1970 GTO Version 2.0

[howehot]

The 70 Corvette manual MC has a 1" bore:



I would be curious to know what the rest of your system consists of and how much your car weighs. Your pedal must be pretty firm unless you have a high pedal ratio.

Andrew

System consist of wilwood 13" with 6 piston front and 4 rear, wilwood adjustable portioning valve, and the Corvette master. The Monte Carlo weights 3407# with a full tank of gas. I used the factory brake pedal and raised the rod to the top hole in the pedal, same as non power factory g-bodies. Jeff Schwartz recommended this mc when I ask which unit to use when I picked up the chassis. Pedal is firm but very manageable. The weight is the biggest disadvantage.

[andrewb70]

Happen to have the part # for the Dodge unit?

There are numerous options from various manufacturers. The application is 1995 Dodge Spirit with manual brakes (14" wheels). I got my MC from O'Reilley Auto Parts. It is brand new, is made out of aluminum, included the reservoir, and seems to be well made.

Andrew

[andrewb70]

Yesterday afternoon I got down to the task of of getting the car ready for the Holley LS Fest, which is only a couple of weeks away, and performing the few little upgrades that I had planned. First order of business was to take the front wheels off the car, break them down, install the wider inner hoop, reassemble, and reseal.

The wheels started life as being 8" wide. In case anyone was wondering, wheel width is measured at the area where the tire bead sits, not on the outside edges.



Here is the backside of the wheel. Notice the generous scalloping on the back side of the spokes and the hub area of the wheel. This is the reason why this particular wheel is only about 20 pounds. Also notice the generous amount of brake dust. I drive this car!



There are 40 fasteners that hold the wheel together. Once the nuts are removed, the wheel center comes out and the wheel halves can be separated. Notice the dead bugs on the inside of the wheels.



After disassembly, I cleaned the wheel centers with hot water and soap. This works very well to remove all the brake dust and general grime. The wider inner hoop was installed and the fasteners were torqued to 18 lb/ft, in two steps, and in a start pattern, much like when you torque lug nuts.



Here is the finished wheel, now 9.5" wide and ready for the new BFG Rival 275/35-18 front tires. Important safety tip: make sure you let the silicone dry before putting air in the tires. The pressure will penetrate the uncured seal and will leak, resulting in taking the tire off and doing the seal over again. Not fun!



This is what we saw after taking the tire off the leaking wheel. The pressure pushed air through the spaces between the fastners and created multiple leaks.



Here is the rear Rival compared to the Falken 615...



Today I will be installing the Dodge 7/8" bore MC, so stay tuned for more updates.

Andrew

[andrewb70]

As promised, here are some details for the Dodge 7/8" bore MC. This is what you get for about $60 bucks at O'Reilly Auto Parts. It is a MC for a 1995 Dodge Spirit with manual brakes (14" wheels). This particular model is brand new, made out of aluminum and has a plastic reservoir. These are all features that I like. Wilwood makes a nice 7'8" bore, direct bolt-in MC, but it has a reservoir lid that can only be taken off with an allen wrench. While it looks nice, I want to be able to check the fluid level without getting my tool box out.



This MC has two ports that have rather small fittings. The catalog description lists the outlet ports as being 3/8" inverted flair, but they sure seemed smaller.

The rear port of the MC is plumbed to the front brakes and nothing was needed to attache the line. The front port of the MC is plumbed to the rear line and required an adapter fitting that you can see in the picture. However, this adapter was too small for the fitting that was on my rear brake line, so what we decided to do was bend another line for the rear brakes. That way if I ever wanted to swap back to the other MC, it would be very simple to swap lines. We bent up a 5/16" line, using the old line as a template. It was fairly straight forward and simple.

The other issue with using this MC is that the mounting holes don't quite match the GM pattern. As you can see, we elected to notch the holes to make it easier.









The other issue with using this MC is that the pushrod hole is not as deep as the GM MC I was using, so the rod had to be shortened. The tip of the rod also had to be ground down slightly because the Dodge MC has a smaller diameter hole.

The bottom line is that this MC is a fairly easy swap into GM vehicles and is a viable OEM alternative to some of the aftermarket offerings. With a little ingenuity it can be made to work in applications that require a 7/8" bore MC.

The brakes feel very different now. The pedal feel is softer but I haven't really noticed a big increase in pedal travel. I am now easily able to lock up the brakes, when before I couldn't. Clearly the MC is generating more force at the caliper, which is what Ron was attempting to show with his spreadsheet.

A huge thanks to Ron Sutton for giving me the last needed nudge to make the swap to the 7/8" MC.

To wrap it up, here is a picture of the 275/35-18 BFG Rivals on the front.



There is mild rubbing on the sway bar at the extremes, but I don't see this as a huge issue. I may run a small spacer in the front if it become annoying, but for now I am going to work on a few other minor issues before the Holley LS Fest.

Andrew

[andrewb70]

After I had made my previous posts, I realized that I never posted a picture of the MC as it was finally installed. You can see the new 5/16" rear line along with the adapter that was needed. The rear port for the front brakes worked as is.



I also want to make some comments regarding my first impressions of the Rival tires. I haven't really had a chance to test out the handling, but I can say that the tires are very sticky. I was driving and happened to go over a spot that has some loose sand and I could hear the tires picking up every little pebble as I drove over them. Also, with the Falkens, even when they were new, I could be rolling slowly in 1st gear, punch the throttle, and the tires would spin until I let off or shifted. With the Rivals, doing exactly the same thing, the tires dead hook. I am really excited to get the car out on the autocross and on the drag strip.

Andrew

[Ron Sutton]

The brakes feel very different now. The pedal feel is softer but I haven't really noticed a big increase in pedal travel. I am now easily able to lock up the brakes, when before I couldn't. Clearly the MC is generating more force at the caliper, which is what Ron was attempting to show with his spreadsheet.

A huge thanks to Ron Sutton for giving me the last needed nudge to make the swap to the 7/8" MC.

Andrew

No worries. Glad to help.

[69*Goat]

I also want to make some comments regarding my first impressions of the Rival tires. I haven't really had a chance to test out the handling, but I can say that the tires are very sticky. I was driving and happened to go over a spot that has some loose sand and I could hear the tires picking up every little pebble as I drove over them. Also, with the Falkens, even when they were new, I could be rolling slowly in 1st gear, punch the throttle, and the tires would spin until I let off or shifted. With the Rivals, doing exactly the same thing, the tires dead hook. I am really excited to get the car out on the autocross and on the drag strip.

Andrew

I can hear my drive line parts breaking now as I read this. My rear end carrier will need to be replaced ASAP.

[andrewb70]

If I can't toot my own horn, who will?

Got a nice 4 page feature story in the current (February 2014) issue of GM High Performance and a action shot from LS Fest in the current (February 2014) issue of Popular Hotrodding. Woot!!!

Andrew

[Ron Sutton]

If I can't toot my own horn, who will?

Got a nice 4 page feature story in the current (February 2014) issue of GM High Performance and a action shot from LS Fest in the current (February 2014) issue of Popular Hotrodding. Woot!!!

Andrew

Nice !!!!

[BossaNova]

Andrew, always loved your build thread.

I hope you continue to update.

[ETexGTO]

Very nice! Congrats!!

http://www.popularhotrodding.com/eve...photo_03.html#

[andrewb70]

Very nice! Congrats!!

http://www.popularhotrodding.com/eve...photo_03.html#

That picture was actually taken at LS Fest in 2011. I don't believe PHR has coverage for the 2013 LS Fest up on their website yet.

Andrew

[jerome]

Hello Everyone...

I have to apologize for the less than timely update to this thread. It has been a very busy week and a crazy few days. As promised here are a few more pictures of the CV driveshaft from the DSS.





On Wednesday I headed out from Pigeon Forge to Bowling Green, KY. It was the most pleasant drive I have ever done in my GTO. The vibration that I was experiencing before is now completely gone. The car was smooth as glass at all reasonable highway speeds. I ran it up to about 90 and there were no noticeable driveline vibrations that I could detect.

From BG, KY I headed to Chicago to pick up my son. On Friday morning we headed out to the Lane Automotive Motor State Challenge. My goal for attending the event was to enjoy some time with my son and reconnect with some car friends. However, I couldn't resist taking my car on the Gingerman race track. I also figured that some track time will really test my newly rebuilt transmission and the new driveshaft. Gingerman has two long straights where the car can be easily taken up to over 120 mph.

On Saturday we headed to the track, passed tech, and were ready to go. I ran three sessions with my son riding shotgun and managed to get into the to 16 in the Pro-Touring class which consisted of any vehicle older than 30 years. My best time was 1:55.xx At high speeds the driveline was super smooth and the car performed very well. No drama, no puking fluids, 200 degree water temp.

I will post more later...

Andrew

Andrew,

Great project - good to see the evolution of the GTO over the years. I am on the verge of getting a DSS driveshaft for my S10 project. Long driveshaft length with a 5 degree operating angle at the transmission means I will need to get a very similar driveshaft to yours.

Just wanted to see whether you have continued to be happy with yours and how it has held up to all the driving you have been doing.

Thanks,
Jerome

[andrewb70]

Andrew,

Great project - good to see the evolution of the GTO over the years. I am on the verge of getting a DSS driveshaft for my S10 project. Long driveshaft length with a 5 degree operating angle at the transmission means I will need to get a very similar driveshaft to yours.

Just wanted to see whether you have continued to be happy with yours and how it has held up to all the driving you have been doing.

Thanks,
Jerome

Thanks Jerome,

Yes, the car is still very smooth and I attribute that to the CV driveshaft. If I had to do it over again, I would have Frank uses a non-telescoping CV joint. The slip in the CV is not needed since the yoke is still a slip design.

Andrew

[andrewb70]

Thanks GM High-Tech Performance!!!

http://www.gmhightechperformance.com..._gto_ls3_swap/

Andrew

[andrewb70]

There have been various discussion on several forums that I frequent regarding driveline vibrations, angles, etc...

In one of the posts, I made the comment that just about every modern, rear wheel drive, performance car uses CV joints for the driveshaft. We spent all kinds of stupid money to buy the latest engine, transmission, and suspension parts, but when it comes to our driveline components, we still use u-joints that date back to the 19th century. I have used a CV driveshaft with great success, but the optimal solution would be to use a driveshaft that uses a CV joint at both the transmission end and at the pinion. So I called Frank at The Driveshaft Shop to discuss this further and after telling him all this he starts to laugh. Then he proceeds to tell me how he just made a batch of pinion yokes for the Ford 9" and the Chevy 12 bolt rear ends that will accommodate a 108mm (Porsche 930 style) CV joint. He sent me the picture below:





That particular yoke is for the Ford 9" rear. What this means is that if someone wants the ultimate solution for a driveshaft, this is it. Using CVs at both ends of the driveshaft means that driveline angles become largely irrelevant. The CVs can accommodate up to 9 degrees of articulation and the front and rear angles operating don't have to match, be opposite, or be as small as possible.

Andrew

[wiedemab]

Very Cool!

[tommycomfort]

Somehow I've missed this thread for a long time. Now one of these days I will go through the whole thing, but for now, I will just keep up with the new things!

[raustinss]

Andrew

Don't suppose you know if the 12 bolt design is a high dollar item do you?

Ryan Austin

[andrewb70]

Andrew

Don't suppose you know if the 12 bolt design is a high dollar item do you?

Ryan Austin

Ryan,

Frank and I didn't discuss cost, but I would imagine that it is comparable to other billet yokes on the market.

Andrew