A833OD with worn output spline

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Binderman

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I am using an A833OD with an iron main case behind a 440 in a street rod pickup. Having noticed a vibration when "floating" the drive train at over 70 mph. I have narrowed it down to a sloppy fit between the slip yoke and the output spline. With the main shaft in the vise with full spline contact, I am measuring more than .027 vertical end play on both a used slip yoke, and new one from Spicer. I have managed to get my hands on another shaft, and it is just as bad if not worse. In comparison, I measured a Saginaw 4-speed, and only saw.004 vertical end play. Is it normal to see the A833 this sloppy? Is there a possibility of getting the spline or slip yoke coated with a product that will tighten it up, maybe similar to the coatings on piston skirts? With 4:33 gears, the driveshaft is spinning 3300 plus at highway speed. No issues well past 100MPH as long as I either stay on the gas, or completely off it. Anywhere near neutralizing it will shake the mirror off the cab. Any guidance is much appreciated.
 
Same vertical travel with new and used slip yoke points to bad extension housing bushing. Not bad once you get the tail housing off.
 
How much play is in the front input.
Sounds like that trans could use a rebuild.
A rebuild with all new bearings does not cost that much.
Contact Wayne at Brewers. http://www.brewersperformance.com/
 
Thanks for the reply guys. I previously changed the bushing with no change, as my first instinct was that the bushing was worn. Using a dial indicator, I measured the same play before and after the bushing swap. After being told the slop was not an issue, I have since had three different driveshafts in it including a new slip yoke, and had the rear gear apart twice. Eventually it all pointed back to the slip yoke. The tranny is out and apart now, and I am measuring the end play with the shaft in a vise, therefore all other parts are no longer a factor. Although I agree there may also be some play in the input shaft, and I do have the parts for a complete rebuild there is no point to putting it back together until I have solved the spline issue. In my comparison with the Saginaw, I had to limit the yoke to 1/2" of spline engagement to get .027 vertical end play. Please don't take it as arrogance on my part, but my interest is really only limited to the fit between the spline, and the slip yoke. If I cannot get a better tolerance on the spline, I will need to devise a new plan.
 
Binderman said:
Thanks for the reply guys. I previously changed the bushing with no change, as my first instinct was that the bushing was worn. Using a dial indicator, I measured the same play before and after the bushing swap. After being told the slop was not an issue, I have since had three different driveshafts in it including a new slip yoke, and had the rear gear apart twice. Eventually it all pointed back to the slip yoke. The tranny is out and apart now, and I am measuring the end play with the shaft in a vise, therefore all other parts are no longer a factor. Although I agree there may also be some play in the input shaft, and I do have the parts for a complete rebuild there is no point to putting it back together until I have solved the spline issue. In my comparison with the Saginaw, I had to limit the yoke to 1/2" of spline engagement to get .027 vertical end play. Please don't take it as arrogance on my part, but my interest is really only limited to the fit between the spline, and the slip yoke. If I cannot get a better tolerance on the spline, I will need to devise a new plan.
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Call Wayne at the link I posted above, he is a wealth of knowlege and very helpful.
And if you need any parts he will have them reasonable.
 
Yep,I'd rebuild the tranny. Cheap insurance at the least.
 
I have spoken to Wayne at brewer's, as well as Jamie Passon. I get the impression from both of them that this is not a common complaint. This would generally lead me to believe that a sloppy slip yoke fit on these shafts is the norm. It should be noted that the key factor here is the higher than usual shaft RPM. If I were to run a higher rear gear, the problem would subside, but what fun is that? I also tried my slip yoke in a 727, and it was quite snug. Is it possible that just the OD shafts are out to lunch?
 
Mic the od of the 4-speed splines and 727.
Also compare the distance between the splines
 
10/4, I will try to measure the better looking of the 2 shafts, and compare to the 727. As the 727 is at a friends shop, it may take a couple of days to net the results. The original shaft is hard to measure, as the splines have a ridge on the top on the drive side from repeated hammering due to excessive clearance. This will skew the measurement, as the tops of the spline teeth are no longer flat and consistent. I am assuming the distance between the splines is referring to the measurement between the tips of the teeth. I expect this is where I will see the issue, as that would indicate the wear on the mating surfaces. The question is, how do I deal with that? Is it possible to teflon coat, or flame spray the spline to build it up, then machine to proper tolerance?
 
You might also want to try a yoke from a 518 transmission (if you can find one to borrow) to see how tight it fits. They have a slightly different spline shape and normally fit too tight on a 727 or 833 but maybe with the wear you have, it might work.
 
I'm beginning to think the slip yoke splines on the cast iron OD units are a little different than everything else. I bought a new yoke from Brewer's and it fits my '68 A-body unit perfectly, but on my cast iron OD shaft the new yoke will go on about two inches VERY TIGHT and then stops, and I have to use a rubber mallet to get it back off. Both are 30 spline. And you say you have a new yoke that fits your OD shaft too loose? I am very confused.
 
opnwhlracer said:
I'm beginning to think the slip yoke splines on the cast iron OD units are a little different than everything else. I bought a new yoke from Brewer's and it fits my '68 A-body unit perfectly, but on my cast iron OD shaft the new yoke will go on about two inches VERY TIGHT and then stops, and I have to use a rubber mallet to get it back off. Both are 30 spline. And you say you have a new yoke that fits your OD shaft too loose? I am very confused.
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10/4, I have a spare non OD 833, and my yoke fits it fairly sloppy as well, but it is brutally loose on the OD shaft. There is another thread on here that I have been following where a fellow has had some similar fitment issues whereas his new yoke is too tight on a 727. The main issue appears to be quality control issues on the part of the slip yoke manufacturers regarding tolerances. That being said, I wouldn't be surprised if the factory tolerances on the shaft were less than stellar. None of this would be a problem if I weren't spinning the drive shaft at 3300 RPM plus at highway speed. I feel as if I am on the verge of a solution, and if so will share the results so we can all learn.
 
Measured the spline on both of my mainshafts last night. They show the following:
Original Shaft Major= 1.275
Minor= 1.273
Used Replacement Shaft Major= 1.273
Minor= 1.271

Interesting, a .002 difference between the 2 shafts. Doesn't sound major, but I measured a Muncie shaft, and new slip yoke, and came up with a clearance fit of .003. That almost sounds too tight but it corresponds with a beautiful snug fit on the yoke. Although it has become obvious that the replacement Mopar yoke tolerences are all over the place, I am almost positive the shaft spline tolerances are out to lunch also. I made my measurement using a quality vernier caliper. I spoke to Powertrain, as their name is on the yoke. They said this particular yoke is an "Off Shore" unit. The Major spline measurement on it is supposed to be 1.312. In my case, that would mean .039 clearance on my replacement shaft. That is way crazy for loose fit, howver there must be an adjustment for the fact that the yoke has a V in the Major measurement, whereas the tooth is flat on the yoke. If anyone following this thread is interested in sharing the Major, and Minor measurements on their spline, I would be interested in seeing the differences. The search rumbles on!
 
I will measure both my '68 and '75 main shaft tonight and post what I come up with. I have a nice digital caliper that is pretty accurate. I hope I don't have to buy 3 or 4 yokes to find one that will fit my OD shaft.
 
The OD main shaft: 1.281 major, 1.182 minor
The '68 A-body shaft: 1.280 major, 1.183 minor
I think it's how the splines are cut in the aftermarket yoke. I''l post some pics.
 
I measured the spline on the 727 i mentioned in an earlier post, and found the following: Major= 1.277
Minor= 1.191
The major is obviously .002 larger than than measurement on my 833, but the minor is.018 larger than mine, Yikes! This only serves to confirm the tolerance differences between shafts. Incidently, my yoke fits beautifully snug on the 727, but brutally sloppy on my 833. Again,the difference in Major and Minor has me a little confused, as with the tooth being flat on top, and the root being a V, I am thinking this may not be the correct way to measure this type of spline. Anyone know a machinist or engineer that can give advice on this? As the contact is on the flats of the "V", I can't see how the major and minor measurements as compared with the slip can have any useful meaning. sireland67 mentioned the distance between teeth, and I also believe that to bey the key, but I am not sure how to accurately measure that. What is the part# on the yoke from Brewer's? I may order one to try.
 
Brewer's # for it is TY8330. 7260 joint. But, I believe it's the same Chinese manufactured yoke everyone is selling. I'm going to order one of the PTI made yokes and see if I have better luck. This may be a combination of manufacturing tolerances from the OEM shaft and the aftermarket yoke making the fit all over the place. I hate to say it, but I might have to buy several yokes to get one to fit right. Great.
 
Based on my experience so far, I would prefer your situation in that the yoke needs to be tapped lightly to get it on the spline. An interference fit is going to cause issues, but due to the fact that there is usual a little roughness on the splines on a fresh yoke, combined with the fact that you have the shaft out, making it easier to work with, I would consider putting the shaft in a vise, and gently tapping the yoke back and forth on it until it wears the roughness off the spline. I am wondering if you could use some lapping compound to ease the process. It may seem extreme, but a snug fit on that yoke will make for happy cruising, particularly if you plan on putting steep rear gears in it.
 
Finally got my old truck back together tonight. A month ago, I convinced Wayne at Brewers to run some measurements on one of his replacement main shafts vs a new TY8330 yoke. Having found a matched set that measured less than .010 vertical end play, I told him I would buy them, but suggested he sift through his stock of yokes, as I was convinced the tighter the better. In the end I basically told him I would like one that you need to grunt to push it in. He laughed, but in the end the one he sent was extremely tight. I measured the end play on the shaft and yoke in the vise, and it was less than .005. Had the tranny reassembled with this shaft, and new synchros, bearings etc. Took it for a test run tonight, and no more vibration at any speed. Doing the happy dance now! Bottom line is there are many things that can cause a drive line vibration. A loose slip yoke is one of them. Hopefully others can learn from my experience. Thanks to all for the interest and suggestions.
 
I might just ship Brewers my main shaft and see if he can fin a yoke that fits it then. Due to a lot of other stuff going on in my life right now my 69 Dart project has been dormant lately, but I am ready to get back on it again here pretty soon.
 
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