What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Gear Pattern Checks

Well, after a freakish snowstorm and loss of power for over a day here in Charleston, SC, I finally went back into my 14 BFF and reset the backlash to .006 and settled for a pinion shim that gave me a decent gear pattern and put it all back together. I would have posted some pics, but my battery died in my camera (kids and their snow pics!). The result is still a vibration about 50 mph or so. Looks like I might have a bad u-joint in the rear. I am looking at picking up a new drive shaft with a SYE for a NP208. Anyone out there know of a good deal on this type of set up? - Wes
 
There isn't a real SYE for a Chevy 208 .

Its either drill the output shaft for the one available kit ( bad idea ) or use parts from another 208 that had a fixed yoke ( dodge pass drop in the 80's ) .

I myself finally scored a passenger drop np241 ( part of my tbi/4l60e swap ) , those have a SYE available . I will be going that route when I can afford the SYE .
 
I've set up quite a few rear ends in my day..... why did you change the pinion shim to something other than factory?? your changing the gears and not the housing so pinion depth should not change. So, use the factory shim or atleast use a shim the same thickness, and set the backlash in spec. And also, most after market gear sets are harder than and OEM gear set, which they tend to make more noise. I have to explain that to alot of mustang guys when I tell them to order explorer 8.8 4.10s b/c they are quieter. Also after learning how to set gears up from a guy whos being doing it for 30+ years, thru his NHRA career and all, he explained to me if you get it in spec and there is noise or vibration, you could have a bad ring and pinion. Also when push comes to shove if everything is in spec the pattern doesnt me squat.
 
iwaxmyjimmy said:
I've set up quite a few rear ends in my day..... why did you change the pinion shim to something other than factory?? your changing the gears and not the housing so pinion depth should not change. So, use the factory shim or atleast use a shim the same thickness, and set the backlash in spec.
Click to expand...

He's changing gear ratio's, that almost always means a different pinion shim than the one that was in there.
 
I changed gear ratios from 3.73 to 4.56, changed carriers, replaced all bearings and used the original shim to perform the initial checks and even though I am not an expert at doing this, I could tell the pattern checks were not right. But, I am inclined to think like Chris that there is something out of balance with my drive shaft set up or maybe bad u-joints. Looking at replacing the u-joints soon (I have to use the PU 447 ones for the 14 BFF conversion with my existing drive line). I want to get rid of the slip yoke and replace it with a fixed yoke sometime in the near future.
 
38377k5 said:
He's changing gear ratio's, that almost always means a different pinion shim than the one that was in there.
Click to expand...

Even if you change the ratio of a rear end, the pinion gear isnt longer or shorter than factory. I've set up a good bit of ring and pinons, because it was my job. And thats going from 2.73s to 4.56s and stuff like that. Using thick cut ring gears instead of carrier shims or different carriers. If you were using a different housing then yes the pinion gear might not use the same shim. This is just from my person experience, I could be wrong. But I can officially say that I've never had one fail, make a noise, or cause any problems.
 
iwaxmyjimmy said:
Even if you change the ratio of a rear end, the pinion gear isnt longer or shorter than factory. I've set up a good bit of ring and pinons, because it was my job. And thats going from 2.73s to 4.56s and stuff like that. Using thick cut ring gears instead of carrier shims or different carriers. If you were using a different housing then yes the pinion gear might not use the same shim. This is just from my person experience, I could be wrong. But I can officially say that I've never had one fail, make a noise, or cause any problems.
Click to expand...

So you've changed gear ratios many times and never changed a pinion shim? That's contrary to EVERY piece of literature I've ever seen including GM stuff.

I've setup 25-30 diffs and I've only seen one that didn't need the pinion deeper or more shallow.

Generally, replacing the gears with the same ratio in the same housing won't need different shims. Changing ratios almost always does.

I don't want this to get into an argument or anything but what you're saying is contrary to my experience and contrary to everything that's been put into print concerning gears.
 
Okay, guys, I have a question. If my pinion preload was set at 55 in/lbs vice the 25-35 in/lbs, would that make any difference in setting up the pinion shims? I found out today from my friend who set up my pinion that he set it that tight because "that's how we did it in drag racing cars".
 
pierce88K5 said:
Okay, guys, I have a question. If my pinion preload was set at 55 in/lbs vice the 25-35 in/lbs, would that make any difference in setting up the pinion shims? I found out today from my friend who set up my pinion that he set it that tight because "that's how we did it in drag racing cars".
Click to expand...


Yep, that will make the pinion more shallow. I'd redo it, those pinion bearings will get awfully hot.
 
38377k5 said:
So you've changed gear ratios many times and never changed a pinion shim? That's contrary to EVERY piece of literature I've ever seen including GM stuff.

I've setup 25-30 diffs and I've only seen one that didn't need the pinion deeper or more shallow.

Generally, replacing the gears with the same ratio in the same housing won't need different shims. Changing ratios almost always does.

I don't want this to get into an argument or anything but what you're saying is contrary to my experience and contrary to everything that's been put into print concerning gears.
Click to expand...


Well I'll let you know if one fails, but so far so good (knock on wood). And the patterns were all pretty good, but yet some were damn near perfect. Not chastising reading literature to gain knowledge but sometimes doing is alot better than a book. I've set up atleast 200 if not more with 75% being aftermarket. Thats also from camaros and s-10s, mustangs (last one I did was a full spool, c-clip elminator, 4.30 gears all to go into a 04 cobra that was making mid 600s in horsepower and its still going strong), all the way up to hogs heads in dana axles under medium duty trucks.
 
Well, both of you were right about the pinion shims. Since I had nothing to lose, I put the original shim in and took a reading and it was pretty near where it was supposed to be. I did have to take of .002 to get it more centered. Backlash was at .005 and I took it for a test run. It still has a slight vibration around 55-60 but no vibration around 70-75 (which is as fast I will probably drive it on the highway). The pinion preload being at 55 in/lbs now has me wondering if that is the source of the vibration at 55-60 mph. It could just be a new resonance vibration I am getting from the drive shaft spinning faster too. Still working on that fix. Thanks everyone for the help. - Wes
 
Used to live in Goose Creek,bout 4-5 of the best years of my life. I have a vibration thats been with my K5 since I bout it.( 45-55mph) After swaping axles with deeper gears and double cardon shaft it's still there and is a little worse. I believe the slip yoke is to blame. I just live with it.
 
Well, I finally got around to posting the pics of last night's gear pattern checks. The first pic is with the original .019 shim and the B/L set to .008.
The second pic is with the .017 shim and the B/L set to .005 and it is the one I finally settled on. I drove for about 20 miles and checked the pinion to see if the bearings got hot and they were only warm to the touch so I don't think having them set to 55 in/lbs preload is hurting them any. I will recheck the preload after the 500 mile break in just to be sure though.

019 shim.jpg

017 shim.jpg
 
Johnathan,
I believe the slip yoke is my problem also. With the vibration, how often do you have to replace your u-joints? - Wes
 
Wes, I hav'nt noticed any wear at the joints. I've had tha new shaft since I installed the lift and swaped axles about 4-5 yrs ago. The vibe I get is worse if I accelerate through the said speed. It's really annoying but like I said I have just lived with it.I would like to replace the bushing in the transfercase, I've heard this can help with vibration. If you search you'll find that it seems to be a slip yoke problem. A fixed yoke really cleans up your driveline.
 
pierce88K5 said:
Okay, guys, I have a question. If my pinion preload was set at 55 in/lbs vice the 25-35 in/lbs, would that make any difference in setting up the pinion shims? I found out today from my friend who set up my pinion that he set it that tight because "that's how we did it in drag racing cars".
Click to expand...


55 is NOT within tolorance.


Pinion Bearing Preload
Set to: 5-15 in-lbs for used bearings / 25-35 in-lbs for new bearings

55 is way to tight and you have over crushed the sleeve now. You'll need a new one.



Like someone said, you are going to over heat the bearings. You may not see it in the begining, but they are going to fail at some point for sure.
 
I did not see any indications of overheating for a 20 mile test run so I thought I was safe and took it on the interstate for a 70 mile round trip to a pistol match yesterday. After I got to the range I hopped out and felt the pinion and just about left fingerprints behind it was soo hot! So, today I picked up a new seal and luckily I had purchased some extra crush sleeves and pinion nuts and tore the pinion assembly back down to parade rest and inspected everything to make sure I did not damage any of the bearings after my limp home from the range yesterday and reset the pinion preload to 30 in/lbs. That is a lot of torque by the way. I had to go to Sears and pick up a 3/4" socket set ($268!) in order to get the crush sleeve to even start to crush! I went very slowly and measured about every 1/64th of a turn after I started making bearing contact and about 30 minutes later I was at 30 in/lbs and called it good. So yes, 55 in/lbs is too tight for a daily driver. Maybe not for a drag car but definately for a daily driver!
 
You must log in or register to reply here.

Latest Posts

Top Bottom