Club Cobra - MGB Front Suspension

I just spent way to much work time typing up this note in response to a question about wilwood brake upgrade and some misc. thoughts on the hawk suspension pieces for an Arntz owner. So for what it is worth, I thought I would share my thoughts:JEKYLHYDE

"I to have talked a number of times to Wilwood. They do not seem at all interested in the making a kit for the MG. There is a company in the UK that does. I think it is Rally Design. This may be a route that you want to take if this all seems to daunting. But you will still need to go through all the calculations to get your brake balance in the ball park.

By the time you are done here, you will have in excess of $2000 in the brake and suspension upgrade. Have you looked into the front end sold by Unique?

Here is a link to the post about the subject:

http://cobra.terraworld.net/forums/...od+adaptor+move

As word about what I had to do to get the hubs to fit correctly. According to Unique, the rotor for a 1970 Monte Carlo is supposed to be a bolt on affair (in addition to the castle nut and inner bearing spacer mods). However, after trying at least two dozen different rotors, I could never find on that fit in a fashion that I considered to be correct much less they way the old one on my car fit. This leads me to believe that since there are many MG fronts fitted this way that mine is either slightly different or I did not hit the precise rotor from the precise manufacturer and that some rotor manufacturers make the rotor more generic in order to fit a larger body of applications. Or perhaps I am just overly picky! For this reason I have hesitated to offer a kit to the MG front end owners or publish this information as 'gospel'. So I will be very interested in hearing your experience. It is entirely possible that you may buy the kit, bolt it on, make a set of caliper adaptors and go! But, I would not count on that!

Don't forget to check out the link about putting caged roller bearings in place of the bushings in the steering column. Assuming of course that you also have a MG column. Everyone I talked to wanted in excess of $400 for a column set up this way. Seems to me it cost me about $12 and a afternoon!

Basically you want to buy the kit and mock every thing up. Put it together, look at it, think hard about every little detail. Take it apart and do it again. If in doubt, seek advise (start with the books listed below, they ARE the word)! While I have yet to do exactly what you are about to, I hope it will become apparent that I fully intend to and have given the subject a great deal of thought.

I would recommend the kit that comes with the 12.19" rotor if you have clearance inside of your wheels (don't forget to allow for wheel weights). Get the slotted/vented rotor if possible. Check with wilwood and be sure about the clearence before you buy, as I have not yet changed the 10.75" rotor to the 12.19. I bought my kit from Jegs but I see them all the time on EBAY. The only potential issue I can see is that the rotor may come in contact or to close to the tie rod end. If this is the case, you will have to change the tie rod to a spherical rod end. Use one of the rod ends designed for a greater range. What I mean by that is a typical spherical rod ends ball is only designed to rotate 10 degrees either direction from square in the bore. There are ends that are designed to rotate to a greater degree. If you picture the rod end laying horizontal attached to the steering arm as the suspension goes through its travel I am sure you can see that a total of 20 degree range may be insufficient and the bearing may bind. Of course to do this correctly the steering arm will need to be drilled so that there is no longer a taper where the tie rod is bolted into the arm. Depending on the finished size of the hole it may require that the arm be bushed to fit the bolt holding on the new 'tie rod'. The bonus here is that you will now be able to adjust bump steer. Adjust your bump steer with stacks of washers until you have it where you want it and then buy the appropriate bolt and make a spacer (aluminum bar stock, such as 6064-t6, the diameter of the flat on the ball cut to length and drilled to snugly fit the bolt) to replace the washers. Be sure to use a large 'fender' type washer of aircraft quality under the bolt head on the opposite side of the steering arm. That way if the ball come out of the rod end, the rod end will not be able to completely come off the bolt and leave you with no steering.

If you do not have Carol Smiths books, buy them. They will help in your work. Also Fred Puhn's Brake Handbook will be of great assistance. I think that all of these books should be in every Cobra owner library.

While I made my current caliper adaptors out of two pieces of .375 6064-t6 aluminum (same as Wilwood uses), I am fairly sure that the next set will be out of steel but I have not settled on the alloy. That is where Carol Smiths books come in. Once you have the rotors on and placed they way they need to be, make the caliper adaptors out of wood until you are satisfied with the fit. Then you can take them to any machine shop and have them cut. You could even having a welding shop cut the shape you need and then drill them yourself to save a few bucks. Be sure that they have been stress relieved. Particuarly the bolt holes! Imagine the shear force on these bolts and holes!

Be aware that depending on your current braking system you may have to make master cylinder changes. The larger rotor, higher coefficient of friction pads and caliper piston area difference all will change your brake balance. If you have a single tandem master cylinder, this will complicate the process but not make it impossible. Fred Puhns book is indispensable in helping you work through this.

Do NOT go to a hardware store and buy your bolts. These are OK while you are figuring out the final dimensions but they are not OK for the final assembly. Buy AN/MAS spec bolts. Use self locking nuts where possible and where not, safety wire AND lock tight the bolts. You will never have to worry about them again. You can get them from the local airport aircraft repair shop or order through Aircraft Spruce.

A word on pads. You can use the tan 'cold stoppers' that come with the kit but if you find that you need a little more torque then you can try the 'd' compound. The other compounds are VERY dusty and should be reserved for track work. I have had good sucess with the Wilwood 570 brake fluid. Watch the paint!

A good source for master cylinder (assuming you have Girling or Tilton) and spherical ends is True Choice. Check them out on the web. Seems to me the place that you can get virtually an metal in any size and quantity you want it called The Metal Wharehouse. Look them up on the web. I was surprised how much trouble I had finding some one that would get me what I wanted. I think the total cost of the metal required for the caliper adaptors was like $20.

Use Aeroquip braided lines for the brake 'hoses'. There are ready made to length. Don't forget that both ends are female ends so you will need a fitting between the caliper and the hose. I used a 90 degree fitting which helped with suspension clearance. The hose MUST be long enough that the suspension can go through its full travel with out pulling or kinking the hose and the hose must not get pinched nor rub against any suspension piece.

www.mgbmga.com offers the Hawk kit for $945 US. The also have a complete hardware kit for an additional $250. I forget what type of fasteners etc that they come with but look at it carefully before you buy. After seeing some of the bolts, nuts and washers that come with some kits I am always sceptical. Carol Smiths books will help in deciding if they are giving you hardware that you can rely on or junk. Pick your bushings with care. There are many, many sources for the bushings. Standard polyurethane bushings can be very 'squeaky'. Seems to me that Delron (sp) is the latest in a bushing material. Ones that can be greased may be a plus. If the ride is to harse, you can always go with the 'V8' bushings.

As I recall, the weight on the front end of the MG was surprisingly similar to my car. With that in mind I would think that the shock valving and spring rate that comes with the Hawk kit would be fairly close. Of course what they designed the kit for (racing or what) and what you want to use it for may be two different things. JBL (the Cobra not the speakers!) web site has some good information on suspension frequencies (and hence spring rates). Check it out and see if the springs provided are in the ball park for what you are looking for.

Be sure and index your rotors. It costs nothing but time. With a fixed position calipers this is more important. When I first bolted together my rotors I had in excess of .012" of 'wobble'. After indexing, I got that down to less than .003". That is a significant difference and JUST within tolerence. .000" is best!

This may sound overwhelming but it really is not at all. Armed with the books and some common sense, you will have a MUCH better braking system.

Of the top of my head, that is all I can think off. PLEASE take some time after you are done and let me know what you ran into with the brake and suspension upgrade. I will be very interested to hear. If you find this information to be of value, and of course accurate, feel free to share it with the other MG front end owners!

Rick"