Glad to see you are enjoying your car Andrew!

I just caught back up with your thread, and it really makes me want to get back to work on my Buick!! I haven't made any real progress on the LS1 C4 in over a year (and the Buick for longer than that). I have been distracted by Jeeps and off-roading, which has been fun.

Off-roading is more similar to road racing than many know if they haven't done both. Lots of cool, well built, american made aftermarket parts (some even in aluminum for weight OCD guys like me). Vehicle control is the name of the game when negotiating muddy, tight trails and extreme inclines. And family oriented road trips to events is common. I have a weekend road trip scheduled w my son this weekend to enjoy an off road park in Indiana (The Badlands).

The major upside for this part of the country is you can enjoy off-roading year round.

All that said, a Jeep does not drive like a muscle car! I have seriously considered slapping the L92 in my 03 Rubicon.

 

I am not excited to drop 1400 on a solution to the driveshaft vibration problem, but if that is the only way, I just might. My car is smooth until I eclipse 62 MPH, then the driveshaft starts to vibrate pretty bad. I too have tried the adjustable rear control arms to match the pinion angle to the engine trans. It did not work for me either.

How much would this deal cost if it was aluminum and what is the diameter of your shaft?

 

I really can't comment on pricing since I am not the one making the driveshafts. I would give Frank @ The Driveshaft Shop a call. He is a sponsor on this forum and make a lot of axles for the new cars that have IRS.

(800) 564-2244

The shaft that is in my GTO is 3.25" O.D.

Andrew

 

Good thing I called him. He said that my situation is actually different than yours and that my solution is a $450 dollar item as opposed to $1450.

 

Maybe it is, maybe it isn't. Driveline vibrations are probably the most difficult and frustrating ones to track down. To make matters worse, when A-bodies are lowered the rear end centerline gets higher than the back of the transmission. That is what causes the front working angle to become extreme. There are other solutions to the problem besides the use of the CV in the front, but that is the route I chose.

If you have taken the measurements and you know that your front and rear working angles are less than 3 degrees, and all of your various components, such as, output shaft, slip yoke, pinion yoke, and pinion gear have run-out that is within tolerance, then you may very well be OK with just a new driveshaft.

However, I have been working on A-bodies for 25 years, and I can tell you that unless you have made major changes in the angle of the engine and trans, or if your car is not significantly lower than stock, you will not get rid of your vibration with just a new shaft. But please keep us posted how it works out.

Andrew

 

For the sake of continuity I wanted to post an update to what's been happening with my car. Since doing the LS swap, I really haven't been able to do many events due to the circumstances in my life. Also, the car has been in storage, with the kindness of friends, but I now have the car with me in Memphis. Back in March I looked at the schedule of events at Memphis International Raceway, and I noticed that the local BMW club holds regular autocrosses at the track. My girlfriend and I attended the March autocross hosted by the Rivercity Bimmers. As it turned out, any car is welcome to participate and the guys were all very friendly. We decided that for the next event we would bring the GTO and participate in the fun.

Yesterday was a gorgeous day. We finally had a break from the rains and the temperature was in the high 60s. There was a slight breeze, but overall, it was a great day. The course wasn't really a true autocross. There is actually a road course setup at MIR and the autocross used a section of the road course for sections of the track. It was very fast and a lot of fun. Cars were a mix of BMWs, a Miata, and a small contingent of Subarus.

The fast time of the day was set by a lightly modified Subaru STi. He ran the course in 56.xx seconds. My first run of the day was 1:04.xx, but as I got more familiar with the course and got a few pointers from a more experienced driver, I was able to get down under a minute. My best run was 59.xx, at which point I called it a day. This was about as much fun as I have had for 30 bucks...

I had a car mount for my cell phone, and I was able to capture some decent videos of my runs. I made a compilation of a several runs. Enjoy!


Andrew

 

Great video. I love seeing these cars being driven like they were meant to be.

 

I have a curse. It is the same curse that inflicts many of you. This curse makes people crazy and makes them do things for no apparent reason. I am speaking of the inability to leave well enough alone. My car is fine. It drives great, runs hard, brakes well. But I can't leave it alone.

I have never been 100% satisfied with the rear brakes. It is an older Baer Track system that uses a small C4 Corvette caliper (40mm piston bore) and a 12" rotor. When I was doing the last round of updates a few years ago, I noticed that the caliper bracket was slightly bent. I never really tracked down the reason why this might happen, but it was a little unsettling. So after doing some reading on the forum, I decided to install the 4th gen Camaro LS brake system. The LS brakes have amazingly sturdy cast iron caliper brackets, bigger calipers (45mm piston bore), and I will eventually incorporate the drum style e-brake.

Here are a few teaser shots of the components.

I sourced the brackets from a very good seller on LS1tech, who was parting out a 1999 Firebird. After a trip to the sandblaster and a couple of coats or Rustoleum Silver grill paint, they are good to go:



Being on a limited budget, I was basically forced to use re-manufactured calipers. I got on Rockauto and found that Powerstop sells a set of calipers that are powder coated red for under $150 for the pair. They look very well put together and will add a touch of matching color to the rear:





To round out the brake upgrade, I got a set of Raybestos professional grade rotors and semi-metalic pads. Raybestos is currently running a rebate of $5 per rotor and $15 for a set of pads. The rotor is coated (maybe e-coat) and should stay looking nice for a little longer than plain rotors.



The other main reason for the timing of this upgrade is that I will be having the ring and pinion gear swapped by a shop. I don't have the space or tool to do any of the work myself, and I figure that since the rear end will be completely disassembled, adding new brake components should add minimal to the cost of the swap. The main reason for swapping gears is to eliminate excessive gear whine under light load. This is very annoying when going down the highway, and after talking to several trusted people, the consensus was that a new R&P set would be needed. I am also going down to a 3.42 gear (from 3.73) to reduce highway cruising RPM.

Stay tuned for further updates.

Andrew

 

Andrew,
What brand gears you plan on running? I've been doing some research on this very topic earlier today and I am interested in seeing your results.

Jim

 

Jim,

I struggled with this as well. It seems that everyone you talk to has their own opinions. I am going with Motive Gear, mostly by default. The gentlemen that will be doing the work likes them and says they are quiet. He also said that he will stand by his word and take care of it in case I am not happy. Since he is taking ownership of the decision as to the brand of the gears, I am defaulting to his judgement. For what it's worth, he came highly recommended and is said to set-up the gear for many of the local racers.

Andrew

 

The girlfriend laughing is classic, and the bitch comment, she showed you!!,

Good to see you out there having fun with the car Andrew, you still in school??

 

From what I read in the GEAR & AXLE section......the quietest gears will either be AAM Motive blue box, or yukon brands. https://ls1tech.com/forums/gears-axl...ion-brand.html Post# 2

Anyone have any experience with either of these?

 

The car is at the shop now, and will be getting Motive gears. Should be wrapped up by Wednesday.

Andrew

 

Some progress has been made. I feel terrible having to outsource some of this work, but I really have no choice. Luckily, the shop where the work is being done came highly recommended and they allowed me to hang out while they did the work. The owner's son was doing the work, and he was doing a good job.

Here is the new gear installed:



The brakes were mounted on the passenger side without any drama. The caliper abutment was well spaced away from the rotor and there was no contact even when the axle was pulled out all the way against the C-clip.



The driver's side, for some reason, wasn't as cooperative. The caliper abutment was nowhere close to fitting and after taking some measurements, we determined that the axle offset on the driver's side was .125" more than on the passenger side. I don't know why this is the case, but we ended up using some precision washers to space the caliper bracket away from the rear housing flange. Once that was done, everything lined up great.



Luckily, the guy doing the work was paying attention and he noticed that the driver's side hard line from the center to the caliper was pinched.



There were marks on the exhaust where it looked like the rear end hit during a hard bump. Since the hard line runs over the top of the axle it got smashed. New lines will be made and they will be routed along the backside of the axle tube instead of over the top.

Andrew

 

Well, the gear swap is finally done and I couldn't be happier. It is quiet and the ratio is perfect.

The rear brakes are definitely exerting more force. This is due to the larger bore of the piston and the fact that Raybestos Advanced Technology pads are fairly aggressive, even when cold. The rear brakes lock up now, and they never did before. I have an adjustable prop valve, so if need be, I will reduce the pressure to the rear. I will hold off on doing that now, because I am first going to change the front set-up slightly.

I got ahold of Alan Bailis, who used to work at Kinesis when I bought my wheels. My name came up on his caller ID and he knew exactly who I was. Pretty amazing for a man that has serviced thousands of customer. He is now working for Fikse, but after explaining what I needed, he was able to help. I ordered two inner wheel halves that are 1.5" wide than my current wheels. This will widen my from wheels from 8" to 9.5". I checked for clearance, and I see no reason why I can't run 275 tires in the front. I am also considering running the new BFg Rival tires in 275/35 front and 295/35 rear.

When I widen the front wheels, I will also install a set of Raybestos pads on the front in place of the current Hawk HP pads. I like how the Raybestos pads work when cold and after talking to Tobin at Kore3.com, he said that I will probably like the Raybestos pads. If, after going to a wider front tire and new pads, the rear still lock up before the front, then I will reduce pressure to the rear to balance things out.

I also got my speedometer working and calibrated. As you all might recall, when I had the Richmond trans rebuilt, I had them take out the speedometer gear. I did that so I would not have to worry about the slip yoke hitting the gear. This is a concern with the Richmond 6 speed transmissions. With the loss of the speedo gear in the transmission, I no longer had a source to drive my VDO speed sensor.

Luckily, I have ATS spindles that have a built in ABS sensors in the C5/6 hubs. Dorman sells the ABS jumper harness that fits the C5/6 ABS sensor: PN 970-007.



One of the leads needs to be grounded, while the other lead is the signal wire. It doesn't matter which is which. Run the signal wire to the Autometer gauge and recalibrate. The ABS sensor will start sending pulses after 2-3 turns of the wheel.

The C5/6 hubs have a 48 tooth reluctor wheel. I am running 255/40-18 tires in the front, which according to TireRack, are 801 turns per mile, so for the two mile calibration period, they will turn 1602 times.

1602 x 48 = 76,896 pulses per 2 miles. Having that information, you don't even need to measure out an accurate 2 mile stretch of road. I started my calibration and when the counter on the speedo got to 76,000 I stopped it. I compared the speedo reading to the GPS reading on my phone and the speedo was slow by about 2 mph. I assumed that the GPS is accurate. So I repeated the calibration and stopped it when the counter got to 74,000 and now the speedo reads exactly the same as the GPS.

Andrew

 

It is time to post a few updates on the car. I haven't really been driving it much this summer because of a lack of time, but I am getting excited for my next event. I just registered for the Holley LS Fest and it is time to get the car ready. Here is a list of things that I plan on doing.

1. I noticed when the car gets hot, while siting in traffic, the steering effort increases. I double checked the fluid level and even though it doesn't seem to be boiling or spilling out, I decided to add a power steering cooler. I realize there are various options for this, but it seems that the easiest and most sanitary install will be to use the 4th gen f-body cooler that mounts in the upper radiator hose. Several people have mentioned that this might not be the best solution, but I have the cooler already and I will give it a try.

2. I changed my rear brakes over to 4th gen f-body "LS1" brakes using Raybestos premium pads. I chose these pads after several conversations with Toby at Kore3. As much as I want to believe that I have a race car, I do not, and thus I need my brakes to work even when they are cold. The Raybestos pads have a similar friction profile to the Hawk HP pads. I will be swapping out the Hawk HP pads, that I have in the front, to the Raybestos premium pads, to match the rears.

3. There is no denying that having bigger front tires is more desirable. My current tire size is 255/40-18. I've been running this size mainly because my front wheels are only 8" wide. During the recent brake upgrades, I've had the opportunity to really examine how much room I have in the front, and it was clear that I can go with a wider tire and wheel in the front. I managed to track down Alan Balis, who used to work for Kinesis wheels, and after getting some measurements, he sent me these:



The beauty of having 3-piece wheels is that they can be altered to suit the needs of the application. These are wider inner hoops that will increase the width of my front tires to 9.5" :screwy:

4. With the increase in the front wheel size, I now need bigger tires. I struggled long at hard over my tire choice. My current tires are Falken R615s, which are admittedly an older tire technology. Falken does make a new version of that tire, called the 615k, but I was reluctant to use them because of size availability. I currently run a 295/40-18 in the rear. This is a 27" diameter tire. I want to run a 275/35-18 tire in the front, which is 25.5" tall. I felt that from an aesthetic perspective, the front tires would look too small compared to the rear and it would look funny. Again, as much as I want to believe that I have a race car, I don't, and looks are a factor. Ideally, I would run a 295/35-18 in the rear, but Falken doesn't offer that size in the 615K....

So, the choice was pretty clear. BF Goodrich just came out with their new Rival tire, and by all accounts, this tire kicks a$$. So I pulled the trigger on a set of these:



The 275/35 fronts and 295/35 rears are a perfect match. The rear is about 26" tall, which is a hair taller than the fronts. They are designed to be used on 9.5" and 10.5" wide wheels, which is exactly what I will have after widening the fronts. The Rivals are a true street tire, with a tread wear rating of 200, which allows me to use them at events like the Holley LS Fest. Using the Rivals was just a natural choice. I am very excited to get them on the car and see how they work, both on the street and on the autocross track.

I will be doing these upgrades sometime in August, so stay tuned for more pictures of the installation process.

Andrew

 

I want to know how the 9.5 wide 275 in the front works. I am going to have to size mine out for my 69 GTO, I want 275 35 19 in front and 315 40 20 in the rear. I know its going to be a tight fit, but I want to see what happens.

 

Project GatTagO,
I always love reading your thread. You always teach me new things or give me ideas. And I thank you for this.

Jim

 

Check my PM on pro-touring.com. The short answer is that it is really hard to say what will fit and what won't because everyone runs such different suspension components and even alignment settings. All of this plays a factor with respect to wheel fitment.

Andrew

 

Jim,

Thank you for the kind words. The goal of my posts are to inform, entertain, and delight the readers.

Andrew