'70 Nova LY6/TH400 6.0VVT
01-29-2018, 01:19 PM
#1302
Now it's time to reassemble the diff. I have done a handful of gear installs on Toyota diffs, but this is my first time assembling a 12bolt. I am reusing all the old gears and bearings, so I am confident the pinion depth is already set. First step was dropping the yoke-side bearing into the housing and installing a new pinion seal.
Many moons ago I made this pinion flange holder for doing Toyota diffs. I was able to drill a new hole in it and use it to secure the yoke on the 12bolt. The holder is basically a long piece of square tubing with a tab welded on and I clamp it to the workbench to keep the pinion from rotating while torquing it down. I'm reusing the gears and bearings, but a new crush sleeve is required to make sure the bearings have proper pre-load.
I used a 1/2" breaker bar and a long piece of square tube to crush the sleeve. I would have started the crush sleeve in a press, but it didn't seem like it had very far to go so I went straight for the cheater bar. This is a bit risky because you can easily turn a 1/2" breaker bar into a 1/2" broken bar. I decided to take the risk and it worked out this time, but I have previously broken these when setting up diffs. A 3/4" drive would be much better suited for the task.
And for giggles, here is me doing the same job on a Toyota diff about 10 years ago. It looks like I may have even used the same piece of tubing for leverage.
Once I got the sleeve crushed most of the way, I removed the nut and added Loctite. The pinion nuts on a Toyota diff can be staked into place, but this 12 bolt pinion doesn't have that provision. Hopefully Loctite is sufficient.
If you've never done a gear install before, one must-have tool is an in-lb toque wrench for checking bearing preload. I got this one from a bicycle shop. There are better more expensive versions out there, but this does the job.
I read the target for new pinion bearings on a 12 bolt is 20-25in-lb and used bearings should have 10-15in-lb. When I got to 10in-lb, I decided to give it just a hair more and unfortunately overshot to 20in-lb. Then I did a little more research and found specs as low as 6-8in-lb for used bearings! So it seems 20in-lb is just way too much. I will have to get a new crush sleeve and redo it. I definitely don't want to grenade my pinion bearings over a $5 crush sleeve and a little bit of time to get it right.
Many moons ago I made this pinion flange holder for doing Toyota diffs. I was able to drill a new hole in it and use it to secure the yoke on the 12bolt. The holder is basically a long piece of square tubing with a tab welded on and I clamp it to the workbench to keep the pinion from rotating while torquing it down. I'm reusing the gears and bearings, but a new crush sleeve is required to make sure the bearings have proper pre-load.
I used a 1/2" breaker bar and a long piece of square tube to crush the sleeve. I would have started the crush sleeve in a press, but it didn't seem like it had very far to go so I went straight for the cheater bar. This is a bit risky because you can easily turn a 1/2" breaker bar into a 1/2" broken bar. I decided to take the risk and it worked out this time, but I have previously broken these when setting up diffs. A 3/4" drive would be much better suited for the task.
And for giggles, here is me doing the same job on a Toyota diff about 10 years ago. It looks like I may have even used the same piece of tubing for leverage.
Once I got the sleeve crushed most of the way, I removed the nut and added Loctite. The pinion nuts on a Toyota diff can be staked into place, but this 12 bolt pinion doesn't have that provision. Hopefully Loctite is sufficient.
If you've never done a gear install before, one must-have tool is an in-lb toque wrench for checking bearing preload. I got this one from a bicycle shop. There are better more expensive versions out there, but this does the job.
I read the target for new pinion bearings on a 12 bolt is 20-25in-lb and used bearings should have 10-15in-lb. When I got to 10in-lb, I decided to give it just a hair more and unfortunately overshot to 20in-lb. Then I did a little more research and found specs as low as 6-8in-lb for used bearings! So it seems 20in-lb is just way too much. I will have to get a new crush sleeve and redo it. I definitely don't want to grenade my pinion bearings over a $5 crush sleeve and a little bit of time to get it right.
Last edited by -TheBandit-; 01-29-2018 at 01:28 PM.
01-30-2018, 11:24 AM
#1304
I'm surprised you didn't weld the tubes to the pumpkin. tisk, tisk, tisk.
02-01-2018, 02:59 AM
#1306
Fair enough. At least they didn't appear the be leaking. You're doing a great job on the 12bolt.
02-01-2018, 10:58 AM
#1307
Thanks Jimbo. I think welding the tubes is a good idea from the leak perspective but I was pretty nervous about welding and given the issues I had with welding the housing ends I'm glad I didn't attempt the tube-to-housing welds.
Yesterday I picked up a new crush sleeve and reset the pinion preload. This time it's at a easy-turning 7.5in-lb. I have seen specs of either 6-8in-lb or 10-15in-lb. I haven't seen a definitive answer on which is "right", but I have seen a few threads where gear techs recommended the lower spec. It was also pretty freewheeling when I took it out, so I'm going to err to the low end.
After getting the pinion preload set, I was ready to drop in the carrier. It was tough getting out with a pair of prybars so I didn't expect it to be easy to go back in. I was thinking a spreader would be needed, but I saw a few videos of people successfully installing the carrier shims with a dead blow so I thought I'd give that a try.
So yeah that didn't work out so great. The shim was scooting in with each blow from the hammer, but it couldn't take the shock. Now I'll have to order a set of shims and I guess I'm going to build a case spreader and/or a shim driver.
Yesterday I picked up a new crush sleeve and reset the pinion preload. This time it's at a easy-turning 7.5in-lb. I have seen specs of either 6-8in-lb or 10-15in-lb. I haven't seen a definitive answer on which is "right", but I have seen a few threads where gear techs recommended the lower spec. It was also pretty freewheeling when I took it out, so I'm going to err to the low end.
After getting the pinion preload set, I was ready to drop in the carrier. It was tough getting out with a pair of prybars so I didn't expect it to be easy to go back in. I was thinking a spreader would be needed, but I saw a few videos of people successfully installing the carrier shims with a dead blow so I thought I'd give that a try.
So yeah that didn't work out so great. The shim was scooting in with each blow from the hammer, but it couldn't take the shock. Now I'll have to order a set of shims and I guess I'm going to build a case spreader and/or a shim driver.
02-01-2018, 12:58 PM
#1309
I know! It's a thick shim too (0.234in). I really didn't think it would snap based on how not-very-hard I was hitting it. Maybe it was weakened during the original install. I could chance just pounding in another set of shims but I think I am going to take the time to build a simple spreader. Hopefully I can cobble together something with material on hand.
02-01-2018, 02:00 PM
#1310
TECH Senior Member
02-01-2018, 03:24 PM
#1311
Clint,
Keep up the great work. I'll probably be visiting this part of your thread if I decide to mess with my 8.5".
Keep up the great work. I'll probably be visiting this part of your thread if I decide to mess with my 8.5".
02-01-2018, 05:35 PM
#1312
I did a little research and made a couple phone calls... I think my problem here is that I was beating on a brittle cast shim. Apparently the aftermarket shims can take more of a beating, so once my new "super" shims show up I'll give this method a second try without using a spreader. Yukon tech advised against using a spreader on this housing because "more often than not people end up damaging the case". Their advise was to use a dead blow.
02-02-2018, 12:09 PM
#1315
That's funny. Glad to see you paint the cover too. I tend to like the stealth look myself.
02-02-2018, 01:28 PM
#1316
Clint, did I read here about the MC-Booster setup?
If so, i changed mine, went from the Wilwood 7/8th manual brake to the booster.
Ended up buying the following, and it worked perfect.
TFF-2229NC
RSD-R03
DSR-050302
ACDelco 18M974 - Bought it from Tobin, Kore3
Tobin basically told me what to get.
If so, i changed mine, went from the Wilwood 7/8th manual brake to the booster.
Ended up buying the following, and it worked perfect.
TFF-2229NC
RSD-R03
DSR-050302
ACDelco 18M974 - Bought it from Tobin, Kore3
Tobin basically told me what to get.
02-02-2018, 02:52 PM
#1317
Thanks for the info Sebtarta! I have not yet committed on a master/booster combo. That 18M974 appears to be a Sonoma/S10 right drive 1" diameter master with standard inverted flare ports and I see you're using a 9" dual diaphragm booster. I think that would be equivalent to using a C5/C6 master/booster, except the C5/C6 is widely available used but unfortunately uses metric ports. The 'vette stuff is pretty easy to find used (around $100 for a master & booster combo). I am not sure yet what I want to do but I need to figure it out pretty soon. Thanks for the info.
02-09-2018, 12:49 PM
#1318
Family life is picking up steam right now. My son just started baseball and this year I've taken on assistant coach duties. We had our first practice and I was really missing the fun of taking my son in the Nova like we did all last season. He loves baseball and he loves going out in the car, so putting those together makes for some special memories. I've got to get this thing back together soon - he'll only be 7yrs old once.
I once again used an opposing set of crowbars to pull the carrier out and fetch the broken shim. I learned that this is a cast shim and is much more brittle than the aftermarket shims I've dealt with in the past. It was broken in several places so I took a measurement in order to replicate the thickness..
I bought a set of "super shims" from Yukon Gear (they are manufactured Motive) and matched the thickness to the thousandth. Then I proceeded to drive them in after placing the carrier into the housing. What I realized is that this really is not a good order for installation. The shims are thin and when you pound then between the bearing race and the housing, they are not well supported and more easily damaged, not to mention it's very hard to strike a good hammer blow as they get deeper. I would not suggest doing what's shown in the photo below unless you have a shim driver and/or case spreader in use.
When I realized what I was doing wrong, I pulled the carrier back out and changed the order of things. I wiped some grease on the shims and placed them into the housing. The grease helped stick them to the surface while I carefully dropped the carrier in. With this assembly order, the shims are fully supported on one side against the housing and I could use the dead blow against the carrier itself to drive it in. It took quite a few blows to get it in with the smallish 3lb dead blow I have, but it got home without any observable damage to the shims or bearing races.
Once the carrier was in, I proceeded to install the bearing caps. I have this neat Snap-On ratchet (the ONLY Snap-On tool I own) that converts to a speed wrench. It's great for stuff like this.
Since I thought I would be done, I went ahead and torqued the caps down.
Next I figured I should run a pattern. I've been running these gears for about twenty years and in this build I haven't changed bearings or pinion shims, so my hope was to just put it back together the way it came out. I've heard used gear patterns can be all over the place, but I thought I'd give it a shot just to see.
The coast side on this location looked pretty centered heel to toe, but maybe a tad shallow/toward the face.
The drive side looked okay, maybe a bit toward the toe and deep/ toward the root. I'm thinking with the coast side a little toward the face and the drive a little toward the root, pinion depth is probably okay since I couldn't really center one without messing up the other.
Next I checked backlash. It seemed a little excessive when I pulled the rear and the measurements back that up. In the image below I measured 0.017in, but when I rechecked and moved the ring around to a few different locations, it was more like 0.020in! The spec for new gears is 0.006-0.010in.
Unfortunately I just can't unsee that. I was tempted to put it back together knowing it has been running like this for a long while without issue, but I also think I'd be kicking myself if I had problems out of the rear as a result of excessive backlash. So I'm currently in the process of swapping shims.
I'm anxious to get that sorted so I can shove the axles back in and start working on brake lines. I got a little motivation this week when another set of "parts" arrived.
I can't wait to get this thing back on the ground!
I once again used an opposing set of crowbars to pull the carrier out and fetch the broken shim. I learned that this is a cast shim and is much more brittle than the aftermarket shims I've dealt with in the past. It was broken in several places so I took a measurement in order to replicate the thickness..
I bought a set of "super shims" from Yukon Gear (they are manufactured Motive) and matched the thickness to the thousandth. Then I proceeded to drive them in after placing the carrier into the housing. What I realized is that this really is not a good order for installation. The shims are thin and when you pound then between the bearing race and the housing, they are not well supported and more easily damaged, not to mention it's very hard to strike a good hammer blow as they get deeper. I would not suggest doing what's shown in the photo below unless you have a shim driver and/or case spreader in use.
When I realized what I was doing wrong, I pulled the carrier back out and changed the order of things. I wiped some grease on the shims and placed them into the housing. The grease helped stick them to the surface while I carefully dropped the carrier in. With this assembly order, the shims are fully supported on one side against the housing and I could use the dead blow against the carrier itself to drive it in. It took quite a few blows to get it in with the smallish 3lb dead blow I have, but it got home without any observable damage to the shims or bearing races.
Once the carrier was in, I proceeded to install the bearing caps. I have this neat Snap-On ratchet (the ONLY Snap-On tool I own) that converts to a speed wrench. It's great for stuff like this.
Since I thought I would be done, I went ahead and torqued the caps down.
Next I figured I should run a pattern. I've been running these gears for about twenty years and in this build I haven't changed bearings or pinion shims, so my hope was to just put it back together the way it came out. I've heard used gear patterns can be all over the place, but I thought I'd give it a shot just to see.
The coast side on this location looked pretty centered heel to toe, but maybe a tad shallow/toward the face.
The drive side looked okay, maybe a bit toward the toe and deep/ toward the root. I'm thinking with the coast side a little toward the face and the drive a little toward the root, pinion depth is probably okay since I couldn't really center one without messing up the other.
Next I checked backlash. It seemed a little excessive when I pulled the rear and the measurements back that up. In the image below I measured 0.017in, but when I rechecked and moved the ring around to a few different locations, it was more like 0.020in! The spec for new gears is 0.006-0.010in.
Unfortunately I just can't unsee that. I was tempted to put it back together knowing it has been running like this for a long while without issue, but I also think I'd be kicking myself if I had problems out of the rear as a result of excessive backlash. So I'm currently in the process of swapping shims.
I'm anxious to get that sorted so I can shove the axles back in and start working on brake lines. I got a little motivation this week when another set of "parts" arrived.
I can't wait to get this thing back on the ground!
Last edited by -TheBandit-; 02-12-2018 at 04:44 PM.
02-12-2018, 03:58 PM
#1320
I did some more research and found a typical backlash for used gears is around 0.012in. Most recommendations are to measure match the original backlash that the gears have worn into since they've already lapped into that position, but in my case I can only guess they had too much backlash to begin with. What to do?
I decided to swap shims and hope the gears are happy lapping themselves into a slightly new position. After measuring the angle of the gear teeth, I calculated I would need to move 0.011in shim to get the backlash down by 0.008in to hit a target of 0.012in backlash. So that's exactly what I did and that's exactly the result I got (how often does that happen? I had a little engineergasm when the indicator gave me exactly what I was going for).
With that set, I torqued the caps down again and thought I would see how the pattern looked. Unfortunately I used up the last little bit of gear marking compound I had on hand and when I went to get some from my local source, they were out. So I decided to try some old oil based paint I had on hand.
After applying, I let it dry a couple minutes before running a pattern. I was really surprised at how well the paint worked. It definitely does not replace purpose-made gear marking compound, but in a pinch it did the trick.
Now as to the pattern, I really am not sure how to read the tea-leaves. Used gears never give a textbook pattern (heck neither do new ones) and these are no exception. To me the drive side looks like the pinion could have less shim but the coast side looks the other way. Since I haven't messed with pinion depth (same bearings and shims that came out of it), it was running without problems previous, and the patterns average on center, I am not going to make any changes.
At this point I could finally stab the axles in and verify the length was proper to completely engage the splines on the spider gears. Yup! Thank you Strange for providing accurate numbers.
With all that buttoned up it was time to drop the cover on. I used a fiber gasket with some Permatex Gear Oil RTV on the housing side and dry on the cover side. Before I put the cover on I snapped a photo of the leveling feet that are used to add support on the bearing caps.
I decided to swap shims and hope the gears are happy lapping themselves into a slightly new position. After measuring the angle of the gear teeth, I calculated I would need to move 0.011in shim to get the backlash down by 0.008in to hit a target of 0.012in backlash. So that's exactly what I did and that's exactly the result I got (how often does that happen? I had a little engineergasm when the indicator gave me exactly what I was going for).
With that set, I torqued the caps down again and thought I would see how the pattern looked. Unfortunately I used up the last little bit of gear marking compound I had on hand and when I went to get some from my local source, they were out. So I decided to try some old oil based paint I had on hand.
After applying, I let it dry a couple minutes before running a pattern. I was really surprised at how well the paint worked. It definitely does not replace purpose-made gear marking compound, but in a pinch it did the trick.
Now as to the pattern, I really am not sure how to read the tea-leaves. Used gears never give a textbook pattern (heck neither do new ones) and these are no exception. To me the drive side looks like the pinion could have less shim but the coast side looks the other way. Since I haven't messed with pinion depth (same bearings and shims that came out of it), it was running without problems previous, and the patterns average on center, I am not going to make any changes.
At this point I could finally stab the axles in and verify the length was proper to completely engage the splines on the spider gears. Yup! Thank you Strange for providing accurate numbers.
With all that buttoned up it was time to drop the cover on. I used a fiber gasket with some Permatex Gear Oil RTV on the housing side and dry on the cover side. Before I put the cover on I snapped a photo of the leveling feet that are used to add support on the bearing caps.
Last edited by -TheBandit-; 02-12-2018 at 04:44 PM.