BUILD THREAD 86 GP 2+2~Blown 6.0

[81cutlass]

I think I meant to say Key Off Engine Off on a timer for that circuit. It was pretty early when I wrote that.

That said... its a shame you don't live closer we could get up to all kinds of wacky stuff.

 

[Supercharged111]

It's a 3/8 air hose on a 2" muffler clamp as a intercooler pump mount.

Now that I'm not looking from my phone, that's quite a bit clearer.

 

[81cutlass]

Spent last night trying to hunt down my slight coolant leak from the radiator area that has started sometime last summer. It's minor but with the dog around and a few neighbors, plus getting flack at the track I wanted to get it fixed.

Texas82GP mentioned his brother's Griffin LS radiator developed a leak shortly after install. That got in my head and now I am worried.

I pulled the rad last night and looked for a pin hole, crack, or something that wore through on the bottom near the mounts and didn't see anything. My rubber isolators weren't ideal but they seem that they are doing what they need, no scuffs. I put a Schroeder valve in one of the steam vent ports and filled it with 5psi and dunked the bottom and each side of the rad in a tote full of water to search for bubbles, nothing.

I put the rad back the car and hooked up both hoses. I filled the entire cooling system with 15psi last night and it had 8psi this morning. I do know I have a leak, but I can't find it. Argh. I might sneak the rad into the house and use the tub tonight. I don't have a tote large enough to hold the entire thing at a time.



In less frustrating, hopefully more beneficial news, I am getting into suspension refinement now that I am happy with my rear ride height. Turbo John has a good few videos on instant center explanation and what a radial vs slick car should behave like.

Basically for the last 3 years I have three problems on my launch. I either spin, bog, or light tire shake. When it light tire shakes it actually goes the fastest. It's knife-edged between spin or bog. My two step has helped immensely, and I hope my clutch delay valve will be beneficial. However, I assume I am going to (at best) end up in the zone where it tire shakes if I adjust it so the engine doesn't pull down or just overpower the track.

I got a quote from a local guy who is a dealer for a pair of Viking Warrior shocks ($385). Double adjustable nice ones. I was hoping for a bit of a discount over list price (it really isn't) but it is what it is.

I have those used comp engineering shocks for the front, I think I am going to buy a set of adjustable rears and put those comps up front to slow down the nose drop on shifts. See how that helps..

EDIT-

For my purposes for than anything.

Hoosier Bracket Radial has a floppier sidewall than the M/T PBR and might be a good compromise for me where it has a little sidewall deflection on the shifts but still acceptable stability.

Hoosier Racing Tire 18820DBR Hoosier Drag Bracket Radial Slicks | Summit Racing

Free Shipping - Hoosier Drag Bracket Radial Slicks with qualifying orders of $109. Shop Tires at Summit Racing.

www.summitracing.com

 

[Texas82GP]

Spent last night trying to hunt down my slight coolant leak from the radiator area that has started sometime last summer. It's minor but with the dog around and a few neighbors, plus getting flack at the track I wanted to get it fixed.

Texas82GP mentioned his brother's Griffin LS radiator developed a leak shortly after install. That got in my head and now I am worried.

I pulled the rad last night and looked for a pin hole, crack, or something that wore through on the bottom near the mounts and didn't see anything. My rubber isolators weren't ideal but they seem that they are doing what they need, no scuffs. I put a Schroeder valve in one of the steam vent ports and filled it with 5psi and dunked the bottom and each side of the rad in a tote full of water to search for bubbles, nothing.

I put the rad back the car and hooked up both hoses. I filled the entire cooling system with 15psi last night and it had 8psi this morning. I do know I have a leak, but I can't find it. Argh. I might sneak the rad into the house and use the tub tonight. I don't have a tote large enough to hold the entire thing at a time.



In less frustrating, hopefully more beneficial news, I am getting into suspension refinement now that I am happy with my rear ride height. Turbo John has a good few videos on instant center explanation and what a radial vs slick car should behave like.

Basically for the last 3 years I have three problems on my launch. I either spin, bog, or light tire shake. When it light tire shakes it actually goes the fastest. It's knife-edged between spin or bog. My two step has helped immensely, and I hope my clutch delay valve will be beneficial. However, I assume I am going to (at best) end up in the zone where it tire shakes if I adjust it so the engine doesn't pull down or just overpower the track.

I got a quote from a local guy who is a dealer for a pair of Viking Warrior shocks ($385). Double adjustable nice ones. I was hoping for a bit of a discount over list price (it really isn't) but it is what it is.

I have those used comp engineering shocks for the front, I think I am going to buy a set of adjustable rears and put those comps up front to slow down the nose drop on shifts. See how that helps.

I hope your radiator isn't leaking. I also hope it isn't something worse. A plastic kiddie pool might be an option for testing. Amazon has inflatable ones for less than $20. You might find a hard plastic one locally for less. I saw one used as a parts washing tub in one of the build threads.

 

[64nailhead]

Tire shake is DEATH to your driveline. It doesn't matter what you have for driveline components - at some point it will break stuff. I know you've seen this, but you have to tune out tire shake. I'm not 100% on whether it is the diff shaking, tires, axles or a combination of all of the above. But I know the result - shock load.

I believe, repeat believe, that being able to put the load onto the diff once it hits the instant center and being able to maintain the load consistently should eliminate it. But WTH do I know lol. I've experienced it as well and when I do I immediately dump the the throttle trying to keep my junk in one piece.

Once you get your driveline angle correct (maybe it's good now), then it will be in your rpm (boost) being ramped in to control the power until you get it moving to stop the shake. I know I've shaken the tires when I have put too much timing in on the hit. Dialing back the hit is the hardest part of my tune and I'm yet to get it right. Once I do I will be happy. And I believe you're in the same boat - and yours is much more difficult IMO because of both the stick(T56) and stock ECM.

My advice - don't hurry and break sh*t - drive it, enjoy it, go FAST

 

[81cutlass]

Tire shake is DEATH to your driveline. It doesn't matter what you have for driveline components - at some point it will break stuff. I know you've seen this, but you have to tune out tire shake. I'm not 100% on whether it is the diff shaking, tires, axles or a combination of all of the above. But I know the result - shock load.

I believe, repeat believe, that being able to put the load onto the diff once it hits the instant center and being able to maintain the load consistently should eliminate it. But WTH do I know lol. I've experienced it as well and when I do I immediately dump the the throttle trying to keep my junk in one piece.

Once you get your driveline angle correct (maybe it's good now), then it will be in your rpm (boost) being ramped in to control the power until you get it moving to stop the shake. I know I've shaken the tires when I have put too much timing in on the hit. Dialing back the hit is the hardest part of my tune and I'm yet to get it right. Once I do I will be happy. And I believe you're in the same boat - and yours is much more difficult IMO because of both the stick(T56) and stock ECM.

My advice - don't hurry and break sh*t - drive it, enjoy it, go FAST

Absolutely. I HAVE to get rid of this tire shake issue. I have killed 3 rear ends at this point and I think 2 are directly related from suspension tuning. I keep putting better driveline parts in to replace broken parts and haven't looked at any of my geometry for quite some time. I went through wheel hop on my 4th gen back in High School and addressed that with cheap shocks and LCA relocation, but at my power level and t56 I probably need to actually buy real shocks.

1st failure was a stock gov lock and totally understandable. I actually drove home from the track and only took a look at the diff because it had a bit of whine. It knocked a tooth off a spider gear and twisted the china slip yoke a few degrees after the trans input shaft. I had stock control arm bushings at that point along with shocks so not surprising . I also didn't have a 2 step and launched really soft so that probably saved it from hurting anything worse.

2nd failure was a stock 30 spline axle which, although is more brittle than an aftermarket axle, it probably wouldn't have broken if it didn't shake. I don't have thorough enough notes but I do remember I had drove through some tire chatter on that drag weekend the track before where I ran my 11.75 at 120.

This is where I was last summer. 2 back to back runs with the same tire pressure. Light tire shake (chatter?) results in 1.77 60 and slight spin results in 1.86. It's fastest when it chatters and I can drive through it but yeah, it's rough on parts and I need to stop.

This is the best pass at the day before I broke the diff last fall. 1.76 60ft, I don't have notes on spin vs stick vs chatter.

And here are the other scrap passes. Lots of spin.

And I wasn't kidding when I said I was throwing the rad in the tub to check for leaks. Filled it up to 10PSI and plugged the hoses. Good news? No leaks. Or at least 'bad' leaks. It is just seeping out of the overflow tank. Bad news? I can't find the leak and why I was dribbling out of the radiator. Maybe it was residual sitting all winter in the bottom of the core support from when I overheated and boiled over last fall due to the fan quitting? Lower rad hose wasn't 100% tight? Not sure.

Anyways the rad and fan is back in and I put the core support lip on.

 

[64nailhead]

Can you retard the timing when launching and feed it back in after clutch release or 2 step release? Possibly with a different tune, i.e a street tune and race tune?

 

[81cutlass]

Can you retard the timing when launching and feed it back in after clutch release or 2 step release? Possibly with a different tune, i.e a street tune and race tune?

Maybe? Hadn't thought about that. One of the sponsors from the drag weekend event I do is a well known local LS tuner and I asked him about some of my problems and he said bogging can be a result of too little timing and to try adding some in the low (3500-4500) RPM WOT area. Then just turn the 2 step down until it stops spinning. Id have to think about how to turn the timing retard on/off. I have a tuning request to him to fix some issues but he hasn't got back so not sure if he is busy or knows my car is hacked and wants to stay with cam and header tunes on ZL1/Z06 stuff.


In other news I got the car back on the road yesterday. I took it for a short cruise and everything seemed good. No coolant leaks, no trans issues with the different bellhousing, no odd rattles.

I took it on a longer cruise and as I was getting close to home I took an off ramp and I heard what sounded like bolts ricocheting off the floor boards combined with an odd shake. I pulled into a parking lot and looked under the car expecting to find the driveshaft u joint cap bolts loose or something from my bellhousing to have rattled loose and the trans to not be tight to the engine. I limped it home and parked it for the night.

Put the car back on jacks today and did a pretty thorough look over expecting to find loose or missing hardware. Didn't find anything. Good news/bad news? I distinctly heard stuff bounce off my floor and saw stuff bouncing on the road behind me when I checked my mirrors but nothing was missing so maybe I hit some road debris? Not sure.

While it was off the ground I addressed my exhaust. It had moved a little lower from when I pulled it apart to pull the trans this winter and with the car being 1" lower in the rear it was lower than I wanted. Redid my clamps to pull the mufflers closer to the floor and I'm happier now. The 3" exhaust had previously forced me to put it lower than I wanted 4 years ago when I originally installed it due to the stock UCA's interfered, but with my adjustable tube ones I have now I had more room.

Since I struck out finding missing hardware I still had a weird shake, almost surge at lower speeds. I put the car in 3rd gear on jacks and let it idle I finally found the issue, the top of the diff was moving about 3/4" front to back. It looked like the UCA bushings on the diff side were really beat up but I have 2 year old spherical joints and they were still good. I pulled the bolt out and realized the issue. The stock 12mm bolt was fine but the spherical joint has an ID of 0.56". Basically there is over 0.1" of clearance between the bolt and hole and it was allowing the rear to shift.

Having a lathe 12ft behind me was the obvious solution. I whipped up some bushings and retested it and it's a lot tighter. My frame side uca bolts were also a little loose so I tightened those up a lot and it moves maybe 1/4" tops now.

Took it on a test drive and it doesn't shutter nearly as bad. I almost wonder looking back if something loosened up on the cruise on drag weekend last year which caused the really bad wheel hop and blew the diff up? Totally speculation.

The 12mm factory bolt even necks down right in the bushing.

Bushing is .460" ID and I used a new non necked bolt.

And took a cruise again and overall happy. I haven't taken a photo outside with the 5401 rear springs so this is the result. I'm happy with the ride height as is

I need to paint the thing still.

 

[Texas82GP]

Looks great as-is. Less is more. You're driving/enjoying it!

 

[64nailhead]

IMO you need a bushing on one end of the control arms. I don't know what you have on the body side, but if it's a spherical/solid joint then I give it the thumbs down.

Regarding my son's Cutty, I put solids on the diff, stiff urethane (EnergySusension) and ended up with stock replacmements only for the reason of it stopped hopping. I believe that the rubber loads up and distorts and stays there until lifting the throttle. Perhaps on a full race build only the solids are better. But I found it difficult to keep them tight. He had spreicals on the all of the frame attaching points and the bolts have to be stupid tight to keep them from getting sloppy. I had to weld new washers onto the lower arms frame mounts because the holes were oblonged. Enough of my rant about that and I'm sure that someonewill flame me over it. But a street car needs form of rubber mount on our style rears In My Opinion (IMO ) I understand the spherical joints aren't your issue, but ..........

FWIW, I like the way it looks, if mine looked like that I can safely say the paint job would be saved until I'm retired The stance looks good to me as well.