Inboard Brakes - are these used on any kits?

[Woody]

Just idly thinking whilst looking at a model of a Lotus 72 F1 car if any manufacturers use inboard brakes?
With the mantra for most kit cars being light weight and trying to reduce unsprung weight would these work or would the costs be to prohibitive?

Cheers

Chris

[seansverige]

I'm not sure that costs would be that much different. I'd never want inboard brakes for two reasons: cooling & maintenance.

A few production cars used them in the past and there are probably good reasons why they don't anymore - wasn't there a Jag rear axle with inboard discs? Unfortunately one of my 2CVs had inboard drums at the front: changing the pads took 6 hours, a lot of swearing and skinned knuckles....

[slomax]

2CVs and all derivatives had inboard disks. I also believe that a few lancias did too, although I may be wrong.

A few issues I have found when working on the Lomax.

If you have any sort of oil leak in the engine bay you pretty much lose breaking (pretty scary when you are coming off a motorway sliproad at 70mph)

To replace the disks you have to remove the driveshafts.

They can overheat quicker. The 2CV had a cooling duct with air driven from the main fan. Being so close to the engine and gearbox, they can get rather warm if there is no/little air flow over them, especially in a tight/compact engine bay (not too much of a problem with the Lomax).

On the upside it makes the car look so much neater as there are no brakes on the front hub for all to see

Slomax

[slomax]

Damn- beaten to it by Sean

Should say earlier 2cvs had drums and later models had the disks.

I hadn't thought about it before Sean, but drums must have been a right pain in the arse, especially with all of the gubbins on a 2CV in the way. I presume you have to remove wings, duct, shafts before even touching the pads?

[Woody]

I know a ocuple of Alfa's used them - the 75 IIRC.
Just thought it would look neat and reduce the unsprung weight.
Wouldn't have thought cooling would be too much of an issue on a 7'esque type car with inboard brakes.

[seansverige]

@Slomax: Yarp.

Your post actually reminded me that all 2CVs were inboard, but the drums are so much more hassle I was sort of forgetting as I don't have any bad associations with the disc version

Would also point out that on those vehicles where unsprung mass matters most they tend to use discs the size of dinner plates these days, so not only would cooling be tricky, just physically packaging them would a challenge

ETA
re: an LSIS, wouldn't the rear brakes be awfully close to the fuel tank (nothing like a strong incentive for ensuring adequate colling ), and front ones require some sort of 'drive'shaft?

Edited by seansverige on Friday 17th June 10:38

[Sam_68]

Woody said:

I know a couple of Alfa's used them...

The AlfaSud had inboard disc brakes at the front, too, which means that several Sud-based kits have used then (Minari, Raffo, Pelland/Kudos, etc.).

Jag IRS also uses inboard rear discs, hence various Jag and Cobra replicas.

In terms of LSIS type cars, the original Eleven, upon which the Seven was based, had inboard rear discs, but then the feul taknk was located over the scuttle (though I doubt that Chapman would have worried about anything as trivial as burning his driver to death in a petrol fire if it offered him a perfomance advantage, anyway).

Edited by Sam_68 on Friday 17th June 12:14

[Frankthered]

Sam_68 said:

The AlfaSud had inboard disc brakes at the front, too, which means that several Sud-based kits have used then (Minari, Raffo, Pelland/Kudos, etc.).

This is true, the Alfasud did have inboard discs at the front and outboard discs at the rear. Just to make things easier , IIRC Alfa decided to have the handbrake operate on the front discs too.

When they developed the 33, about the only significant mechanical difference between the models (at least initially) was that they changed the brakes to outboard discs on the front and drums on the rear, with a proper handbrake on the rear. (The last few years of 'sud Sprints were like this too.)

Speaks volumes that they did that, IMHO.

[Sam_68]

Frankthered said:

IIRC Alfa decided to have the handbrake operate on the front discs too.

They did indeed - which meant that the installation was absolutely perfect for mid-engined use, as on the Raffo and Pelland, where access wasn't a problem.

[.Adam.]

I'm pretty sure my old Elan +2 had inboard brakes on the rear.

[Sam_68]

.Adam. said:

I'm pretty sure my old Elan +2 had inboard brakes on the rear.

The Elan (both 2-seater and +2) had semi-inboard brakes; the discs were mounted outboard, but inboard of the uprights/bearing carriers (ie. Differential>>donut>>driveshaft>>donut>>brake disc>>upright>>hub>>wheel).

True inboard brakes are mounted directly to the differential/diff output shafts.

[ColinM50]

XJS had inboard rear brakes. Nightmare to change pads esp without a ramp so didn't bother. Sold the car instead

[Toltec]

The TVR wedge has inboard discs on the rear, jag diff setup as it happens. Apart from changing pads, bleeding and adjusting the handbrake being a pain they also got rather hot on a track day. Marshals used to come ask why so much smoke was coming out the wheel arches quite often. Generally something to do with the discs getting so hot the grease boils out of the UJs and deposits itself onto said discs.

[seansverige]

Frankthered said:

Just to make things easier , IIRC Alfa decided to have the handbrake operate on the front discs too.

Aaahh, front axle handbrakes. Years ago, on wintry roads above Llanrwst, a schoolmate thought he'd show off by pulling a handbrake turn in his mum's Saab 99.... cue catastrophic & terminal understeer into the nearest snowbank.

Another mate did something not entirely dissimilar years later on a mountain bike; another friend who'd settled stateside came over with his bike, first mate borrows it for spin round campsite, goes to finish with drifty skid; which in fairness he did, just not with the wheel he - or we - expected.

2CV's also had these, using separate brake pads that - iirc - weren't that much bigger than an old 2p coin. Had to really make sure that was properly engaged as might otherwise let go as brakes cooled down, especially on an incline. Doubt any current Citroëns have this arrangement but heard it was an issue with Xantia's.