Ring gear backlash states TK instead of number?

mgphoto · 03-11-2022, 09:01 PM

Hello
I am replacing the differential in my transmission with a limited slip.
The factory manual shows the location of the mating number the backlash and the deviation from blue print.
My pinion shows N17 (deviation) and 717 (mating number) the ring gear states 717 (mating number) and TK for the backlash?
The backlash typically would be a decimal ie .17 I have never seen letters.
Anyone ever seen this, and if so what does it mean?

Thanks for your help.

Dave at Pelican Parts · Dave at Pelican Parts's Garage

I've reached out to a transmission guru who is active in other forums here. Hopefully he will take a look and comment.

--DD

mgphoto · 03-13-2022, 05:23 PM

Thanks Dave, I appreciate the help.

Matt Monson · 03-14-2022, 09:17 AM

TK is someone's initials.

Standard backlash is .15 and then usually they would also mark a second number for deviation from that, determined when they run them in together to make the least noise. Absent any other markings on the ring, I would set it at the standard .15.

mgphoto · 03-14-2022, 10:09 AM

Thank you Matt, saves me swapping to a different pinion and ring gear.

Matt Monson · 03-14-2022, 10:52 AM

You’re welcome. Always happy to help.

mgphoto · 03-17-2022, 09:54 AM

Matt I have another question, I am using the factory manual book #3, the procedure that I used was to set the spacers for the differential (my measurement was 6.3 with bearing drag at about 40 in lbs for the FAG bearings) that gave me 3.05 for ring gear side and 3.15 for the other in keeping with the manual statement that the spacers are -.1 and +.1 difference. I measured the old gasket it was .25 I used a .1 + .15 to replace it, I also did the measurement with the VW385 the distance was .22 rounded up to .25. This setup produced a backlash of .55. I replaced the differential spacers using 3.1 for the ring gear side and 3.2 for the other, this increased the bearing drag to almost 60 inch lbs. when assembled this produced a backlash of .41. I tore the .1 gasket disassembling the unit so I tried measuring the backlash at .15, it measured .33 closer but incorrect pinion depth.
My thinking here is to move the ring gear closer to the pinion decreasing the backlash, the manual states to change the differential spacers but increasing the size of the spacers will push the bearing drag way out of spec, the manual states to divide the total size of the spacers in half and minus .1 for the ring gear side and plus .1 for the other.
Can I move the ring gear side closer to the pinion without having to keep to the +1 -1 sizing for the spacers or can I vary the size to +2 -2 this moves the ring gear closer to the pinion reducing the backlash?
If I am mistaken here what should I do instead? Below is the setup for measuring the backlash.
Thanks again Mike