Confused,Need help

[71see10]

I'm am confused about lower control arms,are the 67-70 the same lower control arm as the 71-72 lower control arms. I know the ball joints are diffent and will be replacing them and the bushings.Needing to replace some on a project,Need to know what to buy!!!! thanks in advance.;Brian

[71see10]

ttt

[XXL]

Originally Posted by 71see10

I'm am confused about lower control arms,are the 67-70 the same lower control arm as the 71-72 lower control arms. I know the ball joints are diffent and will be replacing them and the bushings.Needing to replace some on a project,Need to know what to buy!!!! thanks in advance.;Brian

Yes.

[shifty]

This could also help:

You can install 71-72 balljoints in 67-70 control arms.

In fact, you can install 67-70 balljoints or 71-72 balljoints or 73-87 balljoints in any of the arms from 67-87, from what has been explained to me.

Basically, it doesn't matter which arms you use...just make sure that your center link and tie rods match the year of spindle and balljoint you use - rather, whatever balljoints you use, you'll need to use the same spindle for that year range. Whatever spindle you choose, you also need to use the same tie rods for, and thus *might* need to use the same center link (I am not 100% on the center link, though, but I'm pretty sure)

If you're looking for some control arms in good shape, I have a pretty greasy (e.g. barely any rust, if any at all) '68 arms and front suspension I'm getting rid of CHEAP with (4) wheels and tires, and you're just "down the road" from me. I also have a set of new 73-87 balljoints on the way from CPP as we speak (which I don't think I'll be using) and '77 control arms I can get rid of as well, AND even some brand new '67-70 tie rods, sleeves and center link

Click the blue link in my signature to get some pictures. It may or may not be of help.

Anyway, hope this helps. I'm in the midst of a suspension overhaul and frame rebuild right now, so ...

[shifty]

PS - as a point of note:

You can also upgrade to disc brakes pretty cheap, and I'm learning this in retrospect, and if you're screwing with the control arms and ball joints, now is a good time to do it.

If you get 67-70 control arms, put in 73-87 balljoints ($90 from CPP or less from board vendor, or $75 if you want mine), go to a junkyard to get some 73-87 spindles (or buy drop spindles for $200 from ECE), then all you need is two 73-80 calipers ($20/ea reman'fed at auto parts store), two rotors ($20/ea at auto parts store), all the seals and bearings and dust cap ($20 total @ auto parts store) and then the associated lines. I hear you probably want to upgrade your MC as well, you can get one from Wilwood @ Summit Racing store in McDonough for $80-120.

I learned this the hard way. You will need a new proportioning valve, and you'll need to get the rubber line to go from the UCA to the caliper, but ... that's pretty much everything you'll need to swap to disc in front.

[71see10]

Thank you for the great info!!! Brian

[nightmare]

Originally Posted by shifty

... I hear you probably want to upgrade your MC as well, you can get one from Wilwood @ Summit Racing store in McDonough for $80-120.

I learned this the hard way. You will need a new proportioning valve ...

Can you explain why someone would need to change the proportioning valve, and possibly the MC?

[shifty]

Originally Posted by nightmare

Can you explain why someone would need to change the proportioning valve, and possibly the MC?

I was talking about upgrading to disc brakes. Disc/disc, disc/drum and drum/drum use diff't types of valves for the brakes.

[71Farmtruck]

What if I wanted to use 73-87 upper and lower control arms, but keep my 71 spindle and disk brake set up? I need to replace my ball joints, I thought using the later model control arms would be a good upgrade with the rubber bushings. Opinions?

[shifty]

Originally Posted by 71Farmtruck

What if I wanted to use 73-87 upper and lower control arms, but keep my 71 spindle and disk brake set up? I need to replace my ball joints, I thought using the later model control arms would be a good upgrade with the rubber bushings. Opinions?

If you have '71 spindles and brakes, you should be able to use 73-87 control arms, just make sure you pop in some '71-72 balljoints.

The U-bolts for the lower control arm are different diameters between these two years, but the same general arch, so you can use the older hardware with the newer arms.

[shifty]

BTW - why would you want to upgrade to newer control arms? There really aren't any worthy differences between the 71-72 control arms and 73-87 control arms that I could find

[Shane]

rubber bushings in the new arms vs. steel bushings in the old style ... some say it makes for a smoother ride ... I've never been able to tell the difference.

[71Farmtruck]

I have the newer control arms ready to go, blasted, painted, and with new bushings. I refurbished them awhile back. I have heard that there is not really a big difference in ride quality too, so other than that I have them ready I can't give a valid reason for using the new ones.

[shifty]

Well, here are some pics of the arms - '68 in the first pic, '77ish in the second - they're basically the same, although the upper arm is slightly more different than the lowers (bumpstop) and I swear I got the uppers in the right order, but it looks like I have a '68 and '77 in each of the pics ?.

[nightmare]

I understand that. But is it possible to use the proportioning valve from the drum/drum setup on a disc/drum setup? If not, why?

[shifty]

Oh boy. It's that time again

Please read this: http://www.mpbrakes.com/technical-su...nce-valves.cfm

Basically, one setup uses a proportioning valve, and other uses a combination valve (metering + proportioning?). Each valve is required for different reasons, depending on whether you have discs, drums or disc+drum.

I am taking this from another page to explain it, because this is basically what I've always been told about the subject:

A combination metering/proportioning valve comes on most new vehicles since the addition of front disc brakes. not to over simplify but refresh (perhaps) what each does is in order. You should do 60/75% of your stopping with the front brakes. Therefore the fronts need more pressure, hence the smaller lines to the front. The rear uses a larger line which in and of itself reduces the pressure.

An adjustable valve is to be installed in the rear line to reduce the pressure to the rear so that the front brakes do their job. A combination metering/proportioning valve not only splits the intake lines (from the master cyl) into the front two and one rear line but also meters the pressure to each. Anytime a master cylinder is placed beneath the floor residual check valves need to be installes to prevent fluid 'bleed back' to the master cylinder which would lead to excessive pedal travel on the next brake application. Jimsnicecar is correct as to a 2lb to the front brakes and 10lb to the rear. This keeps light pressure applied and stops all the fliud from returning to the master cyl. If you use an under the floor unit all you need is a proportioning valve and residual valves. If you are using a firewall mount, use the combination valve without the residual valves. As to if you can buy the proportioning valves at your local parts house, yes you can. They are sold either drum/drum, disc/drum, or disc/disc.

Long story short, you nearly always need to change your valve when getting rid of either one or both pairs of drums to ensure you don't lock up your brakes every time you tap the pedal, and don't cause premature wear and fatigue.

I'm not a brake expert, I'm simply sharing with you what I've read about here and elsewhere. There are probably a hundred threads on this subject around the forum, but I rarely see on that provides a concise answer.