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Yes, I had to drop the front end of the diff to create enough space. I also swapped the original adapter for one that was 1/8" shorter.
I am currently running RevShift Blues for motor mounts. One of the best things I did to reduce the vibes was get away from their transmission mount insert and go to the Creative Steel version. I suppose a stock would reduce the issue even further but I am not very comfortable with the stock mount from a support or longevity standpoint.
That adapter could not be right in my mind as its compressing the cvs from what you're saying.
The trans mount has been challenging. I had the CS mount and per Frank's advice I swapped the stock one back in and noticed improvement. My stock mount had 180k on it when I first took it out and while it sagged, I'd bet it sagged after 5k miles to begin with.
In the end, I'll have CS soft cradle and motor mounts (after ditching the UMIs) and maybe a window welded stock trans mount as the compromise I think I'll need between performance and comfort.
That adapter could not be right in my mind as its compressing the cvs from what you're saying.
That was my concern and the reason I had Max swap it to the shorter adapter. Whether or not it is a legitimate concern or not is questionable. I assume the CV joint on the end of the driveshaft would tolerate some plunge variation as the we know the Getrag diff in the stock setup allowed the nose of the diff to move up and down a bit which would effect plunge depth somewhat. However, I would think this variation in plunge depth is likely less than an 1/8".
Yes, I had to drop the front end of the diff to create enough space. I also swapped the original adapter for one that was 1/8" shorter.
I am currently running RevShift Blues for motor mounts. One of the best things I did to reduce the vibes was get away from their transmission mount insert and go to the Creative Steel version. I suppose a stock would reduce the issue even further but I am not very comfortable with the stock mount from a support or longevity standpoint.
Whoa...Let's back up. So there is an option for one that is an 1/8 inch shorter? I didn't see it on CS web site when I ordered mine. Is this a special, have to ask for it thing? Now I'm kinda pissed, should have just sent the one I got back and ordered one shorter...son of a bitch! I think I might just put the DSS shaft back in since my vibration issue did not go away and was not related to the drive shaft.
What I haven't been able to answer is just how much plunge should a cv have? If it has a total plunge of half inch, should it be operating at say a quarter inch of plunge so its working in the middle of the joint? Would this be the "sweet spot" for cv operation?
Reason I wonder is that my DSS shaft was, IMHO, over extended because the joints were extended well beyond the theoretical "sweet spot". They lasted 10k miles...
What I haven't been able to answer is just how much plunge should a cv have? If it has a total plunge of half inch, should it be operating at say a quarter inch of plunge so its working in the middle of the joint? Would this be the "sweet spot" for cv operation?
Reason I wonder is that my DSS shaft was, IMHO, over extended because the joints were extended well beyond the theoretical "sweet spot". They lasted 10k miles..
You probably know this already but there are multiple types of CVs, Some deal with plunge MUCH more effectively than others. From just the feel of this one I would say it has very limited ability to deal with variations in plunge. This was another one of the reasons I was so concerned with the first adapter.
You probably know this already but there are multiple types of CVs, Some deal with plunge MUCH more effectively than others. From just the feel of this one I would say it has very limited ability to deal with variations in plunge. This was another one of the reasons I was so concerned with the first adapter.
I didn't really look too closely at the stock shaft when I put it back in but I think the 930 joints on the DSS shaft had a 1/2" each.
if you grab the stock driveshaft installed in a gertrag equipped V, wonder how much movement it has fore and aft on the CV joints? IIRC, my DSS shaft had less than 3/8" left in it by the time I got it installed.
As the 930 were designed originally to work as an axle joint, wonder if spinning them 3.73 times faster than they originally worked is having a negative affect on them? The original 930 would do 150mph but if you install them on a v driveshaft and spin it that fast, it would be like going 600mph!
I think I might just put the DSS shaft back in since my vibration issue did not go away and was not related to the drive shaft.
I was reading this other thread and if I get you right, the vibration you noted above, which you thought might have been 8.8 related, was really the UMIs? I've always though my UMIs were a problem but if you think it solved most of yours, I'll speed up the replacement process!
I was reading this other thread and if I get you right, the vibration you noted above, which you thought might have been 8.8 related, was really the UMIs? I've always though my UMIs were a problem but if you think it solved most of yours, I'll speed up the replacement process!
So what's the agreement on the front diff bushings? Shorter ones should be on top? My bushings are all the thick ones. Probably causing the pinion to point down too much. I added washers to the top bushings to tilt the diff down some and it didn't make it any better or worse so maybe going the other way will help.
I'm running the Creative Steel 8.8 front diff bushings (call and ask them). They didn't have them listed anywhere on their site, but they make them too. The bushings are both the same size Upper/Lower and a washer goes on each.
I'm running a unique combo from a driveline perspective. Not sure if anybody else is running anything similar.
Stock length (getrag rear end distance) 1 piece DSS Carbon driveshaft.
+DSS Adapter that converts the DSS shaft end to Getrag
+ CS adapter that converts the Getrag shaft to mate to 8.8".
So I'm basically running two adapters since I didn't want to buy a new slightly longer CF driveshaft.
The install was super tight. I wish I had known about asking for a 1/8" shorter adapter as it seems like it took all the plunge out of the DS to get it to fit. I'm also running CS motor mounts and their 2years ago design trans mount (not as soft as their newest one). I'm also running DSS 1khp axles
I have all new parts sitting in the house waiting for eventual install. I have Prothane bushings - they've got the different thicknesses. I believe the stock rubber bushings on my junkyard diff were also different thicknesses. The 8.8" kit from CS came with bushings (I didn't realize it would, hence the Prothane ones) - they're all the same thickness. I didn't measure anything, but eyeballing it I'd say the CS bushings are in between the Prothane tall and short bushings.
The install was super tight. I wish I had known about asking for a 1/8" shorter adapter as it seems like it took all the plunge out of the DS to get it to fit.
With this setup. I have no vibrations.
Wonder if a lot of preload on the cvs helped here? My DSS shaft had very little and it didn't last that long.
I feel for you and admire the efforts you've made as they are the most intensive I've seen posted here on this subject. Thanks for posting about it!
I believe you're right about the statement above but i think every mount in the drivetrain is part of this equation, not just the driveshaft carrier.
You failed to mention anything about what kind if motor mounts you're using. I'm using UMIs which have zero compliance and I feel it is disrupting the entire drivetrain in mine.
I've been through some of this with my cf 1 piece and in discussions with frank at DSS I've concluded that the entire drivetrain needs a little "wiggle room".
The thought of going back to stock mounts is rediculous but I do plan on going with the softest aftermarket alternatives available to help eleviate drivetrain vibes.
Good luck!
Motor mounts are 80a revshift, subframe are 95a, trans is new stock mount, rear is oem terminator mounts, 8" innovators west damper, al flywheel, ls7 clutch, full upgraded axles. That's all I can think of that would contribute.
So here is an update with my latest:
Rear end developed an oil leak, slow drip at the nose seal that I was watching. I left for vacation for a week and on return all the oil was pooled under the car. I then changed the nose seal and noticed the rear CS mount / diff cover bolts had backed out.
I pulled the rear at that point and found a couple teeth missing from 2 side gears. Ring and piñon had all teeth.
Built a new rear with 3.27's for the standing mile and with an auburn pro LSD. I'm unsure if the side gears were overpowered, just fatigued, overheated from low oil, or somehow damaged from the driveline vibs.
I also drilled the 30a DS with 1/8" holes before reassembly.
Whatever I did is much better. I'd love to say it was the side gears but I have a hard time reasoning through that since they don't rotate relatively driving straight. Also, I previously really noticed the vibes through the armrest with the voodoo chicken DS. It is very diminished now. I still have a little little bit at ~50 mph. Everywhere else is butter smooth. I don't remember it being this smooth in a long time.
I'm tempted to try the CF shaft again or drilling a little larger hole size in the carrier.
Well I don't believe that it is all carrier bushing. When I installed mine I went with the stock carrier (with window weld) that had not vibrated prior to the CS 8.8". Sooo, who knows. My vibs aren't terrible now. Just in a bad speed, 62-70. So I just bought a radar detector and sped up.
Well I don't believe that it is all carrier bushing. When I installed mine I went with the stock carrier (with window weld) that had not vibrated prior to the CS 8.8". Sooo, who knows. My vibs aren't terrible now. Just in a bad speed, 62-70. So I just bought a radar detector and sped up.
What do you mean window weld? Epoxied center carrier support?
It is a urethane based product. Cheap and easy way to firm up factory rubber bushings. I have used it before to stiffen up hydraulic motor mounts. Drill and hole in the mount, drain the fluid, and squirt this stuff inside. Kind of a PIA but it works.
I can tell you guys that the poly carrier is NOT the cause of the vibrations but more than likely allowing existing vibrations to transmit more into the car. 99% of the cars with our poly units have ZERO vibes afterwards and majority noticed a complete dismissal of previously felt vibrations after the install. So... drilling holes in the 30a will allow it to absorb vibrations and not have them felt through the car, but the underlying cause of them is still there. :/
I can tell you guys that the poly carrier is NOT the cause of the vibrations but more than likely allowing existing vibrations to transmit more into the car. 99% of the cars with our poly units have ZERO vibes afterwards and majority noticed a complete dismissal of previously felt vibrations after the install. So... drilling holes in the 30a will allow it to absorb vibrations and not have them felt through the car, but the underlying cause of them is still there. :/
Sure a bushing doesn't cause vibs. But they can make them worse or better. Just like why OEM motor mounts do a better job damping engine vibrations than poly mounts. The OEM mounts are engineered to do that. It doesn't make the engine bad.
I think the Voodoochiken DS is good and the service is great. I would just equat it to the motor mount situation.
Bought a maggied V over the weekend with an 8.8 and carbon one piece and I'm squarely back in driveshaft hell. Although it's smooth up to a 85 or so, you don't want to drive it at a 100mph.
04-23-2015, 10:17 AM
