Using a manual transmission with handcontrols

Topic: Using a manual transmission with handcontrols (Read 20143 times) previous topic - next topic

Using a manual transmission with handcontrols

Reply #120 – May 26, 2006, 06:32:28 PM

I got the car back from the garage. They ran the lines from the clutch master to the trunk and then back to the slave. Tomorrow I have find the other fitting I had made up (still at the garage) and to hook up the power assist.

Using a manual transmission with handcontrols

Reply #121 – June 06, 2006, 11:21:43 AM

Time for an update! I've been working on this when I get a chance and I've got it all hooked up.

I've connected the power assist slave to the brake master cylinder with a lever system that results in 3/8" travel on the slave producing a little over 3/4" travel on the brake master.

But I've run into a problem. I'm not getting nearly enough travel on the clutch slave to disengage (or is it engage? IDK) the clutch.

First, I thought it was air in the lines. I bleed the lines and managed to get 1/16" of travel on the clutch slave. Not nearly enough to work. I need 1/2" of travel to work the clutch.

I've got a couple ideas on what's going on. First, if you look at the picture of the power assist unit, you'll see that I've looped the front brake line back into the front master cylinder.

I think that maybe there is still air in there that is compressing when I activate the system and is preventing enough presure/fluid to come out of the rear master cylinder to press the clutch. To fix this, I'm going to cut the looped line and connect one end to the rear master cylinder and send the other to the clutch slave. At least this way I can bleed the system and be pretty sure there is no air in there to compress.

Another thing I'm going to try, if the above doesn't work, is replace the power assist slave cylinder with the one FordTruckFreeek sent me. I'll measure them first but I'm pretty sure the original FTF slave has a smaller bore than the parts store replacement I'm using now. A smaller bore on the slave will mean I'll get more travel on the brake master cylinder and, therefore, more travel on the clutch slave.

Am I on the right track? Any ideas would be appreicated. :)

Using a manual transmission with handcontrols

Reply #122 – June 06, 2006, 11:46:43 AM

Sounds good to me - I was gonna suggest a smaller cylinder until I read the last paragraph :D

Have you considered using an old, 60's-style master cylinder - one with only one cylinder (non-split system). It would likely have a larger bore (you could use a bbigger bore in the master for more fluid flow) and would only have the one line, so there would be no need to loop anything

Using a manual transmission with handcontrols

Reply #123 – June 06, 2006, 12:02:59 PM

Quote from: Thunder Chicken

Sounds good to me - I was gonna suggest a smaller cylinder until I read the last paragraph :D

Have you considered using an old, 60's-style master cylinder - one with only one cylinder (non-split system). It would likely have a larger bore (you could use a bbigger bore in the master for more fluid flow) and would only have the one line, so there would be no need to loop anything

agreed, but maybe use something to narrow the bore, or a regulator? You are going to lose travel on the second loop, even if it is just feeding itself, you still have to move that fluid around..???

either way. looking good.. keep up the good work and don't get discouraged.

Using a manual transmission with handcontrols

Reply #124 – June 06, 2006, 01:34:53 PM

Quote from: Thunder Chicken

Have you considered using an old, 60's-style master cylinder

Yes, I already considered the older one line/non-split but I wanted to experiment with parts I already have on the shelf. I.E. I'M CHEAP :) If I can get something working but need a little more travel then I'll consider spending more money. Also, I want to be sure I can drive the manual with handcontrols before I spend a wad of money making a nice system. After all, if this doesn't work I'll need the money for the 5.0/AOD swap.

Quote from: Funky Cricket

agreed, but maybe use something to narrow the bore, or a regulator? You are going to lose travel on the second loop, even if it is just feeding itself, you still have to move that fluid around..???

either way. looking good.. keep up the good work and don't get discouraged.

I'm not sure what you mean!

Here's what I'm thinking: The clutch master (on the firewall) only pushes out a certain amount of fluid determined by it's bore(B) and the stroke(S) of the piston. 3.14x((B/2)^2)xS=displacement of hydraulic fluid(V)....This amount of fluid(V) moves the piston in the slave 0.25" and it has a bore of 1.25" so V=0.3 cubic inches. So if I put 0.3 cubic inches of fluid into a 1" bore cylinder then the stroke will be = 0.38".

Through the lever system I have set up, the stroke of the stock slave will result in an extra 0.4" on the stroke of the master cylinder...or it will go from 0.75" to 1.15".

A 0.75" bore in the master cylinder then with the lower 0.75" stroke, mensioned above, will result in V of the master cylinder = 0.33 cubic inch which should result in a 0.42" stroke in the clutch slave which is not quite enough - 0.5" is needed. If I go with the higher 1.15 stroke I'll get 0.51 cubic inch resulting in 0.65" on the slave which should be plenty.

Using a manual transmission with handcontrols

Reply #125 – June 07, 2006, 09:34:23 PM

Quote from: thundergrowl

I bleed the lines and managed to get 1/16" of travel on the clutch slave.

I reconfigured the brake lines tonight and bleed the master cylinder. I hooked it back into the system and I got a 1/8" movement on the clutch slave. If my math is right I should be getting almost 7/16".

I think there must still be air in the system. I've never bleed a brake master before so I'm not sure I'm getting the job done. I'll ask my mechanic to drop by and help me bleed the system...hopefully tomorrow night. This is starting to get frustrating.

Using a manual transmission with handcontrols

Reply #126 – June 07, 2006, 11:30:37 PM

cant you move the rod out more to get more travel?

Using a manual transmission with handcontrols

Reply #127 – June 08, 2006, 08:15:25 AM

Quote from: Haystack

cant you move the rod out more to get more travel?

Right now I have the lever system set up for the most travel on the power assist master with the smallest movement on the power assist slave. The only thing I can do now to get more travel on the clutch slave is to change the slave(s) to one with a smaller bore and/or change the master(s) to one with a bigger bore.

How much will the fluid compress in the small brake lines over a 12-14' run? It shouldn't be that much, should it?

Using a manual transmission with handcontrols

Reply #128 – June 08, 2006, 09:16:59 AM

Don't forget that at rest the master's rubber piston cups are behind the internal ports leading up to the reservoir. They have to be, to allow the fluid to flow down when brake pads wear, and up when retracting the pistons to replace pads or shoes.

You won't get any fluid going to the clutch slave until the master's cups have moved past the ports. Not a lot of movement, but probably measureable.

Using a manual transmission with handcontrols

Reply #129 – June 08, 2006, 09:35:26 AM

Good point but we shouldn't be talking a great amount. I would guess 1/16" to 1/8". I was under esitmating the travel on the master to reflect that. The actual travel is a 16th or 2 over 3/4". The master with nothing connect will travel a full 2".

If the mechanic doesn't drop by tonight, I'll change out the 1.25" slave in favour of the 1" slave. Maybe I'll do it anyway. That will get me 1.15" out of a possible 2"

Using a manual transmission with handcontrols

Reply #130 – June 08, 2006, 05:08:53 PM

IF you T the two lines from the Master cylinder to the slave you will be moving double the fluid... Think about that one....

I breezed through the last few posts, so if that has been discussed just ignore me...

Using a manual transmission with handcontrols

Reply #131 – June 08, 2006, 05:35:21 PM

I think that is effectively what I have done now. There are two lines coming out of the front master and one coming from the back master. I have the back line connected to one of the front lines and the other front line going to the clutch slave. I've studied this site and I think I have a good understanding of how the master cylinder works. Maybe I should just hydrolock the rear master?

EDIT: Added picture

Using a manual transmission with handcontrols

Reply #132 – June 08, 2006, 07:49:24 PM

I think even with looping them, you are still only moving half of the fluid.

If you tie the two together and then go from well pretend a 1/2" and 1/2" then it would be a 3/4" or so line.

Using a manual transmission with handcontrols

Reply #133 – June 08, 2006, 10:19:20 PM

And they say a picture is worth a 1000 words, yet I missed the loop(guess I really didn't look at it)...

OK Paul I see what you are saying... As long as there is no check valve(doubtful) that restricts the flow back into the chamber that should be fine...

I have one of those M/C from the old grey Sport I'll check it out in the next day or two...

Using a manual transmission with handcontrols

Reply #134 – June 09, 2006, 12:37:42 PM

My plans for last night fell through. The mechanic has a bad back so I decided to swap in the 1" bore slave in place of the 1.25" bore slave. I had taken apart the 1" slave earlier and I was going to put it back together last night. However, I couldn't find the clip that holds it all together. I ended up cleaning up the garage in hopes of finding the clip but no luck.

Now I don't know what to do next.