Installing (Upgrading to) '75 Manta calipers on GT

[opelgt1976]

I recently got a set of used '75 Manta Calipers and want to install on my '70GT. I have two questions:

#1
I am missing the small metal lines and brackets that go between the caliper and the flex hose. Does anybody have a good source for these? At least a good source for tubing so I could fab my own...

#2
What is the difference between the '70 GT and '75 Manta Flex hoses? I noticed different p/n at OGTS and don't know which ones to get.

Thanks for the help.

[Phoenix]

brake lines

The type of flare is different.

Either you need to make up custom brake lines or buy the correct brake hoses. I chose to buy the brake lines with the inverted flare from an auto parts store and had a friend make the bubble flare on the other. It requires special tools.

[blancojp]

Originally Posted by opelgt1976 I recently got a set of used '75 Manta Calipers and want to install on my '70GT. I have two questions: #1 I am missing the small metal lines and brackets that go between the caliper and the flex hose. Does anybody have a good source for these? At least a good source for tubing so I could fab my own... #2 What is the difference between the '70 GT and '75 Manta Flex hoses? I noticed different p/n at OGTS and don't know which ones to get. Thanks for the help.

Autozone sells an 8" hard line which will work for the application. It is a metric line which has a bubble on one end and IF on the other. They cost about $6.00 however I should have a few ready made in the work shop.

The difference between GT and Manta hoses is just the length. The GT uses a shorter 10" hose and the Manta I believe is 9" longer. Both end connectors are the same on both hoses. A 1964 VW bug hose will work well on a GT and will eliminate the hard line since it is 16" long and it is made to go straight into the caliper. Best this is you can buy a set from Voltronix for $15 including shipping.

You can see them here: VW Beetle Bug Ghia Front Brake Hose 47-64 PAIR:eBay Motors (item 360201700939 end time Nov-04-09 21:26:02 PST)

If you are using '75 calipers, you must also use the '75 rotors otherwise your pads will sit outside the perimeter of the rotor 4mm. Also the '75 calipers are made for a 12.5mm thick rotor and the GT has a 10mm thick rotor. This increases compliance and pedal travel slightly.

Hope this helps.

[jmbinjax]

Opel GT Source has hoses and adapters for exactly this conversion.

[opelgt1976]

Originally Posted by blancojp Autozone sells an 8" hard line which will work for the application. It is a metric line which has a bubble on one end and IF on the other. They cost about $6.00 however I should have a few ready made in the work shop. The difference between GT and Manta hoses is just the length. The GT uses a shorter 10" hose and the Manta I believe is 9" longer. Both end connectors are the same on both hoses. A 1964 VW bug hose will work well on a GT and will eliminate the hard line since it is 16" long and it is made to go straight into the caliper. Best this is you can buy a set from Voltronix for $15 including shipping. You can see them here: VW Beetle Bug Ghia Front Brake Hose 47-64 PAIR:eBay Motors (item 360201700939 end time Nov-04-09 21:26:02 PST) If you are using '75 calipers, you must also use the '75 rotors otherwise your pads will sit outside the perimeter of the rotor 4mm. Also the '75 calipers are made for a 12.5mm thick rotor and the GT has a 10mm thick rotor. This increases compliance and pedal travel slightly. Hope this helps.

Do you know the autozone p/n? Or the line size and fitting names to ask for.

Should I remove the dust shields, look for larger ones, or just cutoff the lip?

If I go with all rubber, do I need to worry about the line rubbing on the wheel?

Thanks...

Thanks

[blancojp]

Originally Posted by opelgt1976 Do you know the autozone p/n? Or the line size and fitting names to ask for. Should I remove the dust shields, look for larger ones, or just cutoff the lip? If I go with all rubber, do I need to worry about the line rubbing on the wheel? Thanks... Thanks

Don't know the part number but they only have one 8" metric line with the setup.

Cut the shield if need to.

I don't believe you will have a problem with the line rubbing. If so, use a tye wrap to hold it in place.

[Anonymous D]

I have seen overlong rubber brake hoses to a 1975 caliper on a GT rub on the inside of the (moving) wheel rim. That situation is extremely unsafe (the hoses slice very quickly), and I would not rely on a mere tie-wrap to ensure it would be held back at all times (for however many years you continue to drive your car). If you choose to do this, definitely check the condition of your hoses frequently.

In general I would advise that you NOT experiment with a critical safety system (like brakes) with parts that haven't successfully been proven to work over the long term. The potential for severe damage (to your car, yourself, or others) isn't worth trying to save a few dollars!

[blancojp]

Originally Posted by Anonymous D I have seen overlong rubber brake hoses to a 1975 caliper on a GT rub on the inside of the (moving) wheel rim. That situation is extremely unsafe (the hoses slice very quickly), and I would not rely on a mere tie-wrap to ensure it would be held back at all times (for however many years you continue to drive your car). If you choose to do this, definitely check the condition of your hoses frequently. In general I would advise that you NOT experiment with a critical safety system (like brakes) with parts that haven't successfully been proven to work over the long term. The potential for severe damage (to your car, yourself, or others) isn't worth trying to save a few dollars!

I agree with you 100%, please make sure you (AnonymousD) work on any brake systems, ever...

[wrench459]

I think Anonymous D has an issue with using tie wraps to hold down the rubber brake hoses.

I've done it before(when young) but in general its not a good idea.

[Rionart]

There is a right way and a wrong way to use tie-wraps....99% of people use the wrong way.
If I get a chance I'll do a couple of examples and post pics...but not tonight...

[blancojp]

Originally Posted by wrench459 I think Anonymous D has an issue with using tie wraps to hold down the rubber brake hoses. I've done it before(when young) but in general its not a good idea.

You obviously not seen the tye-wraps I use.

I use home made 3/8" wide, 26 gauge metal tye-wraps. I have a ton of them on my car and I learned the process almost 15 years ago. I call then tye-wraps but in essence they are c-clamps holding and guiding the hoses.

The hose I recomended I have on all my GT's and the Ascona. On Stealth I have 2-hoses per wheel up front. The two hoses are guided using the upper A-arm until they reach the connection point. There is no possible interference with any components or the wheel. Using a '75 caliper, the hose will be 1.8" too long when connected directly to the caliper.

[wrench459]

Originally Posted by blancojp You obviously not seen the tye-wraps I use. I use home made 3/8" wide, 26 gauge metal tye-wraps. I have a ton of them on my car and I learned the process almost 15 years ago. I call then tye-wraps but in essence they are c-clamps holding and guiding the hoses.

Your right I've not seen what your up to.
How 'bout posting a pic of the tye-wraps so that us little people can learn something?

[opelbits]

I have the 75 calipers on my GT and use the 75 backing plates. Short and simple solution is to call Opel GT Source tell them what you have and they will send exactly what you need. I have their braided stainless hose and adaptor fittings.
There are some differences in the short metal hardlines and the backing plate brake hose bracket between GT and Manta.

[markandson]

Originally Posted by opelbits I have the 75 calipers on my GT and use the 75 backing plates. Short and simple solution is to call Opel GT Source tell them what you have and they will send exactly what you need. I have their braided stainless hose and adaptor fittings. There are some differences in the short metal hardlines and the backing plate brake hose bracket between GT and Manta.

Yup, I agree, I have the big brakes on my GT and used the stainless kit from OGTS. You no longer need the short tubes, you can run the stainless lines right into the caliper using the adapters they supply. You will also get a nice stainless line to use at the rear brake flex connection. This is a link to a picture of mine, BUT it is before I switched the calipers around so that the inlet was on the top, so this picture still shows the short hard lines in place. When I realized I could eliminate them I did. I actually still have them sitting in a coffee can somewhere, including the modified brackets that hold them.