Side Yoke End Play- Tech Friends?
08-30-2017, 01:16 AM
#1
Le Mans Master
Thread Starter
Side Yoke End Play- Tech Friends?
hello fellas- I've had a bad wheel bearing LR sidelining my 69 for a month. I was reading about checking rotor run-out on disc brake cars and I bought an inexpensive harbor freight dial indicator for the job coming up.
In order to become acquainted with this handy device, I went about checking my old distributor end play and moved on to the side yoke end play on my 64.
I found little-to-no front end slop, but I'll be doing the front end anyway as I note below. At the rear (despite how much is new, also listed below) I found a whopping .060-.070 end play at the one yoke I checked. I've been voraciously reading threads here (and in the c3 archives) that say .002-.006 is about ideal! I know I'm losing camber in a turn- and road forces may put even more end play that what I observed!
Some background notes I think some would want to know- and then my real question-
Now, my 64 has been faithful and always "gotten me home" but I've never really known what it was supposed to handle like when new. I have a set of MOOG ball joints and Delco control arm bushings and a set of MOOG front springs for the front end (I need to do this while I'm doing the slotted cross shafts for added caster after my Borgenson swap). I also have a MOOG idler arm and will probably go in for the tie rod ends to finish the job. My sway bar bushings are new poly and the shocks are new (~3k miles) KYB's. Nothing fancy. Rear strut rods are rebuilt by Bair's.
The tires are 205/75 coopers. Trailing arms and rebuilt by Bair's (well under 3k miles). New solid Spicer u-joints in the half shafts only.
Positraction works (empirically tested). New Timken front bearings.
Alignment done by the "old timers" corvette shop in our town. Owner has had his SWC since the '70's, and has a good reputation among restorers and hot rod builders. Not some big box shop.
That's my suspension background.
The 64 has always felt like it pitches over a bit and "takes a set" before entering a hard turn. Sometimes with a light clunk transmitted through the car, sometimes not. Oversteer always seems exaggerated even with a tall (75 series) 205 tire my vanity dictates.
In short I always thought the car should handle much better for a car with a 3,1xx curb weight but I made excuses for it because of its tires (tires being a big difference between it and the 69, chassis wise)
And- admittedly- I never drove one restored to new (much less remember them new).
I guess I'm looking for a little late- night advice- will building the rear end this winter give me much more of a controlled and responsive feel?
I'm chasing balanced handling in a car I really don't want to take off the frame for a decade or more (Lord willing I make it) until the kids are grown. As it is now it's cosmetically perfect for the stage of life our family is in.
In order to become acquainted with this handy device, I went about checking my old distributor end play and moved on to the side yoke end play on my 64.
I found little-to-no front end slop, but I'll be doing the front end anyway as I note below. At the rear (despite how much is new, also listed below) I found a whopping .060-.070 end play at the one yoke I checked. I've been voraciously reading threads here (and in the c3 archives) that say .002-.006 is about ideal! I know I'm losing camber in a turn- and road forces may put even more end play that what I observed!
Some background notes I think some would want to know- and then my real question-
Now, my 64 has been faithful and always "gotten me home" but I've never really known what it was supposed to handle like when new. I have a set of MOOG ball joints and Delco control arm bushings and a set of MOOG front springs for the front end (I need to do this while I'm doing the slotted cross shafts for added caster after my Borgenson swap). I also have a MOOG idler arm and will probably go in for the tie rod ends to finish the job. My sway bar bushings are new poly and the shocks are new (~3k miles) KYB's. Nothing fancy. Rear strut rods are rebuilt by Bair's.
The tires are 205/75 coopers. Trailing arms and rebuilt by Bair's (well under 3k miles). New solid Spicer u-joints in the half shafts only.
Positraction works (empirically tested). New Timken front bearings.
Alignment done by the "old timers" corvette shop in our town. Owner has had his SWC since the '70's, and has a good reputation among restorers and hot rod builders. Not some big box shop.
That's my suspension background.
The 64 has always felt like it pitches over a bit and "takes a set" before entering a hard turn. Sometimes with a light clunk transmitted through the car, sometimes not. Oversteer always seems exaggerated even with a tall (75 series) 205 tire my vanity dictates.
In short I always thought the car should handle much better for a car with a 3,1xx curb weight but I made excuses for it because of its tires (tires being a big difference between it and the 69, chassis wise)
And- admittedly- I never drove one restored to new (much less remember them new).
I guess I'm looking for a little late- night advice- will building the rear end this winter give me much more of a controlled and responsive feel?
I'm chasing balanced handling in a car I really don't want to take off the frame for a decade or more (Lord willing I make it) until the kids are grown. As it is now it's cosmetically perfect for the stage of life our family is in.
Last edited by ChattanoogaJSB; 08-30-2017 at 01:44 AM.
08-30-2017, 01:26 AM
#2
Le Mans Master
Thread Starter
Sorry men- the infernal iPhone will not let me remove the line spacing between paragraphs. When I go to edit it basically cuts off the bottom two-thirds of my post and I've tried it several times. My apologies for it being so hard to read.
John, Duke, 65TripleBlack- others- thank you for the archived posts I've read so far. I'm not trying to complain about my car at all- on the contrary the dial indicator is actually a neat little tool and really opens my eyes to new possibilities. I'm fascinated. I just want the most the car can give me!!!
-benton
John, Duke, 65TripleBlack- others- thank you for the archived posts I've read so far. I'm not trying to complain about my car at all- on the contrary the dial indicator is actually a neat little tool and really opens my eyes to new possibilities. I'm fascinated. I just want the most the car can give me!!!
-benton
Last edited by ChattanoogaJSB; 08-30-2017 at 01:30 AM.
08-30-2017, 08:24 AM
#3
Race Director
Member Since: May 2000
Location: Redondo Beach USA
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...glad you checked the archives, so what I say here may be a repeat.
There is no actual factory spec for side yoke end play other than the Chev. Power Manual saying zero to five thou for an axle being prepared for racing. GM sold shims that you could install between the last Posi clutch and inside end of the case to achieve this.
The only spec, which is listed in later COMs is differential gear backlash, and I recall it's something from about two to six thou.
I bought a new loaded Posi case from GM for my axle, and the differential gear backlash was in spec. Once I got the case installed in the carrier with proper ring and pinion backlash and side bearing preload, the yoke end play was five and seven thou.
I decided to leave it that way. Changing these shims requires dissembling the case, and a shim change affects both end play and differential gear backlash. It can be a tricky operation.
I would say that with a new loaded case if side yoke end play is no more than ten thou, you're good to go.
Yoke end play and diff. gear backlash increases due to Posi clutch wear. Also, beginning sometime in the C3 era the yokes were not as well hardened as C2 yokes, and the yoke ends would wear. It's not generally an issue with C2s, but it should be checked during an axle overhaul.
Duke
There is no actual factory spec for side yoke end play other than the Chev. Power Manual saying zero to five thou for an axle being prepared for racing. GM sold shims that you could install between the last Posi clutch and inside end of the case to achieve this.
The only spec, which is listed in later COMs is differential gear backlash, and I recall it's something from about two to six thou.
I bought a new loaded Posi case from GM for my axle, and the differential gear backlash was in spec. Once I got the case installed in the carrier with proper ring and pinion backlash and side bearing preload, the yoke end play was five and seven thou.
I decided to leave it that way. Changing these shims requires dissembling the case, and a shim change affects both end play and differential gear backlash. It can be a tricky operation.
I would say that with a new loaded case if side yoke end play is no more than ten thou, you're good to go.
Yoke end play and diff. gear backlash increases due to Posi clutch wear. Also, beginning sometime in the C3 era the yokes were not as well hardened as C2 yokes, and the yoke ends would wear. It's not generally an issue with C2s, but it should be checked during an axle overhaul.
Duke
Last edited by SWCDuke; 08-30-2017 at 08:43 AM.
08-30-2017, 09:36 AM
#4
Safety Car
With that much end play, it's doubtful that your posi clutches have proper preload and the posi may be delayed in "locking" as designed. Likely your stub axles are worn as well as the center "pin", c-clips and clutch packs. I have seen cases where even the preload springs and cage assembly are damaged.
If you haven't seen my post in the archives regarding building a posi case without using preload springs, then looc at both parts of the video from Tom's differentials in Idaho. It's not as hard as it looks and the results are amazing:
https://www.tomsdifferentials.com/
Tom's has very high quality parts, and I recommend buying from them, or Corvette International, formerly International Axle in MN. If your clutch packs are worn, DO NOT use the original "snowflake" shaped clutches. Use the solid, circular shaped parts which will not shatter like the snowflakes can.
Another rebuilder, closer to home, in CT, is Gary Ramedei, who uses Tom's method for the rebuild.
If you haven't seen my post in the archives regarding building a posi case without using preload springs, then looc at both parts of the video from Tom's differentials in Idaho. It's not as hard as it looks and the results are amazing:
https://www.tomsdifferentials.com/
Tom's has very high quality parts, and I recommend buying from them, or Corvette International, formerly International Axle in MN. If your clutch packs are worn, DO NOT use the original "snowflake" shaped clutches. Use the solid, circular shaped parts which will not shatter like the snowflakes can.
Another rebuilder, closer to home, in CT, is Gary Ramedei, who uses Tom's method for the rebuild.
Last edited by 65tripleblack; 08-30-2017 at 09:40 AM.
08-30-2017, 10:21 AM
#5
Le Mans Master
Thread Starter
Duke- thank you for the reply! I did read before some of your past comments on spec/no spec and the case hardening thickness difference c2 to later c3. That said, your wisdom is mich appreciated!
65- thanks for pointing me back toward the Tom's video. They make the process much more accessible for a first timer. I'll have to read a bit more about the rest of the rear end rebuild but I do see how my end play and posi clutches should be set. Absolutely!
All i can say about my setup now is that it's a typically neglected part which is probably true at showing 101k. I am getting posi engagement in a nice bilateral pavement pattern (if that is meaningful to you) but obviously I'm suffering the ill effects of inconsistent camber.
Would you guys expect fixing the end play to change the cornering manners of the old girl substantially? I realize that's a less technical sort of question.
Benton
65- thanks for pointing me back toward the Tom's video. They make the process much more accessible for a first timer. I'll have to read a bit more about the rest of the rear end rebuild but I do see how my end play and posi clutches should be set. Absolutely!
All i can say about my setup now is that it's a typically neglected part which is probably true at showing 101k. I am getting posi engagement in a nice bilateral pavement pattern (if that is meaningful to you) but obviously I'm suffering the ill effects of inconsistent camber.
Would you guys expect fixing the end play to change the cornering manners of the old girl substantially? I realize that's a less technical sort of question.
Benton
08-30-2017, 10:40 AM
#6
Safety Car
Duke- thank you for the reply! I did read before some of your past comments on spec/no spec and the case hardening thickness difference c2 to later c3. That said, your wisdom is mich appreciated!
65- thanks for pointing me back toward the Tom's video. They make the process much more accessible for a first timer. I'll have to read a bit more about the rest of the rear end rebuild but I do see how my end play and posi clutches should be set. Absolutely!
All i can say about my setup now is that it's a typically neglected part which is probably true at showing 101k. I am getting posi engagement in a nice bilateral pavement pattern (if that is meaningful to you) but obviously I'm suffering the ill effects of inconsistent camber.
Would you guys expect fixing the end play to change the cornering manners of the old girl substantially? I realize that's a less technical sort of question.
Benton
65- thanks for pointing me back toward the Tom's video. They make the process much more accessible for a first timer. I'll have to read a bit more about the rest of the rear end rebuild but I do see how my end play and posi clutches should be set. Absolutely!
All i can say about my setup now is that it's a typically neglected part which is probably true at showing 101k. I am getting posi engagement in a nice bilateral pavement pattern (if that is meaningful to you) but obviously I'm suffering the ill effects of inconsistent camber.
Would you guys expect fixing the end play to change the cornering manners of the old girl substantially? I realize that's a less technical sort of question.
Benton
Now the good news. If you draw a triangle using .065" and 13" (1/2 the diameter of the wheel/tire) with a right angle between, and solve for the tangent of .065/13, the angle that the camber moves out of spec is less than one degree..................negligible. The deviation due to excess end play is actually: .29 degrees.
Last edited by 65tripleblack; 08-30-2017 at 11:05 AM.
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USMC 0802 (08-31-2017)
09-27-2017, 06:22 PM
#8
Drifting
I hope no one minds if I add a few things.
Original 63-64 diffs used a Dana posi in an eaton housing. Most of these units get replaced with an eaton posi unit.
Minimum stub axle end play is .005 to allow for heat expansion. There are no specs for the range of endplay since the stub axles were considered a non-wear part. If any wear was found then you just replace them. .005-.015 was standard set-up. The .002-.006 is the backlash for the spider gears.
Common wear on eaton clutchpacks over a long duration is around .020 per side. Add .010 for original setup. So any end play above .030 will be stub axle wear.
All 65-early 70 used solid clutches and 10-18 spider gears. Late 70-79 used slotted clutches and 10-17 spiders. 65-early 70 also used copper thrust washers and the stub axles were apprx. .005 longer than the 71 up.
Mid year -70 stub axles rockwelled at 22 for sb and 28 for bb. Early 70's this was changed to 12 across the board and by 77 dropped to 6.
65- early 70 sb and low hp bb used a standard iron carrier. HP bb used a nodular iron carrier Starting in late 70 the "117" large window carrier was used for all and in 1975 was upgraded to the "297" carrier, which was the best of all of them.
Other than wheel bearings and very worn stub axles, the pitching over feeling is caused by worn strut rod bushings. In 1975 they changed to the large bushing strut rod which didn't help at all.
Mike
Original 63-64 diffs used a Dana posi in an eaton housing. Most of these units get replaced with an eaton posi unit.
Minimum stub axle end play is .005 to allow for heat expansion. There are no specs for the range of endplay since the stub axles were considered a non-wear part. If any wear was found then you just replace them. .005-.015 was standard set-up. The .002-.006 is the backlash for the spider gears.
Common wear on eaton clutchpacks over a long duration is around .020 per side. Add .010 for original setup. So any end play above .030 will be stub axle wear.
All 65-early 70 used solid clutches and 10-18 spider gears. Late 70-79 used slotted clutches and 10-17 spiders. 65-early 70 also used copper thrust washers and the stub axles were apprx. .005 longer than the 71 up.
Mid year -70 stub axles rockwelled at 22 for sb and 28 for bb. Early 70's this was changed to 12 across the board and by 77 dropped to 6.
65- early 70 sb and low hp bb used a standard iron carrier. HP bb used a nodular iron carrier Starting in late 70 the "117" large window carrier was used for all and in 1975 was upgraded to the "297" carrier, which was the best of all of them.
Other than wheel bearings and very worn stub axles, the pitching over feeling is caused by worn strut rod bushings. In 1975 they changed to the large bushing strut rod which didn't help at all.
Mike