Who'd you have do the work? Just curious since we are located close...

I've posted a few technical questions on this subject. I donot have a suncoast, but the consensus semms to be a harmonieus vibration in the drivetrain. It onlyu happens to me at stage 3 setting on my edge chip, and full throttle at 50 -57 mph, and not shifting out of 5th.

After seeing all the research on the issue, I'm tending to agree with it being a vibration issue.

Mine still shudders with the Suncoast too.

The search for a fix continues.

I've posted a few technical questions on this subject. I donot have a suncoast, but the consensus semms to be a harmonieus vibration in the drivetrain. It onlyu happens to me at stage 3 setting on my edge chip, and full throttle at 50 -57 mph, and not shifting out of 5th.

After seeing all the research on the issue, I'm tending to agree with it being a vibration issue.

If it were drive line harmonics, or 4 cylinder torque pulsations, it would have done it since new. Most who have the shudder, including myself, have had it get progressively worse with time. Another argument against these two causes is that the shudder does not appear to ever happen when the transmission is very cold and line pressure is high because of the viscous fluid. I have experienced clutch chatter in a number of vehicles in my life and what I have is undoubtedly clutch chatter. I would expect the cause to be inadequate line pressure at low RPMs. Theoretically, increased clutch friction can make up for decreased engagement pressure. I once used Lucas friction modifier in an old Buick and it worked wonders, but had to be replaced about every 10-15 thousand miles. I am going to get some of the DR Tranny stuff mentioned in another recent post product and see for myself.

While your post is logical, I disagree with your conclusion that if it were 4 cylinder torque pulsations, it would have done it since new. My first judder was over a year ago and it was under such exact conditions that I was unable to repeat it. Now, if I hit the throttle just right at 53 MPH in 4th gear lockup and I’m going up hill so that boost can build before accelerating past 54 MPH, it will judder. My engine is a lot more powerful now than when it was new and it seems to get more powerful every year. I think that people who broke their engines in harder achieved break-in and more power sooner and got the judder sooner. Could be my transmission is getting a little weaker through time but I really think the judder is due to increased engine power through time.

Well I've heard it all now. But really, if it were torque pulsations as you theorize, it would be able to be reproduced at will by any of our members with standard transmissions. With a hand shaker you can lug the engine at any RPM desired. No one with a standard has reported being able to achieve this. Besides the fact that pulsations just don't happen at 1600 RPM in ANY 4 cylinder engine (even a Cummins 4b).

Well, maybe you haven’t heard it all, yet. The judder is caused by just enough impulse torque to slip the torque converter a bit at peak impulse torque. Just after peak impulse torque the torque converter grabs with a thunk (under full hydraulic pressure). This happens at 1,800 RPM where there are 2 massive impulses with each RPM. It corresponds exactly with the beat of the engine or we are not talking about the same effect.

In the standard transmission there are 2 things going on that prevent this from happening. The first reason that the standard transmission clutch does not slip and grab is because it is strong enough to hold the impulse torque.

Second reason that it doesn’t happen is that standard transmission diesels, where this would be a problem, have what is referred to as a dual-mass flywheel that is designed to absorb the impulse and not destroy the transmission.

The more cylinders that a diesel engine has the more the impulse torque is smoothed so it’s less of a problem in a V8 diesel. The lowly Jetta TDI standard tranny model has a dual-mass fly wheel. In very rare cases, auto Jetta TDIs can judder. Sometimes even the Jetta dual-mass flywheels give up.

The CRD computer(s) try to protect the torque converter by downshifting when the torque is too high or by upshifting at a higher RPM under high acceleration. Our poor little torque converters in our CRDs have to take it all or they slip just enough to judder when conditions are just right.

I wonder how you can run the edge chip and not have to replace your TC.

Not long after i got the computer reprogramed by inmotion, my tc gave up.

Can you say DUUUHHH!!! What do you think that clutch chatter is? It is described many ways; Chatter, shudder, slippage, judder, etc... In most vehicles the clutch is never under full hydraulic pressure at low rpm. In some vehicles it is a function of the pump being unable to raise full pressure at low speed, but in most, it is because of the programing.



Is that not exactly the reason which I gave as an argument in pro of the TC slipping vs the other theory of torque pulsations? I think my explanation was clear enough. Perhaps you should read it again.





Indeed many Manual trannys do have DMFs. However it must be remembered that DMFs are entirely ineffective outside of their tuned RPM and torque range and will either burn up because of slippage or can even multiply the hammering at certain low harmonic ranges. In our CRDs, they are tuned for the peak torque curve which is much higher than the RPM range where our shudder is occurring. In any 4 or 6 cylinder vehicle with a manual tranny. you can achieve torque pulsations by lugging the engine at RPMs below about 1200, regardless of whether or not it has a DMF.



So what? This is not a new revelation, but it is another reason to suspect TC lockup slippage. If it were torque pulsations as you theorize here, 007Husky would never have mentioned the shudder improvement in the initial post. It would have had the same amount of torque as before. The only difference between before and after is the new clutch material with it's increased lock holding capacity.



So what really is your argument? Above you are arguing for torque impulses being the cause of the shudder but here you say that it is clutch slippage, which is what I initially posted as the cause of shudder.

This is fun.

Actually, you made a good point about full pressure. There is a big difference between full pressure and maximum pressure. If a CRD transmission pump is not making full pressure at 1,800 RPM then even the Suncoast is doomed to judder.

Just finished my TC install with pump, transgo and PML pan. Lots of $$$
STILL SHUDDERS. Quite a bit less violent but still there in same speed range during acceleration (55-65) with TC locked.
WTF. Now what. I am going to install the resistor and see if it changes at all.
I am starting to beleive torsional oscillation.