Porsche 944 Rod Bearings

At our last race at Road Atlanta the driver in the final stint mentioned he saw a red light flash on the dash occasionally but did not know what it was. A routine oil level check showed the oil level had gotten very low by the end of the race. Therefore I decided we needed to inspect the rod bearings. And I am glad we did.

I used info from Clark’s Garage to establish a procedure. I began by purchasing an engine support from Harbor Freight. Then with the car on the lift, I removed the rear control arm bolts, the ball joint pinch bolts, the front sway bar and then lowered the cross member out of the car. It turned out to be much easier than it sounded form reading the instructions.

With the engine supported form above and the cross member out of the way, the 22 bolts holding the pan in place were easy to access. The pan separated easily but it would not drop down. The internal plastic baffle hung on the oil pickup. I ended up breaking the baffle before I figured out he right twist to get the pickup to come out the hole.

With the pan down, I had full access to the rod ends. Knowing number two to be a problem I started with that one. The Babbitt was gone as well as much of the copper. There was copper embedded in the crank throw as well. I thought we were looking at a complete rebuild. However the other three bearings looked fine.

So I decided to try polishing number two in place. I watched several you tube videos on crank polishing before I chose a method. I ended up wrapping a strip of 600 grit sandpaper around the journal and used a string to spin it back and forth. I lubricated it all with WD 40 during the process. In no time at all I had a shiny smooth journal that measured in the middle of the range.

I then installed new bearing in all four positions using new rod nuts as recommended. on reassembly, I notice the strap that holds the two sump tubes together was broken so I took time to weld it back together.

I was not able to source a used baffle in time so I decide to just glue together the crack I caused in the existing one. With it out of the oil pan, I made several practice runs to get the twist right on re installation.

Putting the oil pan back in place was the most challenging part of the whole process. The gasket is very thick and needs to be compressed just to get the bolts to start. I used wire ties threaded through the holes to keep it lined up while I made the twists to get the pan in place. Then I used my under lift support to lightly press the pan up while I started the bolts. I then used my inch pound torque wrench to set all the bolts to 36 inch pounds. This took forever to get the m all down as the gasket continued to compress causing the bolts to loosen as the one next to it was tightened. I hope I figure out a better method next time I do this job. Once they we all at 36 I then put them all to 72 inch pounds. This step went much quicker.

Once the pan was back on, I lifted the cross member back up and reattached all the under car stuff. I installed a new oil filter and refilled with fresh oil.

We are now ready to race at NCM. I will do this all over again after that race to see how much wear is on a fresh bearing set. Since these bearings were in place when we bough the car, I have no idea of their age or history.

Racing at Road Atlanta

2016 ChumpCar race at Road Atlanta

We ran our 1986 Porsche 944 at Road Atlanta.

The car ran flawlessly all day. We got a couple of new battle scars but still drove it on the trailer after the checker flag.

Our pits stops went well and even though our laps times were not as fast as we would have liked, we finished 32nd out of 110 cars. We found that there car can go over three hours on fuel so we skipped fuel on two of our driver swap pit stops. That gained us a lap or two. We completed 338 laps this year in the 14 hour race.

Lexan Rear Hatch for Porsche 944

Lexan Rear Hatch for Porsche 944

944lexan

In order to improve the aerodynamics of our Porsche 944 ChumpCar racer, we decided to add a Lexan hatch. The ChumpCar rules require all glass other than the windshield to be removed. For our first race, we removed the glass and ran just the hatch frame. After looking at the other 944s racing against us we decided to add a Lexan hatch like they had.

We ordered the material from Five Star Race Car bodies on the advice of one of the other teams. This is the same material sold by Porsche specialty shops for about $100 less. The material surprisingly comes rolled up in a small box so shipping costs were reasonable.

Since we already had the glass out of the hatch we were able to start right away. Removing the glass from the hatch frame is challenging and requires a lot of patience. I have seen youtube videos of people breaking theirs out but they still had to deal with all the little pieces in the channels. I used an oscillating tool to cut the bonding material and carefully removed the glass. I had a heat gun for some places but mostly where the bonding material was cut, the glass lifted out.

We began by laying out the screw holes making sure there was no more than ten inches between holes. We paid extra to have the material cut to the size of the original rear glass. We may have been better off buying the oversized version as ours was just a little smaller than we would have liked.

We marked and drilled all the holes in the perimeter of the frame. Then we set the Leaxan in the upper groove and pressed it into place. We then carefully drilled through each hole into the Lexan. I found that if the bit ran too fast, the material would melt rather than drill and would refill the holes when the drill bit was removed. After a few holes I had the technique down. The biggest trouble we had was finding the right place to drill the holes. The best spacing away fort eh edge of the window put us in a ridge on the inside of the frame. This caused some of the holes to be angled which gave us trouble later.

We used a hand brace and a large drill bit to cut the counter sinks. We used the screws provided in the mounting kit from Five Star. The kit seemed a good value as it came with the right screws, locking nuts and a drill bit.

Due to the way the nuts hit the back of the frame, the ridge caused the nuts to not seat right. We ended up using a cutting tool to notch the frame at each of the screw holes so the nuts could sit flat. This also allowed us to use the shorter screws in the kit allowing the hatch to fit better when back on the car. Notching the frame took away some strength but once careful handling allowed us to get the Lexan mounted without it bending. Once the Lexan was in place the rigidity returned.

We added the two required one inch wide aluminum strips over the hatch and bolted them top and bottom. We then put all the rubber trim pieces back on the hatch to cover the holes and retain the look and function of the original spoiler.

The new hatch is very light weight and looks nice. We hope the performance improvement will be worth the cost and two weekends of work required to make the swap.

DIY Cool Suit

It gets very hot in the race car wearing three layers of nomex and a helmet and gloves. Some smart guy several years ago invented a system that pumps cool water through a shirt to keep a driver cool. Unfortunately they still charge a lot of money for their nice system.

Being cheap – I decided to build my own. As a chemical engineer, I figured I could build a simple heat exchanger.

For the cooler pump, I used a cooler I got at Goodwill. I installed a boat bilge pump form Walmart. I drilled holes in the cooler for the wires to exit and one for the line off the pump. I got clear vinyl tubing from ace hardware and some fittings to reduce to 1/4″ tubing.

Next came the heat exchanger itself. I added a piece of cloth to a t shirt that had passages sewed vertically in it. Then I looped the tubing through. There is about 20 feet of tubing in the shirt.

I added dry breaks from McMaster Carr to the ends of the tubing to reduce the water splashed in the car. #5012K115

coolshirtdiy

coolsuitcoolerinside

coolsuitcooleroutside

It seems to work in the garage. We will see how it works at Barber this weekend.

944 rear shocks

Koin Shock

Our Porsche 944 is intended to be a ChumpCar racer. So it has to meet certain rules. One of the controversial rules states that it can’t have adjustable shocks even if it came with them from the factory. We have elected to remove our very nice and expensive Koni racing shocks and swap in some KYB replacements.

The upper mount uses the stock bolt so we will reuse that. It can be accessed by dropping the suspension fully (removing the bottom shock bolt helps) and turning the head of the bolt from inside the wheel well. You will have to hold the nut with an open end wrench while turning the bolt from the wheel well.

The bottom of our Race Konis were mounted on very nice adapters that allowed the use of the spherical rod ends. To remove the adapters, we first had to support the wheel at just the right height to remove pressure from the bolt. Then the mounting bolt could be unscrewed from the adapter. The adapter was them removed from the control arm.

Since we did not have the original bolts to put the bottom of the shock back we started a quest. We measured the threads on the adapter and found they were M14 1.5. We estimated we needed 80mm of bolt. We set off to ACE hardware. They had one. But only in standard grade. I wanted a 10.9. Lowe’s and Home Depot were less helpful.

After some research on the internet we found that the factory bolt is actually 85mm. Porsche no longer sells it but BMW does. We have ordered a pair of part number 07-11-9-914-829 and will try again next weekend to get the bottom of the shock bolted in place. It is a shame to do so much work to make the car handle worse. But that is racing when you try to follow the rules.

Update: got the bolts from the BMW dealer. Also picked up several at pull a part as spares. Drilling the heads for safety wires was easier than I expected.