Mechanical brake booster?

[Wally]

Haven't seen one in a while and would like one. I recall its not much more than a steel plate made to the right dimensions.
Anyone know where to get one?

I now have about the right brake balance I feel (last track experience), but braking force is now a bit on the high side for my liking.

Thanks,
Walter

[Simon]

Are you locking up the wheels? If so, a smaller diameter MC could be an option.
And maybe a pedal with a higher ratio is an option?

[Wally]

Are you locking up the wheels? If so, a bigger diameter MC could be an option.

Nope, like I said above, brake balance is really good now, but pedal force to brake to the verge of blocking is too high. I need a booster.

And maybe a pedal with a higher ratio is an option?
Yes, that is what I am looking for. I know it exists and its a simple item. I hope some company made some for a good price ;)
I looked, but could not find one with some of the bigger US company's. Hoped s/body knew the right company who has them.

[Wally]

Found a picture of it in the old Tafel catalog:

http://www.keversite.nl/fotoalbum/fotos/78987.jpg

[Xellex]

Hoffmann-speedster.com has it listed on their website:

http://img17.imageshack.us/img17/3474/mbs.jpg

[Wally]

Cool! Nice find! Looks like exactly thesame :D

Anyone have experience with this?

[kafercup]

I have one of those in the garage that has yet to be installed. I've had it waiting on the shelf for several years. It seems to be a well-designed piece. Once the ca is back on the road with the new 944 turbo front and rear setup (with 944 m/c) i'll make the decision as to whether the car needs it. With the old 944 n/a setup, my pedal was pretty stiff and the booster would have been a welcome addition.

[evilC]

Whilst the mechanical booster will reduce the effort on the right leg it does seem to be a piece of kit to cure the symptom not the problem. Wally, you either need a stronger right leg or a smaller master cylinder, which for a 30% reduction in pedal effort should be around 16mm or 5/8" (0.625). I would have thought that for a car used so extensively on the track that you would have gone for a balance bar set up that would not only allow the simple change to the master cylinder but also permit very fine tuning of your brake balance for different tracks? Adding yet another linkage on the standard system will only reduce pedal feel.

[NO_H2O]

This is how we took care of that problem on the Herbie X. It is an expencive setup and tok a while to get it installed. But the owner thinks it was the best mod we did to the car (and we moded everything).
http://i209.photobucket.com/albums/bb225/NO_H2O/Herbiepedals1.jpg~original
It is a Tilton 600 3 pedal set-up. It totaly changed the way the car feels to drive.

[evilC]

This is the one I have been drooling over. It is on my list of fabrication jobs to do. As I see it the pull cylinders have a number of advantages:
http://www.apracing.com/info/products.asp?product=Floor+Mounted+Reversed+Pull+T ype%2DCP5516%2D3+Three+Pedal%3Cbr%3E%3Cimg+border% 3D%222%22+src%3D%22http%3A%2F%2Fwww%2Eapracing%2Ec om%2Fpics%2Fproductpics%2FCP5516%5F3%5F1%2Ejpg%22% 2F%3E_2351_2342
1) No binding therefore smoother opperation
2) The cylinders are within the shell and not out in all the crud
3) The balance bar set up with various m/c's will allow tuning of the brake set up.
AP have very kindly offered the detailed installation drawings on the web page so taking much of the guess work out of the fabrication. Also, I have lifted the floor infront of the pedals on the '03 Super, which I highly recommend. It makes the pedal operation MUCH more egonomic and comfortable with none of the foot lifting that you get with the standard car also there is a better relationaship with the seated position. That 50mm void then provides the space for the m/c's
Such a pedal box arrangement would be well within Wally's capabilities I expect.

[NO_H2O]

That AP setup looks sweet too.

[Wally]

Such a pedal box arrangement would be well within Wally's capabilities I expect.

Hehe, well, don't overestimate my 'capabilities' nor my wallet as AP is usually very pricy (but nice) :p
I was/am hoping to be able to get the stock pedal cluster to work as well as I can be when I had just the rear n/a 944 brakes and everything seemed ultimately perfect untill I had to 'upgrade' again :lmao:

The idea was to reduce front pedal braking and up the rear a little more (they now have the largest cups I could find for my rear disks) so the rars would lock up first.
The fronts have smaller cups than the rears now! So I got a brake bias adjuster from Tilton to regulate the rears. But nooooo, the fronts still (just) block first still, so its actually pretty good balance without any adjustment, except for the pedal force...

[Humble]

Hey Dave, what did you guys end up doing to mount the pedal assembly? I talked with you over the phone but I never got to see the finished results. The tilton 600 (and similar assemblies) are by far my favorite and I can't wait to get mine in the new chassis.

[NO_H2O]

If you can see in the pic, we raised the flood with .080 2024 t-3 and some spacers on the mounting bolts. The rods were extended thru the bulkhead (holes cut and spacers inserted) the M/C's are on the forward side of the bulkhead. a flat sheet of .100 2024 t-3 is on the bottom side of the pan. Bolts thru all layers stiffen things up nicely. It took a while to get it all in the way we wanted to but the end result made the owner very happy. The Tilton techs got the M/C size selection right on the money. We put the bias bar right in the middle and tested it in the parking lot of the owners building and never touched it again.
I want a set in my car some day.

[Simon]

This is the one I have been drooling over. It is on my list of fabrication jobs to do. As I see it the pull cylinders have a number of advantages:
http://www.apracing.com/info/products.asp?product=Floor+Mounted+Reversed+Pull+T ype%2DCP5516%2D3+Three+Pedal%3Cbr%3E%3Cimg+border% 3D%222%22+src%3D%22http%3A%2F%2Fwww%2Eapracing%2Ec om%2Fpics%2Fproductpics%2FCP5516%5F3%5F1%2Ejpg%22% 2F%3E_2351_2342
1) No binding therefore smoother opperation
2) The cylinders are within the shell and not out in all the crud
3) The balance bar set up with various m/c's will allow tuning of the brake set up.
AP have very kindly offered the detailed installation drawings on the web page so taking much of the guess work out of the fabrication. Also, I have lifted the floor infront of the pedals on the '03 Super, which I highly recommend. It makes the pedal operation MUCH more egonomic and comfortable with none of the foot lifting that you get with the standard car also there is a better relationaship with the seated position. That 50mm void then provides the space for the m/c's
Such a pedal box arrangement would be well within Wally's capabilities I expect.
You have lifted the floor by 50mm?
Why did you choose 50mm (and not 30 or 70mm for example)?

[evilC]

the floor was lifted by 50mm infront of the pedals to creat a platform about 12-15" deep (there is a sloping front edge). the height of this was determined by finding the most comfortable position with the heel on the (raised) floor and the ball of the foot on the pedal pad. The floor raising suits my size 8 (US size 9) feet and I can pivot my foot between throttle and brake as well as comfortably heeling and toeing. That 50mm height also allows me place pull M/Cs under the raised floor should I eventually go down the route of putting in a brake balance bar a la AP
AP also set their floor position up about 40mm from the pedal pivot point so I can't have got it too wrong. Besides, I first drove a VW beetle around 40 years ago and found then that the pedals were set so high that I had to take my feet off the floor to press them. That to me meant that I had less control over the clutch action but more importantly the braking effort. Bouncing around the local lanes needs all the control you can muster and maintaining your heel on the floor is paramount for that. Many of my friend at Loughborough Car Club have modified their rally cars in this way even though their pendant pedal boxes are not so chronic as the VW one - it was them that gave me the idea.

Clive