Q45 Driveshaft & Trans mount

[wlong]

I am starting my driveshaft replacement tomorrow along with the transmission mount. The shaft was recently replaced (by the previous owner) with one that does not have the flex disk. Just a u-joint at the transmission. I am hoping that going back to the OEM shaft will cure a vibration problem that occurs at various speeds. Based on the Forum's comments, I decided not to waste time trying to get the old one balanced even though it is only 1000 miles old.

Let me know if anyone has any tips for this job.:help

[Q451990]

It's not terribly difficult. I've done it solo a few times on jack stands. I improvised by using a creeper to roll the shaft in place. One thing I messed up once is using the big "Washers" on the carrier brakcet as washers rather than spacers between the body and bracket.

Have fun and welcome to NICO!

Heath

[Q45tech]

As you see there are 4 bolts on the rear flange so you can index the rear section for minimal runout..........selecting the center spacing washer thickness [none, 1 or 2] takes additional time.

The swaping is the easy part, the fine tuning takes days to find the absolute best position//center angle at what ever speed you want to optimize.

You really need a vibration freq/amplitude analyser as human are not good at low frequency amplitude discrimination [ telling a 10% change].

The above is almost never done except new at the factory as the time required is massive.

Don't forget to change the rear transmission shaft seal and check the diff flange for trueness [runout].

Bad shafts tend to turn other attached things bad.

http://cgi.ebay.com/ws/eBayISA...=1504Kent Moore Electronic Vibration Analyzer EVA2 J-38792A ~~$400

http://cgi.ebay.com/ws/eBayISA...=1504

http://cgi.ebay.com/ws/eBayISA...=4678

Always lots of inexpensive old but working vibration analysers on EBAY!

Nice to have something battery operated........IRD is a good choice as is Vitec. The Kent Moore is what dealers have and use ....maybe?.......it shows the 3 highest vibration frequencies and each's amplitude.

[wlong]

Thanks for the replys. Apparently the original shaft was replaced because of a bad center bearing. Suprising since the car only has around 90K.

Headed to the garage!:)

[wlong]

It turns out that the OLD shaft is a different design that uses a different center bearing support. I found no washers or spacers and am now in the position of not having all of the parts I need to finish the job today -somewhat depressing. The old (aftermarket) shaft has a one piece center bearing support that can’t be removed without disassembling the shaft. It wouldn’t fit the OEM shaft anyway.

I was able to remove and replace the transmission mount. The rubber on the old one was broken on one side. Thanks to the info on the board for identifying that problem. Hopefully that will eliminate at tleast one source of the vibration.

I have attached a drawing of the OEM driveshaft showing the 2-piece design on the center support. I also recall someone mentioned an updated or improved design for this. Is this true and does it look the same as the shetch?

I guess I need call someone about which parts to order.

[wlong]

Fred:

Thanks for your reply. What is the best way to find a good starting point on the number of washers I need to get the center bearing in the right spot? Should I recheck the alinment after my new transmission support settles in?

ThanksWill

[Q451990]

That drawing looks right. You'll need to buy the center braket, spacers, and probably the cover the bolts on. Call Joe at 1-888-216-5328 today and he may still be able to ship them out next day air and get them to you on Monday if you need them quickly.

Heath

[wlong]

Thanks. I tried getting ahold of Joe; but, no one answered after the introduction. It looks like I have the bolts and the shield. Just need the bracket and the spacers.

I can get by for a couple of days without the car. In the meantime, I am replacing the belts, cleaning the MAF, etc.

The throttle body looks really clean on the upstream side and I decided it was OK. Hopefully cleaning the MAF will clear op an occasional skip at idle. I have new plugs; but I'm saving that for another day.:patriot

W. Long:peace

[Q45tech]

The rear of the throttle plates are what gets dirty, along with the entire air path till you come to the injectors which tend to wash the rest clean with gasoline........till the stems of the valves which can get caked up again.Then of course the piston crowns.

If the transmission and motor mounts are new and the diff mounts haven't sagged, one washer is the usual starting point.

[texasoil]

It is extremely easy to damage the MAF sensing element. NEVER use anything harsher than a gentle drip if carb cleaning solvent on it no'blast' or air hose, much less anything hard. Damage is 'often' done by 'fine particles' getting sucked past it and erroding it if you do not use the air filter and be careful about trash when changing it.

[texasoil]

unlikely to be HAF, more likely vacuum leak, partially clogged/defective injector, or faulty spark plug/wire. First run Techron through it to clean injectors and intake valves off. You would be shocked to see just how much coke can build up on intake valves if cheap gas is used.

[Q451990]

Texasoil,

I've had good results removing the MAF and misting it with brake parts cleaner to clean it up... do you think that's a bad idea?

Heath

[wlong]

Before I read the post, I was aware that the MAF is a delicate instrument. I ended up spraying some brake cleaner over it and cleaned a couple of small objects off of the screen. Hopefully nothing is damaged. I am waiting on the driveshaft parts before I start the car. I am not too worried since I believe this is a common practice.

[Q451990]

I think you'll be fine... that method has been recommended by Q45Tech before. You just don't want to drench it in cleaner or anything... brake parts cleaner is supposedly not going to leave any residue, so it's a good choice.

Heath

[wlong]

I called Joe this morning. Apparently he is off today and I talked to Ralph who was filling in for Joe. He had no listing for the shims that Q45Tech mentioned. I went ahead and placed the order for the center bearing brackets. These were described by Ralph as new and improved for the new and improved center bearing.

Q45Tech mentioned that I should start with one washer. I think I have some washers that are 50-60 mils thick that may work.

Does that sound like it will work or do I need to pursue the infiniti shims? Does anyone know the dimensions (i.e., thickness) of these shims.

ThanksWill

[wlong]

I finished checking the runout on the differential flange. I don't have the specs yet; but it seems OK being 1-2 mils in the radial direction and 1-2 mils on the face of the flange.

The new center bearing brackets should show up tomorrow. Does any one have any idea how thick the "big washers" need to be to get the right spacing on the bracket. I have no idea if they are 50 mils or 500 mils.

Let me know if anyone remembers.

ThanksW. Long

[wlong]

Well, I received the parts from AZ in just over a day and installed the new driveshaft last night along with the new center bearing support. I ended up using a couple of stainless washers on each stud to space the support around 1/8 inch from the body. It's not obvious why this spacing is needed; but the vibration is essentially gone. I still have some non-driveshaft induced vibration from the engine at 2250 rpm (occurs even in neutral) although this is greatly reduced - I'm guessing because of the new transmission mount.

I am still testing although I think I am now hypersensitive to ANY vibration. I may try removing some washers to see if anything changes. I don't think it's enough to purchase the vibration meter at this point.

Thanks for everyone's help.W. Long

[Q45tech]

http://www.carbidedepot.com/formulas-trigright.asp

1/8" you may not like the error, ideally........the angle should be less than 0.5 degrees considering the 6900 rpm potential.

[wlong]

I used Q45tech's the trig page to do the math and have this observation:

Since the angle should be 0.5 degrees max and the distance from the flex disk and the bearing mount is around 18", the spacers could be as thick as 0.16 inches before the 0.5 degrees was exceeded. This also assumes that the shaft is perfect with no spacers. I used 0.125 inches on my car which makes the angle as much as 0.4°.

It looks like the spacers typically used (assuming they are relatively thin) change the angle much less than the .5°. Just trying to identify what Q45tech is calling "the error". The more I think about this I am worried that the spacers should be like 3/8" thick to bring everything into alignment under "as new" conditions. Am I backwards or what?

It seems the hard part is measuring the angle since there is no good reference point. It seams close from a vibration standpoint -- it just doesn't look close, maybe because the angle is tuff to see lying on your back. Any ideas on how to measuring the angle?

ThanksW. Long

[texasoil]

usually the 2450 rpm vibration is aggravated by stiffer than new exhaust hangers at the rear of the transmission. Try drilling a few 1/4" holes through the rubber blocks to soften them up a bit and see. It may solve the problem easily.