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

**hogan** · 01-03-2013 07:50 PM

Lads recently bout 04 accord euro luxury. The car is auto and when cruising the car will judder, like clutch slipping at 1500-2000rpm if i give it touch more throttle it stops or let off throttle goes away? What could it be?

Will changing atf fluid help?

Any help greatly appreciated.

**ChaosMaster** · 01-03-2013 10:34 PM

How many KM has the car done and when was the last oil change? If it's never hand it's ATF changed, then that could be it. The OEM oil is known to wear out much earlier than what the service book suggest (80k km vs 120k km service book). Fredroops has a good thread on it.

http://www.ozhonda.com/forum/showthr...-to-read-this*

**hogan** · 02-03-2013 08:49 AM

Thanks for that, the car is near at 160km as far as i know it has no history of the fluid being changed. Il try get that done and see if it fixes it.

Any other things it may be?

**hogan** · 02-03-2013 06:07 PM

Any more thoughts on this lads?

**ChaosMaster** · 02-03-2013 06:12 PM

If it hasn't ever had an ATF change, then it's most likely that. Have the filter changed as well. 160km with no change is GG to any car, much less Honda's substandard ATF.

**Jasemas** · 02-03-2013 06:30 PM

Say goodbye to your gearbox in the next couple o years

**hogan** · 02-03-2013 07:55 PM

Im not sure if the fluid has ever been done but i am going to do that asap. Does anyone have the filter part number?

Why would it be goodbye gearbox?

Also bit confused why the fluid would only cause the juddering at 1500-2000rpm and no other rpm??

**Jasemas** · 02-03-2013 09:33 PM

Because that ATF has been in your gearbox for almost 10 years... has never been changed, neither has your filter
Our engine oil gets cooled, filtered and cleaned
And then replaced every 6-12 months
ATF doesn't get cooled, though it does get filtered to an extent (though the filter is clogged by now)
Now think about that same ATF just sloshing through your tranny all dirty and what not

**hogan** · 03-03-2013 12:23 AM

I am just hazarding a guess it may have been changed when in for its services but im not 100% but going to change it. Why would this only cause judder at 1500rpm in 5th and be ok every other time?

**fillit** · 03-03-2013 10:03 AM

Originally Posted by hogan

I am just hazarding a guess it may have been changed when in for its services but im not 100% but going to change it. Why would this only cause judder at 1500rpm in 5th and be ok every other time?

When you take in for servicing they only go by what's required in the log books. Tranny fluid change is not required, it's presumed for a normal car (non track etc) that it will last for the life of the vehicle. Anyway, as per most mechanical issue there is no certain answer but a method of deduction, start off with changing the tranny fluid as it's the cheapest diagnosis to begin with then work from there.

**ChaosMaster** · 03-03-2013 11:07 AM

Originally Posted by hogan

I am just hazarding a guess it may have been changed when in for its services but im not 100% but going to change it. Why would this only cause judder at 1500rpm in 5th and be ok every other time?

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.