[wizzard540]

I am going to need a new driveshaft for my car (1980 Camaro 565BBC 940hp) that weighs 3300 pounds w/driver. I was on the Mark Williams web site looking at the driveshafts. I am going to call them in the morning but was wondering if anyone knew the weight or horserpower limits of the aluminum and cabor fiber driveshafts.

 

[Collinsautomotive]

Go steel unless it is ultra high rpm. Go chromoly if they recomend it due to critical speed.

 

[BillyShope]

Take another look at the Williams' site. Other than the vague statement "...there's performance to be gained," there's no information concerning inertia or equivalent weight. Of course, a driveshaft made of toasted marshmallow will weigh less and accelerate quicker than one of steel. But, what difference will that marshmallow driveshaft make on your timeslip?

I don't know if it was in this forum or another, but I posted...somewhere...the equivalent weight for a steel driveshaft with a size approaching that of "sewer pipe" and, even with those ridiculous dimensions, it was evident that, for someone in a category other than Formula One constructor, there are better ways to spend your money.

 

[wizzard540]

Quick reply

Thanks for the responses. I agree that I might not need the carbon fiber driveshaft but while I am going to get one made anyway, I might as well spend a little more now and get a nicer one. I think I can get a 3" X .083" steel one made locally for about $400.00 including the trans yoke. But if I got one for $700.00 w/yoke made from a stronger, lighter material I think the difference of $300.00 would probably be negliable. Unless someone has some idea of what I could buy for the $300.00 to improve the performance of the car. That sounds like the makings of a contest. Haha. Anyway thanks again for the quick responses.

 

[BillyShope]

Okay, for your "contest":

Rig up a traction dyno and adjust your 4link (or whatever you have) until you have equal rear tire loading on launch. This will give you a definite performance improvement and you'll have most of that 300 sitting in your bank account (until the bank goes belly up, anyway).

 

[wizzard540]

See I knew you could come up with something Mr. Billy. Thanks

 

[Collinsautomotive]

Any good picture examples of a traction dyno ? I have done some reading on them and how to use them but I am still missing the visual concept of it.

Okay, for your "contest":

Rig up a traction dyno and adjust your 4link (or whatever you have) until you have equal rear tire loading on launch. This will give you a definite performance improvement and you'll have most of that 300 sitting in your bank account (until the bank goes belly up, anyway).

 

[JeffMcKC]

I would think two grain scales with some sort of height gauge hooked to a computer would work well

 

[mrdragster1970]

.

Just a thought. Unless heads up, every .001 counts type deal. The piece of mind of having a moly shaft is worth just a tiny ET gain.
Insurance of having one less thing to worry about is worth it. Good luck.


.

 

[BillyShope]

Any good picture examples of a traction dyno ? I have done some reading on them and how to use them but I am still missing the visual concept of it.

The January issue of "Racecar Engineering" has an illustrated article. Unfortunately, that's a British magazine and not as common as "Hot Rod" here in the States. You might try their site for back issues. I'd scan it and post it, but I got into trouble last time I did that. Got chewed out for copyright violations.

I'm assuming "wizzard" has wheel scales. I'm not quite clear as to what Jeff is going to use the height gage and computer for. There's a spreadsheet at my site, so I guess you need the computer. Perhaps Jeff is concerned that the car sit level with only the fronts on the scales, but modern wheel scales are so thin that I wouldn't worry about that.

 

[Collinsautomotive]

I am sort of new to playing with chassis tunning but as always it is good to learn as much as you can. Powertrian specifically late model powertrain LS! LT1 Mod Motors are my gig. Small blocks to.

Anyways I gather that you need to load the car with thrust to the rear. My question is where do you load it ? At the CG or just anyplce in the chassis.

Always trying to learn and I have a car that just needs to hook and its pissing me off to no end.

The January issue of "Racecar Engineering" has an illustrated article. Unfortunately, that's a British magazine and not as common as "Hot Rod" here in the States. You might try their site for back issues. I'd scan it and post it, but I got into trouble last time I did that. Got chewed out for copyright violations.

I'm assuming "wizzard" has wheel scales. I'm not quite clear as to what Jeff is going to use the height gage and computer for. There's a spreadsheet at my site, so I guess you need the computer. Perhaps Jeff is concerned that the car sit level with only the fronts on the scales, but modern wheel scales are so thin that I wouldn't worry about that.

 

[RAGENZ28]

I personally am going 3.5" moly. I would think for your power level a few shafts will work but it is hard to beat the piece of mind you get with a moly shaft.

 

[BillyShope]

I am sort of new to playing with chassis tunning but as always it is good to learn as much as you can. Powertrian specifically late model powertrain LS! LT1 Mod Motors are my gig. Small blocks to.

Anyways I gather that you need to load the car with thrust to the rear. My question is where do you load it ? At the CG or just anyplce in the chassis.

Always trying to learn and I have a car that just needs to hook and its pissing me off to no end.

Take a look at Pages 4, 5, and 6 at my site.

 

[Collinsautomotive]

any Idea how to run the math on a mustang stock rear suspension ? for the CG and IC ?

Take a look at Pages 4, 5, and 6 at my site.

 

[Mod]

Buy a top quality slip yoke, run a steel shaft (083 wall). and tell the driveshaft dude to spin it as fast as he can when he balances it.

 

[RAGENZ28]

Don't forget to get top notch u-joints, for drag racing you should use solid joints.

 

[WJ Birmingham]

I purchased a Mark Williams drive shaft a few years back after having spit out my moly drive shaft with a trans brake accident. Seems the drive shaft didn't like full boost prior to releasing the brake.

At any rate, after talking to the guys at Mark Williams, they said they didn't have a driveshaft large enough in diameter at that time to take the weight/HP of the GMC. My only choice was the carbon if I wanted to purchase it through them.

I can't say it was cheap, as I picked up a Dana 60 yoke and a billet T-400 yoke all at the same time. I think it was around 1200.00 shipped. None the less, the pieces are nothing but top shelf parts, and have served wonderfully for the past several years.

I have no complaints, and my wallet has since healed from the bleeding.

 

[BillyShope]

any Idea how to run the math on a mustang stock rear suspension ? for the CG and IC ?

You don't need the IC location for a traction dyno run. As for the CG height, a guesstimate is good enough. What you're looking for, remember, is an equal amount removed from the right and left front scales (assuming the rear wheels are loaded equally statically), regardless of the chain tension. Whether the chain is exactly at the CG height isn't all that critical.