'88 TC proportioning valve to LX

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'88 TC proportioning valve to LX

October 05, 2013, 02:22:26 PM

I'm installing the TC 8.8 rear end and would like to use the TC proportioning valve since they seem like a direct swap. The only difference is that the TC valve has a two wire connection at the rear end of the valve and the LX does not. What do I do with that? Should I just leave the electrical plug in the valve and swap or do I need to put the old LX plug into the TC valve?

Thanks.

'88 TC proportioning valve to LX

Reply #1 – October 19, 2013, 06:16:28 PM

Ok. I swapped the rear end to the LX (from the TC donor car). New rear calipers, hoses and pads. CoolCats says you need some new brake line to make this swap but I didn't seem to need any. The rear line goes into the same hose in the LX as it does in the TC.

Since I didn't hear from anyone about the proportioning valve question above, I went ahead and swapped it in from the TC. I unscrewed the electrical part (rear of the proportioning valve and closed it off with the plug from the original LX valve. I assume that is part of the ABS system.

Guess what? It doesn't work. I bled the brakes but only get a dribble of fluid to the rear calipers. Not enough pressure to close them. The front brakes work fine. So do I need to take the rear plunger assy (spring and plunger) out of the LX proportioning valve and put it this one, then put the end cap on?

Anybody have any experience with these things?

'88 TC proportioning valve to LX

Reply #2 – October 19, 2013, 06:30:44 PM

Good question. Somebody here will have the answer for this.

'88 TC proportioning valve to LX

Reply #3 – October 19, 2013, 07:23:18 PM

YEP ditch the TC valve and install a wellwood adjustable one and forget all that stock junk. Do not complicate this as it is a simple swap. But many people try to use the stock stuff. Not that it does not work it is to complicated to hook up. Then if the differential is incorrect you can not adjust it out easily. So use a 2 line master and do some line work to the front brakes to simplify that mess. And a simple adjustable Wellwood valve feeding the rear brakes. Also what i do is use 3/16 hard line front and back. It makes the job more stable and uncomplicated. Bellow is one of my modifications to the rear line feed with rear disc brakes. Home made bracket of course and very easy to bias the brakes when on the road to test it. Good luck

'88 TC proportioning valve to LX

Reply #4 – October 19, 2013, 11:29:32 PM

Thanks Tom. So what if I kept the proportioning valve for the front brakes (since that seems to be working), and then installed your Wellwood valve right off the master like you show it in the picture for the rear? I think my stock master has just two lines coming to the proportioning valve -- what is all this talk about 3-2 conversion kits and buying new masters? Can't I just use the one I have?

'88 TC proportioning valve to LX

Reply #5 – October 20, 2013, 06:55:49 AM

The 3-2 Conversion is just used to connect both right and left front calipers together. That is all it is. What ford did was pipe the front caliper hard lines @ the master in stead of a T on the frame and just using one front port. Let me clear this up from this point on. The front section of the system does not have a valve in that system. NOTHING at all other than a balancing shuttle valve. What it does is set the BRAKE warning light on the dash in the event of a system failure in either the front or rear brake system. I never use them. It clutters the system and it in my view is a waste. All you need to do is use a trailer adapter in stead of the 3-2 kit. I have posted it several times. The master i posted is for my TYPHOON conversion but a master is a master. All it does is make pressure in the system when the brakes are applied. Most times if the brake system is balanced like early VETTS a Perportioning valve is not needed and was never used on those systems. So by piping the front brakes with one line to the master splitting it at or under the car and using an adjustable valve to the rear eliminates all the mistery and shabby lines piped to all different valves. One valve clean quick and NEAT!!

'88 TC proportioning valve to LX

Reply #6 – October 20, 2013, 04:29:55 PM

Ok. I think I'm getting this now. The master port underneath goes directly to the left front caliper (which would explain why that one is working). The front right caliper is fed from the side port of the master, through the proportioning valve to the caliper. If what you say is true and the master is acting as a T anyway, why not just bypass the proportioning valve by connecting the two ends (that went to the proportioning valve)together for the right front. Then the master is the T and there is nothing in between.

For the rear, there's only a single port from the master, so you're suggesting just throwing the adjustable valve in line in lieu of the proportioning valve.

Do I have this right?

'88 TC proportioning valve to LX

Reply #7 – October 21, 2013, 09:56:45 PM

NO NO NO. Once again there is no Proportioning valve in the front brake system. Only in the back. The balance valve is used on both front and back.

Here is how it works. On a chevy for example the right front caliper hard line runs over to the left caliper and teed together. Then a single line goes to the master. Normally the larger resivor portion of the master and normally the rear of the cylinder. The rear brakes are connected together at the rear of the car and a single line is fed to the front of the car./ At that point before it goes to the front port which is normally the smaller resivar there is a PROPORTIONING VALVE. The valve reduces the pressure to the rear brakes weather disc or drum. Reason being it prevents the rear wheels from locking up before the front. Once again no apportioning valve in the front brake circuit. Only to the rear brakes or better said rear brake line ONLY!!

'88 TC proportioning valve to LX

Reply #8 – October 21, 2013, 10:01:48 PM

here is a corvette which i eliminated the ABS and up graded to a 5 brake system. Note how i tied the left and right front calipers together and one line up to the master with no VALVE WHATSOEVER

OR NOT EVEN A BALANCE VALVE

'88 TC proportioning valve to LX

Reply #9 – October 22, 2013, 11:57:44 AM

Nice work. I wasn't suggesting putting the adjustable valve in the front circuit at all. I was just trying to eliminate having to make an external T (like you have) and instead just use the two ports that are on the big (front brakes) reservoir (one on the bottom, one on the side) on the master -- hardlined to each front caliper independently. Thus the 'T' would be the master. You're saying that wouldn't work?

For sure the single port for the rear brakes would have the adjustable valve in line.

'88 TC proportioning valve to LX

Reply #10 – October 22, 2013, 05:51:25 PM

YEP you see what ford did was eliminate the T and ran both front hard lines to the master. Both of those ports are on the same piston in the master. Another words they functioned it @ the master in stead of a T. That is why they sell the 3-2 or what ever it is called. It makes it easy for someone that does not want to FLARE AND CUT LINE. Basically it connects the right and left front calipers so you can use a 2 port master,

'88 TC proportioning valve to LX

Reply #11 – October 27, 2013, 09:49:37 PM

Got it. Turns out that my original problem with the TC proportioning valve might not have been the fault of the valve. I tied the front circuit together as Tom suggested. I inserted the Wildwood adjustable valve in the rear circuit near the MC. I opened it up all the way and I still can't get either of my new rear caliper pistons to move. I bled and bled and still get just a small amount of fluid out of the rear bleed screws but no more bubbles. I hooked up the ebrakes and even when I move the ebrake on either caliper all the way to the stop, the rotor is still free. What am I missing here? All the rubber lines are new. Some blockage in the hardline perhaps? A problem with the rear circuit in the MC? It worked with the drum brakes I had before the rear end swap. I'm at a loss. Anybody had a similar problem?

'88 TC proportioning valve to LX

Reply #12 – October 29, 2013, 08:49:52 PM

You have air in the system. use a syringe and back bleed the system. You need to operate the E brake lever several times to adjust the pistons and push them out by constantly moving the arms fully one way and the other till they adjust. If you are not building pressure either your master is air bound on the balance chamber or it is bad. I bleed those brakes in 5 minutes at best. Try back bleeding with a large syringe. This forces fluid from the caliper back to the master. Bleeding can sometimes be a bitch if the balance port has air. You have to bench bleed that master then install it in the car then bleed. Good luck!!

TRY THIS. Get a short length of vacuum hose that fits the bleeder nipple and submerge the other end in a container of brake fluid. With the bleeder cracked on one caliper pump the brakes with the engine running. Have a helper look in the can of fluid and make sure the hose stays submerged in the fluid and pump the brakes till all the air is gone then tighten the bleeder then do the other side.

'88 TC proportioning valve to LX

Reply #13 – October 29, 2013, 09:16:49 PM

Thanks Tom. I did try to pump with engine running but I guess the syringe method is next. I recall having to do that with my sand rail because I couldn't get that to bleed from the master either. When exercising the ebrakes, are suggesting taking off the spring to move the lever on the caliper back and forth or try to do it with the spring on? Just so I'm clear, the ebrake is all mechanical correct? I should be able to get those pistons to move whether or not I have air in the system right? Thanks again for all the assistance -- this part is turning out to be the hardest part of the rear end swap.

'88 TC proportioning valve to LX

Reply #14 – October 30, 2013, 04:19:52 PM

Correct and use a pair of vice grips to do it. That will push out the pistons. Remember the master has a balance chamber. If it is not full of brake fluid you will never get a pedal. Back bleeding should end your issues!