Front brake booster deletion...

budgetzagato

budgetzagato

Administrator
Moderator
In dealing with the huge disaster that is my pedal assembly (frozen nuts=twisted lines etc.), I think now is the time to delete the front brake booster.

Am I correct in that I can simply run a new line from the front circuit pedal assembly bulkhead union directly to the front tee? This would render the line to/from the booster and the booster as unneeded and I could remove it all... Right? :hmm:
 
Yes

budgetzagato said:
In dealing with the huge disaster that is my pedal assembly (frozen nuts=twisted lines etc.), I think now is the time to delete the front brake booster.

Am I correct in that I can simply run a new line from the front circuit pedal assembly bulkhead union directly to the front tee? This would render the line to/from the booster and the booster as unneeded and I could remove it all... Right? :hmm:
Click to expand...
 
BTW, one of the short lines in back leading to the booster can be used as the jumper. No need to buy or make one. Just have to rebend it.

budgetzagato said:
In dealing with the huge disaster that is my pedal assembly (frozen nuts=twisted lines etc.), I think now is the time to delete the front brake booster.

Am I correct in that I can simply run a new line from the front circuit pedal assembly bulkhead union directly to the front tee? This would render the line to/from the booster and the booster as unneeded and I could remove it all... Right? :hmm:
Click to expand...
 
Did you see the Japanese difference?

I wonder if that would be better, especially if you are using X1/9 calipers instead of the originals?

Warren
 
I will warn you to go gently. Personally, I think removal of the booster without an upgrade of the front brakes is a bad idea, but that is just me. I have added 14" Whoa kit and TMH 037/S2 pedal box kit. When rebuilding the pedal box with the 037/S2 kit, I converted it to an X1/9 MC, which required adding an extra bulkhead connection. Here are some pics:

Brake%252520System%252520Layout%2525202.JPG


3%252520Hole%252520BMC.jpg


Revised%252520Pedal%252520Box%2525201.jpg


Revised%252520Pedal%252520Box%2525202.jpg


Clutch%252520Pipe.jpg


Pipe%252520Foul.jpg


Hope that helps.

John O.
 
Huh...

Huh. I thought they were supposed to be over-boosted and the solution was to remove the booster. :hmm:

Also, how does this affect the pressure warning light sender in the rear? I assume it senses a pressure differential between front and rear circuits. How do you bypass or otherwise deal with this part? :confuse2:
 
Interesting

I think it might work with an uno turbo front upgrade on the front brakes which is supposed to be too much. It would be interesting to experiment. I wonder what was actually done in Japan/


Warren
 
I'll offer some opinions on this subject, but I have no data of any kind to back it up...

My personal opinion is that there are inherent weight distribution issues with the Monte/Scorpion that you could spend a lifetime trying to dial out of the brakes. Again, IMO, if you want better braking from the Scorp in wet weather, which is where the lock-up issue presents, put a 50 lb bag of sand in the trunk. Essentially, I've come to believe the nose is far too light for the braking needed to stop a 2,200 lb mid-engine car on a wet road. Again, I have no data, but that's my conclusion at this time.

I've never liked the "instant on" feel of boosted brakes and was convinced that better modulation was the answer to the lock-up issue. Deleting the booster and adding the upgades did actually shift the braking bias rearward and I got much better modulation and feel, with arrow straight braking. I really felt I'd taken my time and done everything "right" ...and yet, this was the result one rainy day on a stretch of straight road:

10-26-07%252520Accident%25252002A.JPG


I was able to slow her down, but there was more lock up than distance for me to pump or modulate. It was like driving on ice, though she tracked dead straight. I believe if I'd had even 25 lbs of weight in the trunk the results might have been different.

So, as I said, go gently into this mod.

John O.
 
budgetzagato said:
Also, how does this affect the pressure warning light sender in the rear? I assume it senses a pressure differential between front and rear circuits. How do you bypass or otherwise deal with this part? :confuse2:
Click to expand...

If you look at my diagram, it gets deleted.

John O.
 
Do we know......

The difference in weight bias in the Scorpion VS the X1/9?
If we look at the X1/9, there is no booster of any sort and the rear caliper piston is smaller than the stock Scorpion. I have raced X1/9's for years and out of all the cars I have driven the X1/9 brakes I found worked the best. So if the weight bias is the same or verry close then there should be no issue using the stock brakes on the Scorp with the booster disconnected. Out side of that then I guess we are starting to beat on that dead horse again. I just have the vacuum disconnected on my booster and I have had no issues what so ever with my brakes and I am using X1/9 rear calipers. I am just looking for some way of getting a bit more initial bite and I really don't want to start playing with pads. (if I remember Ulix had some bad luck doing that)

Warren
 
whitespy said:
So if the weight bias is the same or verry close then there should be no issue using the stock brakes on the Scorp with the booster disconnected.
Click to expand...

Again, I have no data, but my opinion is that they do not have the same weight bias ..along with the Scorp's engine being heavier, there are little differences like the X engine leans slightly forward while the Scorp's leans rearward. Also, the X is so very well designed/engineered and thoughtful in so many respects it makes the Scorp appear almost cobbled together.

But ultimately were talking about lock up IN THE RAIN. Neither car is very well suited to wet weather driving. Over 25 years of driving Exxes, I've swapped ends a couple times in the rain when I wasn't paying attention. Now I know the limits of the Scorp in the rain ...leave A LOT of room for braking!!!

John O.
 
Last edited:
My X1/9 was a blast

My X1/9 was a blast in the snow. The second you stopped watching what you were doing, the same thing....... sit back and enjoy the ride.
The whole point of getting into the different scenario's for me at least is that eventually I will be using my car for Solo2 and I want to get the braking on par with the X1/9 but keeping as stock as I can.

Warren
 
Front Brake lock-up..

Was one of the reasons why the Scorpion has such a short run in the US. It became well-known that the front brake lock-up problem was serious and the insurance companies discovered this problem with the car. It was not long before the car insurance companies decided they would only insure the Scorpion at great expense. This along with all 85hp of US smog spec twin cam power made for sales of about 400 cars in 1977. Even selling those 400 cars in 1977 was extremely difficult for Fiat/Lancia in the US.

Few if any knew the potential of this chassis, some have made the Scorpiacarlo into the car is should have been. Most never reach that potential. IMO, the scorpion is one of the great UN-finished Italian exotic car designs that begs to be properly finished into all it could be. One can consider the Scorpiacarlo a production DIY project car. In comparison, the exxe is far better sorted and refined, specially for the ones built after 1980-81.

The brake balance problem can be resolved by significantly altering the stock brake design beyond bypassing the booster and deleting the miles of brake tubing running around in the car. My suggestion is to go beyond deleting the booster and installing an adjustable brake proportioning valve (Tilton, Wilwood or etc) into the front brake circuit. This would allow adjustment of when the front brakes lock up and go a long ways to resolve the brake balance problem with the Scorpiacarlo.

FYI, the Renault R5 turbo 2 has the same front brake lock up problem. There was a time when the folks who set up chassis for road cars believed rear brake lock-up must be avoided at all cost and the front brake lock up is acceptable. In the real world, this is not always true. At times, the dynamic behavior of the chassis as delivered by the manufacture is simply not acceptable and needs to be altered to meet the harsh reality of the real world driving conditions.


Bernice
 
What I am thinking of

is to install the exact same set up that is in the X1/9 from the master on.
I am pulling my car apart down to the bare chassis so to convert would not be a big issue. Another idea I was floating was to put 2 separate circuits in balanced with a balance bar. (like the set up from PBS shows in their book, but with an e-brake) But if I could take advantage of the booster I would but it doesn't look possible. Lancia could have turned the Scorp/Monte into their version of the 911 and it could have been successful too. But Lancia has no intentions of ever going back to what they once were in motorsports. Pitty.
 
Just curious

but, and I really haven't looked into this at all but, where I live in SC, we have a large salavge yard that is part of a chain company called Pullapat. Lots of late model cars in there. Has anyone ever tried to adapt an ABS system from another car to the scorp? Think of it! No worries about lockup in the wet!No worries about balance between front/rear brakes. Maxium breaking effect on all fours whenever you need it!If they can put it on a Hona Goldwing, why not a Scorp?:shock2:
 
A two pennorth from across the pond.....

Lancia originally claimed some ridiculous fore-aft weight distribution for the Scorpion, maybe 47% front/53% rear, which is patently wrong! And who in their right mind would servo the light end of the car anyway?

You guys never saw the second series Montecarlo as a Scorpion variant, but this is what Lancia did to the brakes to counter the criticisms of the original servoed set-up:

Fitted bigger rotors but retained the same pads and calipers.
Upsized to 14" wheels with a lower profile tire to maintain the rolling radius.
Changed the front hub carriers to get some ackermann effect.
Deleted the servo and fitted a progressive bias valve in the rear circuit.

All this improved things a bit but didn't eliminate front-end lock-up in the wet, which is of course inherent with any mid- or rear-engined car.

Most folks over here have simply bypassed the servo (we supply a bypass pipe, part #MH3277) with no ill effects. Next up is grooved rotors and fast-road pads. Then upgrading to the S2 spec (if you can find the front hubs). After that it depends on your bank balance and your pet theory......

Rod at TMH
 
ABS

One of our customers told me he was going to fit ABS to his Montecarlo. That was around six years ago and I haven't heard from him since.....
 
Thanks and Welcome!

I'm beginning to understand the various approaches to this problem. I hesitate to "fix" it until I understand the problem fully. Hopefully not until after I stuff it because of a front lock-up incident.

Looks like from this and much other info the Series 2 cars were pretty nice.

And welcome to Xweb Rod! :woot:
 
You must log in or register to reply here.
Back
Top