Do we need subframe connectors
01-10-2016, 03:53 PM
#61
The second attempt yielded this. Triangulating off the front of the cradle with existing threaded bolt holes in the floor of the car should stop the wheel hop and address the other concerns I listed somewhere above.
The black parts are weld in, the bare steel parts bolt in using existing threaded bolt holes under the car. The entire setup weighs just under 50lbs with the bolt in portions weighing 35 or so. The weld in units are good enough to go in the car and so are the bolt-ins for that matter but they could be a little more square and maybe a few pounds lighter if I put my mind to it.
Now that all the holes are located, I've talked with a buddy who builds rock crawlers about duplicating this in round tube but the verdict is still out on whether or not he can bend radiuses tight enough to simplify this. As shown here, the bolt-ins are made of 10 different pieces (per side) and is rather labor intensive to duplicate but bent round tubing would cut the number of parts/weld time in half and look sexier.
If anybody wants a set, I may continue on with a version 3 and build a gig but if not, they're going in the car the way they are.
The black parts are weld in, the bare steel parts bolt in using existing threaded bolt holes under the car. The entire setup weighs just under 50lbs with the bolt in portions weighing 35 or so. The weld in units are good enough to go in the car and so are the bolt-ins for that matter but they could be a little more square and maybe a few pounds lighter if I put my mind to it.
Now that all the holes are located, I've talked with a buddy who builds rock crawlers about duplicating this in round tube but the verdict is still out on whether or not he can bend radiuses tight enough to simplify this. As shown here, the bolt-ins are made of 10 different pieces (per side) and is rather labor intensive to duplicate but bent round tubing would cut the number of parts/weld time in half and look sexier.
If anybody wants a set, I may continue on with a version 3 and build a gig but if not, they're going in the car the way they are.
01-11-2016, 09:06 AM
#63
TECH Enthusiast
01-11-2016, 09:45 AM
#64
Originally Posted by barrok69
For what reason do you want a 2pc CF driveshaft? The 1 piece is rated to 199mph and 1000ft-lbs.
And i am hopin to break 200mph this yr...
01-11-2016, 10:58 AM
#66
I am 300lb+ lighter than most Gen 1s plus i made 550rwhp and 500rwlbft which puts me in the same ball park as the vette.
The zr1 has a drag coefficient of .34 and a frontal area of 22.3 giving 7.6 drag area, we are at .35 and 24.3 givin 8.5 of drag area. I also swapped my ratio from 3.73 to 3.42 so i may get a little more out of fifth before slappin it into sixth.
Its possible...
The zr1 has a drag coefficient of .34 and a frontal area of 22.3 giving 7.6 drag area, we are at .35 and 24.3 givin 8.5 of drag area. I also swapped my ratio from 3.73 to 3.42 so i may get a little more out of fifth before slappin it into sixth.
Its possible...
Last edited by Naf; 01-11-2016 at 11:14 AM.
01-11-2016, 11:08 AM
#67
TECH Enthusiast
I've been monitoring the temps on my 1piece joints and they come nowhere near the 300°F limit. I ceramic sprayed my SS exhaust and then wrapped it with DEI titanium wrap in the critical locations that coincide with the front and rear of the driveshaft. If you had more concerns you could actually make a heat shield out of aluminum that would reduce the temperatures even more and sculpt it in such a way to scoop fresh air into that location.
The 200mph may be the only restriction with the 1 piece CF. I would call DSS and see if it's a hard limit or just a suggested limit. Plus... how long do you plan on running at 200mph for? It's worth considering.
01-11-2016, 11:19 AM
#68
Understanding that peak speed could be touch and go, and i still have to balance the aerodynamics of my car way before attempin this, or else these may be some of the last post i do.
I would like multiple passes at 200mph.
My rear section of my ds already had contact with my exhaust. So clearance is tight
I would like multiple passes at 200mph.
My rear section of my ds already had contact with my exhaust. So clearance is tight
01-12-2016, 08:40 AM
#71
I think there are enough of us successfully running the 1 piece to say that this isn't always the case.
I talked with DSS about making a 2 piece carbon and he was all for it. But before I would have him build one, I would want to have a discussion about exactly how long it should be. I've had 2 DSS shafts (1 piece), one as a stock replacement with a Gertrag and the other being used on an 8.8.
The stock replacement shaft was, in my mind, too short by 3/4 of inch because I had to extend the CV joints to get it bolted into the car. That shaft lasted 10k miles at which point it turned into a vibrating, noisy mess.
The DSS shaft I'm using with the 8.8 had to be compressed to go into the car and so far it seems to be holding up well but you never know...is this shaft too long? Even though it seems to be working well, I'd be more comfortable with it if I didn't have to force it into the car.
Each 930 CV has about an inch of compression. The question to answer would be how compressed should each joint be? 1/2", 3/8' what?
Edit: As delivered in a relaxed state, each CV joint had a half inch of compression and a half inch of extension in it (1 inch travel in total). As I recall, most CV shafts/driveshafts I've installed were done so in a relaxed state with very little extension or compression needed to bolt them in place. Our stock driveshaft bolts in this way and if I were building a driveshaft from scratch, I would want it to go into the car this way without the need to extend or compress the CVs to get it bolted it up.
If the shaft isn't made to the optimal length, you're wasting your time.
I talked with DSS about making a 2 piece carbon and he was all for it. But before I would have him build one, I would want to have a discussion about exactly how long it should be. I've had 2 DSS shafts (1 piece), one as a stock replacement with a Gertrag and the other being used on an 8.8.
The stock replacement shaft was, in my mind, too short by 3/4 of inch because I had to extend the CV joints to get it bolted into the car. That shaft lasted 10k miles at which point it turned into a vibrating, noisy mess.
The DSS shaft I'm using with the 8.8 had to be compressed to go into the car and so far it seems to be holding up well but you never know...is this shaft too long? Even though it seems to be working well, I'd be more comfortable with it if I didn't have to force it into the car.
Each 930 CV has about an inch of compression. The question to answer would be how compressed should each joint be? 1/2", 3/8' what?
Edit: As delivered in a relaxed state, each CV joint had a half inch of compression and a half inch of extension in it (1 inch travel in total). As I recall, most CV shafts/driveshafts I've installed were done so in a relaxed state with very little extension or compression needed to bolt them in place. Our stock driveshaft bolts in this way and if I were building a driveshaft from scratch, I would want it to go into the car this way without the need to extend or compress the CVs to get it bolted it up.
If the shaft isn't made to the optimal length, you're wasting your time.
Last edited by ls1247; 01-12-2016 at 10:23 AM.
01-14-2016, 01:54 AM
#73
I think there are enough of us successfully running the 1 piece to say that this isn't always the case.
I talked with DSS about making a 2 piece carbon and he was all for it. But before I would have him build one, I would want to have a discussion about exactly how long it should be. I've had 2 DSS shafts (1 piece), one as a stock replacement with a Gertrag and the other being used on an 8.8.
The stock replacement shaft was, in my mind, too short by 3/4 of inch because I had to extend the CV joints to get it bolted into the car. That shaft lasted 10k miles at which point it turned into a vibrating, noisy mess.
The DSS shaft I'm using with the 8.8 had to be compressed to go into the car and so far it seems to be holding up well but you never know...is this shaft too long? Even though it seems to be working well, I'd be more comfortable with it if I didn't have to force it into the car.
Each 930 CV has about an inch of compression. The question to answer would be how compressed should each joint be? 1/2", 3/8' what?
Edit: As delivered in a relaxed state, each CV joint had a half inch of compression and a half inch of extension in it (1 inch travel in total). As I recall, most CV shafts/driveshafts I've installed were done so in a relaxed state with very little extension or compression needed to bolt them in place. Our stock driveshaft bolts in this way and if I were building a driveshaft from scratch, I would want it to go into the car this way without the need to extend or compress the CVs to get it bolted it up.
If the shaft isn't made to the optimal length, you're wasting your time.
I talked with DSS about making a 2 piece carbon and he was all for it. But before I would have him build one, I would want to have a discussion about exactly how long it should be. I've had 2 DSS shafts (1 piece), one as a stock replacement with a Gertrag and the other being used on an 8.8.
The stock replacement shaft was, in my mind, too short by 3/4 of inch because I had to extend the CV joints to get it bolted into the car. That shaft lasted 10k miles at which point it turned into a vibrating, noisy mess.
The DSS shaft I'm using with the 8.8 had to be compressed to go into the car and so far it seems to be holding up well but you never know...is this shaft too long? Even though it seems to be working well, I'd be more comfortable with it if I didn't have to force it into the car.
Each 930 CV has about an inch of compression. The question to answer would be how compressed should each joint be? 1/2", 3/8' what?
Edit: As delivered in a relaxed state, each CV joint had a half inch of compression and a half inch of extension in it (1 inch travel in total). As I recall, most CV shafts/driveshafts I've installed were done so in a relaxed state with very little extension or compression needed to bolt them in place. Our stock driveshaft bolts in this way and if I were building a driveshaft from scratch, I would want it to go into the car this way without the need to extend or compress the CVs to get it bolted it up.
If the shaft isn't made to the optimal length, you're wasting your time.
No fancy adapters, no extra bolts and defiantly no unwanted weight.
From what i learnt in DS repair, you have to be in the middle of the movement so you have enough sliding in for compression and out for extension. If you were to be at either extreme you put everything at risk for damage. If the DS is too short and you have to extend it to its max to fit you could damage the spindles, if your DS is too long and you have to have it all the way compressed you could damage the DS/diff/transmission when it tries to compress further.
The Stock DS works, you just have to find the happy place for the 8.8 where in a relaxed start the splines are halfway compressed/extended. So you have equal safe travel in and out. May have to do a trip to their shop for proper accurate measurements
Last edited by Naf; 01-14-2016 at 02:05 AM.
01-14-2016, 07:50 AM
#74
I would love a plug and play 2-pc DS to be used with Revshift DS coupler and Gertrag diff. It should be a direct replacement for our Steel 2-pc DS.
No fancy adapters, no extra bolts and defiantly no unwanted weight.
From what i learnt in DS repair, you have to be in the middle of the movement so you have enough sliding in for compression and out for extension. If you were to be at either extreme you put everything at risk for damage. If the DS is too short and you have to extend it to its max to fit you could damage the spindles, if your DS is too long and you have to have it all the way compressed you could damage the DS/diff/transmission when it tries to compress further.
The Stock DS works, you just have to find the happy place for the 8.8 where in a relaxed start the splines are halfway compressed/extended. So you have equal safe travel in and out. May have to do a trip to their shop for proper accurate measurements
No fancy adapters, no extra bolts and defiantly no unwanted weight.
From what i learnt in DS repair, you have to be in the middle of the movement so you have enough sliding in for compression and out for extension. If you were to be at either extreme you put everything at risk for damage. If the DS is too short and you have to extend it to its max to fit you could damage the spindles, if your DS is too long and you have to have it all the way compressed you could damage the DS/diff/transmission when it tries to compress further.
The Stock DS works, you just have to find the happy place for the 8.8 where in a relaxed start the splines are halfway compressed/extended. So you have equal safe travel in and out. May have to do a trip to their shop for proper accurate measurements
I understand the weight argument though.
I think you're right about driveshaft length and o contacted DSS about getting the car to them for measurements (even offered to pay for installation after the second "not my fault" trip up there for parts that weren't sent) but was told they don't have a lift and weren't interested. That's s shame because I wasted a lot of time messing with it and they wound up giving me a full refund. Everyone lost on that deal.
If the DSS shaft I have now fails, I'll get the cvs rebuilt and turn the adapters down to get the length right. The good news is the driveshaft cvs are being articulated so once they're in the car, they shouldn't be plunging much at all, if at all.
Keep us posted!
Last edited by ls1247; 01-14-2016 at 07:57 AM.
01-14-2016, 01:51 PM
#76
TECH Regular
Shifting from 5th into 6th costs 2250rpm, whatever final ratio you have...
With 3,42 final you shift at 7000rpm in the 5th at Speed of 300kph into 6th and there you were at 4800rpm
With 3,73 final you shift at 7000rpm in the 5th at Speed of 273kph into 6th and there you were also at 4800rpm so isn“t it better to install a shorter 6th maybe in the 0.69 area to reach your Goal at 200mph?
With a 0.69 in the 6th you will loose only 1250rpm when shifting from 5th into 6th and reach your 200mph at 6700rpm with a 3.73 final, the better way imo
Best regards,
Ronald
01-14-2016, 09:53 PM
#77
Originally Posted by Choppy_Idle
Whats the gain here, why you are doing this?
Shifting from 5th into 6th costs 2250rpm, whatever final ratio you have...
With 3,42 final you shift at 7000rpm in the 5th at Speed of 300kph into 6th and there you were at 4800rpm
With 3,73 final you shift at 7000rpm in the 5th at Speed of 273kph into 6th and there you were also at 4800rpm so isnĀ“t it better to install a shorter 6th maybe in the 0.69 area to reach your Goal at 200mph?
With a 0.69 in the 6th you will loose only 1250rpm when shifting from 5th into 6th and reach your 200mph at 6700rpm with a 3.73 final, the better way imo
Best regards,
Ronald
Shifting from 5th into 6th costs 2250rpm, whatever final ratio you have...
With 3,42 final you shift at 7000rpm in the 5th at Speed of 300kph into 6th and there you were at 4800rpm
With 3,73 final you shift at 7000rpm in the 5th at Speed of 273kph into 6th and there you were also at 4800rpm so isnĀ“t it better to install a shorter 6th maybe in the 0.69 area to reach your Goal at 200mph?
With a 0.69 in the 6th you will loose only 1250rpm when shifting from 5th into 6th and reach your 200mph at 6700rpm with a 3.73 final, the better way imo
Best regards,
Ronald
I had another larger issue that i wanted to fix. When i had the 305 wrapped on 19" wheels and a 3.73 my traction under hard acceleration was nil. Swappin to a lower ratio will help me gain more traction and goin to a 325 wrapped around 20" wheels hopefully will help keep the rubber gripping the road. The added benefit for me is higher top speed which is great.
01-14-2016, 11:37 PM
#78
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I would rethink measuring square of the car by the wheel points. If one corner has a bit more caster,camber, or droop for thst matter the base of thst wheel will have moved slightly . Also the wheel location with the suspension at full droop has totally changed. Measure corner to corner from front to rear subframes to get a idea of if the chassis and or subframe location is square. P.S. The subframe mounts on at least the front are slotted and can be adjusted left to right. (At least my first gen chas sis does, but almost every car has this or similar adjustment.
Last edited by TaylorMadeMetalWork; 01-14-2016 at 11:50 PM.
01-15-2016, 08:23 AM
#79
I would rethink measuring square of the car by the wheel points. If one corner has a bit more caster,camber, or droop for thst matter the base of thst wheel will have moved slightly . Also the wheel location with the suspension at full droop has totally changed. Measure corner to corner from front to rear subframes to get a idea of if the chassis and or subframe location is square. P.S. The subframe mounts on at least the front are slotted and can be adjusted left to right. (At least my first gen chas sis does, but almost every car has this or similar adjustment.
When its all said and done, its where the rubber hits the road that really matters so when it comes to driveability, it begins and ends at the "hub". Subframe mount measurements would only become necessary if there was a verifiable problem with the hub measurements in my mind. You're absolutely correct in saying that alignment can throw these measurements off but by a half inch, I don't think it would skew it that much, especially on a car that seems to be otherwise driving alright.
Since starting this thread, I've had the subframe out of the car and seen that the rear of the subframe is located on frame dowels so I don't see it twisting horizontally that much, if at all, which was my original concern. We do know the subframe can move vertically as witnessed by the dents in the floorpan of my car where the front of the subframe (just above the front trailing arm bolt) has been beating on it during wheel hop. I probably didn't look as closely as you did so I'd be curious about the slots you're describing. Any pics?
Thanks for posting!
01-15-2016, 08:58 AM
#80
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Sorry I was talking about front subframe because we would be comparing to rear to square. I'm not suprise it moves under load with decent grip. Your probably totally fine with how your measuring for a rough quick measuments your not basing alignment from. What I was saying is its really important to verify mounting locations before measuring what's hanging from it. You can usually align a car around the chassis issue, but alignment shops are notorious of doing that and causing car to "dogleg" while driving. Wheels point straight, car drives straight, but car is not point straight. I've seen this and other issues personally several times. Like I said your car is probably fine , just be careful not to make mistake as using the sub to find square before the subframes are square.