Differential rear-end support cover

[HenryJ]

Thought I'd bring this topic to the modifications forum-HJ

I just recently put on a Summit aluminum differential cover with the bearing cap preload bolts and it also had the oiling holes blocked. What I did to correct this problem was put the gasket on the rear end with the cover off and lined up all 10 of the cover holes and pressed lightly on the gasket over the lubing holes to create an impression of the holes so that I could cut out the holes with an exacto knife. After I did this I laid the gasket on the new aluminum cover and marked the area that needed to cut out. I used a large half round file and made an oiling channel on each side that matched up with the holes I cut in the gasket. IMO this will provide more than adequate oiling for the wheel bearings. As an added benifit the cover has 600 tons of support and keeps the bearing caps from flexing or breaking when under load, and will definitely help protect the gears from rocks and stuff when off roading. It also looks very cool. I wish I had done some install pics for everyone to see, but if you want to see what the covers look like just go to Summit's web site and look up differential covers. Thses covers are very nice and come with the gasket and ARP 12 point stainless bolts for only $139. I think this is a great mod for improving the strength and reliability of the 10 bolt rear end. I hope this info is helpfull, and remember GM will deny that there is any problem at all which really sucks because it affects so many cars and trucks with the 10 bolt.

Link to thread in stock forum

[HenryJ]

I like the "look" of this cover better. It offers a higher fill location and increased oil capacity-

But it is a little over $30 more than the Summit cover

EDIT- Found the LPW cover on Ebay for "buy it now" $139+$10 shipping That would compete with the Summit cover

[killian96ss]

I like the "look" of this cover better. It offers a higher fill location and increased oil capacity,but it is a little over $30 more than the Summit cover.

I had the LPW cover on a 68 Impala that I used to own, and I would have to say that's it is probably just as good as the Summit cover, but not any better. The Summit cover does come with nice ARP 12 point bolts, and I think it's also a little bit thicker. I'm not sure why the LPW cover has a higher fill hole than normal, but I wouldn't fill the rear that high, because you can have too much oil in the differential. I would still fill the rear until the fluid comes out of the side opening, because that's the correct level.

[quickbiker]

I had the LPW cover on a 68 Impala that I used to own, and I would have to say that's it is probably just as good as the Summit cover, but not any better. The Summit cover does come with nice ARP 12 point bolts, and I think it's also a little bit thicker. I'm not sure why the LPW cover has a higher fill hole than normal, but I wouldn't fill the rear that high, because you can have too much oil in the differential. I would still fill the rear until the fluid comes out of the side opening, because that's the correct level.

That's a good point. What's the use in putting the fill hole? Every diff's already got one.

[HenryJ]

...I'm not sure why the LPW cover has a higher fill hole than normal, but I wouldn't fill the rear that high, because you can have too much oil in the differential. I would still fill the rear until the fluid comes out of the side opening, because that's the correct level.

That's a good point. What's the use in putting the fill hole? Every diff's already got one.

The fill is a great option. You use it to add the fluid watching the factory oil level hole for when it is full, instead of trying to fill and watch the same hole to see when it is full.

The advantage of the higher fill hole is not only ease of filling, but should a serious lift be in the future, it will allow rotation of the axle to reduce the severity of the u-joint angle.

[quickbiker]

Mine is still on back-order.

[quickbiker]

Well, They kept moving the back-order date, so I cancelled and ordered this onewhich comes with a magnetic plug!

I think I like it better anyhow.

[Rusty]

Well, I looked at the link to Jeg's diff covers and noted that only the 7.5 is listed and now I have a new question. What exactly is the difference between the 7.5 and the 7.62 rear axles (besides the obvious ring gear diameter). In other words, can you put 7.62 gears, diff, axle shafts, etc, in the 7.5 case?

[quickbiker]

Well, I looked at the link to Jeg's diff covers and noted that only the 7.5 is listed and now I have a new question. What exactly is the difference between the 7.5 and the 7.62 rear axles (besides the obvious ring gear diameter). In other words, can you put 7.62 gears, diff, axle shafts, etc, in the 7.5 case?

Yea, they are identical.

[HenryJ]

...ordered this onewhich comes with a magnetic plug!

I think I like it better anyhow.

Me too, where did you get the idea that it has a magnetic plug?

BTW, you guys are costing way too much

Not really I just happened to notice last winter was not kind at all to my chrome cover. I need to change the rear diff. oil again, so I too ordered the Ultimate cover. I decided on the one with attachment points for axle bracing. I have some heim ends and moly tube around, so I may just fab up a truss.

[quickbiker]

I thought about getting the one with braces, but the guy talked me out of it. I hate when they do that! lol He said something else will break before that, probably right. I called him, cause on the ebay add, it meantioned it came with magnetic plub. So I asked him about it, he checked and said, yes, then new ones come with it. So, I think the ones we will get will look more like the ones on ebay. Funny, they got the latest pics on ebay, but not for the web page. haha

[HenryJ]

After reading this ...

...a stud girdle would help greatly in preserving gear life. Richmond claims that the biggest flaw with the 10-bolt design is the flexibility of the case. When under heavy load, the pinion walks up the ring gear face, and forces the case apart. This totally throws off the gear alignment which causes premature gear failure. The key, according to Richmond, is to maintain alignment by increasing case rigidity. They claim that a stud girdle, like the one offered by Summit Racing equipment, or the TA Performance piece offered by Fast Toys, will "essentially double" the gear life of a differential used under high load conditions. A stud girdle is a very stiff cast aluminum differential cover, with studs that extend to the load bearing caps. It ties the rear of the case to the bearing cap surface, greatly increasing rigidity.

I'm glad that I did order the one that can be braced. anything that I can do to brace up the flexy rear case

[killian96ss]

I thought about getting the one with braces, but the guy talked me out of it. I hate when they do that! lol He said something else will break before that, probably right. I called him, cause on the ebay add, it meantioned it came with magnetic plub. So I asked him about it, he checked and said, yes, then new ones come with it. So, I think the ones we will get will look more like the ones on ebay. Funny, they got the latest pics on ebay, but not for the web page. haha

The guy you spoke to is right about the axel braces. Our trucks will never have enough horsepower to break or bend an axel tube or break the welds. The braces are for very high horsepower drag cars with large slicks. The braces for these cars prevent the axel tubes from moving forward because the tires have so much traction. As far as off road, I don't think the brace will help much unless you were to have an additional brace to support the tubes from flexing up and down as well as forward to back. Make sure that when you install the cover you torque down the cover bolts first then the bearing cap preload bolts. Also make sure you use a torque wrench on all the bolts especially the preload bolts. Do not tighten the preload bolts more than 10 ft. pounds, because if you do your carrier bearings will overhaet and be destroyed very quickly!!!!!!!!

[HenryJ]

...The guy you spoke to is right about the axel braces. Our trucks will never have enough horsepower to break or bend an axel tube or break the welds. The braces are for very high horsepower drag cars with large slicks. The braces for these cars prevent the axel tubes from moving forward because the tires have so much traction. As far as off road, I don't think the brace will help much unless you were to have an additional brace to support the tubes from flexing up and down as well as forward to back. ...

I have to disagree about the axle bracing, fore and aft. While it is true that vertical support is important, the suspension can absorb vertical movement much better than fore and aft. the additional support could indeed be benificial for a 4x4 in a high speed offroad situation (baja).

I'll grant you that, when talking HP, with the 4.3L it would be overkill perhaps, but I've always thought I'd have a V-8 in this at some point. While at that time I may not be using the same rear axle, you never know.

[killian96ss]

I have to disagree about the axle bracing, fore and aft. While it is true that vertical support is important, the suspension can absorb vertical movement much better than fore and aft. the additional support could indeed be benificial for a 4x4 in a high speed offroad situation (baja).

I'll grant you that, when talking HP, with the 4.3L it would be overkill perhaps, but I've always thought I'd have a V-8 in this at some point. While at that time I may not be using the same rear axle, you never know.

I do see your point that the suspension would absorb most of the vertical movement, but how many people on this forum are running high horsepower V-8's and competing in baja style races with their Crews? On the other hand like you said you never know, and it certainly doesn't hurt to have more support on the rear end, especially if you really beat the hell out your truck off road.

[HenryJ]

... how many people on this forum are running high horsepower V-8's and competing in baja style races with their Crews? ...

None that I know of , but it sure would be fun someday!

I do have some fun on the Dry Creek expeditions, there are a few 40-60 mph stretches that can get rough. I love blasting through those sections

[quickbiker]

I would like to see what it looks like with the bracing in place. I just couldn't get a picture in my mind of it. If I did, I coulda decided more. It may get in the way for off-roading.

[killian96ss]

... how many people on this forum are running high horsepower V-8's and competing in baja style races with their Crews? ...

None that I know of , but it sure would be fun someday!

I do have some fun on the Dry Creek expeditions, there are a few 40-60 mph stretches that can get rough. I love blasting through those sections

I wish I had something like that where I live, that sounds like fun!

[HenryJ]

I wish I had something like that where I live, that sounds like fun!

There is nothing quite like being 100 miles from nowhere

[HenryJ]

Well, They kept moving the back-order date, so I cancelled and ordered this onewhich comes with a magnetic plug!

I think I like it better anyhow.

They did the same thing to me last update was an expected ship date sometime around the end of April
Reminds me of the whole reason I boycotted them for a few years...I waited almost six months for a blower for a customers car, finally gave up and ordered from Speedwaymotors. I had one within the week

Anyway my Ultimate cover arrived from Jeg's today. Paul was right these things are "beefy" , the flange is over 1/2" thick I , too like this better
I did follow Killian96SS' suggestion and filed reliefs for oiling the wheel bearings.
Since removal of the cover to change fluid will not be nessesary, now that I have a drain plug, I used silicone without a gasket to seal it.

My old chrome cover did not winter well , the rust was pretty disappointing

[quickbiker]

I did follow Killian96SS' suggestion and filed reliefs for oiling the wheel bearings.

I did partially. I did some measurements and the way the inside of the cover goes, it does give a bit of a gap, so I cut some of the inside of the gasket out on both sides to make sure it get's some flow, I didn't want too much flow. We'll see what happens in 70k miles. lol

[HenryJ]

I did follow Killian96SS' suggestion and filed reliefs for oiling the wheel bearings.

I did partially. I did some measurements and the way the inside of the cover goes, it does give a bit of a gap, so I cut some of the inside of the gasket out on both sides to make sure it get's some flow, I didn't want too much flow.

I don't think that we will have to worry about too much flow. Our covers do not have the inverted V groove (see pic below) to direct the flow to those holes, so it will be harder to get the oil directly in there.



(Some more interesting 10 bolt stuff from "Oldsmobility 10 bolt tech" )

I did not completly open the holes , but filed at approximately a 30* angle across probably 2/3 of the hole. The inside of the filed relief is probably 3/16" to 1/4" deep in the cover. This should leave an opening shaped like a "cat's eye" , maybe 1/4" wide and 1/2" tall, when bolted in place.

BTW, I'm pretty sure that it did not increase the capacity. Stock takes 64 oz. (4 pints) and I'm pretty sure that I used about that to refill. (the covers displacement looks real close to stock, too.

[Rockrz]

Think the Trick Flow Specialties TFS-8510400 would work OK at:
http://store.summitracing.com/partdetai ... toview=sku

Or, would the Summit SME-8510400 be better at
http://store.summitracing.com/partdetai ... toview=sku

[HenryJ]

Looks like apples and apples to me.
Look into cutting grooves for the oil holes.

There are several good threads on what lubricant to use. Some differing opinions on what the best choice may be.

[Rockrz]

Look into cutting grooves for the oil holes

Did anyone get pics of this, and/or do a write up?
I'm all for more lubrication

[killian96ss]

The Summit and Trick Flow covers are nearly indentical and for all we know they might even be made in the same foundry by the same manufacturer.

I have the Trick Flow cover on my 05 ZR2 and the Summit cover on my 88 S10 and they both look and function the same except they are on different sized 10 bolt rear ends and the logos are different.

If they both come with ARP 12 point ss bolts I would just get the one you think looks better.

Before you buy either one call Summit and ask if the cover comes with metric bolts or standard bolts.

When I bought the Summit cover for my 01 Crew Cab (7.6" 10 bolt) the bolts fit perfect, but when I got the Trick Flow cover for my 05 ZR2 (8.5" 10 bolt) the bolts were not correct and I had to buy some different ARP bolts from Summit.

I don't recall which one was metric and which one was standard, but I'm sure someone here will know the answer.

Summit did make me pay for a new set of ARP bolts even athough they were nice enough to give me 60% off the price.

Steve

[Rockrz]

Summit did make me pay for a new set of ARP bolts even athough they were nice enough to give me 60% off the price

I could always buy some bolts locally, if that were a problem.

I did partially. I did some measurements and the way the inside of the cover goes, it does give a bit of a gap, so I cut some of the inside of the gasket out on both sides to make sure it get's some flow, I didn't want too much flow. We'll see what happens in 70k miles

So this is all that needs to be done, is to simply trim the inside of the gasket in the area where we want the rear end juice to flow over into the axle shaft, so it can get outward to the axle bearings?

[HenryJ]

Look into cutting grooves for the oil holes.

I did not completly open the holes , but filed at approximately a 30* angle across probably 2/3 of the hole. The inside of the filed relief is probably 3/16" to 1/4" deep in the cover. This should leave an opening shaped like a "cat's eye" , maybe 1/4" wide and 1/2" tall, when bolted in place.

[Rockrz]

Now, that's the hole on the gasket itself...or the flat part of the cover that would block the hole in the differential housing if not filed open?

I was under the impression that both the stock cover and this after market cover are flat over the hole in the differential housing, right?

Kinda hard to tell exactly what you guys are talking about without pics.

[HenryJ]

You don't file gaskets. You cut them. If you use the correct gasket with the hole open , there are no modifications needed to the gasket.
The covers no longer have provisions for oiling. That is what needs to be modified.
It is possible you might be able to find an old cover that has reliefs for the oil to enter. I have not see them around, but I have not been looking either. It should look similar to the 8.5" 10 bolt cover pictured above.

If you read the articles above you will find that the 7.5" and 7.625" differential housings are flexy. This is where the trussed bearing support covers add benefit. Not to mention that they have enough material in the correct place to allow some filing and opening up the interior to improve oiling.

[Rockrz]

OK, that's clear. Thanks.

Now, any idea where to get a gasket that already has these holes...or, am I stuck with cutting a notch in a standard gasket?

[HenryJ]

They are out there. Check your local parts supplier. I find more of them have the holes, than do not.

[Rockrz]

OK, that's probably the best thing to do on this deal since I would need to see what I'm getting before I buy it.

[F9K9]

When I change my fluid again I am going to just RTV mine. It's allot easier for me.

[Rockrz]

Yeah, I've never trusted RTV sealant since I've seen so many vehicles that came from the factory like that spring leaks

[F9K9]

It's a personal decision. I always change fluids in my POS heep after deep crossings or deep mud without the first sign of leaking with after market covers. They leak from everywhere else but, my diffs don't.......

[barch97]

After 8 years and 105k miles, I'm finally getting around to replacing my rear differential cover. Not by choice of course, I noticed a small puddle of gear oil forming under it yesterday. Upon closer inspection I found that the lower lip of the cover is bent. Looks like maybe I misunderestimated my ground clearance at some point. I suspect this is the source of the slow drip but I haven't gotten a close look at it yet.

Those aluminum covers above look super awesome but the summit one is up to $150 + shipping. I've seen cheaper chrome/steel covers for around $20. I'm guessing the $20 covers aren't worth the effort of crawling under my truck but, the oem cover lasted this long, do I really need the super awesome aluminum one? There's gotta be some middle ground for a miserly old man like myself.

Is there a $50-$75 alternative?

Also as always, any related suggestions advice etc. are greatly appreciated.

[HenryJ]

The chrome covers are not a good investment. Not only do they hold the heat, but they also pit and rust very rapidly. No better than stock.
I have not seen cheaper aluminum covers, or heaver than stock for the 7.625" differential. There are lots of choices for the 8.5" though.

How about another stock cover? If it will fit in a mailer, $10 should get it to you.

[barch97]

Yeah, I wouldn't even consider chrome.

Will an 8.5" fit my stock differential? If so, I've seen other less expensive aluminum solutions (~$100) that probably are not as super awesome as the summit or the lpw (no "bearing cap support") but will likely get me by for another 8 years or so.

I appreciate the offer but, I'm a little reluctant to put another oem cover on after seeing the condition of the one I'm replacing. I'm also hoping that having a drain hole/plug will inspire me to keep the gear oil fresher.

[HenryJ]

The 8.5" cover will not work. I'm with you that a stock cover is not THE answer.
I am afraid that there are just no inexpensive solutions.

I like the Moser engineering cover. Check it out at JEGS.com or their website. It is pricey too , but a very nice truss cover.
The cooler cover Jim used might be another option. I don't recall the cost. It seemed like it was less expensive?
Check out Speedwaymotors.com too. They have quite a few others do not offer.

[barch97]

The cooler cover Jim used might be another option. I don't recall the cost. It seemed like it was less expensive?

I think that might be the one for me. Now to find a place that still sells 'em...

SLP has just released a new aluminum differential cover that not only improves the durability and appearance of the differential, but makes basic maintenance a snap, too. Produced by American Axle Manufacturing (AAM) exclusively for SLP, this new cover is constructed from aircraft-quality cast aluminum and designed to strengthen the differential housing by forming a firm back-bone for the rear end. It also includes cooling ports that are designed to keep the differential fluid approximately 80 deg. cooler, increasing the differentials durability and reliability immensely. The cover is also designed to aid in basic maintenance, as it includes a drain plug that allows you to remove used gear oil from the differential without having to un-bolt the cover. Minor modifications are necessary to improve fluid circulation to the carrier and gain the full benefits of the cover. All hardware and installation instructions are included.

This cover is designed to fit GM vehicles equipped with either a 7.5" or 7.625" differential.

Part #:SLP-65004
Application:1993-2001 f-body
Description:AAM Aluminum Cover
Price:$89.95

*Edit:

or maybe not...

grind through the template opening on the axle tube end until the axle tube is flush with the differential inner wall

That may be a little more than I can handle.

[barch97]

I think I'm going to go with another stock steel cover for now.

Dorman Differential Cover
Part No. 697-701
w/7.625" Ring Gear
$11.99

Hopefully one of you guys will be upgrading and sellin' off some parts sooner or later and I'll be able to pick up one of your super awesome aluminum ones on the cheap. Steel got me by this long, I'll probably be ok for while.

Thanks, Henryj for your great advice as usual.

P.S.
I'd take you up on your offer for your old stock cover but I can pick one up at local parts store for $12. Faster for me and less hassle for you. Thanks anyway though.

[HenryJ]

That sounds like a good solution. That cover appears to have a magnet epoxied to it and you get the gasket too. That is a nice addition. Probably cheaper in the end. Make sure the oil holes for the carrier bearings are open in those gaskets. I can not see them in that picture. Even though the cover doesn't have the reliefs, it may get a little in there.

Too bad I already sold off my Aluminum cover when I parted out my stock rear axle. Someone else already snagged it.
Another may show up someday.

[F9K9]

Looks like a rubber fill plug on the Dorman replacement unit. I prefer metal but, there must be a gazillion rubber plugged Dana 30 and 35s out there that haven't had issues.

[barch97]

Looks like a rubber fill plug on the Dorman replacement unit. I prefer metal but, there must be a gazillion rubber plugged Dana 30 and 35s out there that haven't had issues.

It hasn't got a plug at all. I think you're looking at the...

That cover appears to have a magnet epoxied to it and you get the gasket too.

Yup but, it's not epoxied in, just held in place by some bazaar invisible force.

The fact that it is movable leads me to speculate on the best position, above below or right on the fluid level line?

I had a can of gloss black engine paint in the garage, so I sprayed on a coat last night (exterior only). Hoping this will keep the rust away a little longer and if nothing else, it sure looks pretty.

I've had the truck up on ramps with a catch pan under the differential for a couple days. So, I've been spraying the bolts with pb-blast each evening after work. I was amazed at how easily I was able to loosen all ten. They were snug but, took little more than a firm pull to turn. I guess I should keep this in mind when installing the replacement and not over-tighten.

Also, the oem fill plug appears to be a large allen head? Anyone know what size this this is so I can go get one before I crawl back under and get all greasy?

[border man]

If I'm not mistaken, the fill plug is a square 3/8 female head. A 3/8 ratchet extension will fit in there.

[barch97]

Now that you mention it, it sure did look square. Thanks that saves me a few bucks. Now let's hope it's as easy to turn as the other bolts were. *fingers crossed*

[barch97]

WOW... That somebich is in there. How much force can I put on this thing before something breaks? It wouldn't be reverse thread, would it?

[rlrnr53]

Everyone that I've taken out has been right hand thread. They can be difficult ro get out if not removed every so often. Once you get it out, a good anti-sieze on the threads will make things easier next time. I have seen plugs so tight that it took a long half inch breaker bar, or three quarter inch ratchet with 250 lbs of mechanic hanging off of the breaker bar.

[barch97]

Everything seemed to go pretty smoothly right up until the end. Perhaps the most laborious and time consuming part was CAREFULLY scraping away the old gasket material making sure not to get any in the housing or on the gears. Getting that fill plug out was quite a task but once I repositioned myself and was able to get a little more leverage, it came around. Lastly, and this was just poor planning on my part, there isn't quite enough room to tilt a quart of gear oil enough to pour in. So, I had to make a trip to local parts store to get a flexible funnel.

Not a bad DIY project. I suspect I'd change that fluid far more frequently if it didn't require removing the cover and replacing the gasket every time... nah, I'd probably still only do it every hundred thousand miles or so

Thanks again to everyone for all your help.


*Edit: BTW... The one place the old gasket came off whole and intact was right where the dent in the lip of the cover was.

[barch97]

still dripping

[HenryJ]

Did you use a sealer on both sides of the gasket? Usually I just use a light coat on one side of the gasket, but there is no problem coating both.
You can use the sealer only with out a gasket too. An 1/8" bead if silicone at the center of the sealing surface and all the way around and around each bolt hole usually works. That will not leave you an open hole for the carrier bearing lubrication. That is where the gasket and recessed cover can be an improvement for our trucks.

Is there a chance that there was a burr where the bottom was hit? Laying a large flat file across the sealing surface you can lightly rub it across the face to highlight imperfections. You can then lightly file them down by rubbing it back a forth. Just use you fingertips and work carefully to retain a true surface.

Anything worth doing is worth doing at least twice. There goes the cost savings - bam! right out the window! Average it out over the miles you have and I am still way ahead of you on this task though. I change the fluid pretty regularly. Only twice have I had a chance to use the drain plug though. The rest required removal of the rear cover.

[roadrunner]

Might be worth the time given all that has already been done to inspect very carefully the area where the impact occurred for cracks. Not to be a doomsday-er but I have seen housings cracked by severe impacts before. Good luck!

[barch97]

Did you use a sealer on both sides of the gasket?

Sealer?

I think, I got it this time. I left a clean piece of cardboard on the driveway under the differential. Oughta make it easy to spot any leaks. It's been about 15 hours and not one drip... yet...

[LoneWolf04]

Bringing this thread back up because my stock cover has seen better days and want to upgrade. I've noticed that some covers indicate they add oil capacity, did anyone notice this? Seemed like the ones that did are the LPW, Moser, and such that relocate the fill hole higher, which then you would be overfilling. Didn't know if these covers were shaped differently to accept this extra capacity and keep the proper oil level. Thanks for your guys help.

[killian96ss]

Most of the nice aluminum support covers for the 7.5" 10 bolt rear end don't add much more if any extra oil capacity, but they do improve the strength of the case and add support to the bearing caps to prevent movement. A higher fill hole really doesn't matter since the correct fluid level is determined by filling the side hole in the housing until the oil just starts to flow back out. If you fill your differential using a higher fill hole, you will definitely overfill it. The Trick Flow covers from Summit are nice. I have 1 on all 3 of my vehicles.

Steve

[F9K9]

Steve's right on with fill level. Unless you've lifted so high that your pinion angle has increased, there's no need to use anything other than the stock fill hole. A little extra oil won't hurt but, adding too much will result in your diff puking fluid out of the vent line and possibly blowing out the axle seals. I purposely run too much fluid in my Jeep's diffs because of my pinion angles. I also have "catch cans" to capture the oil coming out of the vent lines so, we can keep the tree huggers from complaining about us polluting the environment and closing more of our public lands.