Steering, Suspension, & Brakes

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

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geezer
Charles Durning
Magee, MS
(45 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
(45 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
(3516 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
(530 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
(45 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
(45 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
(45 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
(45 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


geezer
Charles Durning
Magee, MS
(45 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 27, 2018 05:42AM

FYI. Using a spare prototype bracket I did a 34mm Sentra install on a 77 RBB roadster. There are a couple of challenges. All but one can be resolved easily. The biggest issue is the boot floor for that car is different from the CBB GT. There is interference between the park brake linkage and the boot floor. This weekend we are going to experiment with a different park brake lever on the caliper. Failing that the 34mm 240SX caliper will be a better choice since the park brake lever on the caliper is located close to the axle housing and not out the back.

We did take the car for a spirited test drive on a rainy day and we feel the 34mm caliper is well suited for the RBB roadster. We also took out the CBB GT and feel the 38mm 240Sx caliper is a good match for that car. The early 240sx, target date 1992, has a 34mm bore and the later 240SX, target date 1998, has a 38mm bore. Both will use the same add on caliper bracket since the exterior and mounting dimensions are exactly the same.


geezer
Charles Durning
Magee, MS
(45 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: March 04, 2018 09:19AM

Resolved the park brake clearance on the 77RBB. Originally I was going to make a new arm for the caliper that would lower the attaching point. In the end I just shortened the flat arm on the caliper and that gave enough clearance. I also moved the attaching point for fiber flex for better alignment.


geezer
Charles Durning
Magee, MS
(45 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: March 07, 2018 11:55AM

Latest drawing with corrections for Sentra caliper. It should print full size
MGB-Nissan_Bracket-1-page-005.jpg


geezer
Charles Durning
Magee, MS
(45 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: March 12, 2018 09:52AM

I finally got around to rerouting the brake flex hose to the caliper. On the Sentra caliper the hose went straight in towards the center of the car and behind of the limit strap. I was just not happy with that. For the 240SX caliper i sent over and and in to the center of the car. I didn't care for that either. In reality I was using the hose available to me at the time. In doing further digging I found a vendor on eBay who will make custom brake hoses. For the Sentra conversion on the RBB car I had him make a pair of 18" long hoses with the banjo bent at 45 degrees. I thought the 18" hoses would also work for the 240SX. The 18" does fit the 240SX but a better choice would be 20". What the 45 degree bend does is allow the hose to be routed down the back of the caliper and then up and over the axle tube. That routing keeps the brake hose out of harms way. The pictures are for the 240Sx install on the CBB GT. The 18" hose for the 240SX ends up routing behind of the bump stop on the axle. A 20" hose would be better routed in front of the bump stop. With the Sentra caliper the 18" brake hose can be routed in front of the bump stop also.
hose at caliper.jpg
routing over axle.jpg


geezer
Charles Durning
Magee, MS
(45 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: March 15, 2018 09:15AM

I had a pair of brackets made from the latest drawing. I should be able to do a mock up on a spare housing to prove the drawing this weekend


geezer
Charles Durning
Magee, MS
(45 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: March 15, 2018 08:45PM

Did a test fit. The laser cut brackets are a perfect fit. All I had to do was clean up the bolt holes and make a small radius so it would fit flush against the axle housing flange.


geezer
Charles Durning
Magee, MS
(45 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: March 18, 2018 09:39AM

I have had several requests for clarification on the applications for the Rotor and calipers I have used for the disc conversion. Hope this is useful.

Rotor and Caliper Applications

Buyer's Guide : CENTRIC 12140024 Rotor
ACURA CL 1997
HONDA ACCORD 1991-1997
Please refer to catalog for application details.

38MM 240SX caliper applications
Buyer's Guide : BECK/ARNLEY 0771213S Caliper
NISSAN 240SX 1994-1998
Please refer to catalog for application details.

34MM 240sx caliper applications
Buyer's Guide : CENTRIC 14142512 Caliper
NISSAN 240SX 1989-1993
Please refer to catalog for application details.

34MM Sentra caliper applications

Buyer's Guide : A-1 CARDONE 19B2627B Caliper
INFINITI G20 2002
NISSAN SENTRA 2002-2006
Please refer to catalog for application details.

Manufactures names and part numbers are for reference only. Parts from any manufacture for the application will be suitable

Right and left calipers required



The pics below will show specifics on the Rotors and calipers
1992 240sx.jpg

1998 240sx caliper.jpg


2002 sentra.jpg

CE_12540024_1994 Honda Accord.jpg



MGBV8
Carl Floyd
Kingsport, TN
(3516 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: March 18, 2018 03:26PM

Lot of great info. Thanks, Charles!


geezer
Charles Durning
Magee, MS
(45 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: March 25, 2018 12:45PM

Rhere have been questions about how the secondary bracket for the 240sx caliper and the Sentra bracket fit together. The secondaty SX bracket is attached to the inboard side of the Sentra bracket. That provides the necessary additional offset for the SX caliper. Hope this helps.
2 brackets bolted together for 240sx.jpg


geezer
Charles Durning
Magee, MS
(45 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: March 28, 2018 11:34AM

Made a handy fixture for boring out the center hole in the caliper with a drill press. Found a 2.5" washer with a .75" hole. Used a 7/8" hole saw to make a bushing. Mounted the washer and bushing to a piece if wood that will also be a handle. The washer centers the rotor and the bushing guides the hole saw. Knock out a rotor in 2 minutes.
Fixture.JPG
rotor on fixture.JPG
1 setscrew drilles and counter sink.JPG


geezer
Charles Durning
Magee, MS
(45 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: March 30, 2018 12:14PM

I've had questions about fitment with wire wheels. I don't have a wire wheel so I cannot give a definitive answer. Hoewer ,here are some shots with a wire wheel hub. From that you should be able to discern if this will clear a wire wheel. The rear axle in my GT is a wire wheel axle. There may be some body clearance issues with the wire wheel axle that may not be an issue with a bolt on wheel axle. The conversion I did on a RBB roadster did not have any clearance issues other than the park levers had to be shortened for clearance with the boot floor withe the Sentra caliper. That is not an issue with the 240sx caliper. I'll post the sx caliper fitment with the WW hub later today.
sentra1.JPG
sentra2.JPG
sentra3.JPG
sentra4.JPG


geezer
Charles Durning
Magee, MS
(45 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: March 30, 2018 01:11PM

Here are pics of the 240SX fitment along with a pic with a WW hub
240sx1.jpg
240sx2.jpg
240sx3.jpg
240sx4.jpg
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