ls1247

iTrader: (2)

So in the process of determining what my driveline angels should be in preparation for my CF 1 piece install (which is quickly turning into a nightmare) I figured it would make sense to see how straight the subframe is in the car because that will dictate what the horizontal pinion shaft angle is.

To do this, I figured it would make sense to take x measurements from the LF to the RR and the RF to the LR to see how square the car is.

I centered the wheels up front by taking sidewall sight lines (and found my car is fairly toed-in) and getting these sight lines equal on both sides. After this I took the wheels of the car and hung a couple of plumb bobs off the rotors and found that the car is 1/2" out of square.

As you can see, the subframe is favoring the direction that torque is being applied to it and I was told by some of the racer types that if I straighten it back out (if it has enough movement to be straightened out) that it would eventually migrate back to this scenario because I'm constantly applying torque to it unless I use some subframe connectors or weld the subframe to the car.

While the car tracks straight and drives well (showing again that alignment specs aren't as precise as many believe) I have a feeling that once I figure out how to check the pinion shaft angle horizontally, I may need to correct this. Is this measuring technique precise, no it isn't but I'm close enough to come to the conclusion that the car is not surprisingly crooked.

Anybody have experience with anything like this?

Bio248

domestic v8 solutions (54inches) is making sub frame connectors.

ls1247

iTrader: (2)

Has he released those for resale yet?

Bio248

pretty sure he's getting some betas out into the world shortly, but i'm not entirely sure on time frame or anything.

NIKDSC5

iTrader: (10)

Correct me if I'm wrong but wouldn't a set of revshift/creative steel 95a subframe bushings help this? I realize the torque scenario but......if the answer is subframe connectors they would need to correct that measurement, and be fairly solid. Also, that is measuring the entire span of the car, which the drive shaft does not nearly cover. The pinion angle for this and it's allowable tolerance would all be with in scope. So.....why is this a problem? The CV joint on the front of the 1 piece shaft is an amazing thing. For your angles to be off bad enough to cause problems, I'd imagine your frame to be bent.

Or did I miss something? Are you not buying DSS CF shaft and building your own? Is there something custom here?

Edit: go do some clutch dumps in reverse and remeasure.

ls1247

iTrader: (2)

Thanks for keeping it light!

What you've missed is the fact that I put my new DSS CF 1-piece shaft in yesterday and lost my fillings this morning driving to work... Of course, this was after taking a day off and driving the old S-10 running on 3 cylinders shop truck up there in person so I could get the adapters they forgot to send me so I could put my car back together....BTW, no apologies from anyone regarding that little screw up.

There is something wrong somewhere and as much as I want to believe that the CVs will compensate for driveline misalignment, I have yet to hear DSS or anyone else offering us driveline products say it with any confidence.

I've already got CS bushings in the rear cradle and while I'm sure they do a much better job of locating the cradle but there's probably some "alignment" to be gained by loosening the cradle bolts up and prying on it. As far as measuring the entire span of the car, the car only really needs to be square where the rubber hits the road so that seemed the most logical place to start.
Frame bent? doubting that, GM mass produced slop...more likely.

At any rate, I feel the driveshaft is too short but I know it isn't aligned right either from some measurements I took yesterday. The CVs had to be all but fully extended to make the shaft long enough to bolt into the car...can you say wobbly.

After taking the measurements they outlined in the only instructions that come with the shaft, I found that I was at the limit of what they suggested. So I spoke with the "counter guy" and he said I would be fine, that I worry too much and the shaft was made to handle 1000hp, go out and enjoy the car, we got ya, blah blah blah.

So I'm waiting for the head honcho up there to give me a call so we can discuss this along with the alignment variables and get this fixed before the car gets struck by lightning.

07CTS-V

iTrader: (6)

Same issues with the single CV carbon fiber shaft.

ls1247

iTrader: (2)

Mine measured out just like yours did and I knew when I put it in there it was going to be a problem...still, its better than what I had and I have to say the car is more responsive with the guibo gone. Driveline clunk was also drastically reduced.

Brain, do you still have that spacer you made for you driveshaft???? 1/4 to 3/8 of a inch should be enough.

Bio248

so you fixed the fully extended CV with a small spacer to put them back in working range and all is well after that?

ls1247

iTrader: (2)

Brian tried that with his but he was too late...the cv was already trashed.

I'm hoping that adding a little length to the driveline would help the CVs work more into there sweet spot but I'm also hoping the dual CVs will compensate for the misaligned driveshaft...well see on both counts

Bio248

i've got an aluminum one with dual CV's that i haven't installed yet. maybe i should take some measurements before i get everything apart only to not be able to use it...

Junior-1

iTrader: (1)

If they are that close, I would drive the V up to their facility and have them work it out. There shouldn't be that big of an issue with these. Especially for that kind of money...

garrettg

iTrader: (1)

Do you have access to drive on lift? The measurements may be different with weight supported by the suspension.

philistine

iTrader: (2)

I'm not sure I understand this post. A corner balance will get you where you need to be along with a good alignment - that is custom depending on what you are doing...street, strip, or auto-x.

It's not clear what you measured with a plumb bob. If the rear axles are not equal length (mine are not) then I would expect that to affect your measurements. Also where is the uncertainty with these measurements?

Installing subframe connectors is big-boy stuff for torque monsters - past stock power. The cradle bushings offered by Creative Steel limit or cease the movement of the cradle - something wants to absorb the remaining energy. That energy is going to transmit and rear it's ugly face somewhere else since you remove a dampening effect. You then begin chasing your tail trying to find a way to rid yourself of noise and vibrations.

Personally, I skipped the BS knowing the driveline was a POS and replaced it all - avoided the rabbit trails and frustration of useless bandaids. The stock driveline is a 2pc driveshaft for a reason, the angles - you have to deal with parallelism and angularity with a single shaft with much more precision than a 2pc which can absorb and compensate for the "offsets". So yeah, I avoided pitfalls - been there, done that.

So back to the topic heading...do we need subframe connectors? Currently, there is a member offering these for testing - some of the guys requesting to be testers have serious horsepower and will take it to the dragstrip for empirical data and feedback. That is where you are going to find your answer...from those that will test it - no theory, no discussion...just real data from the field use.

ryridesmotox

I can't imagine a case were there would be a two inch difference in loaded v unloaded suspension with how our rear subframe is formed.

Fuzzy_Wuzzy

iTrader: (8)

I think your 1/2" difference is perfectly fine. when you combine your measurement error (the larger part of the number...) with a small manufacturing tolerance I see no issues.

the rear cradle does have some room to move within the cradle mounts that you could try to correct that. it shouldn't move back, if it does that means the bolted joint has the ability to slip which it shouldn't (we would see bolts backing out with the number of cars and mileage on some)

ls1247

iTrader: (2)

I think I would.

It took 9 weeks to get the driveshaft and even then I didn't get all the parts. I'd like to think they'd prioritize this but I'm not holding my breath.

I wish...


This is "how to square something" up 101. Measure the diagonals and go from there. Why bother? The diff is bolted in the cradle, if cradle crooked, diff crooked, if diff crooked, pinion shaft crooked, if pinion shaft crooked, driveshaft crooked. straighten cradle, straighten diff, straighten diff, straighten pinion shaft, straighten pinion shaft, straighten driveshaft.....


Correct, after spending 5 years in an alignment pit I can tell you I could compensate for this by loading up the RF wheel with positive caster (effectively pushing the RF wheel forward) and the LF wheel with negative caster (effectively pushing the LF wheel back) but the car would drive in circles.

The plump bob is heavy and designed to be center hung. When tied off to a stationary object, it will hang vertically. Hang one off the LF, hang one off RR and measure....switch sides and repeat....don't know how much easier it gets. Uncertainty? probably up to 1/4" but I'm close enough to know it ain't straight.

So you're saying that because one axle is longer than the other, it's pushing that corresponding wheel out further...me no understand this line of thought.

I've installed subframe connectors in several platforms over the years with less motor than this car has and the improvement in ride quality and overall vehicular happiness was well worth the effort.

What about the bolt holes....If I remember correctly, I didn't press the cradle bolts through these bushings...probably a 1/16th in each through bolt at least.

If I had the cash I'd have done the same thing only I would have bought a V2 and be driving the car instead of constantly working on it.

Please publish your findings regarding these angles. As a community we should start documenting these angles so we can figure out which motor and transmission mount combos give us the most favorable dirveshaft alinements.

I took my lead from FoMoCo. They saw fit to equip the GT500 with a carbon one piece over the 2 piece that comes in the GT for some reason. The angles your discussing can be corrected....


The real data is...my rear cradle isn't straight and it might make sense to attempt to properly align it and fix it in place with a set of subframe connectors.

True that!

Correct on all fronts and the bolt loosening thing is the kind of common sense input that identifies and fixes problems like this.

Thanks Guys

philistine

iTrader: (2)

Whew! Easy there plumb bobber... I didn't know you could Chuck Norris a chassis alignment/check with that and a tape measure.

I'm getting an alignment this weekend. I'll ask the pit crew chief to check my chassis.

As far subframe connectors...only seen them on high HP dragstrip dedicated cars. I suppose you can equip them on anything. As for me, I'm eager to see/hear the results - new products are fun!

G-luck

ls1247

iTrader: (2)

I aligned the last 3 cars I owned with a level and eyeball and they all drove great and wore tires evenly. There isn't as much precision in it as many would have you believe because there are too many moving parts and too much rubber involved to get there.

Guess you've never owned an f-body! Subframe connectors were a must have for any and all of those especially if they had t-tops!

My apologies to all for being a ***** if I come off this way. This whole driveshaft thing is turning into a fiasco!!!!!!!

garrettg

iTrader: (1)

or a Ford Fairmount based late model