7.5 Ring and Pinion Pattern

[Bonnewagon]

I think your mistake is that you are attempting to correct the pattern by adjusting the pinion depth. That is why a pinion depth tool is used. As Pontiac455 described, the pinion depth is a relationship between the face of the pinion gear and the center line of the axles. There is only one correct pinion depth for a given pinion gear. That is why I said to re-use the original pinion shim if you don't have access to a depth tool. It is probably right on or very close. Once you get the pre-load on the pinion bearings done, then you make your backlash adjustments by moving the carrier back and forth. The pinion depth should only be adjusted again as a rare last resort. Once you have the backlash correct, and the carrier bearings pre-load, if you still have a crazy tooth contact pattern then something is very wrong. EDIT: did you use new bearings or the old ones?

 

[pontiacgp]

In addition to what Mark said when you are checking the pattern you need to rotate the assembly by the yoke and not by the crown gear.

 

[Rocket Powered]

It' all coming back apart guys. Don' want to but it needs to be done the right way. I' not satisfied with pattern, and over $600 invested. Looks like just the top of the pinion teeth are touching ring gear. I will update. Thanks for the advise. Heck, I could a had a few Engines built in this time. Never tackled a rearend for good reason. I inspect all pro series Engines for Blueprint Engines. 632's,LS 427's, 540's, etc....prepped cranks, blocks, rods, pistion, cams, heads, specialized quality controller .i know my way around a car. 25+years auto experience. This one has got me! I'l get it, just in time. Sooner than later, lol

 

[pontiacgp]

It' all coming back apart guys. Don' want to but it needs to be done the right way. I' not satisfied with pattern, and over $600 invested. Looks like just the top of the pinion teeth are touching ring gear. I will update. Thanks for the advise. Heck, I could a had a few Engines built in this time. Never tackled a rearend for good reason. I inspect all pro series Engines for Blueprint Engines. 632's,LS 427's, 540's, etc....prepped cranks, blocks, rods, pistion, cams, heads, specialized quality controller .i know my way around a car. 25+years auto experience. This one has got me! I'l get it, just in time. Sooner than later, lol

I wouldn't give up, we learn quicker through problems and you'll catch on how to do it. Don't get discouraged and there's alot who wouldn't' even tackle this job. I don't think you are doing anything wrong, I really think it's the gears that are the issue. Once you get it set up you'll be proud of what you did and you won't have any concerns about doing another one.

 

[Rocket Powered]

I think your mistake is that you are attempting to correct the pattern by adjusting the pinion depth. That is why a pinion depth tool is used. As Pontiac455 described, the pinion depth is a relationship between the face of the pinion gear and the center line of the axles. There is only one correct pinion depth for a given pinion gear. That is why I said to re-use the original pinion shim if you don't have access to a depth tool. It is probably right on or very close. Once you get the pre-load on the pinion bearings done, then you make your backlash adjustments by moving the carrier back and forth. The pinion depth should only be adjusted again as a rare last resort. Once you have the backlash correct, and the carrier bearings pre-load, if you still have a crazy tooth contact pattern then something is very wrong. EDIT: did you use new bearings or the old ones?

I think your mistake is that you are attempting to correct the pattern by adjusting the pinion depth. That is why a pinion depth tool is used. As Pontiac455 described, the pinion depth is a relationship between the face of the pinion gear and the center line of the axles. There is only one correct pinion depth for a given pinion gear. That is why I said to re-use the original pinion shim if you don't have access to a depth tool. It is probably right on or very close. Once you get the pre-load on the pinion bearings done, then you make your backlash adjustments by moving the carrier back and forth. The pinion depth should only be adjusted again as a rare last resort. Once you have the backlash correct, and the carrier bearings pre-load, if you still have a crazy tooth contact pattern then something is very wrong. EDIT: did you use new bearings or the old ones?

I used the old stock bearings honed out to a "less" pressed on bearing, inner and outer, and new bearings. I have a puller. Just IN case a difference in the bearings.
I heard the depth tool is nothing but a waste of $. In my eyes. The pattern says it all. I tried original stock shims, new shims to = stock depth. Etc. I' missing something. It' all coming apart. Thanks for the advise. Will update

 

[Rocket Powered]

I think your mistake is that you are attempting to correct the pattern by adjusting the pinion depth. That is why a pinion depth tool is used. As Pontiac455 described, the pinion depth is a relationship between the face of the pinion gear and the center line of the axles. There is only one correct pinion depth for a given pinion gear. That is why I said to re-use the original pinion shim if you don't have access to a depth tool. It is probably right on or very close. Once you get the pre-load on the pinion bearings done, then you make your backlash adjustments by moving the carrier back and forth. The pinion depth should only be adjusted again as a rare last resort. Once you have the backlash correct, and the carrier bearings pre-load, if you still have a crazy tooth contact pattern then something is very wrong. EDIT: did you use new bearings or the old ones?

I think your mistake is that you are attempting to correct the pattern by adjusting the pinion depth. That is why a pinion depth tool is used. As Pontiac455 described, the pinion depth is a relationship between the face of the pinion gear and the center line of the axles. There is only one correct pinion depth for a given pinion gear. That is why I said to re-use the original pinion shim if you don't have access to a depth tool. It is probably right on or very close. Once you get the pre-load on the pinion bearings done, then you make your backlash adjustments by moving the carrier back and forth. The pinion depth should only be adjusted again as a rare last resort. Once you have the backlash correct, and the carrier bearings pre-load, if you still have a crazy tooth contact pattern then something is very wrong. EDIT: did you use new bearings or the old ones?

I used the old stock bearings honed out to a "less" pressed on bearing, inner and outer, and new bearings. I have a puller. Just IN case a difference in the bearings.
I heard the depth tool is nothing but a waste of $. In my eyes. The pattern says it all. I tried original stock shims, new shims to = stock depth. Etc. I' missing something. It' all coming apart. Thanks for the advise. Will update

I wouldn't give up, we learn quicker through problems and you'll catch on how to do it. Don't get discouraged and there's alot who wouldn't' even tackle this job. I don't think you are doing anything wrong, I really think it's the gears that are the issue. Once you get it set up you'll be proud of what you did and you won't have any concerns about doing another one.

That when I do my best. When I am pi $$ed and very determined! Thanks!

 

[Bonnewagon]

I heard the depth tool is nothing but a waste of $. I

Well, time is money- how much time are you wasting on this project? You seem to be up on mechanicals, can't you beg, borrow, or steal a depth tool? I have an actual Kent-Moore GM dealer kit I scored at a swap meet for $100. There are aftermarket ones both expensive https://www.speedwaymotors.com/Speedway-Professional-Ring-Pinion-Setup-Tool-Set,2707.html and cheap https://www.summitracing.com/parts/rat-10003/overview/ There's really no excuse for not using one. Using a "loose" fit bearing to swap out shims is a smart trick. But if you then go to new bearings and races then the setting changes. That's why in the factory manual there are "new" and "used" specs. I think you will be fine. Take a deep breath, find the tools, and ask lots of questions. I only know a handfull of guys that can set up a rear end properly so please do learn this dying skill. By the way, the only guy I ever knew who could set up a rear by just eyeballing the tooth contact pattern is John Giovannini of Gevo's Gears and Rears of Seneca Falls NY. http://www.rearsgears.com/ He has been building rears for over 50 years. This is your first attempt so- don't feel bad.

 

[64nailhead]

I used the old stock bearings honed out to a "less" pressed on bearing, inner and outer, and new bearings. I have a puller. Just IN case a difference in the bearings.

Using the old bearings honed out is not good. Are you using the old races as well? Don't answer that - it doesn't matter.

You should install new carrier bearings and races on the diff. You should use new races on the pinion and the new outer pinion bearing. You only need a setup bearing for the inner pinion bearing. But most importantly, it needs to be a new bearing of the same brand as you intend to use for the final bearing. If it's a Timken, then you need another Timken, If National, SKF, whatever, then you need one of the same brand. It is best if they are from the same lot, but that is almost impossible. The purpose of using a setup bearing for the inner pinion is that removing it multiple times with a bearing separator is nearly impossible to accomplish without damaging the bearing. If you have already removed the new, non setup bearing, a couple of times, then I'd chuck it out and go buy 2 new bearings of the same brand and hone out one approx .0015-.002".

I know I'm sounding somewhat anal about this, but gear work requires as much precision as home tools allow. You cannot build in inaccuracies or you'll be wasting your money. If you can appreciate, I have setup bearings in my basement for GM 7.5" and 8.5" and Ford 8.8". I have 3 different brands for the 7.5 and 8.5 so that I have the correct one depending on the bearing kit I get next time. If you can appreciate, I've setup a good number of rear ends, sometimes it's a pain. But being as precise as possible and patient will yield positive results.

I do agree about the pinion depth tool. It is unneeded, but it would certainly save some time. But even if you had one, then you would still need to check the wear pattern to confirm that the pinion depth was correct in case you have a housing issue.

I'd recommend another crush sleeve as well (they are cheap - less than $5). How are you measuring the pinion preload that you described earlier?

 

[superbon54]

When I setup my 7.5, I used a drop indicator mounted to a magnetic base - industrial quality, not harbor freight junk - to measure pinion depth. Is that acceptable in lieu of a proper depth tool? Either I did it right or got lucky. It was the first rearend I’ve built, and ran good and quiet.

 

[Bonnewagon]

Superbon54, do you mean a dial indicator? What did you measure against? The gasket face of the housing? I guess if you had the foresight to measure the original pinion from the gasket surface before touching anything then you could set the new pinion to the same spec and be good to go. Anyway, the tool I have mounts where the carrier bearings sit which gets you the axle center line. This is with the bearing caps in place and torqued to specs. Then an arbor sits in the axle location and a spring loaded rod extends to the other tool that is installed in place of the pinion gear. The tool has four pads that represent four different GM gear families like 7.5, 8.5, etc.You rotate the tool so your pad is in line with the plunger rod. You let the spring loaded plunger rod touch the appropriate pad and then set up a dial indicator on the other end of the rod. You rotate the indicator to get the most deflection and then set it to zero. Then you rotate the rod off the pad and the amount shown on the dial indicator is the pinion shim thickness needed. So the only thing I can think of to get a setting without the tools is this. I would need to measure the tip of the plunger rod, fully extended, from the gasket surface of the carrier. Then measure the face of the installed gear from the same gasket surface.The difference "should" be the shim thickness. Perhaps those are the values Pontiac455 mentioned? I can see variations such as housing casting, bearing race machining, my measuring skills, etc, all affecting this method. Worse, is the GM tool mimicing the actual parts, or are they some arbitrary values the engineers used? That is why the tool works off the axle center line and measures the pinion distance from that point. I'm pretty sure if there was a simple way to measure this GM would not specify a $1,000 tool.