I am doing my first 12bolt since I broke an axle and needed a new spool I am just going with new gears also. Do you always check the pattern? What I struggle with is this. My new gears have been lapped and run in as a set. They have pinion depth numbers and back lash numbers. If you are right on those numbers why would you check pattern? If you don't like the pattern do you move away from where the gears were lapped?

As a machinist I struggle with something as subjective as a smeared pattern in colored grease causing a change. Just curious what others think.

quote:

Originally posted by CURTIS REED:
I am doing my first 12bolt since I broke an axle and needed a new spool I am just going with new gears also. Do you always check the pattern? What I struggle with is this. My new gears have been lapped and run in as a set. They have pinion depth numbers and back lash numbers. If you are right on those numbers why would you check pattern? If you don't like the pattern do you move away from where the gears were lapped?

As a machinist I struggle with something as subjective as a smeared pattern in colored grease causing a change. Just curious what others think.

I have done several and always checked the pattern. I have toyed with them to get the pattern better (honed out bearings help). NO doubt it's a PITA and subjective. With that being said the gears I installed took a pounding of several hundred runs in a heavy car before breaking. And they were always quiet until the big bang. lol

Always check the pattern, it's ONE of the determining factors in the life of the gear set. Bearing pre-load (pinion and carrier bearings) plus back lash are just as important. I check the pattern in quadrants (four equally spaced locations). It's entirely possible to set the pinion depth and back-lash correctly, and still find that the pattern is not correct.

Bob

The end pattern is most important, in my opinion. That will help ensure a smooth, efficient setup.

Pretty rare to get the previous pattern duplicated.

Start with the pinion shim that has been working in your housing, regardless of what the pinion depth is marked.
I like to get them as close as possible if the existing pattern is perfect, but I won't agonize over a minor deviation, assuming that the new pattern is in acceptable range.

I appreciate the replies. This is just something that I am struggling with because I'm a numbers guy being a machinist for so long.

Curtis, I understand the numbers thing, and I obsess over precision whenever possible.
All of the advice from the guys above is good.

For myself, I always pattern a new gearset, because all the dimensions of the rear end housing you are working with may not exactly match the jig that the set was lapped in. (And it gives you one more little slice of mental assurance as well, which I am sure you can appreciate). And think about it, if your carrier/spool happened to have even a tiny amount of variation or runout, (horizontal or vertical), the pattern will be affected. This is why Bob's advice about checking the pattern in multiple locations around the ring gear is good.

Big tip here: Do NOT use crush sleeves, (the biggest PITA of working on a 12-Bolt setup). I highly recommend the Ratech spacer & shim kit that eliminates / replaces the crush sleeve. (I believe several other gear suppliers are offering them now. Don't buy a fleabay generic copy. If it is from Motive Gear or a brand you trust, then ok. I stick with the Ratech because they designed the original, I've installed several, and I have not heard of anyone having any issues with them). You simply install the spacer sleeve, measure your backlash, then select the correct shim thickness to add, which will get you to the targeted B/L dimension. Better yet, if you have your old stack of sleeve/shims from the same rear housing, measure them all together with a micrometer, then build a stack to the same length using the Ratech spacer & shims. This is basically simulating what Dave was talking about up above, to get you in the ballpark. They are super easy to work with and durable as well. I just checked mine, after 280 passes on a heavy, trans-brake launched car, and things haven't moved more than .001 - I debated changing or adding a shim, but since I had initially it set up slightly on the tight side, (was a new spool, gearset & all new bearings), I left it as is.

This message has been edited. Last edited by: FootbrakeJim,

I have more faith in the pattern. I try and set the pinion depth dead on, but then I check the pattern too. I'd rather have a great pattern than a perfect pinion depth measurement. That's just me.

I also second the solid pinion bearing spacer with shims. As a numbers guy, I suspect you would prefer it also. If you ever decide to swap out the gears due to wanting to make a ratio change, if you keep the pinion bearings and the pinion spacer shim together with the removed gears, you will be able to put it back together without reestablishing the shim size. Since doing away with crush sleeves, I no longer dread the job.

One thing I also do is check the backlash in at least three different places. If it varies too much, it's time to check spool and/or gear ring runout. Take care. Tom Worthington

Agree, alway check the pattern.

Jim, I already have a Ratech solid spacer and also a Strange solid spacer. Both are nice. The Ratech was used with the last gear set that I am taking out and am going to re-use it instead of going to the Strange. The Strange is really nice and traps the shims between two pieces. I think you transitioned from solid pinion spacer to carrier shims in your description though once you started talking back lash.

This rear was set up by a friend before and had 475 passes on it with zero problems. Heck, even those gears looked great. I just wanted to do it myself and not have to rely on anyone else.

As far as checking different locations for back lash I have checked every tooth. LOL If nothing else I'm thorough. Everything that is going in the housing is going to be brand new except the pinion spacer, and yoke.

The axle I broke was just a set of 30 splines and did use a spool. They were untold years old. I put an eye on them every couple years and they had zero twist. Best guess is they could have 6,000-8,000 or more passes on them. They were on borrowed time for a long time. The guy I bought the car from ran it in S/P running 6.40s mostly. I have been going 5.70s and 5.80s for years but in Footbrake. Changing to 35 spline gun drilled and star flanged axles. Surprisingly the new axles with bearing and studs and old axles just the same each weigh 14lbs apiece.

quote:

Originally posted by RPROGAS:
Always check the pattern, it's ONE of the determining factors in the life of the gear set. Bearing pre-load (pinion and carrier bearings) plus back lash are just as important. I check the pattern in quadrants (four equally spaced locations). It's entirely possible to set the pinion depth and back-lash correctly, and still find that the pattern is not correct.

Bob

Good advice here. To me the pattern is the final check that all is well. It's like having O2 sensors but, checking the plugs anyway just to be sure.

The last set I installed obviously had the wrong number for pinion depth. I don't recall the numbers, but to set it with the correct depth it would've required the gear to be machined deeper for the bearing. Made no sense. I installed it with previous shim and only had to adjust slightly from there. Also, the yoke and outer bearing wouldn't fit and required polishing on the lathe.

I can appreciate the thought path here. The numbers should be you measurement of how correct it is set up. Then the pattern is actually what is happening regardless the numbers. So which do you go with?

I have always gone with pattern and rarely ever use numbers except as starting point. If gears are in different case that should be exactly like the next or one. Perfect rarely happens even with modern machine process.

Different animal but same issue. I had friend take a blower that had ran 5.69 off Bob Newberry's car. This was high helix not screw blower and was in mid 90's. He blueprinted every piece and had on built just like it to the numbers. Short of it blower was POS.

I have built rear-ends for 4000 HP plus cars and no issue and always used pattern as final word. Wrong or right it works for me.

I tried the ratech solid spacer, followed all the directions for preload etc. Had a couple of them loosen up. Not sure why but it was a transbrake deal. It would look like it was spinning on the pinion at launch and those little shims dont like that and would spin out.
I went back to crush sleeves and had no more issues. If you have the old sleeve or you know the total dimension from the ratech
spacer you can put the new crush sleeve in a press and leave only about .050 to go in the case. This helps alot. Hone some bearings for checking but the final assembly bearings need to be press fit. It takes alot of tourqe to crush the collar, more than ratech called for with their spacer, maybe that was the problem. I did really like the pinion nut they sold, more area for the socket. After I had a couple of failures I gained some respect for the crush sleeve even though it's a pain. Good luck.

The shims are always to adjust for the case or housing tolerances, since the gear sets are supposed to be very precise, set to set.
Different manufacturers apparently use different measuring tools, or methods, and I've found them pretty useless in general.

The crush sleeve is actually totally unnecessary in a 12-bolt, it's only a production aid. The solid spacer is nice to have in case you need to have the pinion yoke removed, because you can just hammer the nut down and be done.
Retaining the nut is always the key, I stake mine with a punch.
High shaft speeds and instant rotation is what you fight.

A question about 12 bolts, how are you setting side bearing pre-load? 9" is fast fun and easy and you can measure it.

Without a case spreader, which would be most of us, you need to set up backlash with no preload but tight shims on both sides. When you are satisfied with pattern and backlash add .005 to each side and get everything started into the case and tap bearings and shims little by little side to side using a brass drift or punch to make sure everything is seated. If you happen to have the original cast iron shims you can measure them and your total thickness while it may be different side to side should be close to the same added together. A Dana 60 is similar also. I hope this might be helpful to someone, I'm sure there are other ways to skin a cat.

Wait a minute! You mean you are allowed to run a non Ford 9" (or b igger) rear-end in a race car? The only thing Ford contributed to the world . LOL

would never run a 12 bolt with the crush sleeve in a race car. May work fine but seems like a weak link I can easily do away with. Plus hell of lot easier to service rear end w/o sleeve. JMO

I have two Strange 31 spline spools if interested..Sell them cheap.

quote:

Originally posted by Eman:
A question about 12 bolts, how are you setting side bearing pre-load? 9" is fast fun and easy and you can measure it.

k107 laid it out pretty well, but it's mostly by "feel" to get the preload you want, once you've done a couple.

Different methods when you have a bare housing and all new parts that haven't been run together, versus a component replacement operation on an unit that has been in service.

quote:

Originally posted by Al Alguire:
I have two Strange 31 spline spools if interested..Sell them cheap.

31 spline 12-bolt Chevy passenger?
I thought it went 30 (stock), 33, then 35's?