Sparo2

Hey guys,

I was hoping to get opinions from those that build race cars since this basically falls in that category. Here's my senario. I currently have a C5 diff bolted into my C6. For a while now it's been really cost effective considering how much I saved by not having to purchase another C6 diff. Anyhow, the original diff mount I first made has already been tossed in favor of a new and stronger billet mount made from 6061. It's not done yet. I'm still working on a few clearance issues but the car has been driven around and taken a few passes down the 1/4 mile on street tires. Wheel hop is almost gone now and the car feels a lot more solid. I haven't tested the car out with the slicks yet but I will this wknd. There is a noticable vibration which i'm also working on. See pics below...




Well, now i'm thinking about making another mount that's a little different. I'm thinking about something similar but instead of it only being bolted to the cradle in the center it will also be bolted to the cradle at the ends of the mounts. This will be done by simply drilling two holes on each side of the cradle for bolts and slip a rubber isolator between the two parts.

OR

I can just do away with the center mounting point and just bolt it in at the ends. This setup will also be useful if I was looking to do the conversion but didn't have access to a welder to weld the base plate.

So here is my question:
1. What are the PROs and CONs associated with building a mount that eliminates drivetrain movement almost 100%?

I know race cars install solid mounts for the engines but how about the diffs. I know vibration increases with solid mounts but I will be using a med/hard rubber to help with vibrations. The car already has PFADT motor mounts so it helps keep everything in line as well.

Thanks

Joe_G

My buddy Wanttospeed put in Pfadt solid motor mounts and diff mount in his C5 and his car is vibrating him to death. He's going to take them out, he says they are too stiff for a street car. But he believes its the motor mounts, not the rear mount, that is causing the vibration.

Here's a pic of them.




It looks like you are going to do something similar to the c5 Pfadt mount. I think that would be a good setup for us c5 rear in a c6 guys, like below with a shorter middle mount.





Here's my mount that Cartek made.



I'm interested to see the responses you get.

Sparo2

Hey Joe,

I know the PFADT mounts add vibration to the car but from what I keep hearing from the C5 guys, it's their diff mount that's causing most of the vibration. I believe it too because I can notice most of my vibration coming from the rear.

I've talked to a lot of C6 guys and they say when they swap out only the motor mounts, it only adds a little vibration but nothing crazy. The factory mounts are just too weak for performance minded applications. Both of mines were completely busted when I swapped them out.

The diff bracket has to be slimmer/shorter than the C5 PFADT diff mount because anything taller and it will raise the rear of the drivetrain too high. This will cause problems for guys with remote clutch bleeders and even worse, guys with stock motor mounts and remote clutch bleeders. Don't ask me how I know this. LOL!!

The distance from the mounting points of the C5 diff and the cradle must not exceed 2". This means that the diff mount cannot be taller than 2" but I'm thinking it may need to be closer to like 1.75".

Joe_G

Hey Daniel,

First of all I'd like to see this thread get some action as I'm interested in the thoughts you get.

Also, how did you notice your motor mounts are bad?

5 Liter Eater

Link to old mount thread: http://forums.corvetteforum.com/c6-t...-write-up.html

Did the old mount deform or break? After re-reading that thread maybe cutting the channel in the angle iron weakened it too much? Joe's Cartek bracket has been serving him well but I understand you're rtying to emulate the PFADT unit to limit wheelhop?

Sparo2

Sorry Joe. It's been a mess here at work because of all these budget cuts that our brilliant Governor is making. It's taken a lot of time away from my car. I did however take the car to the track to do some testing on the bracket. Makes the car feel a lot more solid but there is some added vibration as you may expect.

I didn't realize my mounts were shot until I installed my remote clutch bleeder from RPM. I did a test pass and after a hard launch the pedal started to lose pressure. By the time I was shifting to 4th the pressure was gone. Since the fitting that screws into the slave sticks out further than the stock bleed screw it had hit the top of the tunnel which caused it to bend and leak the fluid. All this happened at the launch, when the engine was under extreme load at it was twisting. The bad mounts allowed too much engine movement which caused the problem. When I swapped over to the PFADT mounts, I took a look at the original mounts and they were completely torn and rusted inside.

As soon as this weather starts to clear up I'll finish up a few touchups on the bracket and get some final measurements to make more mounts to those that have the C5/C6 diff conversion.

The old mounts tore, broke and died.
The original mount I made held up pretty well. There was nothing wrong with it when I took it out. I just wanted something that would hold the driveline in place better and help eleminate some wheel hop at the same time...which this bracket is doing a good job of.

5 Liter Eater

Well when mine grenades I know who I'll be calling.

Joe_G

Think about something....if you break your case like we all do, you won't get a penny for it. If you sell it to an automatic guy now, you can pretty much put in a new c5 rear with good parts and gears, including the bracket, for what you sell your rear for!

Sparo2

That's true. When I blew my 05 diff I just tossed that damn thing since it was now worthless. Had I sold it I would've had money in my pocket at the end. When I swapped over I just went to a salvage yard and picked up a used C5 ZO6 diff for $600 and fabed my mount. Since I did all the work myself the total investment was $650.

Since then I've invested into a DTE Stg II update. Just for added insurance and gearing.

Sparo2

Hey guys,

Well, I just finished tearing apart my rear suspension for some routine check ups and figured I'd share a few updates on my updated conversion bracket. I know the bracket is not the best looking one but it's still one one piece with no signs of wear.

Here are a few pics....



And here is one of the base plate....


I've recently made a few brackets for a few Vettes in my area with the same conversion. My latest bracket is a little smaller and slimmer than this one. I just never got around to finalizing my bracket. I just wanted to put it thru some wear and tear before anything.

Oh and one thing to note, the vibration damper on the C5 diff will not work with this bracket. I modified the bracket for the damper a bit to make it work.

Enjoy...

Joe_G

Looks great. I like that your mount has side support...I'm using only the center mount on the welded cradle on mine. But knock wood, it's holding just fine.

I think this is really a great mod for our 05's. Saves THOUSANDS over buying an 06+ rear and the adapter plate. And if you do the mod before you blow your rear, you might come out even or money ahead by selling your rear to an automatic 05 guy.

SpinMonster

I have the cartek C5 swap too and its held up fine. I never tracked my car but I know cartek did on thier 2005 R&D car.

I had a vibration until I put on that damper thingy. Runs perfect. I cant tell the swap was made.

Anyone that wants this mod, I'm de-modding my car and need your core. PM if interested. It can save you thousands over a breakage. If anyone in the Mountian area (Colorado or surrounding) wants to head here we can do the swap at my house and both of us can be hooked up and happy. Mine has 4.10's and both shafts are hardened. Its a severe duty diff and Cartek built that too. Its proven so you know its good.

Sorry for the hijack.

Joe_G

I can't tell the swap was made either and I've track tested mine. It's a great mod for the 05.

That's a good deal...I'll forward this note to my buddy Double A Vette..but he's in Md. Maybe he wants a road trip.

SpinMonster

The advantage of the buyer coming here is that they can have my cradle with the welded bracket on it. Its a quick swap and saves everyone time and money. I'll go 1800 plus thier core installed and tuned for the 2nd gear limiter. They get 4.10's and both hardened shafts for what is a 'stage 3' from DTE.

Cartek's 2005 went 9.9 with twin turbos. It holds it. They broke the stock diff at the track on H/C power.

Im 1650 miles from MD. Its a hike to colorado springs, CO

Joe_G

For those wondering about 4:10's...I've had 3.90's and 4.10's.

Go with the 4.10's.

Sparo2

Ya, the side supports held up pretty good and they are "off the shelf" parts too.

My old bracket looked like it held up fine till I start noticing a little wheel hop on my street tires. When I took it apart the bushing was torn a bit. This was also caused by my blown engine mounts that got replaced by the PFADT units. Plus all those hard launches on slicks didn't help.


Ya, that vibration damper does make a differenece. I heard a lot of C5 guys say that they just take them off and didn't notice anything but when I put mines have on after a little modification, a lot of vibration went away. I still get some bcuz of the front PFADT mounts and my rear mount.

This is one heck of a deal you got there Spin. There's been a few guys on here worried about breaking there 05 diffs. This should prove very useful. What are you upgrading to?

lilmiller74

Could you reload your pictures on to this thread, i am about to do this and some pictures would help out alot.

Joe_G

Here are some pictures of my mount, still going strong 150 passes later.

Joe_G

And in the interest of full disclosure, the c6 diff price has come down dramatically. I got one for about the same price as a c5 core.

And the newer 06+ c6 diffs are certainly stronger looking than the c5's...see below.

C6 (2006+)



C5 (I have a brace on mine but it didn't prevent me from bending my output shaft when I broke my 2005 rear)

5 Liter Eater

Joe why did you have to yank it? Just decided to go back to a C6 diff? I'll take that adapter off your hands if you're not using it anymore.