GT 1.1 brake upgrade

[GTRoy]

I'm restoring 69 gt with 1.1 engine. Brakes are small, rear shoes 1/2 size of 1.9. Anyone know of "big brake" bolt in parts to help stop this car ???

[SoCalOpelGT]

Yes. Bolt on the brakes (and axle) from a 1.9.

[blancojp]

There are lots of options, just depends on how much you want to spend.
There are front vented upgrades up to 300mm disks and rear upgrades up to 262mm vented disks. Upgrades range from $300-600 for the front and $250-650 for the rear.

With upgrades you will probably need a new master cylinder and/or brake booster so you need to determine what you can afford.

[Opelkurt]

Originally Posted by SoCalOpelGT Yes. Bolt on the brakes (and axle) from a 1.9.

It might not be easy to find an 1.9 axle with the same ratio (4.12:1, I think).

-Kurt

[PROPEL]

Originally Posted by Opelkurt It might not be easy to find an 1.9 axle with the same ratio (4.12:1, I think). -Kurt

3:89. But won't bolt up, either, without modification.

[Opelkurt]

Originally Posted by PROPEL 3:89. But won't bolt up, either, without modification.

You're right; 3.89 for 1969. It was 4.11 for 1970.

-Kurt

[GTRoy]

Thanks for your ideas, I do have rear from 1.9 parts car, & m.c./booster also. Is m.c. from 1.9 interchangable, and would it help ?? Any source for bigger rear cylinders or really grippy brake linings ?? Front pads are smaller than 1.9 also. This car was a second car/daily driver for several years but has not been driven for over 5 years while body restored (all glass,trim and bolt on panels removed for repair and painting), decided to keep it "original" except for later retractable seat belts, and better brakes if possible and at reasonable cost, am going to rebuild all brake components anyway. Have 3 nos hoses which will be replaced per warnings on this site.

[GTJIM]

There are considerable differences between 1.1 and 1.9 GT brakes.

At the front the discs are the same but the calipers have smaller pistons (45mm vs 48mm) but it is not as simple as just changing the caliper because the mounting brackets are different so the entire spindle must be swapped out. The some of the real early 1.1 may even have a smaller taper on the lower ball joint, so that needs replacing too. If you have a set of 1.9 GT lower A-Arms it is better to swap the whole lot.

At the rear the 1.1 diff is much smaller and lighter than the 1.9 diff - and the backing plates have a different bolt pattern .. at least different to the later 1.9 diff with the conventional wheel bearings. You may be able to adapt the 1.9 backing plates and brake shoes with some creative welding and redrilling .... You need the ratio (3.89/4.125) of the small diff to get the tiny 1.1 motor to do the job, so just swapping in a 1.9 diff is not an option.
Though maybe it is possible to adapt a set of rear discs .... mind you the front brakes do most of the work and the original 1.1 rear brakes with premium friction material on the shoes may do the job as the 1.1 GT is heaps lighter than the 1.9

[GTRoy]

GTJIM & all, decided to keep brakes stock for now with rebuild, got new rear cylinders and more from OGTS today, linings and pads not worn but would replace with more grip if one brand measurably better, any recommendations?? I want to show this car April 29 at Half Moon Bay

[oldopelguy]

Most non-super chain parts stores, like your local Car Quest, NAPA, or family run place will be able to refer you to some place local that re-lines drum brake shoes. (If they can't you can try the yellow pages or ask around at some place that works on big trucks.) All you have to do is give the place a call and drop your shoes off, tell them what you're looking for with regards to compounds, and they'll get you set up. I had a set of shoes for my '40 IH truck done that way for <$25, and it was a two day turn around. The shoes even came back to me sand-blasted and painted.

[GTJIM]

Brake lining material called EBC "GreenStuff" offers a considerable increase in braking performance it is internationally available from good Brake Pad and lining suppliers. Have a wee search for it on the web - here is some info from the New Zealand Agent:

EBC Brakes New Zealand

In the U.S. of A. :

Opel Performance Parts - Active Brakes Direct

Just a thought - the 1.1 GT may have the smaller pads DP105 instead of DP104 ... ask.