I have them in my car as I run it in Time Trials and have 335/35X17 in the rear of the car. Do you need it? It depends on your application. I felt it was worth it.

 

I'm going to have to do the same to mine. Replace the front diff mount and I was wondering if anyone could give a play by play acount on how to do it. I heard of some horror stories cconcerning this. Thanks

 

Thanks TSW. You seem to have a bit of uncontroversal knowledge on most of the threads I've been reading about supsension set-up.

My orginal, and still main goal, was to get the wheels to stick on launch. So I went to my local, highly recommended vette supsension guy, and he said to start with the adjustable camber rods and go with the 420# mono spring for starters, (I have the 9 leaf steel) and a 4 wheel alignement. I also had a worn TA bushing one side, and a little play on a wheel bearing on the other. So I bought two offset TA's from Vansteel, and the adjustable struts w/hiems from VBP. While under there, I noticed the front carrier mount had a 1/4" gap between the frame and the rubber with no load on the rear, so replacing that should help as well. The shocks are old and appear to be stock. So I will replace with KYB gas adjust at his recommendation. The car is a Sunday driver with the occasional street drag race when tempted. Havn't been to the track yet, but will probably go this Spring.

Th offset TA's was my idea because I want more meat on the road without adding flares, although I like the look. He tells me that anything larger than 275 width will cause too much stress for the stock drivetrain (336 rear) He also added that the Hiem joints cause vibration and the locknuts lossen up repeatedly. He says I'm over thinking it and trying to solve the intial problem with too much "smarts". He's got 25 years working on suspensions, motors, etc., I have 2. I'm no dummy, and a do my homework, but mistakes do to inexperience can be costly. (geez, sounding like a therapy session)

There is so much info on this forum, and I find 50% of it is contrary to another thread I read.

So, "Doctor", what's your thought on the above? Oh, since the solid mounts you recommended eliminate any flexing of the pumpkin, do they eliminate the need for the traction bar that VBP has on its website? If you haven't noticed, I am building a Motion replica, and they had a traction bar installed to eliminate the twist.

All advice from others welcome.

 

It's really not that hard to do. Assuming all the usual prep is done with the car on stands, and you disconnected the drive shaft and pushed it up and out of the way, and soak the bolt with some rust breaking juice.

Slip a 5/8 socket on a long breaker bar handle in from the top front side of the frame, in line with the drive shaft. On the bottom, you'll need an 11/16 socket on a long 1/2" breaker bar, or an impact gun if you have one. Off comes the bolt. The rubber mount comes in two peices. The top half comes out from the top side with some wiggling. The bottom slips out after the top is pulled through.

Now, I did this with everthing else remove off the rear, so there was no loads at all, except for gravity, on the pumpkin. If you are doing this with all the crap on, you may want to put a block of wood in between the rear and the body or mount to prevent it twisting and closing the gap on the mount once removed.

This is the first one I ever did, so I am learning as I go. It really wasn't that hard. Watch, I will get blasted for some silly point I missed. Hey, that's what makes this forum so much fun. I' am having a blast by the way. That's why I bought this car rather than buying one already done. Enjoy!

 

I replaced the old rubber diff bushing with a new polyurethane one last week. I can add a little to kellyr073's procedure. I took the driveshaft out completely. (I wanted to check the u joints anyway.) Nut and bolt and top bushing piece come out as described. The big bushing between the diff support bracket and the crossmember wouldn't move. I put a small jack under the back of the diff where it attaches to the spring to take some load off the front but the bushing still wouldn't move. I had to remove the bracket from the diff - two long bolts with cotter pins thru the nuts. After that it all assembles easily. BTW - the torque spec on mine was 80 ft lb. That's pretty tight.

 

I imagine there are some who would disagree with my being "uncontroversial", but I'll take that as a compliment that my efforts to be more diplomatic are working.

Tho it will take a fair amount of abuse, my experience has been that given enough torque and traction it IS possible to overstress the C2/C3 driveline and diff, even on street rubber (BTDT). I'm not saying you have to take things as far as I have, or that there's not more which can be done, but here's what I have for now: 12-bolt Eaton posi IRS diff conversion w/31 spline Hy-Tuff side yokes, solid Spicer U's, 3" late C3 HD half-shafts, Guldstrand modified high-nickel HD stub axles w/0.5" x 3" lugs, solid diff x-member locating kit (3 point), heim-jointed camber struts w/lock plates, and a lightweight flywheel. (PM me if you need a diff guy who really knows what he's doing, BTW.)

FWIW, camber brackets such as that with VB&P's Smart Struts do ease adjusting between deisred camber gain settings for different purposes, but they also make it just as easy to go astray. Trips to the drag strip qualify as one of the exceptions to my standard advice concerning static rear camber and camber gain, where 0* camber and lowering your rear camber struts to level with the half-shafts will keep your rear tires planted more squarely when the car squats into bump during launch (not to be confused with what happens when the car rolls into bump during cornering). As this most likely will not provide the best camber setup for anything else, I'd suggest you raise the inner camber strut links back to the top of the inclination slot for the road until you can play around with varying heights to find the best road setting for you. Then you can fab up a couple of sets of camber lock plates for each setup and eliminate the eccentrics if you desire (my preference).

It's up to you to decide if any additional vibration and/or noise would be a concern worth compromising over. As far as the locating kit completely eliminating movement or twist of the pumpkin, I won't argue that they would necessarily make traction bars altogether redundant.

Higher rear spring rate is pretty much the only measure available to reduce excessive squat in the C2/C3 rear suspension (firmer rear shock bump helps marginally), and IMHO stepping up to a 420# should help load the rear tires during launch. You might also want to consider some adjustable shocks down the road so you can adjust between drag and road damping. Hope I've answered some of your questions...

 

Thanks again. So far I have the adjustable strut rods w/ hiem joints, solid Spicer U's for half shafts and drive shaft, Offset TA's.

A lot to consider as I re-construct the rear over the winter. I will update this thread as I go.

You may have mentioned this before, but what rear spring are you running?

 

Glad to have an opportunity to help, if I've done so. Keeps the little grey cells warm.

Before beginning its current makeover, I was playing around with more rear spring rate (which had required me to begrudgingly increase the front bar), but since I used the Guldstrand shortened main leaf I already had I can only estimate that it probably ended up somewhere in the F41 neighborhood, give or take 20#.

Not that I'd suggest copying my specs in the first place, as I'll just as likely be back to the setup drawing board myself due to the changes in weight and distribution I'm currently making, but it's worth noting that I have >860# Daytona coils under a BB up front. Besides, my setup wouldn't necessarily please most other drivers anyway.

 

I agree, I found the rubber mounts to be problematic and would deteriate in a small amount of time. I don't believe they hold up well to being squeezed. I have a poly mount now and it looks new after a few years of abuse and probably doesn't have much more give than the aluminum disk. I also have the diff. locators.

 

I had the Daytona springs front and rear. They just didn't work well for me. I didn't get any suspension travel. In fact, the suspension never moved. They really are meant for high speed banked tracks. I took them out and am trying the F41 springs. But then again, I run racing slicks that may have been able to been use those springs. Hopefully for tracks like Lime Rock, the F41 will work better.

 

Your experience goes to show that results can and do vary. Of course I don't have a Daytona spring out back, but the big front coils have worked well for me. That said, I could find that I need to step down to 700# fronts with the aluminum heads and other weight reductions. The point to catch here is to not get hung up on one particular setup despite evidence against it.

One place at Lime Rock where you could possibly miss the Daytona coils is the Down Hill. Not saying you will, but that turn being a huge key to lap times you certainly don't want to compromise there.

 

I found the 860 lb coils really helped the front from diving when hard on the brakes. I use them for slow speed AutoX with specialially valved Koni shocks and reduded to a 1" bar from a 1 1/8" bar (which I wished I would have done years ago. I run 295/35/17s' on all four corners and until the last lap of the last event this year, never broke anyyhing it the diff. One axle in 130K miles ain't bad.

 

This is interesting and not to hijack this guys post, but different people try different things and come to different conclusions. A lot has to do with:
a) They way your car is set up
b) Personal preference

That is why advice carries many caveats. Skunk and Jim like Daytona springs. But you have to ask yourself a ton of questions before you consider buying them for your car:
Do they race the car? What tracks (Daytona in Fla is different from the inner course at Pocono, Pa)

Big block? Suspension set up? (rubber, poly, steel), what size sway bars?

Bump steer kits? Which shocks? Racing Rubber or Street tires? 60 series or 35 series tires.

In all honesty, you have to accept some trail and error. You don’t know how may sway bars I went through to find one that was right for me. Not to mention springs and tires.

Personal Bias comes into play too.

Sorry for the rant, but I guess I cringe when a guy mentions he needs brake help and people recommend scrapping the entire system for a Wildwood set up when the guy takes the cars out for Sunday drives.

Sorry kellyr073.

 

Stated by someone who has obviously been around the block a few times himself, IMHO. Moral to the story: There simply is no one-size-fits-all setup for every car/driver/track (or road) combo.

 

Damn, just ripped out the whole rear drivetrain, and ordered the best of everything that was recommended. Can't wait for the next warm Sunday to drive it around the corner, then polish it one more time.

It's all good Cottoneg. I have learned, and keep learning with every post. As many other I am sure do. From these, I try to make the right decision for my set-up, and as you said, (or TSW said), it's trial and error. I am having a blast! And hi-jack all you want, I don't "own" the post, just kicked it off.

 

I just replaced mine with Energy Suspension poly. One question, the lower bushing cushion did not have a metal washer attached to it like the stock (rubber) cushion. Is that correct? Otherwise, it is an easy install. Jack

 

Hello...

 

Here are the various bits-and-pieces in a poly unit.

 

Thank you!

 

No problem. In case anyone is interested in poly vs rubber, the poly is on top in the pic. There is a difference. I may have mocked up the ***'y wrong but what the heck.