1996 Collector Edition Corvette

[MostMint]

Yep. That occurred to me. Pinion seals don't usually fail like this. That was Maverick's thought, too. Have you ever checked this tolerance? Is it just an up and down push/pull to see if movement is detected?

Have not. I have used a dial indicator to set pinion depth. My best guess is that it would be similar - put it up against the pinion shaft and move it to see how much play there is. Also has to be a spec for that somewhere.

[wxo]

With a pleasant afternoon yesterday, I decided to get Silvia up on four jack stands again to get ready for whatever comes next. I started her up to reposition her a bit and noticed that the digital dash came back alive. The ODO was showing 103,742.

Getting to the pinion seal requires removing the exhaust system. It is one piece from the cats back so it looks like another mini-project. First order of business was removing the X-Brace (convertibles only) underneath. It's not really a bad job. They are quite beat up from some off road excursion(s) in the past. I've been dreading the rusty studs and nuts keeping the exhaust together, but I had dowsed them with Deep Creep the day before and my trusty Earthquake impact wrench unscrewed them without complaint. Now i have to figure out how I'm going to get this big ol" thing out of there. I plan to remove the cats, because I suspect a leak where they mount to the engine on the passenger side. With the entire exhaust system out, I'm wondering about replacing the cats with something more modern and much lighter and smaller giving me more room to work in that area. I'm also considering muffler deleted pipes that many C4 guys are installing on YouTube. All in due time, though.

[wxo]

I ran into a problem with State Farm recently. Before I took Silvia off the road for engine work last year, I had gotten her classified by State Farm as a Collector Car. When she was road worthy again, I reinstated all the needed policies. Now that she is up on jack stands again, I called State Farm to remove everything but liability. When I got the bill for the change, it seemed too high for Collector Car coverage so I called my agent. Turns out (somehow) the Collector Car status had been removed and I had been paying normal auto rates for some months. It took conversations with several agents before I was able to learn that this had happened. Now I am waiting for them to, again, re-reclassify Silvia to provide me with the appropriate rates for my coverage. One less issue to deal with.

Since I have to remove the entire exhaust system to get to the leaky pinion yoke, I have given it a closer look and much thought. I decided that it would be prudent to replace the cats so that I don't have to go back and revisit this again. Before I remove the old exhaust, I plan to measure the backpressure in the original system to see how well it is flowing as it is. A lot of nuts and squirrel debris came out of the exhaust when it was first started after it's three years in the barn. I may have to deal with some clogging in the mufflers, also. Worse case, a cat-back system may be the best way to go. Maybe next week I'll get a warm day to make some headway on this issue.

[wxo]

Maverick sent me a link to a tool on Amazon that measures exhaust system pressure. It simply threads into an O2 sensor bung and is connected by a hose to a pressure gauge. The Amazon ad states that 1 psi at idle and <3psi @ 2500 rpm is good.
I decided to make my own. I cut off the top and bottom of an old O2 sensor and JB welded in a brass barb fitting and had this:

Then I commenced to begin the testing process. I installed the tool in the O2 sensor bung nearest the engine so that I could get my initial reading of the whole exhaust system. The readings I got amazed me. They were .5 psi @ idle and .5 psi @ 2500 rpm on each side through the cats and mufflers! Great news (for a change). Now I know the whole system flows extremely well. Next step is to get the exhaust system out of there. I started the process yesterday and found that all my impact socket sets do not provide a 15mm socket! I was stopped in my tracks. They won't arrive from Amazon until next week. Oh well

[wxo]

Since I'm waiting for stuff to work on the exhaust, Dave's post motivated me to get started on my digital dash restoration. I took out the instrument cluster today and watched the Batee video for the restoration. Hmmm...it looks like it could be tricky.

[wxo]

The correct 15mm impact sockets had arrived from Amazon and were waiting for just the right day to use them to remove Silvia's exhaust system. I was not looking forward to this job, but today I thought I'd get started and loosen as many nuts and bolts as I could. Never expecting much success, I was surprised when they all came loose without breakage. I was sure it would be a struggle to get the exhaust separated from the right side cat, so I squirted some Deep Creep into the joint and hoped for the best. I positioned a jack under the exhaust at the balance point and started rocking it back and forth from the rear and suddenly the whole thing just came loose. Easy peazy! I should be able to easily roll the entire system out from under the car but it is raining today and I need to figure a way to get it from the garage into my basement for storage until I get the rear end leak solved. For a change, Silvia gave me a break.

[wxo]

Maverick came over and helped me move the exhaust system into temporary storage in my basement. Now I turn my attention to the "C beam". It is an aluminum beam structure with a "C" cross section which solidly bolts the transmission and differential together. It's likely that I will have to remove it to get sufficient access to change the pinion seal. In researching to get familiar with this area, I read about one fella who had cracks that appeared on his C-beam where the mounting bolts go through it. In response to his issue, several posts pointed to a place in Arizona that sells a set of plates to reinforce the mounting of the C-beam. https://www.corvetteactioncenter.com/pr ... eam-plates . It seemed like a good idea to me, so I ordered a set. With the exhaust out of the car, this is a good time to do this, otherwise it's not really easy to add the plates because the exhaust system needs to be removed to get access to the C beam.

[wxo]

With the exhaust system out of the way, I turned my attention to replacing the catalytic converters. Getting them out turned out to be a two afternoon job. The right side was difficult due to inaccessible hanger bolts. It took me several hours to finally get it out of the car, but it was the left side that really kicked my butt. The top hanger bolt was located in a spot so high up I couldn't touch it with my hand. I tried several open end wrenches and finally ended up getting a ratcheting box end on it to screw it out. To make things even more difficult, the bolt was boxed in by the fiberglass body panel. I was relieved to be able to unscrew the bolt until I realized that I had gone too far. I had backed it out too close to the body and the wrench was captured in place. I couldn't screw it back in to release the wrench because the ratcheting wrench needs to be removed and turned around to turn the bolt in the other direction. I returned the next day to have a fresh look at the situation. I could see the bolt and wrench from the top, so I decided I could get a hand on it from the top if I removed the windshield wiper motor. This is not a simple task, but I thought it would be worth it if I could get myself out of this predicament. Once I got the wiper motor out, I saw that there were bundles of wiring blocking my path to the bolt. This was not going to help at all. So back down underneath. I used a long screwdriver to tap on the points of the bolt head to screw it back in enough to get the wrench out. Then I used the same technique to back it out again, but now it was touching the body with not enough room to get it completely out to release the cat. The next part was sheer desperation. I tapped it and moved it to the side a bit and finally removed all the other attaching bolts on the cat so that I could move things around a bit more. This worked! I now had enough room to push the bolt a enough to the side to allow everything to come loose. I have no idea how I'm going to install the new cat. It is designed to use the old hanger bracket and I will be required to use the same bolt locations to install it. Well, I'll figure that out when I come to it.

Here is a size comparison of the old and new left side cat:

Once I get all this stuff back in place I should have a lot more working room in this area.

[wxo]

Today I did a test fitting of the new MagnaFlow "Direct Fit" cats. I started with the passenger side and ran into this:

The hanger is designed to slip over the body of the cat (where my hand is), then attach to the stock bolt location. The vertical bracket in the photo is bolted in the stock mounting bracket location and the front end of the cat is bolted loosely in place on the exhaust manifold outlet to locate the assembly correctly. With the way this hanger is made, it seems to me that it can't work. I've opened up a trouble ticket with Magnaflow and sent them the picture you see.

[Basement Paul]

If those were cheap replacements, I could see, but Magnaflow I'm sure charges a boat load for those things and thus makes it inexcusable IMO. Frustrating for sure.

-BP

[MostMint]

I trust that by rotating that hanger 180 degrees the loop is still in the same place.

That hanger has to work on some model. Part of me wonders what changed on that transmission between years on the C4 to create this situation.

[wxo]

I trust that by rotating that hanger 180 degrees the loop is still in the same place

Yes, I thought of that, but the vertical bracket is welded in the center of the loop, so it makes no difference which way it is slipped on. If you look closely at the photo, this hanger has an additional bracket welded to the loop. It is a bit shorter and is entirely superfluous and makes no sense, at least in this application. I can't see how this thing could ever work.

[MostMint]

Ok. Could not tell for sure if it was center welded from the pic.

Where it bolts to the transmission- does the hole for that bolt go all the way through? Like if you put a longer bolt in there would it stick out the other side so you could hang the bracket on that side and put a nut on to hold it?

I’m improvising and not necessarily advocating this route, but if it work it could move the project forward faster.

[wxo]

No. The mounting bolt goes into a blind hole.

[TireSmoker]

I'm with Paul, that's frustrating on higher priced stuff like that. Seems like you have some sort of semi-universal hanger. Hopefully they can just send you a correct bracket.