| Author | Message | ||
     Randy Roberson Grand Master Username: wascator Post Number: 331 Registered: 5-2009 |
Both Her brake pumps work now, except the front pump taps; it seems like when there is demand on it, like just after braking it will tap for about 10 seconds. The rear pump is quiet as a mouse. This just after my amateur rebuild. Suggestions welcomed. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1130 Registered: 6-2009 |
Randy, Have you checked your accumulator pressure on that system via "the usual way" at the accumulator control valve? The front pump on my car taps, particularly when cold or after applying the brakes, when the accumulator pressure is low. Brian, who's all too familiar with leaking accumulators even when standard overhaul procedure is followed to the letter | ||
| Chris Miller Prolific User Username: cjm51213 Post Number: 296 Registered: 5-2013 |
Hi Randy, I can think of two possible reasons for tapping. 1) The push rod is coming unseated from the cam and the tap is the result of the cam re-engaging with the seat of the push rod 2) The tap is the result of valves closing. We know the pump push rod rides against a cam, so tapping is the result of the push rod not being in contact with the cam during some phase of the cycle, and the cam re-engaging later in the cycle with an apparent tap. I think this must mean the the push rod is not being fully reset from the compression (pump) stroke. Assuming that the push rod is at liberty to travel the full distance and the reset spring is adequate, the restricted flow of hydraulic fluid would prevent the push rod from resetting. I think I'd investigate fluid intake including the valve and the fluid path. If flow is restricted in some way, the push rod will not be able to completely reset in the time necessary and will lose it's seat on the cam, which will tap when it next makes contact with the push rod. If the valves are noisy, the only reason I can think would be cavitation, meaning fluid is not flowing adequately during intake causing a vacuum allowing the valves to "slam" closed, where fluid would normally damp the action. I have no idea how you'd test this, but I think the common element is restricted inflow of fluid and the question is why... Chris. | ||
| Chris Miller Prolific User Username: cjm51213 Post Number: 297 Registered: 5-2013 |
Hi Randy, During an off-line conversation with Brian, the question occurred to me, what are the circumstances where you hear this tapping with respect to the ACV state? Meaning, is your accumulator "Charging" or in "By-Pass"? The reason it is important is because during "Charging", the pump sees the pressure of the accumulator and during "By-Pass" the pump sees nearly zero pressure. Eliminating one condition, will focus the facts on the other. Chris. | ||
| David Gore Moderator Username: david_gore Post Number: 1492 Registered: 4-2003 |
Are you certain the height of the pump push rod was correctly set before the overhauled pump was re-installed? Did you correctly install the "wave" washer in the discharge valve at the top of the pump and test the pump manually before installation to see if it would hold pressure when manually operated after being primed with fluid and the discharge blocked? Was the correct thickness washer used to seat the pump body on the valley cover? The clearance specification between the push rod and pump piston followed by correct installation of the discharge valve discs are the first things I would check before doing anything else. I suspect lack of back pressure to cushion the pump piston is the reason for the "tapping". | ||
| Bob UK Unregistered guest Posted From: 94.197.122.72 |
The tapping noise might be too much clearance. A bit like engine valve clearances. The push rod is coming off the cam. There are shims that need adjusting. The measurement from the top of the push rod to the top of where the brake pump screws in is 0.525" and a depth gauge is required. The shims are fitted underneath the bit that the pump screws into. This is accessed by removing the camshaft cover plate under the inlet manifold The thickness of the gasket effects this clearance as well as the shims. (Message approved by david_gore) | ||
| Randy Roberson Grand Master Username: wascator Post Number: 332 Registered: 5-2009 |
Bob, David, I am aware of all these things, and I think I got it right as I could when I "did" the pumps. I do know that it is pumping. The spheres are new, and it takes a lot of pedel pumps to make the warning lamps come on: about 25 last test. At least now I can get the pump off without too much bother, and see what I can do. The suction screens in the reservoir are clean, in fact the reservoir was clean when I started. I also replaced the feed hoses and clamps. I am hampered for the near-term by being out of brake fluid. Thanks for the replies of course; always appreciated! | ||
| gordon le feuvre Frequent User Username: triumph Post Number: 54 Registered: 7-2012 |
As soon as R-R changed the brake pump to accumulator high pressure pipe from flexible to rigid (just prior to 8000 series cars) knocking became a problem. The reason was that whatever was tried the flexible pipe would flex at each power stroke of pump and wear through where clipped to engine causing failure and lots of leaks! This was ALWAYS when stopped or just taking off as the revs rose. It is because fluid pressure is drawn off to stop car and needed topping back up. The pumps only ever knock under load when pumping up the pressure, never when the system has reached operating pressure and the fluid is being redirected back to the reservoir. The advise is all good i.e. brake pump pushrod clearance etc. but it was my experience that the problems were related to the non return valve in the brake pump. If the small conical shaped piston has marks on it where it seats this is enough to cause knock the "factory" modified these with a vertical groove in at some point (that i can't remember) I did quite a lot of work with R-R as our dealership was located in small island with low overall speed that is ideal for hearing pump knock. In summary, my experience is that if all clearances and pump build are OK look at the non return valve in top of pump and if not sure replace pump or valve (ue35514) P.S it will not harm the operation, it is just very annoying because staionary there is no general road noise to mask the knock knock that appears to eminate from behind dash. | ||
| Randy Roberson Grand Master Username: wascator Post Number: 333 Registered: 5-2009 |
Fortunately I can only barely hear it from inside the Car. It's good to know that, until I can attempt rectification, it should not be harmful. I drove the Car a 40 mile round-trip Sunday afternoon, and maybe for the first time, I drove it as it was meant to be driven: without worry as to the brakes, as to old tires failing, or anything like that. I will say it is an amazing Car. Of course, the 20 miles one-way is a new, 4-lane divided state highway in great condition, but the smoothness, and comfort were there, and the performance was great. Seventy and seventy-five miles per hour, no problem. Add in the 44 years since it was built, and it was really good. We have had jellybean cars with hard suspensions and revvy v-6 engines so long now in the USA, we have forgotten what great cars we had. | ||
| Bob UK Unregistered guest Posted From: 94.197.122.71 |
If it is barely audible then I would leave it. It might sort itself out with a few miles. An alternative way of measuring the 0.525. A piece of round steel that fits in the hole. Face both ends so that it's 0.510 to 0.515. What ever the measurement comes out at add feeler gauges to make 0.525. Use a steel rule or square as a straight edge. According to the cross section of the pump in the wshop manual. The bottom port of the pump body is not uncovered when the plunger is fully down. This port IMO is for lubrication. I have never actually accurately measured the position of the plunger in the pump only the push rod in the engine bit. IMO the clearance between the the push rod and plunger is actually a minus clearance and the plunger is very slightly pushed in when the cam is fully off the push rod. Otherwise the plunger will hit the bottom clip every time the plunger falls. IMO the 0.525" is to make sure that the rod is not to low. So somewhere between 0.520 and 0.525. Will be fine. IMHO not sure I think. Why not fit the the pump with a tea cosy to deaden the tap. But as has pointed out the solid pipe is amplifying noise. Turn the radio up! This system can be infuriating because we know how good it can be then it does weird stuff like tapping. (Message approved by david_gore) | ||
| Randy Roberson Grand Master Username: wascator Post Number: 334 Registered: 5-2009 |
I used a depth micrometer and I don't recall having any trouble with either pump in that regard. I did replace one of the pushrod guides with the revised version, because one of my waisted pushrods was corroded to the point it broke (had been broken since before I came along, in fact), and I could not find the correct waisted rod for the old pushrod guide. They are slightly different lengths. I think I installed it in the back pump, but not certain. Anyway the rear pump is quiet. | ||
| gordon le feuvre Frequent User Username: triumph Post Number: 55 Registered: 7-2012 |
There was a modified pushrod/housing kit as the original waisted ones used to sometimes break for no reason( they were designed waisted to break in case the pump had hydraulic lock, Still say the same thing, if all else ok, look for marks on non return valve in pump. I cannot recall how many pumps I had in bits to cure knocking AND don't forget cars were NEW then and we still had problems. | ||
| Bob UK Unregistered guest Posted From: 94.197.122.84 |
The valve can be removed with the pump in situ. Only the uoutput pipe needs to be removed. The front one is easy. If the non return valve has vertical marks then it is not turning. The valve seals on the taper. Not the sides. So using blunted 800 wet/dry and water as lubricant, polish the parallel bit. Don't go mad and polish it for hour in a lathe just a 1 minute is enough. Touch the seat up say 3 seconds. The bore I would give that a 5 sec only because the pair were matched I believe. Use wood dowel with split to hold wet/dry. Blow out wash in dot and refit. When fitting the valve back together give the spool a twist on the seat for engineer's luck. A dowel poked where the spring goes will do. The spring gives a turning flick as it compresses and un compresses which hopeful flicks the spool as it seats. Mine are tappy on cold start for seconds then quiet the rest of the day. I have not had to mess with my non return valves. I have a Moore and Wright depth gauge, a digital caliper and dail test indicators and other luxuries. The cheapest is a digital caliper starting at £15 the most expensive is the Moore and Wright micrometer depth gauge because it's accurate to 1/4 thou or closer. However used one's turn up for £30. A digital caliper is good for 1 thou which is plenty good enough for this job. Plus a digital caliper will measure anything else that fits in the jaws. Inside jaws as well. Blunted wet/dry is new paper that has been rubbed on steel. Not rusty steel though. I use a inch dia steel bar in my lathe. Because most haven't got the luxury of a lathe, a pistol drill in a vice will do. Jewelers rouge. If using rouge then extra carefully clean stuff after. These pumps are very similar to in line diesel injection jerk pumps. The same method is used to tidy up non return valves at the top of the pump outlets to the injectors. RR used a modified diesel jerk pump on the very first proto types as brake pumps. Steve Davis a famous snooker world champion said when a sports reporter commented about his luck said "The more I practice the more luck I have." (Message approved by david_gore) | ||
| Jean-Pierre 'JP' Hilbert Experienced User Username: jphilbert Post Number: 23 Registered: 9-2013 |
Bob, I cannot find the procedure for the .525 measurement in the TSD4400 anymore, I've seen it there before though, even got myself a depth micrometer. Would you or anybody else be able to point me to a page number? Thanks a lot! JP Hilbert DAF-10195 | ||
| Jean-Pierre 'JP' Hilbert Experienced User Username: jphilbert Post Number: 24 Registered: 9-2013 |
...just realised that I'm in the RR363 forum and not LHM (my car is LHM), I'm sure there is a difference with shimming the pumps, right? | ||
| Bob UK Unregistered guest Posted From: 94.197.122.72 |
The pumps are similar but not interchangeable. Maybe the measurement is different. (Message approved by david_gore) | ||
| Bob UK Unregistered guest Posted From: 94.197.122.76 |
An interesting idea. Would be to remove the adaptor from the pump the measure the distance from the top of the plunger to the top of the pump body. Then after checking the push rod height and correcting as needed. Screw the pump in and measure the position of plunger. I suspect that the plunger will be slightly higher, thus insuring that the push rod ends stay touching. 5 thou in my engineering mind sounds right. Just a guess.} (Message approved by david_gore) | ||
| Nigel Johnson Prolific User Username: nigel_johnson Post Number: 138 Registered: 12-2008 |
The pump pushrod measurement for our 1980 Spirit is 0.522 to 0.525. I have used Shadow 2 pushrods and reshimmed them to the correct height they were a slightly different length to the Spirit ones. I have the details somewhere if anyone is interested. Regards, Nigel. | ||
| Bob UK Unregistered guest Posted From: 94.197.122.89 |
0.525 to 0.522 sounds good to me. Because earlier I said 0.525 to 0.520 for the shadow. (Message approved by david_gore) |
