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MG MGA - Disc Brake conversion question

I'm considering doing a disc brake conversion on my 1500. As I understand it, if I can find a pair of 1600 steering knuckles I shlould be able to use the Moss adaptors and put B calipers on my A.

However, I have a steel wheel car. I understand that the steel wheels may not clear the B calipers.

Does anyone have any experience with this?

Thanks
SJL Loe

From what I've read the 1500 wheel will not clear the calipers either B or original A. The 1600 wheels have a bit more 'dish' and should clear either caliper, but the holes aren't quite the same so they look a bit different.
Bill Young

Are we talking about say... 1/8" of interference between wheel and caliper - something that could be dealt with by adding a spacer? Or is a wheel with more backspace really required?
SJL Loe

I know someone with a set of steering arms, spindles and hubs. They are for bolt-on MGA with disc brakes. If you are interested, I can send him any contact info you provide.
Steve Simmons

If you convert to B suspension it will be stronger and it will cost less.
R J Brown

I've been tempted to go the B suspension route. The thing holding me back is, it's not clear to me how much work/headaches are involved in getting the front end alignment where it needs to be after the conversion.
Steven Loe

Your 1500 rims will clear the calipers on a B suspension. The only alignment is toe-in, just like the stock A. I added a 5/8"sway bar from a BGT and V8 bushings as well. RJ is right on the cost. I got a set of rebuilt Lockheed calipers with pads for $87 at Autozone. Try to find A calipers...
Scott

I have the disc conversion you are refering to on my 1500 with B calipers, A discs, Green(e?)conversion plate and steel wheels. No problems. It is well worth doing.
Frank Nocera

SJL Loe
Any time you want to come by and see the B front end on my 58 you are welcome to. Where in Colo are you? I am in south Denver metro.
Randy
R J Brown

Steven,

Regarding the b susp on the A.

Alignment is not an issue. All you have to do is cut about 1/2" from each tie rod end and then use a die to cut the threads further down each side of the tie rod 5/8". Allignment is done from this point as described in the manual. Some may complain of "bump-steer" but I have never experienced this issue.

Go here to see details of this conversion:
http://mgbmga.com/tech/mga5.htm

To ad to RJ's comment about safety, the B king pins are much stronger than those found on the A.

If you want to see the conversion completed, shoot me an email, I live in SE Denver.

jmbries@yahoo.com

j
JohnB

I also have a pair of stub axles, king pins, swivels for this for sale. You just need a pair of steering arms and the hubs to complete.
dominic clancy

Good to know that the caliper will clear the 15000 steel wheel when using the adapter formm moss. Pretty sure that's the direction I'll go. Thanks very much for the info.
Steven Loe

i plan on using the same set up,but i was under the impression that i can reuse my 1500 drum spindles.
is this correct?cc
c.callaway

John reading the directions you posted They say to mill the shocks. All I did was reverse the arms. To do that I had to grind a notch opposite the original one where the arm mounts shock.
R J Brown

The things I've read indicate that you must use spindles from a 1600.

Here they are:

http://www.mgcars.org.uk/mgccmga/technic/brake/brake_conversion.shtml
http://www.mgaguru.com/mgtech/brakes/bt202.htm

I wish Moss would document what their disc conversion kit works with...
Steven Loe

CC,
I used the b hubs because they use taper bearings which are supposed to be stronger and easier to adjust. Rollers have no adjustment.

RJ,
Good to know both ways work. I thought about reversing the arms but I don't have a press. I do need to replace one of the shocks as it now leaks so maybe I will hit up your expertise on reversing the arms some time in the near future!

j
JohnB

steve,please read at the point of"I suppose this adds some incentive to keep it original. That adapter is only needed to mount MGB calipers on MGA knuckles. "

john b.so can i install mgb hubs on my 1500 spindles?
cc
c.callaway

CC,

I don't believe so. The conversion I am speaking of is using all of the front suspension and brake components from an MGB.

I am not 100% sure of the compatability btwn B hubs and A spindles. Should be a mute point though, because to me if you are going through the process then you may as well use B king pins and spindles as they are stronger than the screw type king pins that came on the A.

j
JohnB

Are people breaking mgA suspension parts? I never saw a need to modify the car just to add strength.
Steve Simmons

MGA suspension parts don't break unless they are defective.

I spent several years seriously autocrossing every summer weekend using the sticky road racing tires and stressing the car to the point of regularly cracking stock steel wheels. Never broke any suspension parts. I wouldn't spend $.02 to convert to MGB parts if the only concern was strength.

I wouldn't discourage anyone from converting a 1500 to disc brakes (even though I wouldn't bother doing it myself). MGA 1600 calipers and mounting plates will work on the 1500 knuckles.

MGA 1500 wheels will fit around the calipers (surprise). The 1600 wheel design was done to improve brake cooling and to increase strength and reduce weight. The 1600 wheel center disk is thicker and stronger, rim is thinner and lighter, and overall wheel weight is 2 pounds less than the 1500 wheel.

You only need the adapter plates to mount MGB calipers to MGA knuckles. It might be cheaper to procure good used MGA calipers than to buy the adapter plates.

The cheaper MGB pistons can be used to rebuild MGA calipers if you remove the (unnecessary) center guide pin.

You can install heavy duty shock valves to up the damping effect of the MGA shocks, if you have a mind to.

If you have no suspension parts on the MGA to begin with, it might be cheaper to procure all MGB parts rather than all MGA parts. Otherwise I don't know of any good reason to be changing to MGB suspension parts on an MGA.

$.02
Barney Gaylord

The B mod is considerably cheaper and parts are easier to get. Cost is the only real reason to use B parts. Because B's use 14 in wheels you can choose from more wheel options without clearance problems.
R J Brown

B mod is cheaper than what? You can rebuild A calipers using B pistons. If you don't have A calipers you can probably buy used A calipers and standard mounting plates cheaper than either adapter plates or B suspension parts.
Barney Gaylord

I used the B spindles and brakes on my car simply because I had no suspension other than the shocks and lower A arms when I bought the car and a fellow club member donated the parts from a wrecked B. Found that using two 1/2" shaft collars worked perfect as spacers for the B upper trunion in the A shock arm. Using B calipers will require a change in brake hose, as the fittings on the calipers are different.
Bill Young


When I did mine I bought a whole B crossmember with all parts for $50.00. All else I needed were hoses, caliper kits, pads and to resurface the rotors. To do today a B caliper can be bought today for $29.65 + $20.00 core a Rotor for $ 28.95 Pads for $ 19.25. In the long run B parts are much cheaper and way easier to find.
R J Brown

I agree - no reason to replace A parts with B unless you have no A parts to start with or you happen to have a free B crossmember.

The MGA upright is not inherently weak (I've put mine through hell with 7.5" slicks), although there were some poorly machined replacements floating about a number of years ago.

The MGB hub will not fit on an MGA spindle unless you have a Twincam, in which case I doubt you'd be looking to convert to MGB parts.

JohnB, you say the MGA bearings have no adjustment as if this is a bad thing. MGA ball bearings don't NEED any adjustment - taper rollers inherently do. There is nothing at all wrong with ball bearings - my 69 Lamborghini uses them.
Bill Spohn

This thread was discussed between 04/05/2006 and 10/05/2006

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