Trax's 9-inch assembly question thread
Trax's 9-inch assembly question thread I'm assembling a 9-inch center section for the first time, and I have a ton of questions. Instead of starting 25 separate threads I'll just add replies to this thread as I come up with new questions. So here goes...
Setting preload on new bearings Setting preload on new bearings
I assembled the Daytona pinion support with brand new bearings according to the layout in this diagram:
James Oxley's install article says the following:
Here's the approach that I used to assemble the pinion and support:
At this point, the pinion support had no fore-aft play, and I could flick it with my finger and it would spin freely for a few turns. The yoke had no nut on it so I could pick it up off the splines without a problem.
At this point, things seemed fine. However, once I moved to installing the pinion nut, things got a little weird.
Notice that Oxley's article mentions tightening the pinion nut to roughly 175 ft lbs, with a target bearing pre-load of 5 inch-pounds, or .416 ft-lbs.
Well, I had the common sense to torque it in steps and make sure everything was seating properly. I set the torque wrench to 30 ft-lbs and slowly started tightening. I stopped at the first click, and everything seemed OK. The bearings were a bit tight, but after a slight spin the pinion support was rotating freely again.
I stepped up to 45 ft-lbs and tightened the nut again. This time, the bearings felt much different. The pinion support had considerable drag on it. When I hold the pinion support and attempt to spin the yoke with my torque wrench, it takes nearly 8 ft-lbs of torque to rotate the yoke. The bearings are lubricated. What am I doing wrong?
I assembled the Daytona pinion support with brand new bearings according to the layout in this diagram:
James Oxley's install article says the following:
Originally Posted by James Oxley
16. Install New Crush Collar On Pinion (See Picture Below). Install Remaining Pinion Bearing, Pinion Flange, And New Pinion Nut. Holding Pinion Flange With Very Large Adjustable Wrench, Torque Nut To 175 Ft-lbs. Ensure Rotational Force Of Pinion Gear Does Not Exceed 5-8 In-lbs For New Bearings Or 8 In-lbs For Used Bearings. It Is Best To Check Rotational Force Often While Torqueing, As The Rotational Force Will Give You A Better Indication Of Pinion Bearing Pre-load Than The Pinion Nut Torque. Torquing Close To, But Not Exactly To, The Specified Torque May Be Required If Rotational Force Limit Has Been Reached.
- Install outer pinion bearing on pinion gear using a press.
- Stand pinion vertically. Slide crush collar onto pinion.
- Slide pinion support over pinion.
- Slide inner pinion bearing onto pinion until it catches on base of pinion shaft. Slide yoke over pinion splines. Firmly, but not violently, tap yoke with a hand sledge to seat the inner bearing.
- Check fore-aft play and rotational resistance of pinion support to make sure that bearings are seated.
At this point, the pinion support had no fore-aft play, and I could flick it with my finger and it would spin freely for a few turns. The yoke had no nut on it so I could pick it up off the splines without a problem.
At this point, things seemed fine. However, once I moved to installing the pinion nut, things got a little weird.
Notice that Oxley's article mentions tightening the pinion nut to roughly 175 ft lbs, with a target bearing pre-load of 5 inch-pounds, or .416 ft-lbs.
Well, I had the common sense to torque it in steps and make sure everything was seating properly. I set the torque wrench to 30 ft-lbs and slowly started tightening. I stopped at the first click, and everything seemed OK. The bearings were a bit tight, but after a slight spin the pinion support was rotating freely again.
I stepped up to 45 ft-lbs and tightened the nut again. This time, the bearings felt much different. The pinion support had considerable drag on it. When I hold the pinion support and attempt to spin the yoke with my torque wrench, it takes nearly 8 ft-lbs of torque to rotate the yoke. The bearings are lubricated. What am I doing wrong?
TECH Fanatic
Joined: Sep 2004
Posts: 1,124
Likes: 1
From: Las Vegas
Pinion pre-load for new bearings should be around 30-35 rolling inch pounds.
The rolling inch pound measurement is completed by securing the pinion support ridgidly and measuring the rolling resistance of the bearing pre-load with a dial torque meter (dial type, non click torque wrench). This shoudld be preformed with a liberal amount of assembly lubericant on the bearings.
Ok... not everyone has this type of torque wrench. So... this is where the black magic of differential building starts... because it becomes a touch and feel process. The touch and feel part is near impossible to explain... its something you would have to feel for yourself and it then becomes part of memory.
There should be noticable (drag) pre-load. Kinda like a firm hand shake... while turning the pinion itself.
I will say this... dont get caught up in all of the numbers...
The rolling inch pound measurement is completed by securing the pinion support ridgidly and measuring the rolling resistance of the bearing pre-load with a dial torque meter (dial type, non click torque wrench). This shoudld be preformed with a liberal amount of assembly lubericant on the bearings.
Ok... not everyone has this type of torque wrench. So... this is where the black magic of differential building starts... because it becomes a touch and feel process. The touch and feel part is near impossible to explain... its something you would have to feel for yourself and it then becomes part of memory.
There should be noticable (drag) pre-load. Kinda like a firm hand shake... while turning the pinion itself.
I will say this... dont get caught up in all of the numbers...
I gave it another try tonight, and the same thing happened... right around 40 ft-lbs (not 140) the pinion becomes almost impossible to turn by hand with the pinion support held in a fixed position.
Is it possible that when I hit the yoke to seat the outer bearing that I crushed the crush sleeve, and that's why I'm getting such high resistance at a low pinion nut torque level?
Thanks!
Is it possible that when I hit the yoke to seat the outer bearing that I crushed the crush sleeve, and that's why I'm getting such high resistance at a low pinion nut torque level?
Thanks!
Joined: Mar 2005
Posts: 1,599
Likes: 0
From: 32639 Groesbeck HWY. Fraser MI 48026
Originally Posted by trax
I gave it another try tonight, and the same thing happened... right around 40 ft-lbs (not 140) the pinion becomes almost impossible to turn by hand with the pinion support held in a fixed position.
Is it possible that when I hit the yoke to seat the outer bearing that I crushed the crush sleeve, and that's why I'm getting such high resistance at a low pinion nut torque level?
Thanks!
Is it possible that when I hit the yoke to seat the outer bearing that I crushed the crush sleeve, and that's why I'm getting such high resistance at a low pinion nut torque level?
Thanks!
I would recomend you use a solid spacer with shims and not a cruch sleeve to set pinion preload.
Scott -- I thought the idea was to use a crush sleeve first to get the preload, then measure it with a mic to shim the solid spacer, and then use the solid spacer for final assembly? If I tried to use the solid spacer first, wouldn't I have to swap shims in and out trial-and-error style until I found the right height?
Joined: Mar 2005
Posts: 1,599
Likes: 0
From: 32639 Groesbeck HWY. Fraser MI 48026
Yeah it's sometimes a pain but I don't bother with the crush sleeve. I often leave the large pinion bearing off the pinion and set preload in my press to start.
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Well, I gave it another try tonight, this time with a new $3 crush collar from NAPA.
Sure enough, the old crush collar was really smushed... when I torqued the nut with the old one, I was probably putting all the pressure straight on the bearings, hence why the 40 ft-lbs was enough to lock it up.
I torqued up the nut with the new crush collar, then mic'ed it and shimmed the solid spacer accordingly... things are looking up!
Sure enough, the old crush collar was really smushed... when I torqued the nut with the old one, I was probably putting all the pressure straight on the bearings, hence why the 40 ft-lbs was enough to lock it up.
I torqued up the nut with the new crush collar, then mic'ed it and shimmed the solid spacer accordingly... things are looking up!
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Verdad Gallardo Bump again... had to put the project on pause due to a 2-week business trip
This project is almost done! When I get back on Friday I need to swap U-joints and set the pinion angle, and there will be just one more step before I can fire her up...
Next question: Gear oil and break-in. I noticed in searches that this topic has been beaten to death but I just want to make sure I've got all my bases covered.
Keep in mind the vehicle is a street / strip car with a Trac-Loc
Thanks for all the help guys!
This project is almost done! When I get back on Friday I need to swap U-joints and set the pinion angle, and there will be just one more step before I can fire her up...
Next question: Gear oil and break-in. I noticed in searches that this topic has been beaten to death but I just want to make sure I've got all my bases covered.
Keep in mind the vehicle is a street / strip car with a Trac-Loc
- Should I use any special viscosity for break-in?
- Chicane -- I saw in this thread that you like Schaeffer straight 140 weight. Where can I get this thing by the pint? It looks like they only sell it in 40lb and up sizes.
- How much friction modifier should I use?
- How much oil should I use?
Thanks for all the help guys!
TECH Fanatic
Joined: Sep 2004
Posts: 1,124
Likes: 1
From: Las Vegas
Nothing special for brake in... hell, I just fill it and leave it in there until I have to rebuild the posi or something.
If you go to Schaffers website, look under dealer local to your area and give one of them a call. They should be able to get ya what you need.
As for the friction modifier... I like the OE Ford parrifin based stuff as it homoginizes perfectly with the parrifin based Schaffers. 4oz is all you will need... if it requires any more you can always add... but you can not subtract without draining the diff. And, I would get three qts... but it should only use about 2 3/4.
If you go to Schaffers website, look under dealer local to your area and give one of them a call. They should be able to get ya what you need.
As for the friction modifier... I like the OE Ford parrifin based stuff as it homoginizes perfectly with the parrifin based Schaffers. 4oz is all you will need... if it requires any more you can always add... but you can not subtract without draining the diff. And, I would get three qts... but it should only use about 2 3/4.
12 Second Club
Joined: Sep 2005
Posts: 4,273
Likes: 0
From: Bucks County, Pa.
As for the friction modifier... I like the OE Ford parrifin based stuff as it homoginizes perfectly with the parrifin based Schaffers. 4oz is all you will need... if it requires any more you can always add... but you can not subtract without draining the diff. And, I would get three qts... but it should only use about 2 3/4.
, I know, but would the Ford fm mix well with Torco RGO, or should I use the GM stuff with this gear oil?? (Eaton cf clutch pack posi in a 10 bolt) 
12 Second Club
Joined: Sep 2005
Posts: 4,273
Likes: 0
From: Bucks County, Pa.
The wheels are spinning 
After setting pinion angle, I fired her up and let the wheels spin for a few minutes. It seems pretty good, although I noticed that the wheels don't rotate freely in neutral like they used to on the 10-bolt.
I took the car out on the street very briefly to go up and down the block at about 25 mph. So far so good. My biggest concern was the backing plates, since I couldn't get a socket on them to get an honest torque reading. At least from that two minute trip I didn't hear any grinding or feel any weird vibrations, so I guess that's a good sign.
There are a ton of threads on break-in... I'm gonna try the method of 20 miles of light driving followed by a complete cool down. Then I'll make sure to drive non-aggressively for the next 300-500 miles.
After setting pinion angle, I fired her up and let the wheels spin for a few minutes. It seems pretty good, although I noticed that the wheels don't rotate freely in neutral like they used to on the 10-bolt.
I took the car out on the street very briefly to go up and down the block at about 25 mph. So far so good. My biggest concern was the backing plates, since I couldn't get a socket on them to get an honest torque reading. At least from that two minute trip I didn't hear any grinding or feel any weird vibrations, so I guess that's a good sign.
There are a ton of threads on break-in... I'm gonna try the method of 20 miles of light driving followed by a complete cool down. Then I'll make sure to drive non-aggressively for the next 300-500 miles.
