Balance shaft bearing clearance numbers needed - attn: perry951
 

Hi,

Sorry for the long post just want to get this right.

I am resealing the balance shafts and was wondering about the balance shaft bearings. my car has 134 k on it and i considered doing them while i was there. I noticed that the top shaft is a little on the tight side( i have the cover off and the front housing), no problem as oiling is not going on so i figure its ok.

I decided to check the torque but heard that these require t be plasiguaged for clearances.

The lower shaft is really wobbly unlike the top shaft. (I would be under the impression that both shafts would have the same play) this leads me to believe the bearing cap has come loose. I have both covers off but will be removing the pass motor mount today to remove the bs cover. and then i will see for sure.

I can't seem to find the measurements of the bearing clearances for using plasiguage to check the balance shaft bearings.

DOES ANYONE HAVE THESE FIGURES?

I also have tightning specs for the nuts on studs out of the service manuals page 13-40 at the top that say i need a total of 22 ft/lbs for 8mm nuts on studs to be done in two steps. I cant understand this as i used less than 6 ft/lbs on the ones for the bearing caps on the balance shafts and this made the shaft totally unable to be turned.

If you can help it would be greatly appreciated.

If anyone can give me a walkthrough on the plasiguage use I would be greatful.

bump

Alright... a few things to check.

1. Pull the front housings off the balance shafts. Check the bushing in there and make sure it is not galled. If it is, you will need to have new ones pressed in.

2. Pull the side covers and see if the bearing bridges are tight.

3. Pull the bridges and check the bearings and balance shaft bearing surfaces, mic them to check for out of round conditions.

4. If all looks good, replace the bearings, lube with moly grease or assembly lube, and put it back together.

I cannot recall the oil clearance on them at the moment, or the torque for the nuts on the bridge. I am leaving town after work, so I won't be able to look them up until next weekend. I went by the book... and added a little locktite to the nuts just for safe measure.

You will have some end play, but you should have minimal axial play if it is all in and right.

One last thing, the bearings for the '86 motors are diffrent than the later bearings. MAKE SURE YOU ORDER THE RIGHT ONES! If you swap them, you could spin a bearing.

Hey Perry! I thought you were supposed to be on vaca and off rennlist for a week!?! Where are you, the airport internet kiosk or something? I knew you couldn't quit cold turkey!

EDIT: oh,,leaving AFTER work.. I see. Yea RIGHT! Where ya going? Spring break land?

I am heading out tonight at some point. Heading to South Carolina to spend a day with my brother at his race shop (builds NHRA Top Fuel Drag Motors) then on to Atlanta for a few days to catch up with some old friends.

I had planned on going to Denver this week, but could not work it all out. I MIGHT have internet access at some point.

I need to bring this one back to life....

As you all know I am in the process of bringing my car back to life... when I replaced the balance bushing the lower balance shaft turns without problems. The upper shaft would not turn at all... this was after torquing the bolts in the order and to the pounds listed in the workshop manual... I took it apart so many times it was not funny... and yes... all bushings are new and there is a lot of grease in it. Initially I thought some of the Loctite stuff got in the way...

Anyway, I got it back again and it is somewhat hard to turn initially... that initial resistance worries me... after the initial resistance to turn it will turn but not as loosely as the lower one...

problem is that this was like 4 months ago... since then the engine has been back in the car, all installed... There is enough space to take it apart while still in the car (radiator and intercooler are not installed... so there is lots of space in the front...)

This is like that little voice in my head asking me "Did you installed the 'O' ring in the oil pump to avoid leaks thru the shaft"... I know I did... but it was sooo long ago that now I am doubting... "Did you torque the bolts for the crankshaft tower correctly" yeah!! shut up!! I did that three times to be sure!! "Hey! what about the...

I am having post engine rebuild syndrome!! help!!!

The balance shaft bearings on the 86 is not the same size as the 87's on. It appears that this may have been a running change. On my 86 the bearing is thicker/shaft smaller OD. I came real close to screwing that one up even though I ordered the right parts I got the wrong ones. Parts guy didn't have a clue.

86 # 944 101 121 07
87 # 944 191 121 10

Also there is a 0.5mm larger front bushing. That would cause play on a standard shaft.

I just find it strange that they would send me just one wrong set... I replaced it for both shafts... and to have only one give me problems... weird...

I know I will hate this...

I will take it apart and replace the bearings again... It will not be as easy as it was when the engine was on the stand but what can I do!.... :)

Sorry I am just now seeing this. I finally got settled in Atlanta. Funny, back when this post was new.. I was headed off to ATL.

It's very possible that you did in fact get an '86 set and an '87 set. Alan was the one to advised me on the difference, and it saved my motor. I would have run '87 bearings on the '86 shafts and probably locked up a shaft.

I would run it... however, you did just rebuild it. Hate to hurt a fresh one.

Sorry to revive this once again... but starting to work again on the car this week... just to clarify, the bushing I should be changing is the front one, correct??? that is what is giving me problems??

Without the front housing the balance shaft turns freely... it is when I install the front housing that I see some initial resistance in the shaft to rotate freely...

I really do not want to be doing this again... I should have kept the engine out instead of rushing to put it back (well... rushing is such a relative word in this case...)

Alan, thank you for posting the part number, you saved me a bunch of brain damage. I checked the bearings I recived and of course they will be going back today. Does anyone have the correct part number for the bushings?

Alan, is that .5mm larger bushing the oversize one for machining a worn balance shaft? I had EBS doubble check and they swear that the 944 101 125 02 is the only one for 83 to 89.

I'll be home in 2 hours (7:30 eastern) and I will post the PN's I used.

The center bearing halves are the only ones that are different from early to late blocks. The bushing that is pressed into the shaft console is the same for all years.

Jamie - did you have a new bushing pressed in? Perhaps it's not in square?

Huh.. late night. :D

Here ya go. The center shells.
"Bearing Shell" Early Block - 944.101.125.02 $7.67 From Paragon (10/02)
"Bearing Shell" Late Block - 944.191.121.10 $8.97 From Paragon (3/02)

My early block as an illistration:
https://members.rennlist.com/perry95...build047sm.jpg



"Intermediate Staft Bearing" or Console Bearing - 944.101.121.07 $11.09 From Paragon (08/02)

This is the bearing that is pressed into the end of the housing, or "console" as it is called in the manual. It's more of a bushing than a bearing, but it does have some babbit compound on it. It is universal in all years.

You can see the upper console (still seperated) here:
https://members.rennlist.com/perry95...build057sm.jpg

So, if you have 1 piece balance shaft covers with the cap attached, use the late #. If you have an early cap and seperate cover, use the early #.

:cheers: