Intrested in a custom tailstock busing for a PERFECT fit?

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95blklsc

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Well I'm pretty damn sure my vibration is due to too much play in the tailstock. My yoke on the shaft is perfect 1.598, which means the tailstock bushing should be about 1.600. Just enough clearance for fluid and temp changes. Anyway so I took the tailstock out and had a new bushing pressed in at a local trans shop. Guess what about 7 thou MORE clearance than there should be. The thing is just as loose as it was before. So I found a few parts distributors that carry this bushing and specify a 1.599 or 1.600 size, I ordered all of them. They all come in and guess what, basically the same verdict as before, way to big, unbelievable. So here's what I'm doing, making my own. I just bought piece of bronze bushing material from a local supply house to machine it from. I'm going to machine it to the 1.600 ID spec. How many of you would be interested in getting one? I can make a few extra while I'm at it. I have done enough work in a machine shop to make them to a VERY tight tolerance, basically 1.600, +/- .0005. I'm thinking like $35-40 each depending on how long it takes, no prices are set in stone. Just so you know bronze is not cheap, I just bought enough to make about 3 for $30. If you pay a machinist to make this you are looking at $65+ an hour. Anyway, I will let you guys know how it works out. I can also put together a forced lube kit to include with this. The only thing you will have to do is drill and tap the tailstock. BTW,

I've also done some reading on f-150 forums and many guys with 2wd (same trans) have the same problem. I couldn't find anyone that actually found a solution..........so I'm making one.

On another note to those of you that remember my posts about my vibration problems here's why I'm betting that this is the problem now. (besides that it's the only damn thing left)

-new Spicer sealed u-joints
-MMX shaft checked for balance (15k rpm) and run out, PERFECT
-wheels balanced on hunter, came out with less than 5 lbs. of variation, norm is 10-20
- it vibrates with wheels off up on jack stands, it's centered at the tailstock
-the yoke knocks around in the bushings when you move it laterally or vertically
-also pinion angles are witin .5 deg

-MANY people say this is normal, but think of it this way, would you trust the main bearings in your engine of they had 7 thou of play? probably not, different situation but same idea.
 
RE: Intrested in a custom tailstock busing for a PERFECT fit?

If I had more time I'd really think about flash chroming the yoke and have it ground to the right size. It's a really good option. The problem is, this is my daily driver, the only places around here said it would take them about 2 weeks before they could get to it, not an option for me. So on Sunday I went ahead and started at the lathe. I took my time and really got it DEAD on. The ID was exactly .001 over the size of the yoke, and the OD was .0015 larger than the tailstock. I made a small oil galley running the length of the bushing and drilled a .050 hole for the forced lube mod. It was a perfect fit, no slop anymore. Just slid right in and that's it. Put it in and let the car run for about an hour at 40 MPH up on jacks to make sure I didn't have any excessive heating at the tailstock. When the car is sustained at 75 the immediate area around the bushing heats up about 10-20 warmer than the fluid in the pan but I don't think it's anything to be concerned about. And YES it fixed 99% of my vibration. No drive train vibe anymore, the issue I do have is a slight engine vibe at 2500, even when in neutral. My gut feeling is motor mount related, but I'll dig into that next weekend. I can't believe how many transmission "experts" told me I was wasting my time and that was totally normal. It's not and a correct size bushing fixed it. It's just too bad I had to go though all the time of making it but I know it's right now. I'm going to go to a few local CNC shops and see how much it would cost to get bushings that are the correct size made.


SUMMARY: ANY movement of the yoke in the tailstock CAN cause vibrations. FIX: make the parts yourself because all premade bushings I've found have excessive clearance.
 
RE: Intrested in a custom tailstock busing for a PERFECT fit?

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... I took my time and really got it DEAD on. The ID was exactly .001 over the size of the yoke, and the OD was .0015 larger than the tailstock.
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Did you mic the ID after installing the bushing in the tailstock? Seems mighty tight for such a thin section of soft material. Isn't 0.001" clearance awful tight for an application such as this? At 0.001" clearance of the ID and 0.0015" interference on the OD, there isn't much room for thermal expansion IMHO.

What material is the bushing?
 
RE: Intrested in a custom tailstock busing for a PERFECT fit?

ID didn't change at all after installation, I was surprised but my grandfather (a machinist for the navy, worked on torpedoes for 30 years) said it won't change a bit after install. Dammit he was right, I was VERY surprised. And yes. 0.001 is tight but it's enough for fluid to flow. Once it is slipped in there is not binding or tightness, it just rotates very easily without all the play. And as you said thermal expansion, it's something to be very aware of. The clearance of .001 will only get larger as things heat up, both the ID of the bushing and the OD of the yoke will expand as they heat up. The yoke and bushing are generally going to heat up to just about the same temp. While the metals will have different expansion rates, they are pretty close, it shouldn't be a problem, they shouldn't see over 200F anyway. I also had this concern and spoke with a few experts on it. I did talk with a few machinists and a guy I know that build some serious race cars. All of them said about 0.001 should be perfect, more than enough just enough for lubrication but not enough for excessive movement. Although bronze is considered soft, it's still plenty strong enough, absolutely nothing changed in size after installation. I also ran it on jacks for a long time while monitoring it with an IR temp gauge, no excessive temps. Everything was stable at 150-160 (the temp of the trans) and slightly higher when turning at highway speed. I also took it for a 20 minute drive and came home to check the temp. Again, everything was normal and the vibration was 99% gone. What's left for vibration is coming from the front end, 99% sure it's the motor mount, EVERYTHING else in the front end suspension is new including the rack. The only original piece is the spindals, sway bar, and end links.
 
RE: Intrested in a custom tailstock busing for a PERFECT fit?

forgot to say the bushing material is bronze, it's what was reccomended to me by a few experts.
 
RE: Intrested in a custom tailstock busing for a PERFECT fit?

Sounds like you did your homework then. :)

Do you have the forced lube mod in place? What type of oil groove did you cut in the ID of the bushing?

Beryllium copper makes an excellent choice for material to supplant typical bronze bushings. I've seen the material used in extreme applications and hold up very well. Caterpillar even utilizes it for various extreme service applications. Albeit quite expensive and somewhat hard to find, appropriate sized tubing stock should be economical enough with minimal machining and waste. Something to consider should you find the bronze does not hold to tolerances well.
 
RE: Intrested in a custom tailstock busing for a PERFECT fit?

The beryllium copper was actually what I was looking for but the local supply house didn't have any, it's a special order material they said. So I got the second choice bronze. I did put an oil groove and did the force lube mod. I wouldn't put clearances that tight without it, I would be very worried. I did bother me that the stock lubrication system for the tailstock relies on acceleration to slosh the fluid back there. I can see this being very bad if you have gears and do a lot of sustained highway driving. The forced lube is definitely a must with gears, I can really see that now.

We'll see how the bronze holds up, if not I'll search high and low for the beryllium copper. I think the bronze should be ok, that's what I was told anyway. Also, another way to look at this is if you think about it there really isn't much of a load on the ID of the bronze. It's really there to locate the yoke and output shaft more than anything. Anyway, I'll make sure to post if I find it's not working out, or the bronze isn't holding up very well.
 
RE: Intrested in a custom tailstock busing for a PERFECT fit?

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... I did bother me that the stock lubrication system for the tailstock relies on acceleration to slosh the fluid back there. I can see this being very bad if you have gears and do a lot of sustained highway driving. The forced lube is definitely a must with gears, I can really see that now. We'll see how the bronze holds up, if not I'll search high and low for the beryllium copper. I think the bronze should be ok, that's what I was told anyway. Also, another way to look at this is if you think about it there really isn't much of a load on the ID of the bronze. It's really there to locate the yoke and output shaft more than anything.
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In a perfect world, {insert Walgreen's commercial here}, the tailshaft doesn't really require much lubrication for normal service. It's amazing what 'splash lubrication' is relied on in today's technology. The simple fact is you answered your own question. There isn't much SIDE load on the bushing. Look at the predominant RPMs as well. With the exception of the occasional burst at WOT, tailshaft rpms are low for this engineered application. I realize there will always be someone who chants the forced lube mod requirement with 4.10s and higher, but perhaps they have other requirements as well that preclude 'splash lubrication'. In your application for example... with a clearance of 0.001" I would say forced lubrication is a requirement.
 
RE: Intrested in a custom tailstock busing for a PERFECT fit?

well said driller, with 0.001 clearance I wouldn't chance it by not putting in forced lube. Once you have the tailstock off it's very easy to do the forced lube mod, maby an hour of work going slowly. The only thing you need is a 1/8 pipe tap, the proper drill bit (forgot the size) for the tap, a .050 or smaller drill bit for the bushing, a brake line, and a flaring tool. I was thinking about putting braided steel hose but that's some expensive stuff, not in the budget this month!!
 
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