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Discussion Starter #1 (Edited)
I thought I would start a new thread with the information I learned doing my brake master, booster, and caliper rebuild.

My Jalpa is number 336 and was built in 1986.

I have the single brake master cylinder set up. I have included a picture so you can see the exact master and booster that are on my car. Lamborghini switched from a dual master set up, to a single master cylinder. At some point, Lamborghini also switched the rear calipers to a different model. My reservoir tank broke on one of the shipping trips, so I learned that tanks are available, but most available tanks are a dual compartment set up.

-The brake master cylinder is a Benditalia unit. Not available anywhere I could find.
-The brake booster is also Benditalia. I found one for sale, but it was a fortune.
-The reservoir tank is Benditalia from an Alfa Romeo. I found the tanks at Alfaholics and a few other Euro part suppliers. If you want the tank to look authentic, specify the single tank unit. I found that the spare tires hits the larger tank so I had to lift the tire slightly.
-The front brake calipers are Ate. They are also used in Porsche, Volvo, Mercedes, Alfa Romeo, the Countach and others. There are a lot of pad options.
-The rear brake calipers for the later Jalpa are from a 1969 to 1976 BMW 2002 model. This is not documented anywhere..... All information in the part catalogs and online will give you a different part number that is wrong for the later cars. The original pads I got did not fit, though everything I read said they were correct.
-Part for early Jalpa rear brake pads is Hawk Performance HB172E.595, Raybestos 94789YX, EBC REDSTUFF CERAMIC PERFORMANCE BRAKE PADS - REAR DP3104C or many other brand options. These will not work for the later cars.
-The parking brake calipers are a separate unit made by Brembo. Same as in the Countach. Circular puck style brake pad.
-The bleed screws are an unusual short type. The longer Ate replacements seem to work just fine, they just stick out further. I used Part #: FR-208-508 the nut size is 9mm, rather than 7mm like the originals. See picture below.
-The bleed screw rubber dust caps are available through "Parts Geek" part # ATE W0133-1800817
-Calipers are slightly modified so Lamborghini caliper rebuild kits are required. Kits are the same for the Countach.
-My brake portioning valve was faulty. A new modern valve was installed. Adapters had to be made to link the new valve to the old lines.
 

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Discussion Starter #2 (Edited)
A quick summary of my project is as follows.

Oct. 2017 discovered a substantial brake master cylinder leak. Pondered options and decided to get a rebuild. I sent the brake master cylinder and the brake booster off as a unit to get rebuilt.

About 2 months later I got the parts back. I was told the brake booster had a bad valve and could not have been working. They said the master had the wrong seals. Told me everything should be good now.

I installed everything and bled the system. Brakes still sucked, so i took it to a brake shop and got a proper bleed. I got the car back and everything worked better, but not great. I noticed a couple weeks later that the front compartment was full of brake fluid and there was a serious leak.

Dec 2017 I took the car to a shop because I was in the middle of a move. They removed the brake master cylinder and sent it back to the re-builder. The reservoir tank broke a nipple off in the process. The re-builder said the kit they installed had the wrong seals. They replaced them and sent it back. I ordered a new reservoir tank online. A shop did the reinstall and I drove the car home. The brakes worked poorly and by the time I was home, one reservoir compartment in the tank was completely void of fluid.

April 2018 I sent the master cylinder back for a re-sleeve. This took a couple months. When I got the master cylinder back, I put it back in the car, bled the system and took it for a test drive. The brakes still behaved poorly and when I parked, I found the master leaking.

July 2017 when I sent the master off for the 4th time. They kept it until they were absolutely sure it was working properly. While I was waiting, I bought new brake pads. When the master arrived, I changed the brake pads and bled the system. I stripped the bolt on one of the bleed screws and was unable to get it off. The brakes were awful, but I found the master was not leaking. I struggled to find a bleed screw, but finally got everything installed and did another brake bleed. I taped paper towel around every connection to identify and pinpoint any leaks. A couple line connections needed tightening, but I was able to eliminate all leaks.

The brakes are still poor, but I feel like I am back to about where I started as far as brake performance. In hind site, I really should have done a conversion. I hope my story helps the next person to see the logic in switching to a different system. I am hoping that things will improve as the new pads break in, but I will most likely switch over to a whole new system in the future. I want to dive the car a little and make sure it is necessary before I tear it apart again.

Brake Master Cylinder and Brake Booster rebuild were each about $500 for $1000 total
New reservoir tank was about $250
Bleed screw was $20
Dust caps were $40 (6 or 7 of the things went missing in the process)
I easily spent another $100 for shipping.
 

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Discussion Starter #3
Finally had a chance to take the car on a longer drive. Brakes are great. It must have taken a little while for them to get seated properly. After some highway driving and stopping, I tried some hard stops again. I can lock up the wheels with minimal effort. Hard stops are no longer white knuckle thigh bursting affairs.
 

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I know the feeling. I finally got mine fixed by replacing the brake boosters with alfa ones and making adaptors for the lines. They look identical but work perfect. Congrats.
 

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Discussion Starter #5
Another issue appeared. The dual tank fluid reservoir is a little bit taller than the original. When I put the spare tire back in place, it hit the tank. The new tank came with a brass and rubber cap that fit over the filling cap. This pushes the spare tire up about 1/2 inch. Half the weight of the tire presses on the tank.

I took the extra covers off and the tire barely touches the top of the tank now. I am going to put some foam pads on the tire contact points and that should get it up off the tank. Hoping it does not hit the hood.
 

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I hope it fits. If you still have problems, take pictures and maybe I can help.Lee
 

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Discussion Starter #7
It all fits. I had some dense foam that was about 3/4 of an inch thick. I cut blocks and set them in with carpet tape on top of the wheel support posts. Just needed a little lift to clear the tank. I was worried about hitting the roof, but it all fits. Everything is black, so it looks like it could have been original and does not draw notice.
 

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Discussion Starter #8 (Edited)
I have been trying to sort the rest of my brake system for a couple months now. The braking was inconsistent and still not nearly as good as it should be after the booster rebuild. I took the car to a local shop and asked for a caliper rebuild. I thought the calipers were standard Ate units and we ordered standard rebuild kits in the standard sizes. The rebuild kits did not fit. The shop said they were close, but not quite right. After some research, I learned that Lamborghini modified the calipers slightly and a Lamborghini caliper kit is required. The kit was readily available and only slightly more than the standard rebuild kits. For some reason, the rebuild gave them a hard time and took ages longer than they expected. The last caliper had a chipped piston that needed to be replaced. They believed that a bur created by the chip was cutting the caliper seals and creating an air leak.

Once they got everything back together and bled properly, they found that the bias valve was faulty. It was not possible to fully engage the rear brakes. A new valve is on the way.

So when I started, I had a leaking master cylinder, air in my lines from a bad caliper seal, a broken valve in my booster, and the rear brakes were not fully engaging. No wonder I could not not stop that stupid car!

I think that once I got the master working properly, I was able to lock up the front brakes, which is why the car felt so much better. It stopped much better at slow speeds. Air was getting in the system, which is why they were inconsistent. A little air and no back brakes is what was making it so terrible, especially at high speed.
 

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Well you have come a long way from..."push harder" :)

The bias valve is by now a problem for all Jalpas and Urracos unless the brake oil has been fastidiously replaced every 2 or 3 years since new !

What exactly is the difference in the "caliper-kit" other than the rear spacer ?

Paul
 

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Discussion Starter #10 (Edited)
Well you have come a long way from..."push harder" :)

The bias valve is by now a problem for all Jalpas and Urracos unless the brake oil has been fastidiously replaced every 2 or 3 years since new !

What exactly is the difference in the "caliper-kit" other than the rear spacer ?

Paul
I need to ask the shop for exact details. When the first rebuild kit arrived, they said it was really close and thought it might be the brand they bought. They said there sometimes is slight differences between manufacturers. They were going to order a different brand thinking that might solve it. It seemed fishy, so I called Derek, who just did his Jalpa calipers. That is when I found out I needed the Lamborghini rebuild kit.
Most of my info is coming through the receptionist, so I did not get great details on what was different. They are still working on it, so I will get more info when it wraps up.
 

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Discussion Starter #11 (Edited)
Shop is still fiddling with the brakes. They called last week to tell me they were pretty much done and everything was working well, but they were not getting much vacuum to the brake booster (10 PSI). I was going to tell them to drop it and work on the vacuum system myself, but they said they planned to install an electric vacuum pump. They had learned about the Jalpa vacuum issues and recommended I skip the whole system. Pump will go just under the booster in the front compartment.

I like the concept and look forward to seeing how it works.
 

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Without Perfect-Seal piston rings, the vacuum is somewhat lacking but the tank in the rear fender well should be a considerable help.

Nevertheless, the electric vacuum pump should provide more than enough vacuum :)

Paul
 

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Discussion Starter #13 (Edited)
Without Perfect-Seal piston rings, the vacuum is somewhat lacking but the tank in the rear fender well should be a considerable help.

Nevertheless, the electric vacuum pump should provide more than enough vacuum :)

Paul
It seems like there are a lot of places the car can lose vacuum pressure to the booster. Lines could be bad, check valve could be bad, reserve tank could be leaking, connections might be faulty, engine might have issues, etc. I feel like even if I got the whole system working perfectly, some link in the chain could act up in the future. I really like this pump idea.

I will let everyone know how it works shortly. Everything is supposed to be done late this week.
 

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Chris,
You can check the whole system component by component pretty easily. The vac pump is an ok fix but draws current. The vac is free . If the brake place cant find the leak or source of the weak vacuum then they are not very skilled. Vac systems are very simple. You can use a handheld vac pump to test components for leaks. If you decide to try , let me know and I will give you a tutorial. Lee
 

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Discussion Starter #15
Finally got the car back. Brakes work like they would in a normal car.

Not loving the air pump. It makes noise and takes up more space than I expected. The nice part is that I get loads of vacuum.

I figure I could work out the existing vacuum system, but honestly I am tired of screwing with the brakes. The pump dropped in and solved the last issue. Plan to enjoy the car this summer and work on some smaller issues over the coming winter.
 

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Discussion Starter #16
Well you have come a long way from..."push harder" :)

The bias valve is by now a problem for all Jalpas and Urracos unless the brake oil has been fastidiously replaced every 2 or 3 years since new !

What exactly is the difference in the "caliper-kit" other than the rear spacer ?

Paul
I spoke to the shop about the caliper kit. They said that the spacers are different and that the pistons are larger than the Ate calipers I believed were compatible. Though the pads are compatible, the shop said that the calipers are most likely a different model with a bigger piston.

The mechanic found it odd that the rear brake disks are vented, but the fronts are not.
 

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Neither of mine are vented. Normally the front discs do most of the stopping so it is odd that the back are vented and not the front. I wonder if someone upgraded your brakes. Does anyone know if drilled disks are std? Let me know if this winter you decide to chase the problem. Maybe we could do them when I come to Oregon> lee
 

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Discussion Starter #18
Neither of mine are vented. Normally the front discs do most of the stopping so it is odd that the back are vented and not the front. I wonder if someone upgraded your brakes. Does anyone know if drilled disks are std? Let me know if this winter you decide to chase the problem. Maybe we could do them when I come to Oregon> lee
My understanding is that Lamborghini changed to a different caliper mid production. Since you have an early car, you have the original set up. I have a later car, so I have different rear calipers, and apparently, different rotors. From what I gather, this is factory. It looked original (or at least really old) to the mechanics, but who knows?
 

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As you can see from this Lambo parts schema from 9/84...both
front and rear Jalpa-Urraco rotors are vented !

Possibly the very last 87-88 cars had a different set-up

Paul
 

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Discussion Starter #20
As you can see from this Lambo parts schema from 9/84...both
front and rear Jalpa-Urraco rotors are vented !

Possibly the very last 87-88 cars had a different set-up

Paul
Good catch. So weird. Wonder why mine are different front to rear...... The "update" idea doesn't hold much water after seeing this. My car was is a 1986 model. I will have to ask around and see what other late model owners have....
 
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