It is currently Thu Mar 28, 2024 11:36 pm

All times are UTC + 1 hour




Post new topic Reply to topic  [ 12 posts ] 
Author Message
 Post subject: T251 Discbrakes.
PostPosted: Wed Mar 11, 2015 4:47 pm 
Offline
User avatar

Joined: Tue Nov 04, 2008 5:07 pm
Posts: 1018
Location: Vienne France
Having the original patterns,as well as the general arrangement drawings.I decided to make a single demonstration example of this interesting design.Designed by Rene Strub at the Bugatti factory,It is fairly obvious that he had never seen anybody elses discbrake.Bugatti would have been proud of him and his creation.When completed, it will be on display at the study centre and after maybe at the Chateau St Jean.


Attachments:
IMG_6478 (1).JPG
IMG_6478 (1).JPG [ 37.3 KiB | Viewed 15142 times ]
IMG_6480 (1).JPG
IMG_6480 (1).JPG [ 38.33 KiB | Viewed 15142 times ]
IMG_6473 (1).JPG
IMG_6473 (1).JPG [ 39.85 KiB | Viewed 15142 times ]
Top
 Profile  
 
 Post subject: Re: T251 Discbrakes.
PostPosted: Wed Mar 11, 2015 5:10 pm 
Offline

Joined: Wed Jul 15, 2009 5:38 pm
Posts: 642
Thank you very much for sharing. Most interesting topic for a long while...

I see 2 calipers in a mounting/housing that encloses the disc. I guess this was for keeping the braking warm ? I can imagine this could also cause overheating and fading ? Despite the cooling ducts.

Are the 4 connections on the inner side (where the calipers ought to be) for the hydraulics ? So only a single side action ? How about the outer side? A static brake liner ?

Keen to learn more of this interesting part.

_________________
"Barttore has left the forum"


Top
 Profile  
 
 Post subject: Re: T251 Discbrakes.
PostPosted: Wed Mar 11, 2015 6:42 pm 
Offline
User avatar

Joined: Tue Nov 04, 2008 5:07 pm
Posts: 1018
Location: Vienne France
barttore wrote:
Thank you very much for sharing. Most interesting topic for a long while...

I see 2 calipers in a mounting/housing that encloses the disc. I guess this was for keeping the braking warm ? I can imagine this could also cause overheating and fading ? Despite the cooling ducts.

Are the 4 connections on the inner side (where the calipers ought to be) for the hydraulics ? So only a single side action ? How about the outer side? A static brake liner ?

Keen to learn more of this interesting part.

I will be taking this example to show Rene Strub in a week or so.There are four disc pads.Quite big in fact.The pads are connected with "scissor" type linkage [ very similar to a bicycle brake ] There are two hydraulic cylinders connected to the inner pads and which push the outer pads by pushrods.You need to see the assembly drawing to understand all this.The 4 locking screws with locknuts which you mention in the housing,are the adjustment for the inner pads.The outer pads being adjusted by altering the relative position between inner and outer pad linkages.The pads,linkages and cylinders are all free floating in the aluminium housing.There being no connection between the mechanism and the housing at all.The housings are shaped to take the pads,with a wearing face rivited into the housings in four positions.Thus the thrust is taken by these wearing faces.The discs are chrome plated aluminium and ventilated.The hubs are liberally drilled to allow air to enter the middle of the discs and allow the air then to be thrown out at the perifery rather like a water pump.As I said when I posted,Ettore would have loved these very idiosyncratic and totally different brakes.They are so "Bugatti" Given that all you actually need is a disc,a support,two pads and one or two cylinders.............................According to Rene,they worked fine.According to another account,Trintignant was very impressed by their efficacity.But yet another account says that they did not work very well and Trintignant asked for their removal and replacement by drums [ another version of the story is that it was Roland who got cold feet and demanded their replacement ] My study of the brakes suggests that perhaps they might have overheated in a race.They would certainly have worked though,maybe better than the drums of the period.Thank you for your interest Bart, if you wish,I shall post the drawings and photos of the cylinders and pads.


Last edited by Lazarus on Wed Mar 11, 2015 7:33 pm, edited 2 times in total.

Top
 Profile  
 
 Post subject: Re: T251 Discbrakes.
PostPosted: Wed Mar 11, 2015 6:52 pm 
Offline
User avatar

Joined: Tue Nov 04, 2008 5:07 pm
Posts: 1018
Location: Vienne France
barttore wrote:
Thank you very much for sharing. Most interesting topic for a long while...

I see 2 calipers in a mounting/housing that encloses the disc. I guess this was for keeping the braking warm ? I can imagine this could also cause overheating and fading ? Despite the cooling ducts.

Are the 4 connections on the inner side (where the calipers ought to be) for the hydraulics ? So only a single side action ? How about the outer side? A static brake liner ?

Keen to learn more of this interesting part.

Here are some photos which might amuse you.I do not have any working drawings,so all machining is "speculative" although as the patterns are original we cannot be too far out.You can see also that we now have sump,heads,blocks,gearbox and other castings for the engine.Things do not always have to be sucessful to be interesting.....


Attachments:
IMG_2298.JPG
IMG_2298.JPG [ 51.41 KiB | Viewed 15131 times ]
image-265 (2).jpg
image-265 (2).jpg [ 44 KiB | Viewed 15131 times ]
Gearbox casting 001.JPG
Gearbox casting 001.JPG [ 36.2 KiB | Viewed 15131 times ]
Top
 Profile  
 
 Post subject: Re: T251 Discbrakes.
PostPosted: Wed Mar 11, 2015 6:53 pm 
Offline
User avatar

Joined: Tue Nov 04, 2008 5:07 pm
Posts: 1018
Location: Vienne France
Lazarus wrote:
barttore wrote:
Thank you very much for sharing. Most interesting topic for a long while...

I see 2 calipers in a mounting/housing that encloses the disc. I guess this was for keeping the braking warm ? I can imagine this could also cause overheating and fading ? Despite the cooling ducts.

Are the 4 connections on the inner side (where the calipers ought to be) for the hydraulics ? So only a single side action ? How about the outer side? A static brake liner ?

Keen to learn more of this interesting part.

Here are some photos which might amuse you.I do not have any working drawings,so all machining is "speculative" although as the patterns are original we cannot be too far out.You can see also that we now have sump,heads,blocks,gearbox and other castings for the engine.Things do not always have to be sucessful to be interesting.....


Attachments:
IMG_2297.JPG
IMG_2297.JPG [ 49.44 KiB | Viewed 15131 times ]
Top
 Profile  
 
 Post subject: Re: T251 Discbrakes.
PostPosted: Wed Mar 11, 2015 8:22 pm 
Offline
User avatar

Joined: Tue Nov 04, 2008 5:07 pm
Posts: 1018
Location: Vienne France
Here are the highly original cylinders.All of the part numbers are lockheed except the body of the units.As one might have expected.


Attachments:
IMG_6485.JPG
IMG_6485.JPG [ 42.37 KiB | Viewed 15125 times ]
IMG_6486.JPG
IMG_6486.JPG [ 46.01 KiB | Viewed 15125 times ]
Top
 Profile  
 
 Post subject: Re: T251 Discbrakes.
PostPosted: Thu Mar 12, 2015 6:41 pm 
Offline

Joined: Wed Jul 15, 2009 5:38 pm
Posts: 642
Thanks for the additional pictures and drawings !

A hydraulic piston that operates a mechanism, so no direct hydraulic piston on the brakepad yet. A bit like the clutch slave cylinder operating the release bearing fork on my Frogeye's clutch.

So no vented disk yet. A quick wiki search learned that they did exist in 1950. Do we know if Bugatti ever tried those ? (not counting Bugatti revivals)

_________________
"Barttore has left the forum"


Top
 Profile  
 
 Post subject: Re: T251 Discbrakes.
PostPosted: Thu Mar 12, 2015 7:42 pm 
Offline
User avatar

Joined: Tue Nov 04, 2008 5:07 pm
Posts: 1018
Location: Vienne France
barttore wrote:
Thanks for the additional pictures and drawings !

A hydraulic piston that operates a mechanism, so no direct hydraulic piston on the brakepad yet. A bit like the clutch slave cylinder operating the release bearing fork on my Frogeye's clutch.

So no vented disk yet. A quick wiki search learned that they did exist in 1950. Do we know if Bugatti ever tried those ? (not counting Bugatti revivals)

The discs are ventilated Bart,you read it too quickly ! Ventilated aluminium discs reappeared only a few years ago on Lotus cars.


Top
 Profile  
 
 Post subject: Re: T251 Discbrakes.
PostPosted: Fri Mar 13, 2015 12:49 pm 
Offline

Joined: Wed Jul 15, 2009 5:38 pm
Posts: 642
Lazarus wrote:
[Bart,you read it too quickly !


Yes I did ! But I was looking at the drawings when I wrote it. :wink:
Those did not seem to show vented discs - as fas as I could determine.

_________________
"Barttore has left the forum"


Top
 Profile  
 
 Post subject: Re: T251 Discbrakes.
PostPosted: Fri Mar 13, 2015 3:09 pm 
Offline
User avatar

Joined: Tue Nov 04, 2008 5:07 pm
Posts: 1018
Location: Vienne France
barttore wrote:
Lazarus wrote:
[Bart,you read it too quickly !


Yes I did ! But I was looking at the drawings when I wrote it. :wink:
Those did not seem to show vented discs - as fas as I could determine.

Here are photos of a disc and an original hub.You will notice the hub is very unusual.There are two flanges instead of the more normal one.The star shaped flange,is fed through the disc and then turned to align with the six holes [ not drilled in this disc ] This allows a clear path for the cooling air to pass through the drilled wheel hub then through the hub,then up inside the disc.


Attachments:
IMG_6491.JPG
IMG_6491.JPG [ 19.63 KiB | Viewed 15075 times ]
IMG_6492.JPG
IMG_6492.JPG [ 38.25 KiB | Viewed 15075 times ]
DSCN3681[1] (1) (1).JPG
DSCN3681[1] (1) (1).JPG [ 33.63 KiB | Viewed 15075 times ]
Top
 Profile  
 
 Post subject: Re: T251 Discbrakes.
PostPosted: Sat Mar 14, 2015 8:10 am 
Offline

Joined: Wed Jul 15, 2009 5:38 pm
Posts: 642
Thanks again Jean !
You really see they engineered for racing with the air ducting and "quick" changeable disks.

This really sparked an interest for the postwar cars (normally I prefer the very early ones). I will read up on the 251/252/253 in my books soon.

_________________
"Barttore has left the forum"


Top
 Profile  
 
 Post subject: Re: T251 Discbrakes.
PostPosted: Sat Mar 14, 2015 8:31 am 
Offline
User avatar

Joined: Tue Nov 04, 2008 5:07 pm
Posts: 1018
Location: Vienne France
barttore wrote:
Thanks again Jean !
You really see they engineered for racing with the air ducting and "quick" changeable disks.

This really sparked an interest for the postwar cars (normally I prefer the very early ones). I will read up on the 251/252/253 in my books soon.

You will have to wait for my book to get published.You won't find anything accurate written any where else.You are correct of course,these brakes would not have been serviceable during a race.Indeed,changing pads would have taken maybe an hour per wheel.The pads would have to be filed to fit into their housings.The pads are held onto the linking arms with steel rods which are crossdrilled and pinned.As I said,a very Ettore Bugatti design,even though he was already dead.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 12 posts ] 

All times are UTC + 1 hour


Who is online

Users browsing this forum: No registered users and 8 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  

Valid CSS :: Valid XHTML Copyright © 2007 by Bugattibuilder.com :: Disclaimer :: Contact :: Advertising possibilities

Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group