Custom driveshaft
 

As some of you may know, im swapping in an s2000 engine into my FC. So I have pretty much everything sorted out except for the driveshaft. I found a guy that can make a custom one for me, but he said he can’t balance it. He told me not to worry because it’s pretty close after he makes it. I dont know if I should believe him or not. He can’t balance it because the s2000 side has a CV join and not a U-joint and he can’t mount that.

Does anyone have experience with this? Do I need to get it balanced? Anyone know of a shop that could make me a driveshaft for my application or balance this?

Since the S2000 engine spins as fast as the stock engine I would find some way to get it balanced. I had a custom driveshaft that was not balanced well enough cost the race team about $10K. It really causes problems at higher speeds but that just means because you can't feel the vibe a low speeds. There is a place in Michigan that can do it called Dynotech Engineering but I would just search for a place close to you and call them and tell them what you have.

Do a search for "The $10,000 drive shaft" on the forum to read the whole story, its not pretty.

I get a custom drive shaft from an internet site calling BBS Drive line. I use the Turbo2 yokes, replaceable joints and a 3" pipe balanced. Here in PR you can get any custom drive shaft and the balance it so there is not a problem. I buy mine in the US because was cheap ($225 shipped vs. $300 local)

Do you have a link for that palce? i tried donig a seach and couldnt find anything.

I also dont understand what engine speed has to do with the rpm of the driveshaft. is it because faster turning engines are more susceptible to viberations?

Yes, in general. But the main thing is gearing with the driveshaft. The final drive ratio is really what will 'set' the driveshaft speed. There is a constant relation between road speed and driveshaft speed. The transmission is where all the speed variations occur between the engine and driveshaft. So, when you have an engine designed to run at high RPM you need gear ratios that will let it get up there.
We run a 5.12 final drive ratio on tracks that don't have long highspeed sections so the engine can run from 6500-9500rpm in 3rd,4th, and 5th gears. For Daytona this weekend we have a 4.10 in the car because we expect to hit over 145mph, with a 5.12 we would need to be in 5th gear for that speed. Overdriving the driveshaft(5th gear,.71 overdrive)means it would be spinning over 11,000rpm, using 4th gear and a 4.10 at that speed only spins the driveshaft at 9500(4th gear,1:1). That is a huge difference because nobody we've found can balance a driveshaft for over 8000rpm.

it is critical to have your driveshaft balanced... the problems can be expensive to fix or as minimal as completely annnoying vibrations transmitted thru the entire car... the more you get to a racecar thats super stiff and with harder bushings, the worse it is and the more of a pain it is to live with.

definitely find a place to balance it. you can have your buddy make the shaft, then send it out to be balanced by any shop that can balance the S2000 style shaft.

good luck on your project, love that motor/trans and the FC chassis, I think its a great combination. I'd love to have an F20c-FC of my own, all gutted and superlight.

Hmmm.. This could be quite a problem. I can’t remember what the rearend gear is on a S5 N/A but I remember looking it up in the past I think it’s the same as the s2000 rear. Honda put those CV joints on instead of U-joints for a reason, I hear that’s the new way to go for high rpm driveshaft.

Oh, my car is pretty much turning into a race car. I mean, the engine is solid mounted to the chassis. I'm sure its going to be uncomfortable, to say the least, with an out-of -balance shaft.

Yes, the car is pretty much all gutted too, not even a dashboard. I got a s2000 gauge pod that i have to make a new dash for. Plus, the S5 dash weighed in at about 50lbs. ;)

http://www.dennysdriveshaft.com/
this place says that they can balance to 10,000 rpm.