ABS Brake system fitted to the 97 GTR

[Le Man]

Ok everyone, this thread is to try and collect as much info as possible about the ABS system that was developed for the 97 longtail GTR. This may be a hard task to fulfil, I will add as much info that I have over this weekend, but if anybody else has any information relating to this brake system please feel free to post.

On a slightly different note, has anybody. in their pic collection, have any pics of the 97 GTR,s during manufacture at the factory, not sure which factory they were made in , but I have a feeling that they were made in a factory that we are not familiar with.

[hurstg01]

Martin

Found this in my Le Mans DA -



To me it reads that Lehto's exit of the 97 Le Mans was possibly ABS related....


Also, I can't seem to locate any in-build pics of the '97 GTR's - I'd like to echo Martins post and see if anyone has some they would like to share

[Le Man]

^^^ Thanks Greg,

I,m sure JJ spun accelerating out of the corner and T boned the wall, I will check my DVD to confirm.

[Le Man]

Very little data exists on the ABS system that was developed for the 97 spec GTR. So I will post what I have found so far, pics posted are not all of my own, so if nobody objects to me using them as reference material here for the purpose of this thread, then all credits must go to the original photographers.

I have found that McLaren installed ABS to four chassis #, those being 10R, 19R, 24R and 26R.

10R was used to test the system early in the development program, this may have been as early as mid to late 96. I have a small bit of footage on tape showing 10R testing at Paul Ricard circuit early in 97, maybe McLaren were still testing the system on 10R even at this late stage in the run up to LeMans that year. In the pic below, the only proof that I have found so far that the system existed on 10R are the two holes positioned in the bulkhead just above the right hand master cylinder (more on these holes later)



19R, in the first pic below is the std brake master/cyl set up on the 97 GTR, if you look above the right hand m/cyl you will see further holes, these are for mounting the single master cylinder used only on the ABS system, this, one would presume, be a tandem cylinder feeding fluid to both front and rear braking circuits (with or without a servo) and with the assistance of the ABS control unit to prevent wheel lock up, as in a normal road car set up. In the second pic you can see where ABS related components have been fitted to the left hand passenger (road car) footwell area. It still has in place, the carbon angle brackets that support the main component cover.




24R, pics 1,2 and 4 show its current set up, ie converted back to std brake configuration. this was done soon after LeMans 97 by GTC Motorsport when Thomas Bscher purchased 24R from BMW Motorsport as a replacement chassis, due to 22R being out of action due to fire damage. In these pics you will see similar component removal as described for 19R but also showing in pics 2 and 4 a half round blanking panel, positioned next to the drivers right thigh on the main R/H chassis tunnel, more on this with 26R. Pic 3 (The master in his office) shows the ABS component cover and the position of the driver adjustable AP Racing brake balance unit, low down in the (road car) passenger footwell area.




26R, at last a chassis with the system still installed, the first three pics are by our very good friend Rogerph from his trip to BMW Motorsport museum. Pics 1 and 2 show how the single master cyclinder set up is installed in the bulkhead, with a new dedicated brake pedal and pedal mount, more on this different pedal mount later, as I have the one that was removed from 24R. Pic 3 shows that the system has an electronic switch control to enable/disable and reset the system. Pics 4 and 5 show the main component cover, clearly showing the AP brake bias unit, also exiting to the rear of this cover is a main section of wiring loom.




All we need now is someone from Mclaren to join in and explain the whole system set up and why it was only used in anger by BMW Motorsport............. but maybe thats just wishfull thinking .

[Le Man]

According to these two extracts from the BMW Motorsport press release pre 97 LeMans. The ABS system did include a hydraulic power booster (servo) Although both BMW Motorsport chassis had the ABS installed for the race, I cannot find confirmation anywhere, if the drivers had the system switched on or off.



For reference I have added these two pics from the 97 GTR engineers manual, showing the std 97 GTR brake set up and a very nice drawing of the 8 pot Metal Matrix Composite front brake caliper. Its not until you hold one of these very large calipers in your hand, its only then when you appreciate how light they are,........and VERY EXPENSIVE TOO!!

[Peloton25]

Thank you very much for the education here Martin. Learning new things about the F1 is one of the joys of participating in this forum and this was clearly a fact I had somehow overlooked all this time.

I hope we do find someone else with more info to share, but you have done a great job so far bringing the available details to the forefront.

>8^)
ER

[Sami Aaltonen]

Le Man; this is superb, thank very much indeed for these informationd rare images!!
I knew BMW Motorsport used ABS brakes during Le Mans 1997, but never expected to have images of these cars with this kind of information!
Thanks!

[hurstg01]

I always wondered why the cars had differing pedals - just thought it was driver preference; echoing the above, Martin!

[Le Man]

^^^^^ Many thanks guys for the appreciation, makes the posting all worth while .

I still have some more info/pics to add.......maybe later this week .

[cabrio92]

Hello,

thank you and bravo Martin for this technical post.

I hope Davidoff41 will see it and maybe be able to help.

Phil

[Le Man]

^^ Many thanks Phil .

Found this article while looking through my brother,s collection of Racecar Engineering mags. Although brief, it has some very interesting details, about the ABS system. I.ll let you all read through and await your comments gentleman . Enjoy.



Please bare in mind that not all the text is correct IE:- The 97 GTR used forged, not cast magnesium wheels.

[McF1]

Nice topic, very well documented indeed!

I recall that ABS were fitted on the BMW works cars not only for the primary purpose of having ABS, but also in order to move up on the class weight, allowing for larger air restrictors.
Does anyone have such evidence?

[McF1]

Ok ok, mea culpa. I just read the great two pages from "Class 97 of Le Mans", and it is confirmed in the second page.

[tortoise]

Originally Posted by McF1

Nice topic, very well documented indeed!

I recall that ABS were fitted on the BMW works cars not only for the primary purpose of having ABS, but also in order to move up on the class weight, allowing for larger air restrictors.
Does anyone have such evidence?

Anything is possible, but how would that work? Do you mean that ABS was literally required in order to move up in weight?
Perhaps what you mean is that they wanted larger air restrictors, doing that they thought would be worth the trade-off of adding weight, and, as it happened, in the heavier class the cars were allowed ABS? I don't know that that was the case, but I don't think that the reverse order would have made sense.

[DocGTR]

Originally Posted by McF1

Nice topic, very well documented indeed!

I recall that ABS were fitted on the BMW works cars not only for the primary purpose of having ABS, but also in order to move up on the class weight, allowing for larger air restrictors.
Does anyone have such evidence?

I also had in mind that there were somewhere something about the driver comforts for Le Mans on those Fina McLaren Le Mans cars (24R & 26R) as I just remembered the GT Endurance 1997 book has the Fina Motorsports Le Mans 1997 chapter in the end and there is the section "The Car":

Originally Posted by GT Endurance 1997 - Fina Motorsports Le Mans 1997 (p. 9)

The Car

The two F1 GTR Fina McLarens were of exactly the same type as those used since the start of the season (1997) but modified to cope with the specific requirements of the Sarthe circuit. After five weeks wind tunnel work to improve air penetration so as to achieve the highest maximum speed without affecting fuel consumption the height of the rear wing was reduced by seven centimetres. The air intakes were modified and the air flow under and over the car optimised. As the Le Mans 24 Hours race authorises the use of ABS which spares not only the tyres and brakes but also drivers, it was installed together with hydraulic braking system. Finally, the comfort and the safety of the drivers were maximised thanks to a rehydration and liquid nourishment system plus a supply of fresh air in the cockpit. With all these accessories on board the Fina McLaren weighed between 950 and 1000 kilos some fifty more than in the FIA-GT Championship. The V12 cylinder BMW engine was unchanged and its power out put was just over 600 bhp.

And just few pages earlier it is said:

Originally Posted by GT Endurance 1997 - Fina Motorsports Le Mans 1997 (p. 5)

BMW delegated the honour and responsibility of looking after two McLarens to the Schnitzer team which was given two completely new chassis, different from those raced in the FIA-GT Championship, and destined for the 24 Hour race only.

And as we know the 24R was sold to Bscher after his 22R had the fire damage at Le Mans as he needed a car to continue racing in the FIA GT Championship, it is possible that the ABS was then changed to the more conventional braking system used on the other FIA GT racing McLarens. Sadly it wasn't long as Nielsen then had the shunt in the practice for the Suzuka 1000km and almost destroyed the chassis. But I guess the ABS didn't make a return to this chassis even after the rebuilt as it was still used for other races and even Le Mans 1998 where it finished fourth.

Just my