6 speed HD. How smooth is smooth?

[egrout]

With the 6 speed HD how smooth is smooth? Have 1300 miles and 2nd, 3rd and 5th is getting a little harder to get in gear. Our truck is a 2001 4 wheel disc brakes. Anybody know if this is the bad 6 speed? This site is better than mom's apple pie.

 

[Evan A. Beck]

It took my '01 6-speed about 15K to get broken in. Up until then, the shifting was fairly stiff. I got 64K on it now, and it is very smooth. SInce you have 1,300 miles on yours, I would give it some more time to get broken in. Check the oil level to be on the safe side.

 

[jtisdale]

gear jammin

I also have a six gun. I bought my truck new and it shifted fine till I hit about 4000 miles, and then... 1st, 2nd,3rd and R was a pain in the backside to shift into. I took it to the dealer and they couldnt find a problem. I now have 6000 miles on it a it keeps getting smoother everyday. It could be a break in thing, but I would suggest to take it to the dealer so they have a record of your problem. And yes check the transmission fluid level. Good luck

 

[WestTN]

I've noticed I tend not to press the clutch pedal ALL the way down sometimes. When I don't, it hangs a little on the shift. Could this be your problem too?

 

[Texas Diesel]

Re: gear jammin

Originally posted by jtisdale

I would suggest to take it to the dealer so they have a record of your problem

Take his advice!! I had intermittant grind / rough engagements since new and I had the dealer make note several times. When it got bad at 24,000 I pointed out that I had been been documenting this problem since new. They replaced it because the problem was existing since new (because of RO), if it was the first complaint I probably would have got it rebuilt. My new 6 sp was very difficult to get into reverse but with 500 miles it is getting very easy.

 

[klenger]

WestTN



I've noticed the same thing with pressing the clutch all the way down.



Mine never grinds, but you can't shift it very fast either. All-in-all, I love it.



I saw an interesting post on the irv2.com forum about the "flat tire" noise when towing. I posted a question about this when I first got my truck, and thought that it was comming from the transmission because it ususally happened in 5th gear. Since then, I have traveled with the wife in the right seat, and she says that the noise is comming from the right side forward of the firewall, not from the transmission. Someone else on this forum has since commented that the noise may be comming form the snorkle collapsing under high boost. What is interesting about the post on irv2 is that he has an auto, so the problem must not be the transmission.

 

[Diesel Freak]

I have been paying close attention to how my Sixer shifts. One day I slipped my new SBC MU Con FE really bad (yes you read that right), and all of a sudden my transmission shifted like a dream. HMmmmmmmmmmmmm. Well, the clutch shaved off I guess . 01 of material, and was no longer dragging... but slowly it became harder to shift, and now It is becomming hard to get into gear again.

I am going to go out on a limb and say that the problem with getting the truck into gear and notchy shifting is a problem with the Hydraulics..... not the transmission or the clutch. The notchy shift to 3rd is due to temperature and tolerances with is the transmission itself and is not an issue. If you have trouble getting it into gear at a stop light and need to shut the truck off to get it back into gear, then your clutch is dragging and the hydraulics are screwed up somehow.

 

[DHenry]

I'm still refining my shifting technique for this particular transmission, but one thing I've noticed is that if I don't let all the way off the throttle so that RPM stay up a bit during the shift, it's much smoother. Or am I imagining it? Don't think so. Has anybody else experienced this?

 

[Texas Diesel]

Originally posted by DHenry

I'm still refining my shifting technique for this particular transmission, but one thing I've noticed is that if I don't let all the way off the throttle so that RPM stay up a bit during the shift, it's much smoother. Or am I imagining it? Don't think so. Has anybody else experienced this?

I've noticed the same thing. I punch the throttle a little bit as I shift it into gear as well, tried to explain how to do this to wife and got the same expression from her as I got from the last deer I ran over...

 

[JTroiano]

Try not using the clutch at all. When up shifting, let off the go pedal and at the same time put tension on shifter to go into neutral and it will pop right out, then put slight pressure againts next gear syncro's and when the rpm's are correct it will pop right in. I wouldn't do this all the time but it will dive you a good idea on what the trans. wants to see in regards to rpm's to shift, so when using the clutch wait a seconds to go into the next gear. Semi's don't use the clutch except to start from a start. If you want to down shift it is alot harder. You need to get it into "N" and then stab the gas pedal to get the rpm's higher than what it would be after down shifting with the clutch. Then put slight pressure on the lower gear and when the rpm's are correct it will pop right in. Don't try this unless you understand!! It takes alot of practice. I don't drive my truck like this because I heard that it is tuff on the sycro's. I don't know if this is true. But some times when it is hard to down shift I do let the clutch out and stab the throttle to get the gears to speed up and then it will shift right in. The only time I shift without the clutch is when I have a cup of coffee and am talking on the cell phone and steering with my knee. Then I let the kid sitting in the middle shift, just tell them the number

Jon

 

[Texas Diesel]

Shifting without the clutch is very hard on the syncros. Dont do it. Big rig transmissions have rounded teeth for shifting without the clutch, our transmissions do not. I saw the gears on my old 6 speed that had faulty syncros ( I did lots of unsynchronized shifting because of that ) and the gears were badly chipped. I'm not saying it cant be done but you must anticipate the correct engine RPM BEFORE shifting into the gear.

 

[mbrolin]

There has been documented cases of the 6spds not wanting to go into gear at idle. I know of one member who had this problem at 32000 miles. The shop called Star. They said to replace the clutch,pressure plate and flywheel under warranty. There have been rare occurences,especially when towing at or near max GCVW,of weak pressure plates. After the tech removed the clutch they saw that the throwout bearing was not hitting all of the forks on the pressureplate. At this time Star said to replace the slave cylinder because a small internal part will break off unbeknownest to the driver. All of this was done under warranty and has happened to about 600 trucks. BTW,the clutch had no signs of wear. A quality shop who knows which person to talk to at Star can get answers.

 

[jtisdale]

Who or what is STAR? I have wondered this for a long while now. I have read a lot of posts with references to them.

 

[HEYBOSS]

Hard shifting

I have the auto so no shifting problems Just a suggestion to you 6 spd guys. Does anyone ever tried synthetic gear oil in their trans? I don't know what DC puts in it for gear oil. We've had BMW, Toyotas and other makes with hard shift complaints and after we switch the trans. oil to synthetic it was a night and day difference. We used Red Line gear oil, excellent it looks like automatic transmission fluid and it is as thin but has the qualities or better then conventional gear oil.

just my 2cts.



Fred

 

[Texas Diesel]

HEYBOSS,



Sure wish we could find a synthetic that was approved for use in the 5600 series.

 

[HEYBOSS]

Originally posted by Texas Diesel

HEYBOSS,



Sure wish we could find a synthetic that was approved for use in the 5600 series.

Fill me in on this. Is the 6pd transmission different than others or is there any thing special about them. I'll have to check what specs DC calls for on this transmission. I know Red Line is used on high end cars like BMW and others with great results and is comparable with other gear oils. As I said before I'm not familiar with the 6spd and its fluid specifications, but I can check on it.

 

[Texas Diesel]

Please do check. I am going by the warning label on the PTO cover that calls for Texaco MTX, any other WILL void warranty. There is a .pdf document that gives technical information regarding it's makeup. Others have successfully (short term) used 5W-30 systhetic motor oil as well.

 

[HEYBOSS]

Texas Diesel

I did a little research on red line gear oil and I don't think it is approved for the 5600, according to owner's manual DC already uses synthetic on the 5sp so for the 6sp they may be already using something similar or better. I'll still search it a little further and if something comes up I'll post it.

 

[THubbard]

BADDDD ADVICE

This is information is about as bad as it gets. Over- the-road truckers may do this; but they do not have to buy the parts for the repairs and you are not a full time drivers. Can it be done... yes Should you try it. Most certinly not.

Originally posted by JTroiano

Try not using the clutch at all. When up shifting, let off the go pedal and at the same time put tension on shifter to go into neutral and it will pop right out, then put slight pressure againts next gear syncro's and when the rpm's are correct it will pop right in. I wouldn't do this all the time but it will dive you a good idea on what the trans. wants to see in regards to rpm's to shift, so when using the clutch wait a seconds to go into the next gear. Semi's don't use the clutch except to start from a start. If you want to down shift it is alot harder. You need to get it into "N" and then stab the gas pedal to get the rpm's higher than what it would be after down shifting with the clutch. Then put slight pressure on the lower gear and when the rpm's are correct it will pop right in. Don't try this unless you understand!! It takes alot of practice. I don't drive my truck like this because I heard that it is tuff on the sycro's. I don't know if this is true. But some times when it is hard to down shift I do let the clutch out and stab the throttle to get the gears to speed up and then it will shift right in. The only time I shift without the clutch is when I have a cup of coffee and am talking on the cell phone and steering with my knee. Then I let the kid sitting in the middle shift, just tell them the number

Jon

 

[Diesel Freak]

Re: Texas Diesel

Originally posted by HEYBOSS

I did a little research on red line gear oil and I don't think it is approved for the 5600, according to owner's manual DC already uses synthetic on the 5sp so for the 6sp they may be already using something similar or better. I'll still search it a little further and if something comes up I'll post it.

I am using Red Line MTL in my sixer... so far so good.



the Texaco STF 1874 is not synthetic