5 Speed gearbox flaw repair

[Nicholas R]

I just might make it to the Celebration Exotic car show this year... Fingers crossed!!

You had better be there! Someone has to win "Best in Show," it might as well be you!!

[DMC-81]

You had better be there! Someone has to win "Best in Show," it might as well be you!!

Thanks Nick! Barring anything unforeseen my D will finally be there.

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Yesterday, I picked up the car from DMCFL. They did an outstanding job! Now I'll button everything else up that I took off and refurbed.

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Today, I reinstalled the the diagnostic protecting plate, the crossover pipe, new O2 sensor, and finally, the drive axles, in that order. Tomorrow I'll install my refurbed starter and I'll see if it works with the new solenoid and the starter recall done. I can't wait to hear the engine with my new exhaust manifold gaskets. Plus, I haven't driven it since November.

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[DMC5180]

Did you have all the transmission bolts re-plated? They look very fresh.


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[Chris Burns]

Awesome work on this DMC!!

Love to see her at a show some day.....

[DMC-81]

Did you have all the transmission bolts re-plated? They look very fresh.


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Thanks Dennis. I didn't have time to have them replated, but it did soak (in engine degreaser) and scrub each bolt, nut, and washer.

Awesome work on this DMC!!

Love to see her at a show some day.....

Thanks Chris. I plan to be at Celebration.

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Well, I finished up the parts that had to be reinstalled, and started it today. It sounds good.

Here is the starter reinstalled..

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I initially had a problem with the drive axle flanges being too loose. It turned out that I missed one extra turn on the differential adjustment nut from when I counted the turns until the threads disengaged. All fixed now, and I drove it to fuel it up with non ethanol. I got the usual attention, cameras, 4 people approaching me to compliment the car, and a fist pump of a guy out the window of a passing car.

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I have a few adjustments to make, but it works.

[DMC-81]

Thanks Dennis. I didn't have time to have them replated, but it did soak (in engine degreaser) and scrub each bolt, nut, and washer.


Thanks Chris. I plan to be at Celebration.

-----------------------------

Well, I finished up the parts that had to be reinstalled, and started it today. It sounds good.

Here is the starter reinstalled..

image.jpg

I initially had a problem with the drive axle flanges being too loose. It turned out that I missed one extra turn on the differential adjustment nut from when I counted the turns until the threads disengaged. All fixed now, and I drove it to fuel it up with non ethanol. I got the usual attention, cameras, 4 people approaching me to compliment the car, and a fist pump of a guy out the window of a passing car.

image.jpg

I have a few adjustments to make, but it works.

Oh my, I typed "comment" on the car. Dang auto-correct! Oh well. I'm still adjusting the linkage, etc.

[DMC-81]

Hi there,

I need your opinions and experience...

After my rebuild, the 2nd gear popping out problem is fixed, and the shift action is smooth. However, I am getting gear noise only on deceleration/ coasting in gear. It's not present in 1st gear, but starts in 2nd, and gets progressively quieter in 3, 4 and 5. It sounds not like a whine, but like the gears are not meshing right... click click click. Its loudest in 2nd gear.

A quick Google search on other vehicles points to bearing preload. When I put the transmission back together I put the Differential Adjustment Nut in the exact same place (I believe) that I found it... 8 1/3 turns out and in.

First I thought that I had it too tight. I backed it off a little and tested it....no difference. Then today, I put it back at 8 1/3 turns, and then tightened it some. After tightening, this is how much horizontal and vertical play there is in the drive flanges...

http://youtu.be/u7cUclF5j2c

Question: is this normal, or is the drive flange not supposed to move at all?

I'll test it again tomorrow to see if tightening it some made a difference, but I don't know whether the flanges should be solid or have some play as they are only attached with a roll pin. (The flanges and pins are new if that matters)

Thanks for your input.

[Nicholas R]

Axle flange movement is a difficult measure of whether anything is loose because they're not directly connected to the bearings. That movement is not something that should ever really change because all it is is the backlash in the gears inside the differential. The bearings are actually on the differential crown gear and the differential housing, not on the axle shafts. The movement is just whatever play there is between the shaft gear and the spider gears. In my experience, some play is normal.

This image explains what I'm trying to say a lot better:

[DMC-81]

Axle flange movement is a difficult measure of whether anything is loose because they're not directly connected to the bearings. That movement is not something that should ever really change because all it is is the backlash in the gears inside the differential. The bearings are actually on the differential crown gear and the differential housing, not on the axle shafts. The movement is just whatever play there is between the shaft gear and the spider gears. In my experience, some play is normal.

This image explains what I'm trying to say a lot better:

Thanks Nick. That makes a lot of sense.

Well, I test drove it again with the nut tightened approximately 1/8 turn from where it was originally.... The result was no real change. My thinking is if the bearing preload was off, the noise should change as you make adjustments.. Correct?

Here is more detail on what the symptoms are:

1) I verified that the noise is not happening in 1st gear, either under load, decelerating, coasting in gear, or when the clutch is engaged or released.

2) There is a slight clicking in neutral, no matter when the clutch is engaged or released.

3) The noise happens loudest in 2nd gear, only when decelerating or coasting in gear. It doesn't matter when the clutch is engaged or released.

4) As mentioned the same thing happens in 3, 4, and 5 to a gradually diminished degree.

I'm afraid the gearbox needs to come out again but beforehand, I am trying to pinpoint as much as possible what to look at because the first time, I corrected the visible damage and all seals were replaced, plus everything else looked great.

Question: would damaged spider gears cause the noise? I couldn't really inspect them inside the differential housing.

Or how about worn bearings on the 2 shafts? (With only 27k on the clock, I wouldn't expect that.)

[David T]

There is no good way to check bearing preload except the procedure in the Workshop Manual. If it was ever improperly set you could have damaged the carrier (dif) bearings so no amount of adjustment will stop a noise. Make sure you have the proper amount and the correct type of gear oil. The spider gears have no effect unless you are turning or a wheel is spinning faster or slower than the other. Worn bearings is a possibility but unless the box was operated without oil it is a rarity.