Did you try all the Corvette vendors?

Corvette America

Corvette Central

Corvette Pacific

Mid-America

Volunteer Vette

Ecklers

Zip Corvette

as well as eBay and vette2vette

Good luck

See if this helps...


Tired of a lurching, squealing ride? Corvette U-Joints might be the answer. View this email in your browser
Mid America Motorworks 800.500.1500 | mamotorworks.com
Replacing Corvette U-Joints
The U-Joint, or universal joint, transfers the motion of your Corvette engine to the wheels and compensates for alignment changes when it's not possible to make a straight connection from the drive shaft to the wheels. Most U-Joints are permanently lubricated these days to ensure proper function, and those that aren't will let you know with noise and vibration if there's trouble brewing. Mid America Motorworks gives you the tips to ensure a smooth ride and steps to replace your U-Joints.
The Importance of U-Joints
If it's time to replace your U-Joints, you'll get some quick indicators. This is because U-Joints work together as a team. When you notice squeaking, vibrations and lurches in your once-smooth ride, it's probably the U-Joints.
When U-Joints fail, it can damage the drive shaft, the yoke on the differential, and the yoke, tail shaft, and output shaft of the transmission itself. Routine maintenance and lubrication of the U-Joints can greatly extend the life of the joint and save you the time of having to replace parts more often than necessary.
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Quick Tips to Check U-Joints
• Listen carefully to your Corvette as it is moving. Take note of any squeaking or metallic sounds, as these can indicate a dried out or is under-lubricated U-Joint.

• Any vibration caused by a worn drive shaft U-Joint is usually an indication that the U-Joint is close to failure. If you detect a vibration, do not dismiss it.

• While stopped in a driveway or parking lot with the engine running and your foot on the brake, shift the car from park into reverse. Listen for a clunking or banging noise as it goes into gear. You will often feel it jump when it bangs, indicating a loose U-Joint.
U-Joint
• Park on flat ground and shut the engine off. When the car is safely parked, try turning the drive shaft and note any play in the U-Joints of the shaft. Loose joints can allow the shaft to move a quarter-inch to as much as a half-inch in either direction when turned.

• Insert a large, flat screwdriver into the yoke that connects the drive shaft to the transmission yoke or differential yoke. Try turning the shaft by pushing up or pulling down on the screwdriver. Note any movement in the shaft that would indicate a loose joint.

• Inspect the U-Joints using a flashlight. Look into the yokes for chipped or broken bearing caps, rust or missing bearings and retaining clips. These signs are indications of a severely worn U-Joint.
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Types of U-Joints
Greasable U-Joint Pro:
Can be re-greased to ensure the best function. They are typically re-greased on the same schedule as an oil change.

Greasable U-Joint Con:
The U-Joints are hollow in the center, which can compromise the integrity of the joint in situations that can shock your drive train.

Standard vs. End Cap Grease Zerk:

A Grease Zerk is a metal fitting used to lubricate bearings under moderate-to-high pressure using a grease gun. Where a standard Grease Zerk is more difficult to access without removing parts, the End Cap Grease Zerk is positioned in a way to make it easier to re-grease the U-Joint and get back on the road.

Non-Greasable U-Joint Pro:
A non-greasable or sealed U-Joint is a solid piece and typically more durable than the greasable kind.

Non-Greasable U-Joint Con:
No access or ability to add grease to the U-Joint
end cap grease zerk and non-greasable u-joint
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Your Next Weekend Project
U-Joints should be routinely greased and inspected for signs of wear. A damaged or worn U-Joint can fail and cause severe or even catastrophic damage to your Corvette. Replace factory U-Joints with high-quality aftermarket joints for regular maintenance and longer service from each joint.
Keep in mind that because Corvettes have Independent Rear Susupension, the U-Joints are laid out a little differently.
corvette diagram
Replacement is relatively simple for the garage mechanic, with only a few basic tools required:
tools
Steps to Replacement:
1. Back your Corvette onto ramps so that the rear of the vehicle is lifted off the ground. Engage the parking brake and put the transmission into park. Under the Corvette by the rear axle and gear housing, locate the U-Joint by finding the junction of drive shaft to the rear axle. The U-Joint sits between the two yoke ends of the drive shaft and rear gear housing.

2. Two U-Bolts loop over two of the four posts of the U-Joint. They lay over the cup bearings and are secured by two bolts that hold it in place to the rear gear yoke. Use a small wrench and hammer to break loose all four bolts before removing each one. Loosen all the bolts first; then continue to loosen and remove them. Two U-Bolts have four fasteners that secure the U-Joint in place. It is not a good idea to mix and match the U-bolt parts, so keep all matching fasteners together to go back to their original locations during installation. Pull the U-Bolts from around the cup bearings on the U-Joint.

3. Separate the drive shaft from the rear axle by pitching the U-Joint so that the end of the joint that has been freed from the rear axle yoke is pointed away from the rear axle, and the other is pointed closer to the rear axle. Put the vehicle in neutral and turn the drive shaft by hand.
u-joint
4. As the drive shaft is turned, the position of the free cup bearings will allow for the drive shaft to turn away, and out, from the rear gear yoke. When free, hold the end of the drive shaft above the rear gear yoke and pull the drive shaft out of the back of the transmission. Once free from both the rear gear yoke and the back of the transmission housing, take the drive shaft to the work bench where there is a vise to work with.

5. Extract the U-Joint from the end of the drive shaft yoke by first removing the fasteners that hold it in place. Some yokes secure the U-Joint into position using snap rings that fit inside the yoke at the top of an installed cup bearing and do not allow it to exit. Another yoke clamp that may be holding your U-Joint in place is a ring clamp. You need to either use the screwdriver to get the snap ring out or a pair of pliers to release the pressure of the ring clamp that holds the U-Joint into the drive shaft yoke without nuts or bolts.
6. Squeeze out the cup bearings that are holding the U-Joint in place after the clamps are removed from the yoke. It takes a great deal of pressure to push a U-Joint cup bearing out of its seat in a yoke, but it can be done with a table vise and two sockets. Get one socket that is smaller than the opening of the drive shaft yoke that allows access to the top of the bearing, and another that is bigger than the opening on the other side of the yoke for the bottom bearing to be pushed into.

7. First position the small socket inside the vise, then the yoke with the universal joint, then the large socket. As you tighten the vise, you will push one cap down and out with the smaller socket. You will also be pushing the other end of the universal joint out of its seat.
u-joint
8. Replace the U-Joint with new cup bearings or a whole new joint. To seat the bearings in place, grease the new U-Joint and cup bearings and insert the joint into the two openings that the bearing cups will be seated. Place one bearing cup on the joint and insert it into the seating hole. This cap will be pushed up into the space using the other bearing cup on the outside of the yoke. Tighten the yoke and bearing cups together so that the outside bearing is pushed into the seat and onto the other end of the U-Joint. After the bearing seats onto the post, it will push the other bearing into place.

9. Use the small socket to continue pushing the U-Joint into position after the bearing has been seated inside the yoke and is even with the inside edge of the opening. The joint should be positioned so that the snap or ring fasteners can secure the U-Joint into position.

10. Get back under your Corvette and hold the drive shaft in position for insertion into the back of the transmission. Hold the yoke end of the drive shaft above the yoke of the rear gear and insert the spindle end of the drive shaft into the opening in the back of the transmission. Push the drive shaft in as far as it can go and then lower the yoke end of the drive shaft down to the yoke of the rear gear.

11. Pitch the U-Joint so that one cup bearing is pointed away from the rear axle and the other is pointed toward the rear axle. As the drive shaft is turned, position the loose bearing cups onto the yoke seats of the rear gear yoke. Replace the U-Bolts around the open cup bearings and tighten securely.

12. Place your Corvette in park and release the parking brake. Start the engine and drive off the ramps to complete the job. If you still experience vibrations or noise, lubricate or tighten the U-Joints where necessary.

Grounds can cause weird problems with the electrics on our glass bodies I would start checking those out first

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It's not like the filters take up that much space LOL

I had started the job on my '91 but was not able to finish it, mainly because I have no garage and have to work in my driveway :-) My mechanic finished the job and said it was quite a bit of work, including having to drop the rear half of the exhaust system. I think I could have finished the job had I been able to work in a garage with some more time (I ran out of patience LOL)

Check distributor rotor, wires, etc. first

On my '91 if the airbag fuse is not live there will be no fuel to the injectors...

I have had extremely good luck with used parts from www.vette2vette.com

Not the original in fact I think it's a Racetronix I bought a few years back which I why I would have been surprised if it was a bad pump...

Got her running again...hooked up the fuel pressure gauge, cranked it for a bit; zero. I jumpered to the fuel gauge circuit, nothing. So I took apart the fuel pump assembly and jumpered directly to the pump and it ran. Found some crud on the intake inside the sock, cleaned it out, check all the wiring, put her back together and she fired right up. So I'm guessing it was either the crud in the intake (I had the tank down real low) and/or something electrical not making contact but it's running like a champ now, thanks to everyone for all of your help!

I'll put the fuel gauge on tomorrow; how would I know if it's a bad filter as opposed to the pump?

I think my fuel pump may have died, car cranks, will start with starting fluid but will not stay running. Car started fine a few weeks ago, went to move it a few days ago and nothing. I have checked all the fuses, they are all good, if I remember correctly, when the ignition is in the ON position, shouldn't I hear the fuel pump going? Now nothing but silence.

What it the quickest/easiest/best way to test? Or is there something else I should be looking at? thx

What brought this issue to your attention? Leaks or just visual inspection??

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I've always had good luck with vette2vette.com

I cannot think of any reason why you couldn't use it extensively. I have a trickle charger in the cigarette lighter of my '91 and not had any problems, and I've used many other accessories in other older ('90s) vehicles extensively with no problems.

The only thing you might need to watch is the current draw, if it's too much it could blow a fuse or possibly cause wiring damaging/overheating (but the fuse *should* blow first)

Without running out to look at mine...it doesn't look factory to me, almost looks like something someone ran to an aftermarket device like an alarm or sub woofer etc.

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Very tough to track down leaks on the C4s, I've had wet carpets on the driver's side of my '91 for a long time even after all new weatherstrip.

Need to get inside while someone hoses down the top and see where the leak is coming in, so many possible points of entry.

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With a bad MC wouldn't the pedal go to the floor?

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Broken motor mount, yeah but could be just loose; happened on my Sonata.

Total shot in the dark; engine mount(s)

Have had to put this project on hold recently due to other issues, but ready to get back to it now...

Question; if the pre-cats are shot wouldn't that cause my high HC emissions? The idle HC dropped a lot when I replaced the main cat, figuring if the main one was that bad (totally blown out) the pre-cats may not be so hot...

If that is the case, would replacing the pipes without pre-cats and leaving just the main cat cause trouble passing the NJ emissions?

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Main cat on my '91 was completely (and I mean completely, nothing but a metal shell) blown out. Still failing emissions I think the precats are likely shot too.

How did you determine all 3 cats bad, did you pull and inspect them all?

As for the slow start, I'd begin with checking the fuel pump that caused a of problems on my L98.

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Same here with Interstate not so impressed...I'm thinking of trying Autozone

My '91 coupe has only ONE fuel pump and it's in the tank, replaced by removing the fuel sender assembly from the top of the filler neck. I don't know that the convertible would be any different, have to check the manual.

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Not sure on your cause but it's pretty easy to change the fuel pump.

This is strictly a SWAG, but I thought there is a connection between the oil pressure switch near the distributor, and the fuel pump, so that if there is no oil pressure the fuel pump will not run. Or maybe if the distributor isn't spinning as in when starting/running, the switch won't close and thus no fuel?

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No headers, stock manifolds. Pretty sure it's not in loop how can I tell for sure?

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Cap rotor and plug wires are all less than 5K old.

Had an exhaust leak (at back of cat) fixed it when cat replaced.

Tried the "guaranteed to pass" stuff before all it is is injector cleaner. I did put a can of Seafoam in the fuel tank and a bottle of Heet figured it couldn't hurt.

CTS?

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Just the main cat; don't have the time, money or facilities to replace the precats too

Have not checked the plugs but they have less than 5K miles on them

Gas is recently filled

Well, here is the latest, but NOT the greatest;

Brought the car back to NJ inspection yesterday, and failed (again) but this time for high HC at high idle; reversed results of the first fail.

Here is a recap;

First fail;
@idle
HC 491 allowed 220 (FAIL)
CO 0.88 allowed 1.20
CO2 8.5
O2 8.2

@high idle
HC 58 allowed 220
CO 0.53 allowed 1.20
CO2 10.7
O2 5.4

Second fail;
@idle
HC 199 allowed 220
CO 0.56 allowed 1.20
CO2 14.0
O2 1.1

@high idle
HC 446 allowed 220 (FAIL)
CO 0.71 allowed 1.20
CO2 14.5
O2 0.4

I don't get it, and I'm ready to throw in the towel and bring it to my mechanic.

Changes between tests:

New Magnaflow catalytic converter -- also fixed exhaust leak and replaced air pump hose

New O2 sensor

New air intake bellows

Change oil and filter

Clean air filter

Clean injectors

Check timing (was at 7, spec is 6)

Observations;

I have had an Accel foam filter for years, it passed with this filter before, I cleaned it but did not re-oil it so it is almost dry.

I was getting a code 32 for (literally) years, now I don't get it any longer so there is no need to pull over before the inspection and disconnect the battery briefly to clear the check engine light.

There is a very slight miss at idle which I can't trace down, it's been there for quite some time not sure it has anything to do with the numbers.

So, what in the heck caused the changes in numbers, and
most specifically, the "new" fail, HC at high idle? I am baffled. Any help is appreciated....thanks all.

These tips were for 92 to 96. I thought I saw tips like these in one of the Corvette catalogs recently when I was looking for parts for my '91.

They may not be exactly like the factory but they were close. I think it was Corvette America, Corvette Central, or Ecklers.

Well check this out, I don't think the cat does a very good job when there is nothing inside it eh? LOL Wow I've never seen this before. Ya think this could be why I failed emissions? :-)

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Thanks guys I don't know what I would do without you

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So...there is a donut? or not?

OK, getting ready to replace the cat on my '91...quick question, on the stock exhaust) is there a 'doughnut' between the rear of the cat where it connects to the rear 'Y' pipe? or is it just a pressure fit?

I could not find any parts listing for a doughnut/gasket in any of my manuals etc.

Right now there is an exhaust leak around that fitting and I'm not sure why as I haven't taken it out yet. Thanks!

Just thought of something; if my air pump is bad, could that be a/the cause of failing NJ emissions for high HC at idle?

Is there a quick test to check if the air pump is working?

thx

Well I notched the plastic ring around the terminal and replaced the bolt, all is well now. I still have the 'check gauges' light on all the time, but that's a problem for another day LOL

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My KYBs are fine, no complaints at all. I probably wouldn't use them for any kind of competition for a daily driver/street use they are the best value, IMHO

Well my new Magnaflow converter arrived this week, hopefully this weekend I'll be able to install it. I've already replaced the O2 sensor, cleaned the air filter, changed the oil and filter; I'll check the timing then cross my fingers and bring her back to the testing facility soon, thanks all for your help.

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I have had the KYBs for a few years and they are great. Best bang for the buck, good ride and handling. For a daily driver/street ride I think they are the best choice. If you're going to race/autocross/etc. they may not be the best choice but I can vouch for them for regular street use.

I saw the Random Tech units, they look nice, but pricey...I'm not loaded like you guys LOL

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Maybe it's just me :-) but I'm confused

http://shop.advanceautoparts.com/weba ... teel-magnaflow_22317388-p

Says only not for sale in CA, nothing about NJ. Most other sites list this and other cats (e.g. Catco) as being "49 state legal".

Is this cat not legal in NJ? or is it just not as good?

One more ? do I need to worry about the pre-cats or if I replace only the main should that do the (emissions) trick?

Thanks all!

I'd love to replace the whole system right now but can't afford it...

If I replace ONLY the main cat, should that be enough to clean up the emissions issue?

I can get a Magnaflow cat for about $140 from Summit Racing.

I'm guessing I still have the OEM cat(s) on the car, and it's got a little over 100K miles.

What is the "normal" life expectancy of a factory cat?

Is there any way to do any actual testing of the cat?

Thanks everyone!

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I though EGR would only impact NOx too, that's what my research shows.

Not sure if the solenoid works, it's a part that's no longer available. Also not sure how to test it but if it's in the Helm's I'll look it up...

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Been getting a code 32 for (literally) a few years after any time at constant highway speeds for more than a little while.

Code 32 is EGR, valve was replaced not long ago, no help, I tried replacing the EGR solenoid, no go.

Somewhere I read that a problem with the evap control system could trigger a code 32 but I have not yet had time to track that down yet.

Since a check engine light is an instant automatic fail, for the past 2 inspections (every other year here in NJ) I have pulled over a ways before the inspection station and briefly disconnected the battery since I always got a (code 32) check engine light on my drive there.

It's passed the other times, though I believe that between this inspection (failed) and the last one 2 years ago when I passed, they now check emissions at idle instead of only at fast idle.

Just got new bellows today hopefully this weekend will be nice I can do some more investigation and get this thing through emissions...

I *THINK* I may be found the problem; see picture, today I found the air intake bellows has 2 small holes in it right near the throttle body, one pretty good size you can see the white behind the openings.

Can someone confirm that this could very well be the cause of my high HC at idle emissions failure? Maybe even a occasional slight miss at idle? It would be the cause of a vacuum leak, correct?

Hopefully it's something simple like this and not big $ like the cat. Thanks all!

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That's helpful :-)

A little more info...after warmed up fully (surges when cold, been doing that for years) when idling in Drive there is an occasional slight mis...

Also what about CRC "Guaranteed To Pass"...?

And, just noticed, it looks like NJ added an idle speed emissions test, the previous inspection did not show 2 tests, only one, at "2549 RPM", which would seem to me to be equivalent to the "new" "high idle" test...apparently they didn't check (low idle) speed emissions before?

NJ stinks BTW LOL

Thanks again all!

Hello all,

I know this has been touched on in past messages and I've searched but I'd like new and fresh opinions.

My 'stock 91 L98 just failed NJ emissions for high HC; allowed is 220 I blew 491 on the idle test. CO is OK 1.20 allowed blew 0.88, CO2% 8.5, O2% 8.2 and the high idle test is OK, 220 HC allowed blew 58, CO 1.20 allowed blew 0.53, CO2% 10.7, O2% 5.4

Car was hot when tested, what I had to do so I did not fail for the check engine light was pull over about 1/2 mile before inspection, shut off engine, and disconnect battery for a minute to clear the light, then went to testing within 10-15 minutes -- this couldn't be the cause could it? I did the same thing 2 years ago...

Only code is a 32 after extended highway driving which I've had for years, the car passed emissions with flying colors only 2 years ago and nothing has been changed except for maybe the evap canister and lines (had fuel tank replaced).

Injectors were replaced probably 3-4 years ago with units rebuilt by FIC, along with many other items, plugs, wires, cap, rotor, EGR valve, etc. Car is driven under 5K a year.

I've seen and heard many different things, what really works?

Seafoam? if so how, exactly?

Timing? if so, how, advancing a little beyond 6 BTC or wouldn't the ECM automatically compensate?

Pulling a vacuum hose (wouldnt' this create a vacuum leak and increase HC?)

This has been really frustrating, especially since it passed with the same setup...thanks all!