Steering, Suspension, & Brakes

tips, technology, tools and techniques related to non-driveline mechanical components

Go to Thread: PreviousNext
Go to: Forum ListMessage ListNew TopicLog In
Goto Page: Previous12
Current Page: 2 of 2


geezer
Charles Durning
Magee, MS
(25 posts)

Registered:
11/16/2017 01:16PM

Main British Car:
1974 MGB, 1967 Morris Minor

authors avatar
Re: MGB rear disc brakes
Posted by: geezer
Date: January 15, 2018 03:25PM

The additional bracket for the 240sx caliper has to be changed. The difference is the spacing as shown in the pic. That spacing will also change on the Sentra bracket.


geezer
Charles Durning
Magee, MS
(25 posts)

Registered:
11/16/2017 01:16PM

Main British Car:
1974 MGB, 1967 Morris Minor

authors avatar
Re: MGB rear disc brakes
Posted by: geezer
Date: January 29, 2018 09:48AM

Yesterday I got a chance to make the adapter brackets for the 240sx calipers. Those brackets move the mount holes out and provide the necessary offset. As a precaution, I bolted and welded the 2 brackets together.

I took the GT out for a vigorous test drive with the 38mm bore 240SX rear calipers. The stopping is satisfying, Very little nose dive. almost flat. In checking the temps front to rear and they we within a couple of degrees front to rear. We had a steady rain all day yesterday so there were still patches of wet asphalt. The car braked well on both wet and dry pavement. In places where the pavement alternated between wet and dry the car behaved predictably. I even tried hard braking on a curve both wet and dry and the car behaved. No surprises. I had a buddy with me who has a stock1972 roadster. His gut feeling is the 38mm calipers may give a roadster a little too much rear bias. We'll try the 34mm Sentra calipers on his car sometime in the future.

The 240SX provides for a better routing for the hydraulic hose and the park brake cable, in my opinion. I did have to make a simple modification to the park brake lever by welding a small piece of metal to close off the open hook for the brake cable. That may not be necessary, I just wanted to be assured the cable end could not fall off the arm.

The Sentra 34mm calipers have some benefits in that the pads are longer than the 240sx pads. As I understand it longer pads may not give more stopping power but may have an advantage of lasting longer and operate cooler. The other benefit is the bracket is one piece. The disadvantage is the park brake lever has to be modified and the park brake cable ends up being very close to the boot bodywork.

The benefit for the 240sx caliper is the brake hose port is in a place for better routing of the hose and the park brake cable is in a better location. The disadvantage is the 2 piece bracket and the brake hose routing I used is close to a mount bolt which means the brake hose will have to be removed to change pads. There may be a workaround for that issue.

I had to remove the squealer from the inside pads because of interference with the adapter bracket I made. The bracket could be modified easily.

In the end, I like the 240sx calipers for the GT and the jury is out about those calipers on the roadster without adding a porp. valve.
240sx adapters.JPG
lefr bracket 1.JPG
left bracket.JPG
park brake cable attachment clearance.JPG



Edited 1 time(s). Last edit at 01/29/2018 10:38AM by MGBV8.


MGBV8
Carl Floyd
Kingsport, TN
(3273 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
79 MGB, Buick 215

authors avatar
Re: MGB rear disc brakes
Posted by: MGBV8
Date: January 29, 2018 10:40AM

IMO, the wet pavement brake test should have shown if there was too much rear bias.


Scott68B
Scott Costanzo
Columbus, Ohio
(504 posts)

Registered:
10/25/2007 11:30AM

Main British Car:
1968 MGB GM 5.3 LS4 V8

authors avatar
Re: MGB rear disc brakes
Posted by: Scott68B
Date: January 29, 2018 01:34PM

Hi Charlie,

For the Sentra 34mm calipers, you mention they are close to the body work. Would clocking the caliper at a different angle help with that? Nothing you mentioned about either caliper sounds like a show stopper though.

Thanks for keeping us informed. Great job!!

Scott


geezer
Charles Durning
Magee, MS
(25 posts)

Registered:
11/16/2017 01:16PM

Main British Car:
1974 MGB, 1967 Morris Minor

authors avatar
Re: MGB rear disc brakes
Posted by: geezer
Date: February 02, 2018 04:05PM

Scott,

The caliper is not close to the body work it's the park brake cable on the right side. In reality it just rubbed so all I needed was a little more clearance. I solved that problem with drilling another hole in the lever on the caliper. That brought the cable in enough to clear the boot floor.

It's suppose to rain this weekend so I'll take the GT out and see how the brakes react in the rain. We have some smooth roads out in the toolies so I can give it a brake test in the wet and on a curve. That should show any glaring balance issues.

I am having the drawing corrected so a laser cutter can cut out the bracket with the one stray hole in the right place. It would also be easy enough to make one from some 3/8 flat stock if you so choose.

I'll see if I can post a pick of the redrilled lever this weekend.


geezer
Charles Durning
Magee, MS
(25 posts)

Registered:
11/16/2017 01:16PM

Main British Car:
1974 MGB, 1967 Morris Minor

authors avatar
Re: MGB rear disc brakes
Posted by: geezer
Date: February 03, 2018 08:57PM

Attached is a pic of the shortened lever. That provided enough clearance for the park brake cable. I did notice that the caliper does get close to the body in full compression. I did not find any evidence of the caliper contacting the body, however I did take the time to bend over the lip for additional clearance. If you choose to rotate the caliper down a bit that can be done with the Sentra caliper but not with the 240SX caliper. There is a clearance issue with the extension strap mount on the axle with the 240SX caliper.

Another change. I will change the flex hose to a shorter hose. 12 or 13 inches long should clean that up.

I did find a defective 240SX caliper. That is now changed out for another reman caliper. I took a vigorous test drive today and the temps are 145 degrees for both rears and 265 for both fronts. That coincides with the predicted brake balance of 67-33. It's raining now so I should be able to take it for a wet test drive in the morning.
body clearance.jpg
need a shorter hose.jpg
shortened lever 1.jpg



Edited 1 time(s). Last edit at 02/03/2018 09:00PM by geezer.


geezer
Charles Durning
Magee, MS
(25 posts)

Registered:
11/16/2017 01:16PM

Main British Car:
1974 MGB, 1967 Morris Minor

authors avatar
Re: MGB rear disc brakes
Posted by: geezer
Date: February 05, 2018 10:37AM

Unfortunately the streets were dry on Sunday. It may rain later this week so I'll give it another try then.



geezer
Charles Durning
Magee, MS
(25 posts)

Registered:
11/16/2017 01:16PM

Main British Car:
1974 MGB, 1967 Morris Minor

authors avatar
Re: MGB rear disc brakes
Posted by: geezer
Date: February 06, 2018 03:41PM

OK I'm happy with my rear disc brake conversion. Bob Harper in Australia was kind enough to correct the drawing for the Sentra/Sunny caliper bracket. The drawing has been checked and to the best of my knowledge it is correct. The dimensions have been changed to make it easier to layout on a piece of steel or aluminum with easy to locate reference points. I'm not going to develop this conversion any farther.

If anyone wants the drawing for the caliper bracket send me a PM with your e-mail address and I'll send the drawing along with part numbers for the caliper and rotors that I have used. As far as the additional bracket for the 240SX is concerned, it is easy to make at home out if 1/4" flat steel stock so I'm not going to commission a CAD drawing at this time. If someone wants to make a CAD drawing of the additional 240SX bracket feel free to do so and share. Also feel welcome to use the finished drawing as a basis for any rear disc brake conversion you care to undertake. All of the basics are there.

Charlie Durning
Goto Page: Previous12
Current Page: 2 of 2


Sorry, only registered users may post in this forum.