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Agreed dumping the clutch on the starting line at a drag strip is amazingly violent.
Everyone should be able to try it just once, BUT ONLY in a car that is built to take it!
5000 rpm...hold it...slip foot left off the clutch pedal .... go WOT....at the same instant.
VIOLENT barely describes the sensation!
Flat-shifting it as just as bad....
GLUE throttle to floor....stand on it... do not lift... no matter what....go to redline....pull on shifter hard...it won't move yet....pound the clutch pedal as fast as humanly possible.....pray the engine did not rev up too far... if it did you are too slow....oops....second prayer you do not miss third gear.... double oops....the first time is the hardest and the scariest....time for next gear already...
Everything in the car bangs so hard and so loud I am surprised it all survives more than one shift!
NO WAY a Vette diff would handle that, not for long.
Thank you everyone! The insight has been great. Lots to consider and having real world builds and experiences to glean off of helps a lot. I think the common theme I'm seeing is that I have two generalized paths. Either make a fun cruiser with an easy clutch and hard rubber street tires and keep the thing off the drag strip OR make an all out money pit drag car which an unending battle.
It'd be fun to run the christmas tree but I should just go destroy another vehicle if I actually have that much of the go fast bug. Side note, my grandfather was known to a lot of people as "Johnny GoFaster" and I certainly got the bug from him. I really can't justify two cars. So I should probably just cut out my plans of an all purpose car and just stick to making a smiles machine that will roast street tires on government/municipality owned asphalt instead of VHT and concrete. That is the primary goal of the car anyway.
Someone mentioned a clutch that is easier on the drivetrain(thank you). I looked into Blackmagic centrifugal clutches for that reason. It's an extra $1k on top of my currently planned clutch but it might save me more than that in driveline upgrades or breakage . Rebuilding a clutch is easier AND CHEAPER than turning everything downstream into a pretzel factory or worse.
My 350 just isn't a good base to start a build with because most of it needs replaced. It's worth more to sell it as is. I got a bare big block for a song and decided if I'm replacing "everything" anyway it might as well be a big block.
Tom's 31 spline outers seem like a no brainer. I'll certainly start with that.
I have a Black Magic clutch in my car. Cale Aronson did a great job putting together an adjustable one with a sintered iron disc with a spring and weight combo that would work with my twin turbo combo and not so great gearing. I ran a McLeod Soft Lok for years with great results....but I finally reached the limits of what it could handle.
The 31 spine outers are a definite need for sure.
Vette's actually make great drag cars once you sort out this rear end issue. Mine has a custom built Dana 60 IRS that's been under there for nearly 20 years now and I haven't touched it since installing it. Heavy as heck but it's taken the abuse. We've got great engine setback etc for traction...just gotta figure out what to do with all of it!
I have a Black Magic clutch in my car. Cale Aronson did a great job putting together an adjustable one with a sintered iron disc with a spring and weight combo that would work with my twin turbo combo and not so great gearing. I ran a McLeod Soft Lok for years with great results....but I finally reached the limits of what it could handle.
The 31 spine outers are a definite need for sure.
Vette's actually make great drag cars once you sort out this rear end issue. Mine has a custom built Dana 60 IRS that's been under there for nearly 20 years now and I haven't touched it since installing it. Heavy as heck but it's taken the abuse. We've got great engine setback etc for traction...just gotta figure out what to do with all of it!
JIM
I had a "slipper" style clutch twice. They were cool.
Once in a motorbike. once in a car accidentally. It was also quick reving car with not a lot of torque. The clutch had 280k miles on it and when I took it out it had zero clutch material on it, just steel on steel. But it never did not hold. After a shift, when it bogged a little, you could squeeze the clutch gently and it would gain 500-1000rpm and pull away. Sometimes I would do that 2 or 3 times coming out of one turn! It was fun! That car drove like a 2 stroke motorbike. The new clutch was actually awful, cause it just grabbed.
But the friction coefficient of steel on steel drops by half, while it is sliding.
It would take some trick clutch to be able to do that on a V-8. But It would definately soften the shock on the driveline.
Don't the top fuel cars run just one gear and with special clutches like that? That slip the whole run? They just get tighter and tighter?
Copied from McLeod Soft Lok clutch info:
"CONCEPT: Most clutches are high-pressure lockup types and will have steel flywheel. When you launch the car with these, the high spring pressure and the stored energy of the steel flywheel will shock the car like pulling the trigger on a shotgun and feel like someone hitting the back of the seat with a baseball bat. The trouble is it breaks parts and sometimes will cause the tires to spin and get the car out of shape. The steel flywheel will get you to 60 feet faster but after that the steel flywheel becomes an anchor and will rob you of horsepower. Using the Soft Lok your ET and MPH will improve. You will have little to no breakage because we are causing a controlled slip in the clutch that takes out all of the shock and violence. With its lower spring pressure and lighter weight, it will not hit the tires or chassis as hard and tire spin can be controlled so traction is better and the lighter weight will let the engine rev quicker and pull harder through mid range and top end."
Yes...fuel clutches have several stages of controlled slippage where the throwout bearing is gradually released to grab more. You can also get a device to do similar on cars with hydraulic setups called a 'Clutch Tamer".
Mine has adjustable static spring pressure as well as weights to add to the fingers to change centrifugal assist. All of that can be juggled to change the rate it grabs.
When it's adjusted right it's amazing. When I was N/A I would launch at 5000-5500 RPM and it almost felt like a car with an auto/converter. Wheels in the air....grab 2nd gear and hang on. Really smooth...
I've almost got the "turbo" setup figured out. Cale's setup got me out of the 9.0's into the 8.80's in first outing and I'm sure there's a lot more to go. I just ran out of time. It's tough because I'm launching off boost...but as soon as the engine is loaded slightly those two little snails build boost VERY quickly and that clutch has to catch the engine and control it somewhere between slipping and pulling the wheels to the sky and heading into a wall! But we're close!
To me it drives fine on the street...but it's admittedly a hard core setup with a crash box trans like ML67 has. But that's what I like about it!
Interestingly...Mcleod still hosts a magazine article I did years ago about using a Soft Lok clutch on their site.
So i did some quick and rough scanning. I need to get another one now that the original Diff is out. but by the looks of thing Im going to have quite the time fitting this 9" in the rear of this car....... The challenge is enticing me though. Boy it sure is tucked in there between the rear fiberglass boxes.... it definitely wont fit unless its moved back a little from the stock yoke (which can be seen poking through the output flange of the 9") it could go a little lower but I think the driveshaft will hit the crossmember.
Well then.... Bad news. Thanks to the excellent threads you guys suggested I knew where to look and sure enough it was there. This is adding to my pile of reasons to not use the original setup.
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Well then.... Bad news. Thanks to the excellent threads you guys suggested I knew where to look and sure enough it was there. This is adding to my pile of reasons to not use the original setup.
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Yup one hard launch and you have instant junk in the diff.
Probably my last post on this thread before I make a new one or just follow someone elses super 10 bolt build.
If anyone still feels like chiming into my thoughts, I have narrowed it down to two options. I am leaving out some a lot of research that determined how i arrived at my final two options but I would like some opinions if you guys got them (silly question right?). I came to the conclusion that I will not be trying to 60ft this car. If i want to go 11s 10s or 9s, i will buy a completely different racecar. YES I KNOW 600HP is too much for any kind of street tire. YES I KNOW a 4 link solid is "easier" but it is easier and cheaper for me to design "bolt in" stuff in CAD than it is to put bigger electrical service in my garage and buy a welder. I simply dont have easy access to fab tools that are close enough to the car for me to make stuff from scratch without drawings. although i can fab my own parts in a shop that I rent for weekend use or at work. Just can't bring the car with me. A 40T brake, lathe, mill, punch, press, and welder are all available there.
1. S550 Ford Super 8.8 swap with custom trailing arms and suspension and diff mounting all made in Solidworks by yours truly. Following the advice of this thread: https://www.corvetteforum.com/forums...the-irs-4.html
2. Super 10 bolt build. buying everything brand new and installing myself.
After tearing apart the diff and the trailing arms I found out that EVERYTHING i have is 100% junk. Trailing arms, strut rods, and the center section are all trash. not to mention every bushing everywhere. Thats the unfortunate thing that is making me lean towards the S550 Super 8.8. If i need to baby the super 10 and worry that it will explode if it gets wheel hop even once then Im not sure i have a choice...
Can i put ~275 street tires on a "super 10 bolt" and have it live? Will it be an undriveable ice rink in 2nd or even 3rd with street tires? RoscoBBC has one that lived well with a lot of stock parts. but mine is already blown so that makes me second guess my luck.
The term Super 10 bolt diff is one I came up with years ago. It is a specific build with specific parts. A conman in TX took to using the name of my build to con guys here and elsewhere out of money for a knockoff version that was nothing like the original.
So, if you use the term understand the build. I used to coach guys in building them but no more. I still have the parts to build them, some are no longer available anymore. One quick thing. When you see knockoff work that claims to have a tuned posi and you see the spring pack installed- you were just ripped off.
If you aren’t going to race this car, then build a nice street engine and have fun driving it on the street like a responsible driver and build a race car for the track.
Keep the hp/tq under 550, build a super 10 bolt and run street tires.
My original 496 build target was 630+ hp, but I had the engine builder down grade it a bit to 570 so it had better street manners and I wouldn’t be breaking things.
With street tires it will still be a blast to drive and I’m not the least bit sorry.
The term Super 10 bolt diff is one I came up with years ago. It is a specific build with specific parts. A conman in TX took to using the name of my build to con guys here and elsewhere out of money for a knockoff version that was nothing like the original.
So, if you use the term understand the build. I used to coach guys in building them but no more. I still have the parts to build them, some are no longer available anymore. One quick thing. When you see knockoff work that claims to have a tuned posi and you see the spring pack installed- you were just ripped off.
The term Super 10 bolt diff is one I came up with years ago. It is a specific build with specific parts. A conman in TX took to using the name of my build to con guys here and elsewhere out of money for a knockoff version that was nothing like the original.
So, if you use the term understand the build. I used to coach guys in building them but no more. I still have the parts to build them, some are no longer available anymore. One quick thing. When you see knockoff work that claims to have a tuned posi and you see the spring pack installed- you were just ripped off.
Gary, I was definitely referring to your builds or others on this forum that have followed your build guidance. I absolutely respect your claim to the name and the quality behind it and was not referring to anyone else's setups. I was thinking of building my own but if you say you only do builds yourself nowadays then I'll dm you for a quote if that's what works best.
If you aren’t going to race this car, then build a nice street engine and have fun driving it on the street like a responsible driver and build a race car for the track.
Keep the hp/tq under 550, build a super 10 bolt and run street tires.
My original 496 build target was 630+ hp, but I had the engine builder down grade it a bit to 570 so it had better street manners and I wouldn’t be breaking things.
With street tires it will still be a blast to drive and I’m not the least bit sorry.
That really sounds like what I'm aiming for. I think I got caught up in the catalogs and what I could do with pump gas and modern parts. 570hp is still an incredible amount of power and that extra ~50 you shaved off is probably for the better like you said. Thanks for the input.
OCB has terrific advice, if that works for you.
It works for quite a few of us on here with BBs.
Keep street tires on it so they are the weak link and/or safety fuse.
No slicks, clutch drops, or powershifts.
Then at ~500ish HP the IRS should live for quite a while.
It is only labor polishing that posi housing to prevent those cracks. (They form easily at stress points / sharp edges.)
That and solid Spicer u-joints and you should be pretty good.
The next weak link is probably the outer axles, but it's not too likely you'll break one of those unless you break rule #1 or 2.
550HP in a 3300# car is a blast
Just remember there is always somebody faster. It doesn't even matter how fast your car is! There is always another one!
I broke outer stub axles (as well as most of my buddies) before we hurt the diff. U-joints were next, then halfshafts and then finally the diff's. Tom's stub axles took care of the outers.
My buddy has a 525HP 388" in his '65 we built with a 4 speed. Prior to that were several much milder 327/350's which broke a lot of rear parts because it didn't have enough power to spin the street tires and it would hook pretty hard. Once he installed the nasty motor he hasn't broken anything. It just spins and he bangs the devil out of the gears every time he drives it. He runs 255/60 BFG street tires. Only "good" part in the rear is the Tom's outer stubs and Spicer solid u-joints. The tire smoking and launch from the tree pics are how he drives it everytime he gets in it these days with the 388". The "standing on the track" pic is with one of the "mild" engines where it stuck and busted a stub axle. Got Tom's outers after that.
Another thought is to build higher RPM power. Don't build an ungodly TQ monster at low RPM. Launch it pretty hard but count on the fact the real power will come as RPM's increase. Even though I have a lot of cubes....my engines make max power up around 7000 RPM and hang on to well after that. Doesn't 60' ft as strong.....but comes on hard once you're moving. Now I've got a custom Dana 60 IRS under mine...(but it only has 3.07 gears) and it could handle whatever I throw at it....but the good news is I haven't touched it since installing it many, many years ago. I like overkill.
Clutch management is vital to making things live. You need the right one.....or an auto softens things a bit.
That really sounds like what I'm aiming for. I think I got caught up in the catalogs and what I could do with pump gas and modern parts. 570hp is still an incredible amount of power and that extra ~50 you shaved off is probably for the better like you said. Thanks for the input.
Mines similar spec' to OCB's with 570 hp @ 5850 and 606 ftlbs tq @ 3850....... (at flywheel) with 3.08 rear, M21 & 285 section street rubber. Been installed about 15 years now......all held together as far as the rear end is concerned.......deliberately haven't tried it on a sticky 'prepared' strip.
Allan definitely has a bad boy there. I took this pic years ago at one of the test sessions with the old engine combo. Catching a wisp of air with the big heavy front tires. We did a magazine feature on the car...it has a really cool history with a NASA engineer as the original owner.
05-12-2024, 04:51 PM
instead of VHT and concrete. That is the primary goal of the car anyway.
