Please help 1500rpm judder, what is it ?????

At chaosmaster thanks for explaining that, i understand what your saying i will do the fluid swap i just need to get the atf filter, not paying honda $60 here for it when its $17 in states.

@osman1 you mean clutch slip? Dont think its that well i hope not.

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Originally Posted by ChaosMaster

If you knew how a Torque Converter works, then it's pretty simple. If I had to dumb it down, I would say, think of a river and it's currents. At low speeds, the currents are relatively weak, but at high speeds, it can knock back just about anything. In a torque convertor, the engine creates currents in the transmission. At low speeds, the currents is weak, thus when you stop at the lights, it feels like the car wants to move forwards (it does when you let go of the brake), but it isn't much. When you accelerate, the engine speed increases, thus the current increase, which in turn pushes the car forward.

Now, here's the important part, I guess. Torque converter efficiency increases with engine speed. Efficiency I'm talking about here is transferring power from the flywheel to the transmission. They have been designed so that at 1000 rpm, the efficiency is low (e.g. 20%) while above 2000rpm, the efficiency is high (e.g 95%). The reason for this, is because at 1000rpm or idle, the lower efficiency means less stress on the engine, thus more fuel efficient, where at higher rpm, you basically want to get all the power from the engine to the wheels.

Now here's the problem, as the oil ages, it wears out. So at 1500rpm, when it's efficiency should be say 90%, it's now only 70% (again, figures are purely for demonstrative purposes). At lower gears, it's fine, because the engine isn't producing much power/torque at 1500rpm anyway, and the lower gears multiply the input, so the load isn't that great (think gears on a bike, lower gears are much easier, but higher gears require more muscle). At 5th though, which is the tallest gear, the ratio is actually taller than 1:1, meaning the load is much higher. In this case, because the oil's efficiency is much lower, it's slipping, thus causing the judder or w/e sensation you're feeling. At say 2000rpm though, the efficiency is much higher, so even though the oil is worn out, it's still able to transfer 85% which is enough to avoid slipping.

This is in theory anyway, it's a bit difficult to explain simply and accurately, but I think you get the idea. Of course, all transmissions are different, especially Honda's ATF, but this is the general idea.

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You must spread some Reputation around before giving it to ChaosMaster again.

I have a 2005 honda euro luxury auto, now at 110,000km, purchased at 80,000km, has developed a slight shudder at 40 to 60kph, 1500 to 2000rpm, not noticed if driving hard.
Interbnet searches so far have found suggestions of wheel balance and alignment, drive shafts and now this forum.
GWS Mazda suggest its drive shafts and advise to replace them for $2300.
Frankston Honda suggest its the torque converter so do transmission oil change now and again in 3 months, as first transmission service is due at 120,000km, and even then there is a risk some mechanics/dealers may just top up the transmissions and do nothing else.
ChaosMaster info and link very helpful.

The CL9 did have a drive shaft problem, so it could be that, however from memory, I thought it only affected the Manuals (not sure why I was under that impression). Logically speaking though, transmission type wouldn't influence drive shaft wear.

My problem solved with a transmission flush and new synthetic transmission oil. I got advice from Travis Honda in Frankston that its the torque converter causing the shudder and to flush the transmission and replace oil now with upgraded synthetic oil and do this again in 3 months. After one flush and oil change the problem has gone, Travis Honda ended up not charging us, they told my wife when she went to pick the vehicle up that she has been messed around so it was free, usual price is $200 approx. Also it appears the transmission oil should be changed at 60K and not be left to 120K for the routine oil change, and in my vehicles transmission the oil filter is internal and is not able to be changed so that's why the flush is required, so I am told. Good outcome. Thanks for this thread and comments, it has been very helpful to me.

Nice to see dealers being generous for once.

Sorry to high jack thread, but i just bought an 06 luxury with the 6 speed manual and it shudders under acceleration between 45-55km/h and also at about 90km/h. Would this be related to the afformentioned drive shaft problem? It doesn't seem to be as bad when the car is at the beginning of the journey but once it warms up fully then it is present and can be violent depending on the amount of acceleration.

I changed the wheels and tyres to ones i know are good and that helped the problem but it was still there slightly (might be wheel alignment?).
I just did engine oil, filter and spark plugs but have not touched the transmission oil yet. Unsure of when/if it has been replaced.

Any help would be good.
Cheers, Paul.

Don't think the manual fluid needs to be replaced, not normally anyway as far as I know. Is it at certain RPM that it shutters? Also checked the nuts on the tyres are tightened correctly. Could be some loose nuts that are causing the problem.

Chaos, from what I can tell it isn't related to a certain RPM. I could be accelerating in 2nd gear and it always shudders at those speeds, or in 3rd gear and it does the same thing. Usually the shudder is worse in a higher gear at lower RPM (i.e. more load). Also, if I back off the acceleration or accelerate very slowly the shudder goes away. At crusing speeds the car drives brilliantly.

I was looking at this thread --> FINALLY THE ANSWER TO THE SHAKING EUROS and I think that this might be the cause. I will see what a mechanic says about this idea.

same problem with my 05 euro, 140,000 ks, diagnosed as torque converter, Honda in Canberra are asking 2600 for a new one to be installed

My 05 has started the shudder at 1500 rpm - it has 125,000 on the clock and probably had the original transmission fluid so I did it's first change today. Got around 5 litres out of it so will wait about a week and change another 5 litres and then fit the filter I got from US eBay. I am trying Valvoline Full Synthetic DEX/MERC which meets Honda's spec and hopefuly it will fix the problem.