here goes.
When viewing that beautiful piece of artwork (worthy of an Old Jock exhibition) thinly disguised as a Mk 1 restoration by Canuck 750. I notice that he fiddled with the concept of putting the calipers behind the fork legs a la Mk 2.
What are the benefits, perceived or otherwise, of front versus rear mounting ?

[Groover]

In my mind, leading calipers (mk1, sp, g5) = less dive when front braking.

I have nothing to back that up, just my thoughts on it.

Edit: Not SP

[oldbike54]

 There are about 4 pages on this somewhere on WG , no conclusion was reached , other than no one could prove any difference to speak of . Don't remember if any U or CV joints were involved 

 Dusty

[MotoBug]

Could it be to do with better cooling?

[oldbike54]

Could it be to do with better cooling?

 Oh just great , now you've gone and done it , Huzo will be up for days thinking about that 

 Dusty

[beetle]

What are the benefits, perceived or otherwise, of front versus rear mounting ?

None. Zero. Zip. Zilch. Nada.

[Huzo]

Oh just great , now you've gone and done it , Huzo will be up for days thinking about that 

 Dusty

Yeah that's a problem I have Dusty.
I tend to think too much before I expound my theories. But if I'm allowed here for long enough, I'm sure I'll kick the habit !

[Huzo]

None. Zero. Zip. Zilch. Nada.

Thanx Beetle. Other than one possible theory, I thought it was just fashion.

[Huzo]

In my mind, leading calipers (mk1, sp, g5) = less dive when front braking.

I have nothing to back that up, just my thoughts on it.

Edit: Not SP

Ok mate. That's what I asked for. Thanks.

[Huzo]

There are about 4 pages on this somewhere on WG , no conclusion was reached , other than no one could prove any difference to speak of . Don't remember if any U or CV joints were involved 

 Dusty

Hag !!!

[beetle]

In my mind, leading calipers (mk1, sp, g5) = less dive when front braking.

No. To reduce dive, there needs to be a mechanical action on the stanchion to slow it. In classic anti-dive technology, it was an increase in damping via the brake fluid.  As the forward mounted caliper is only connected to the fork lower, there is no way to stop the momentum of the mass of the bike other than the static damping and spring.

[oldbike54]

No. To reduce dive, there needs to be a mechanical action on the stanchion to slow it. In classic anti-dive technology, it was an increase in damping via the brake fluid.  As the forward mounted caliper is only connected to the fork lower, there is no way to stop the momentum of the mass of the bike other than the static damping and spring.

 This .

 Although just to confuse the issue , wasn't it Honda who experimented with antidive technology where braking introduced some pressure applied by brake fluid to augment compression damping? There ya go Peter , something extra to contemplate 

 Dusty

 Oops , sorry Mark , didn't mean to repeat what you had already said .

[Arizona Wayne]

I know a former guzzisti that made the brake caliper swap on his LM I before he swapped it for a Ducati 996.  Only reason he did it was to make it look more in vogue with newer Le Mans.  Actually it's a trade off when it comes time to change brake pads or anything else for maintenance on the brakes in reality.  Maybe if you're racing it helps a bit for aerodynamics, but for a street rider it's just image.

This reminds me of a co-junior college student that had a `63 Corvette Stingray w/ the split rear window.  As soon as the `64 Stingray Corvette came out w/o the same rear window he had his window changed so his 'vette would look newer.   Nowadays the Stingray with the split rear window is worth more. 

[beetle]

Oops , sorry Mark , didn't mean to repeat what you had already said .

That�s OK. I don�t know about Honda, but Suzuki definitely did. I disconnected it on every Suzuki I owned that had it. It just made the brakes feel mushy.

 

[oldbike54]

That�s OK. I don�t know about Honda, but Suzuki definitely did. I disconnected it on every Suzuki I owned that had it. It just made the brakes feel mushy.

 

 Yeah , looked good on paper , never really worked in metal .

 Dusty

[Testarossa]

I recall reading in some motomag, decades back, that putting the mass behind the fork legs means it's closer to the extended axis of the steering head and thus reduces polar moment of inertia in steering. Or not.

[Huzo]

This .

 Although just to confuse the issue , wasn't it Honda who experimented with antidive technology where braking introduced some pressure applied by brake fluid to augment compression damping? There ya go Peter , something extra to contemplate 

 Dusty

 Oops , sorry Mark , didn't mean to repeat what you had already said .

Already had Dusty. Beetle's version of why alteration of caliper  position was clear and made sense. The sum of forces around the axle are balanced wether ahead or behind, but I asked for informed opinion, and that's exactly what it smelled like.

[Huzo]

I recall reading in some motomag, decades back, that putting the mass behind the fork legs means it's closer to the extended axis of the steering head and thus reduces polar moment of inertia in steering. Or not.

That was the one I pondered. Reduction in oscillatory forces that increase in amplitude in a tank slapper.
But it doesn't seem (yet), that it's anything more than adherence to fashion. Also I guess, given that having the calipers behind, puts the mounts in compression, you could get away with lighter castings and reduce un sprung weight.
But I'm scraping the barrel there.

[beetle]

Dunno about tank slappers. Wouldn�t the increased moment of inertia for forward mounted calipers reduce the likelihood of a tank slapper?



Discuss.

[oldbike54]

Dunno about tank slappers. Wouldn�t the increased moment of inertia for forward mounted calipers reduce the likelihood of a tank slapper?



Discuss.

 Oh noes , now you have REALLY done it  Didn't we just discuss trolleys and wheelbarrows ? Let me say this , a high speed wobble with a wheelbarrow carrying a load of wet concrete going down a 2X6 on a 5 degree grade is nothing to laugh about , especially with a 5 ft drop off on either side and a cliff looming ahead 

 Dusty

[beetle]

Wheelbarrows? O...kay.... 



...backs away slowly....

[Huzo]

Dunno about tank slappers. Wouldn�t the increased moment of inertia for forward mounted calipers reduce the likelihood of a tank slapper?



Discuss.

Yes Beetle, but once the motion begins, the mass increases the amplitude of the oscillation. Effectively storing extra kinetic energy in the system.
But for me it's all a big guess.

[beetle]

I disagree. The increased moment of inertia would act like a damper, reducing rotational velocity. Think of an ice skater pulling their arms in during a spin. You still get a tank slapper, but it’s whack..whack..whack instead of whackwhackwhack.

[Dukedesmo]

No difference to braking but behind the leg gives the caliper better protection from water and other road crap and being slightly lower down would have a small affect on lowering the weight distribution.


Also means you could engineer lighter (less material) mounting points as the caliper is being pulled against rather than away from the fork leg.


Would suspect the main reason for the switch was the protection issue?

[Huzo]

No difference to braking but behind the leg gives the caliper better protection from water and other road crap and being slightly lower down would have a small affect on lowering the weight distribution.


Also means you could engineer lighter (less material) mounting points as the caliper is being pulled against rather than away from the fork leg.


Would suspect the main reason for the switch was the protection issue?

Ok then..

[Sheepdog]

Back in the early days of disc brakes, the motorcycle journalism set declared that calipers behind the forks were better supported by the sliders and allowed more neutral steering (as their weight was nearer to the steering axis). The protection from road detritus is another small advantage...

[Groover]

I have been looking for an opportunity to post a recent photo of my G5, and I think this might be the right thread.... 

I searched this topic a little more, and it is indeed an unsolved mystery out in the world or motorsports.. Seems it's may be just a matter of convenience in the design/application, fluid bleeding, access to pads, etc.

Either way, I really love the looks of them on my G5!

1981 Moto Guzzi V1000 G5

[guzzisteve]

Pretty nice G5!!

[oldbike54]

Wheelbarrows? O...kay.... 



...backs away slowly....

 Trust me , before this is all over we will circle back around to wheelbarrows and the need for brakes on them 

 Dusty

[Two Checks]

Quote from: Testarossa on Today at 02:05:50 AM

I recall reading in some motomag, decades back, that putting the mass behind the fork legs means it's closer to the extended axis of the steering head and thus reduces polar moment of inertia in steering. Or not.

This.