TR4/4A 63 TR4 clutch and convertable top questions

[steve_sims]

Howdy Folks, Thanks Again for previous advice. My current problem is with the clutch. I bought a NOS slave cylinder and rebuilt the master cylinder. We Bled , Bled and bled the cylinder and aren't getting any air but i need to pump the clutch twice to get smooth opperation when starting and when shifting if it has been a while since i have shifted. After double clutching to get in gear , i only have to push clutch in once to shift. The original slave cylinder was stuck from sitting since 1994. Piston is about 7/8 inches in from end. NOS cylinder only comes out to 1 1/2 inches from outside. Took NOS cylinder apart, honed, lubed , put back together. No change. I just ordered a slave rebuild kit but can't help thinking that there is air in there somewhere. Any Advice Appreciated. Next question, the convertable top the same for TR4 and TR4A. Any advice on getting a {hate to use this word} Cheap top for TR4. I will very rarely use the top and have a hardtop for winter. Thanks Steve

 

[CinneaghTR]

I'll answer your top question for starters:

The 4 and 4A tops are different. The latter is permanently fixed to the car.

Take a look at eBay for a cheap top. Since you have the flexibility of removing the top and putting it away, you probably don't need a really, really nice one, but you always get what you pay for.

If you are on a budget and will be driving the car, maybe a nice tonneau may fit the bill?

I always have to add this line:

TRactor motors are great!!!

 

[Adrio]

I found the same on the clutch for my TR4A (and TR3A for that matter) they are hard to bleed. I ended up just opening the bleed screw and letting the fluid flow down while I kept pouring more into the master. I did this a few times and the bubble finally worked out. I had no luck bleeding the conventional way (that seems to work just fine for brakes).

Thinking about it now, I wonder if the way to bleed these would be to stop the slave from moving, and keep it all the way in (that is with the piston retracted). Then open the bleed screw and push the pedal down, then close the bleed screw. I think the large movement of the slave gives the bubble a place to "hide". If you don't let the slave move then the bobble has to go out the bleed screw.

As for the top, the TR4 and TR4A are different. The TR4 top comes off and is stored in the boot (like the TR3), while the TR4A top folds up and remains attached to the framework. As to a cheap one.... I never use my top but I just bought one form one of the big three and deal with the fact that it never gets used. After a while the pain of the expense goes away. In my case the top sat in the box for three years before I even installed it! You could look on Ebay for a well priced used one. I have seen some that were new but the owner had put the holes for the lift a dots in the wrong place.

 

[MrAlex]

On the clutch slave, make sure that you have it installed with the bleeder on top and the hydraulic connection on the bottom.

 

[Geo Hahn]

My TR4 clutch got harder and harder to disengage (esp in 1st & reverse) until finally something broke and locked it up. This is what I found...

One of the fingers was breaking making the clutch less effective, it finally broke completely. Probably not your problem but things can go wrong in there.

Shop around for the new top. I too seldom use my top and the cheapest I found was a Robbins from BPNW. Whio is cheapest will vary with the sales & deals but a Robbins from the major suppliers is a good top.

 

[TR3driver]

Piston is about 7/8 inches in from end.

I'm puzzled by this statement. Unlike the later TRs, the TR4 should have a return spring on the slave, that always pulls the piston all the way back to the bottom of the bore. Then the pushrod should be adjusted to provide minimal (but more than zero) free play before the slave applies pressure to the TOB.

On my TR3A, I've usually found that I can do an effective job of bleeding the clutch by pumping it up 3 or 4 times, holding it for 20-30 seconds, and then releasing it. Wait for a bit and repeat the process; usually 3 or 4 times is all it takes. The air gets blown back into the MC reservoir.

Your symptoms sound a lot like a weak return spring combined with bad adjustment. The springs do get weak with time, and attempts to replace them with screen door springs just don't work out. Have to get the right spring (available from the usual suspects).

If the pushrod cannot be adjusted to give almost no freeplay with the piston bottomed in the slave, IMO most likely the dreaded taper pin has broken.

 

[steve_sims]

Hi Randall, It has a new spring. What is this taper pin that you dread so much. Thanks Steve

 

[DougF]

If you don't like a top all that much, it's easy to get by with just the tonneau cover. As long as you are moving, you don't wet. Maybe a little damp. I drove 100 miles to MidOhio Race Track a few years ago in a steady rain armed with just a roll of paper towels in my TR3. I kept the top of the windshield frame wiped off and I stayed dry.

 

[TR3driver]

Inside the bellhousing, the fork that operates the throw-out bearing is located to the operating shaft with a taper pin. The design was less than wonderful, basically it flexes the pin every time you use the clutch, which over a long period of time (like 30 years) weakens and breaks the pin.

The problem was compounded by inferior quality pins being supplied; but today most vendors offer "uprated" pins that are actually about the equivalent of the original ones IMO.

It's "dreaded" only because you have to remove the gearbox to replace a $5 part; it's not especially hard to replace or anything.

Lots of cures have been proposed, my favorite is to assemble the shaft, fork and new pin outside of the gearbox, and drill a slightly undersize 1/4" hole (ISTR I used a 'D' drill, .246, but 1/4" would do) through the fork and center of the shaft, off to the side and roughly perpendicular to the original taper pin. Fit a 1/4" bolt (I prefer Grade 8) that is somewhat too long (so the unthreaded portion fills as much of the hole as possible), then cut the end off just long enough for a Nyloc nut. Now reassemble the whole thing into the gearbox, making sure the protruding end of the bolt cannot foul on the gearbox front cover.

I believe the Wiki portion of BCF has an article showing another cure, using a commercial taper pin instead of a bolt.

 

[steve_sims]

Would this let the clutch work after you pump it once? If i push the clutch once before i try to go in gear everything is fine and it shifts thru all of the gears normally. If i need to downshift a few minutes later, i have to pump the clutch once before shifting and then it works fine again.
The car came with a toneau cover and a mice chewed top. I am getting a new zipper put on the toneau and i am going to ask if the upholstry shop can repair the old top. I bought a TR4A top on ebay thinking it might work but i guess back on Ebay it goes unless someone on this forum can use it.Thanks Again Steve

 

[TR3driver]

It could, but you should also be able to notice that the freeplay adjustment at the slave is way out of whack. Basically your first pump is taking up the slack created by the broken pin, but it takes some time for the spring to return the slave piston all the way.

The other thing that might cause that symptom is a broken spring inside the MC. Mine came out in 4 pieces ... got in the habit of riding the clutch all the time so I didn't have to pump it /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

 

[steve_sims]

Hi guys, I just ran about a pint thru the system using the "pour it in /let it run out method". Still No pedal on first pump/ great pedal second pump. I once had to bleed the front brakes on a BMW R100/7 and it was almost as big of a pain. I will keep trying and let ya'll know. Maybe i should just keep running it like this!!! Great Theft control. Steve

 

[steve_sims]

Howdy Again, If the problem is the DREADED PIN, can i drive it like this for a while or will there be a sudden complete failure? Just got the car on the road and love it and would hate to tear it down again right away. Thanks Steve

 

[TR3driver]

Howdy Again, If the problem is the DREADED PIN, can i drive it like this for a while or will there be a sudden complete failure? Just got the car on the road and love it and would hate to tear it down again right away. Thanks Steve

If that is the problem, most likely you can drive for quite awhile before it gets worse, IMO. The broken stub of the pin binds in the other side of the fork.

Not sure offhand how long I drove mine, but it had to be a couple of years at least ... thought I had mixed up the slave parts when I switched gearboxes with a car with a Lockheed clutch slave; so I made up a longer pushrod and kept going. Didn't discover the broken pin until the TOB failed.

 

[steve_sims]

Howdy, Just got back from a trip to the big city of Martinsville, Va. and noticed that i had to pump twice several times to get pedal compared to only pumping once yesterday. Yesterday was back roads with very few stops.Today was city and it seemed like i got every stoplight. It was 90 plus degrees today. Would these clues help in diagnosing the problem. Thanks Again. Steve

 

[TR4]

On my 4, I had to detach the slave cylinder and let it hang down so the bleed nipple was on top. That let the air float up and out as I pumped the pedal to get all the air out of it. No more double clutchin.

 

[trfourtune]

a couple of points,
assuming you bled the master cylinder before you re-installed it, and it generated full pressure before you hooked up the brake line, then you either have a leak in the piping,hose or slave. Assuming there are no leaks on the floor and the slave rebuild is perfect (absolutely no pitts and the cylinder has not been honed out too far and the cup is tight) i would tighten all you connections again. Sometimes a hose can suck in air (rarely)but i would guess your master is not working properly. also if you used NOS rubber parts do not use regular dot3 or dot4,it makes the rubber swell.

about the top-i have spares (black)i will be selling on e-bay since i want to return my car to original build colours- ie.white soft top. send me a pm with a reasonable offer before september to consider. i am heading out on holidays so i need 1.5 weeks to get you pictures.
thanks
Rob

 

[tomshobby]

fill reservoir, have assistant push pedal all the way down and hold, open bleeder, close bleeder, have assistant release pedal. have assistant push pedal all the way down and hold, open bleeder, close bleeder, have assistant release pedal.

repeat 8 to 10 times. it is more often than you will need but better than four times and still having air in the system.

it might also be helpful to raise the front of the car slightly first to get the slave to an angle where the bleeder valve is higher than the air pocket would be in the cylinder.

 

[steve_sims]

Hi Rob, I am interested in your top. I bought the new amco TR4A top on ebay for $199. I honestly don't know what to offer for yours. I don't need a picture, just describe and let me know how much you have to have. I can Paypal or send Money Order. Thanks Steve

 

[steve_sims]

Howdy All, I did use DOT 3 fluid with NOS slave cylinder. Should i rebuild slave cylinder with new kit that i just got and refill with DOT 3 or ?????? I did take the car out for a quick 10 mile run while it was cooler this morning. Definately better that 90 plus degrees yesterday. Am i right in assuming that this is more of an air/ fluid problem than the dreaded tapered pin. Thanks Steve