Well at least some of those cracked bellhousings had double block plates on the block.
Those were 800+HP dragsters IIRC.
It had to be frame twist in those cases.
The others were more normal cars, also drag racers or strong street cars, and also probably frame twist. Less HP than the dragsters.
I've seen broken AL bells, not steel ones, broken manual AL trans in a couple spots both front & back, and cracked AL bells on the autos.
All had solid trans mounts AFAIK. And switched to rubber.

What kind of benefit would you expect from a solid trans mount?
How are those two bolts at 2" apart going to add any frame stiffening? There's no leverage.
What other benefit is there? It is just a locator bolt.

Now handling wise, a front and rear motor plate, at rear of block to frame, ditto front, holds some promise to use the cast iron block to help stiffen the frame. But if I remember my layout the rear of the block is near the S-bend, and that seems like where the most twist would be, once you get past the a-arm shake. So as much trouble as that would be and I don't even know if it would help much. A roll cage would be better for sure.

 

Loving this thread

 

I have never said that solid tranny tail shaft mounting block did anything for handling or frame stability.

I only did it for ease of transmission installation. Your drive line has required angles to avoid vibration. So when I made the cross member and I needed a two bolt spacer. aluminium blocks are the easiest to machine and drill to the custom size

 

I like the looks of this method to read directly off of the components. If the car is supported, without the wheels, on jack stands under the front shocks would that be comparable to the way you are loading the suspension with straps in the photos? I would place the stands so that the hub is at the same height as with wheels mounted.

 

What is AFAIK?

I was trying to think of the dynamics required to break a bell housing in a c-3 vette. Not some unibody solid axle Camaro or some Hill Billy noodle framed dragster. Most c-3's have some stock tranny crossmember or possibly something like the G-Force piece when they installed 700R4 or TKO type manuals. Engine TQ with solid engine mounts and stock rubber mounts once compressed will cause the frame to rotate. Probably compressing the passenger side tires more than the drivers side. I just don't see any big load imparted by the tranny cross member. Just think about central steel plate with two big bolts through it. The solid or rubber being tighted down into the tail shaft tabs basically becoming one piece no matter what the spacer is made out of. Because you are compressing hard rubber tightening it down. The two bolts make it ridgedly mounted. Rubber might have some minor vibration advantages.. Oh, I did have a solid aluminum block spacer under my 700R4 racing transmission before my 5 speed. 3800 stall and in it's final phase my 7500 rpm shifted 427 and yes drag slicks. It never broke anything

On road racing cars at the shop I saw broken muncie transmissions. The internal TQ would break the case. So back then we installed Texas racing transmissions. Gt40's would break the transaxles on missed down shifts where the car was hopping on the rear tires and the tattletail tach would be pegged at 9000 rpm. None of that had anything to do with how the tail shaft was mounted. I also 1/2 owned and raced a NHRA rear engine dragster in the late 80's through the 90's. At a typical national event you might have 60+ dragsters and roadsters all trying to be in the final 16 spots for the sunday event and classes are all pitted together and I don't ever remember even one person saying that they broke a bell housing. We had a 2 speed power glide 6500 stall with a tranny brake. My supercharged local friend was running a th400. Everyone had motor plates front and rear of the block. Mine had nothing holding the tranny tail shaft. Just a coupler to the solidly mounted narrow rear end. The aluminum motor plates were made out of tempered aluminum and bolted to it were rounded tabs that fit over the dragster frame rails. These 4 tabs were held in place by 4 wide SS typical hose clamps. It gave you the ability to R&R motor in a very short period of time.

 

Ok I'm done with this.
I am glad it works for some.

My main point is what possible handling or frame stiffening advantage could a solid SBC trans mount have? I just don't see anything positive coming from this mod.
Convince me.

Engine mounts are a whole 'nother story.

 

Like I said none, nada, nothing. But ease of custom fabricated mounting devices.

Now solid engine, solid differential I believe adds lateral strength. Solid differential snubber makes it possible to set the drive line angles and not break the differential cross member

 

We all agree that our vettes are 50 years old and in various states of disrepair.

So the best advice is to plan ahead and not having to do things twice or upgrade to what you really wanted. No baby steps!

If you're not mechanically inclined have a person check everything out. Ball joints, bushings, steering, and shocks. If those things aren't right you can't even align the car.

The best thing that I did when my vette was new was the Street and slolam kit. Then I went to wider wheels. Every discussion on shocks really comes down to what you can afford. To me I should have skipped the baby steps and gone straight to the top with dual adjustable. I probably tried 4 -5 kinds over the years. Just turn a couple of ***** with 10 clicks each.

Springs and sways are always a discussion. From touring cars to responsive safe cars. Every person has an opinion. I was asked to look at a restored vette with everything done. It was like an NCRS vette for sale. The way it wallowed down the road reminded me of when my 79 was new and it just didn't give me that safe feeling like a stiffer vette or a modern full sized car. My Audi q5 SUV is a better canyon carver.

My buyer's report is that it's 100% with everything done as advertised. Very original and probably better than it was on the show room floor and feasibly a top flight car. The owner had some judging certificates and was pretty much a trailer queen. It was a lot of money for a low mileage chrome bumper car.

The subject of years of owning and driving vettes. If you have two vetts of any kind and you have 20 years with one and 12 with the other. You have 32 vette years.

 

With that formula, I guess I have a lot of Vette years. Just look at my avatar.
But.
My take on this thread. At least perhaps what it is that I would like to see.
Is solid advice to the newer C3 Corvette owners on what works for the average guy on a street car.
I'm assuming that the average forum member is not a experienced racer. And is looking to make his 50 year old car handle really well with a minimum of trial and error. As this gets expensive fast.
What are the things that Joe Average can do to set up his 68-82 Corvette for spirited street driving?
Some really good advice in this direction is what I feel is most needed on a forum such as this one.
Yes I know, what wins on Sunday sells on Monday.
However, what works for a pro driver and what works for Joe Average may not be identical.
What works well in a respectable price range for the average enthusiast?
This is the information most are looking for.
Why run a rear sway bar on the street? What size? Why the different sizes? Etc. Etc.
Do I need 10,000 dollar shocks on a street car? But clearly the AC Delco's Suck. What works for the average guy?
Etc. Etc. Etc.

 

Excellent focus!

 

This is QA-1 for C-3 vette. So you end up with $1200 for a set of shocks for the life of your car. There are other brands of dual adjustable. I've just never used them.

TD507 STOCKER STAR SHOCK, DOUBLE ADJUSTABLE, 9-5/8IN. TO 14-1/2IN., STUD/3.5" T-BAR

QA1

SKUTD507
$296.95

 

I personally think for the average guy who maybe runs a mild built sbc or bbc, that a completely stock suspension, frame, chassis, drive train, brakes and steering would be perfect.
Before I started the craziness on my 73 build, driving my C3 was enjoyable, comfortable and was a nice all around car.
Even with the 50 year old bushings.
Knowing what I know now, I wish I would have, installed new bushings, a Borgeson steering box, new oem style shocks and just rebuilt the original engine and left the TH400.

 

Ah come one - Don't use oem delco shocks - at least Bilsteins - they ride very well!

 

Ok maybe Bilstiens.
Mine were decades old but they still kinda worked

 

A completely stock suspension is probably just fine for someone with a TH400, who lives near a town with no hills or curved roads, and has a short drive to the weekly car show.

A complete stock-spec suspension (brand new components, built or rebuilt to the original spec), is probably fine for most folks, too. Think @Alan 71's car.

Maybe either of those options would give you an enjoyable, comfortable, and nice all around car.

Having done the replace every bushing with poly (except trailing arms - rubber, and strut rods - heim joints), Bilsteins, stiff springs and swaybars, and other direct swap mods to bring my 80 up to a bit better than FE7 level, I'm still underwhelmed, but it is WAY better than it was, and way better than my creampuff 79.

@gkull is correct. Don't do it twice. So I'm not for my 79, though I'll end up replacing most of the suspension in my 80 eventually. I'll keep a few things, but not the Bilsteins.

 

And yet, I really like the Bilstien's. And I live in an area full of twisty roads!
And perhaps there are even better options. But the Bilstien's were expensive enough. So much so I did a pair, waited a year, saved up, and then finally the other pair.

 

It would be interesting for us to put a step program together for "suspension beginners"

Like you I agree a 100% stock suspension is pretty darn good for a show car and comfortable evening cruiser, and nice curvy road driver.
It'll feel good at near stock speeds, and beyond.

Tires quickly become the limiting factor.
There is only so much you can do to upgrade the handling performance on 60 series T-Rated 15" tires. And that is all there is.
There are virtually no performance tire options left anymore in 15" sizes. There used to be, but not now.

Now once you skip the 16" plus 1 wheels and go straight to 17" or even 18" wheels, you now have access to modern high performance tires. They have a much higher performance envelope.
And those will very quickly show the limitations of a stock suspension, but only if you push it, Say up to 80% of more of the tires capabilities. If you are just going to cruise, it still doesn't matter. You will not hit these tires limits at anything near stock speeds.
At that performance level you need to start thinking about some somewhat suspension upgrades, so that you can take advantage of the tires.
And that will catapult the car's handling forward 30-40 years.
I am not talking new suspensions here, but your common sway bar, spring, bushing, shock and alignment upgrades. Let's call this the street & slalom package.
But without the wheel & tire upgrade, most of the improvement potential of this suspension package is lost if you keep the low performance 15" tires. It will still feel better tho.
Both of those changes together will drastically upgrade the car's handling.
Now you have a car that will be fun at an autocross, of a HPDE track day, and still be as comfortable as it was before on the road. It might not be super competitive, but it will be fun.

All the other hardware changes are just incremental improvements, beyond that level. If we stick with the same tire & size, the difference in performance is so minor it could easily be overcome by a better driver, or more practice.

All the other hardware changes, like: coil-overs, adjustable shocks, spreader bars, tubular a-arms, borgeson boxes, rack-n-pinions, brakes, caster changes, bump-steer kits, new suspensions like VS, DSE, Ridetech and Sharkbite, etc. are just icing on the cake. All of those are nice, and they have their place, but the improvement potential beyond the street & slalom package with good tires is much more minor, than the huge first increase in going from stock to street & slalom. But if you are seriously going to race, you will need some of them, or at least find them very useful. The bigger the tire and wheel you squeeze on the car, and the more serious the tire compound is, the more those items become useful.

The most cost effective way of doing these upgrades, is deciding how far you want to go, before you start, so you do not do the same things twice.

You guys agree?

 

OK, so I thought over what Leigh had to say about tires, or tyres as they say here. So, I walked into the garage and took a photo of one of my tyres.

So as not to argue about what tires are available to fit factory wheels.
I have found these to "Stick" way better than Cooper's or Mickey Thompson's and everything sticks better than BF Goodrich.
I run a mostly stock setup that came factory as the gymkhana suspension set up. The original sway bar in the rear I thought did very little. The original rear spring just didn't last. The original Bilstien's finally gave up when they were around 30 years old. Which I felt was actually pretty darn good.
So being on a budget, I've done those basic back yard kinda things that I would think many would also be interested in. Getting the best handling on somewhat of a budget.
And I prefer the look of the original wheels. I understand that modern wheels and tires would transform my car. Not really wanting that however. In some ways I want it to feel like that car from my youth when I drive her. Warts and all.

 

Well done Doc!
Are those V rated tires?
If so, I am glad you found some!
And let us know what brand they are!

I honestly did not know any still existed in 15" sizes.
I ran V & Z rated DOT "0" treadwear autocross specials on my car back when, in that size and a couple others.
And they did stick so much better than BFGs or Coopers, the standard T rated tires, Goodyears, etc.
The stiffer belt packages gave much better handling response also.
I first cracked the 1.0G barrier on such a tire.
Because I raced & tracked that car, a dozen or two times a year, I bought a lot of tires in 27 years.
My goal was a set lasted a whole year, so I got to do a lot of experimenting.
And I am always looking for the best bang for the buck.

Dropping sidewall height, wider wheels, etc. also made a difference.
But the largest difference of them all was simply going from stock tires, to V Rated ones! Even in the same & original sizes.

If you are determined to stick with original wheels, tire size, etc, they are definately worth searching out for such a tire.

 

Those are Vitour Galaxy tires. You can buy them at Walmart, like many other things made in PRC. There have been several threads on them.

If they work for you, great! I'm not aware of any other V-rated alternatives for our 15" wheels with white letters.

Here are sticker tires in 255/60R15, but with black sidewalls. And at that price, you should just upgrade to 18" wheels and run Pilot Sport 4s, or whatever.

https://www.summitracing.com/parts/MTT-3452?seid=srese2