Thread: Project Sebring GT Spyder

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That looks killer, and nice work ! Your doing an amazing job covering the ugly on the LS and those valve covers will work great!

Thanks guys.

Unfortunately, they may be good at making HP, but there's an awful lot of ugly to cover up on an LS. At least to an old guy, like ,me!

"......Unfortunately, they may be good at making HP, but there's an awful lot of ugly to cover up on an LS. At least to an old guy, like ,me! ......"

Ain't that the truth....... might be the reason so many of the new engines are just covered with a big piece of plastic.



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With the engine done as much as possible right now, I turned to the rearend and rear suspension. This was the biggest change from the last time most of you saw this chassis. The 8.8 Explorer axle looked wrong to me every time I was under the car. Even though I narrowed it and centered the pinion, it still just looked wrong. The whole thing just looked too big and heavy. Plus I wasn’t satisfied with the 3rd link bracket. The way I attached it to the rearend looked like it might cause problems and you couldn’t pull the back cover without disconnecting the 3rd link.

The way I built the Watts link had it in the way of pretty much everything, especially the exhaust. Don’t get me wrong, the geometry was correct and the parts fit, but it just wasn’t as good as I felt it could be. I had been kicking around redoing it, but really hated to take the time. The final nail in the 8.8 ‘s coffin came when I discovered that I had made serious error when I welded the lower link brackets to the axle tubes. They weren’t centered. Not sure how that happened, but no use saying it wasn’t my fault because I built this junk! Might as well own it.

Instead of trying to fix what was there, I decided it would be easier to just start over. I had picked up a nice older 9” Ford axle in a trade a few months ago and decided to go back with it. The 9” had several advantages over the 8.8 for me. For one thing, I like working on the drop out gear carriers better than the open backs like the 8.8. Gear setup is easier and of course it’s easy to swap chunks around for quick gear changes and the 3rd link brackets could be welded to the housing. I was also convinced from eyeballing the two rearends, that the 9” might actually be lighter. With an aluminum chunk it could be several pounds lighter.

I found several different weights listed online for both rearends, but none of the info really agreed. Besides, most 8.8 weights you find are for a Mustang type 8.8. The Explorer rearend is a whole different animal. It almost looks like a light duty ¾ ton truck rearend compared to a Mustang type rear. I had another Explorer rearend that I had picked up cheap when a salvage yard closed near me. Just for my own info I stripped both the 9” and the Explorer rear down to the bare essentials, no brakes, to keep things even and weighed them. The box in the picture is a new pinion yoke. I added that because the 8.8 didn’t have a yoke and I wanted to keep things as equal as I could. Turns out, I was right. The 9” was 19 lbs. lighter than the 8.8 Explorer. In the spirit of full disclosure I have to add that the 9” had 28 spline axles and small bearings, while the 8.8 had 31 spline axles. The 8.8 was a few inches wider, too.

I shortened the 9”, centered the pinion due to tunnel clearance and added a small brace to the back. I was concerned that with the 3rd link, I was adding stresses to the housing that it wasn’t really designed for. The brace also gave me more surface to weld the 3rd link brackets on. The bearing housings were changed to the big bearing Torino style since I had already had the brake setup I built using Mustang Cobra SVT brakes that fit the Explorer axle. The Torino ends are pretty much identical to the Explorer flanges. The SVT brakes use a vented 11.6” rotor and a caliper with a built-in emergency brake. The setup is a lot lighter than the Explorer rear brake setup and should stop better.



These are the tools I made to align the ends. I used 2” shafting based on a conversation with a fellow I know that builds fabricated 9” housings. I originally made the tools to narrow the 8.8 and had to make some new end tools for the Torino housings. The rectangular end pieces sure make aligning the ends easy. I didn’t get a picture of the bushings that went in the 9” carrier. Turns out they were the same diameter as the 8.8 carrier bearings, so I didn’t have to make them over.

I have to say that the brace on the back of the housing gave me a lot of trouble. Of course, the heat from welding pulled the tubes toward the brace. I expected this, but it moved way more than I thought it would. This is the first housing I’ve straightened with a brace and it was chore to say the least. I gave the only piece of beam I could have used to build a straightening jig with to a friend for something he was doing. That left me with just heat and shrink to move it around. It took a lot of heating and shrinking over several hours. Occasionally, I would have to stop and let the whole thing cool down or it would just quit moving, but eventually I got it straight. The line up tools, and ultimately the axles, just slid in.



And yes, I did get the link brackets centered this time!

More nice work, looks beefy.

The chunk for the rearend is cast iron at this point. I’m considering swapping to an aluminum carrier later when I decide on the final drive ratio. The gearset is an old 3.25 Ford brand set that I had. They are pretty worn and didn’t have really good pattern (even in the original stock setup from Ford), but will give me a starting point to judge what gears I want to run. As it stands now, with the transmission ratios and 26” tires I’m running, the gear splits with the 3.25’s are almost exactly the same as the LS6 powered Z06 Corvette though 5th gear. I was originally planning to use an LS6 cam, so this made sense then. My gut tells me that the cam I’m actually using will probably be happier with more gear. I’m thinking that I will wind up with 3.50 – 3.73 gears. Going by the dyno pulls I’ve seen for both my cam and the LS6 cam I may not be too far off with the 3.25’s, though. The cam I’m using doesn’t appear to give up much, if anything, in low end torque over the LS6 cam. My problem is the 2.97 first gear in my trans. If I go too high numbered on the rear gears, I risk making 1st gear too short to really be of any real use for ordinary driving. Luckily, the gearset in this transmission has a .64 6th instead of the more common .5 ratio, so my cruise RPM’s won’t make as much of a drop. Because this is primarily a long distance cruiser, I don’t want to run any more rear gear than I need to keep the cam happy. Time will tell. For now, this gearset will get me by for engine break in.



I also swapped in an Eaton TRU-TRAC Torsen style limited slip differential. I’ve never ran one, but like the idea of how they work. One crazy issue I ran into was finding ring gear bolts that were the correct length. This is a 9” Ford, so that stuff should be easy to find, but not with this diff and ring gear combo. The flange on the Eaton diff was thicker than the Ford diff and I think the ring gear bolt holes were a little on the shallow side of Ford’s tolerance. I tried 4 different sets, from stock Ford large head bolts to ARP bolts. They were either too long and bottomed out or they didn’t have enough thread engagement to be safe (IMO). I wound up making a threaded collet to hold the too-long large head Ford bolts so that I could shorten them in the lathe. Even then, I had 3 holes that required lengths shorter than the rest. Crazy, but true.

I used an aluminum Daytona pinion carrier and solid crush sleeve, too. The Daytona carrier pushes the yoke about .200 further forward on the pinion splines than the stock carrier. This means that you either have to run a thin pinion nut or machine the nut mating surface in the yoke deeper. I chose to cut the yoke deeper to use the stock pinion nut, so it took a ride in the mill.






I also got ambitious and built the handy, dandy carrier stand. In the past, I just rolled them around on the bench, which pretty much sucked. The stand sure makes things easier.

The stand is nice.

quote "I used an aluminum Daytona pinion carrier and solid crush sleeve, too. The Daytona carrier pushes the yoke about .200 further forward on the pinion splines than the stock carrier. This means that you either have to run a thin pinion nut or machine the nut mating surface in the yoke deeper. I chose to cut the yoke deeper to use the stock pinion nut, so it took a ride in the mill."

Curious how you found out about the .200 thou difference? Did Daytona tell you? Or you were measuring the parts.?.? Curious minds need to know... LOL

34, I really can't remember where I found that out. I think it was on a Ford specific website. This was the first "Daytona" carrier I have ever setup. I'm certainly no expert on setting up gears, for that matter as I've only done a few sets in my life, but I researched as much as I could find on the Daytona setup. This was internet info, so take it for what it's worth.

What I learned is that it was originally designed by Ford for their high horsepower cars back in the 60's. The Daytona name is kind of generic for this style of heavy duty carrier and there are many versions available from a bunch of different sellers. It uses a bigger bearing set than the standard carrier and since the pinion has to stay in the same place, the yoke has to move farther out. The .200 number is one that I found online somewhere, but it was a good one. The problem is that the self-locking portion of the standard pinion nut hangs off the end of the threads. The original yokes for the Daytona were cut deeper, but the aftermarket sells a thin locknut so that you can use the uncut yoke. I already had the standard nut and the tools to cut the yoke, so I went in that direction. Even after cutting the yoke .200 deeper, you can see in the picture that the end of the splines are still about that much below the shoulder.

Ford's version was cast or nodular iron as far as I could find out ,but the aftermarket has been making them in aluminum. I went with the Daytona just so I could run the aluminum one for weight. It actually saves a few pounds, but not a lot.

If anyone on here has better info, please feel free to correct me. Like I said, all my research was on the internet.

Thanks for sharing all the info Mike. I've been mulling over a gear change and maybe doing a whole "pumpkin" so I could drop and swap. One of the plans was to do as you did and use a Ally pinion gear bearing mount. I hadn't read of the distance change but it makes perfect sense once I read it! So again. THANKS!

Your welcome. Glad I can help.

FWIW - I'm leaning toward the Yukon aluminum chunk. It's reasonably priced and has through bolts on the diff carrier bearings as opposed to just being threaded into the aluminum. Supposed to good for something like 800 HP! They are supposed to save 20 lbs over a cast iron unit.

What I would really like is a NASCAR style cast steel drop out. They are lighter than the cast iron parts, but not as light as the aluminum pieces. They're supposed to be the strongest regular carriers that you can get, but they are big $$$$. I've read that they turn up used from NASCAR teams, but wouldn't have a clue as to how to find one.

Originally Posted by Hotrod46

What I would really like is a NASCAR style cast steel drop out. They are lighter than the cast iron parts, but not as light as the aluminum pieces. They're supposed to be the strongest regular carriers that you can get, but they are big $$$$. I've read that they turn up used from NASCAR teams, but wouldn't have a clue as to how to find one.

How about Racingjunk? I recall Dave Severson used to talk about stuff he'd found there, and they list a YUKON nodular iron unit, ready to go - https://www.racingjunk.com/Rear-Ends...=8&from=search

Thanks. I didn't know about that site. I keep an eye on it.

I swapped over to 31 spline axles, too since I needed new ones for the shortened housing anyway. The axles I bought were from Quick Performance. Nothing special. They were just regular cut-to-fit axles that they cut for me. I was able to order them with the correct hub diameter for the SVT brake rotors.

The axles came with studs already pressed in, but I had to change them out. I wasn’t comfortable with the amount of lug nut engagement that I had with the aluminum wheels I’m running. The new studs are from Moroso. I was not impressed with the Chinese bearings that the axles came with, either. I’m glad that I ordered them with loose bearings for me to press on. I needed a bearing spacer to get past the thick caliper mount and had to install that before the bearings went on. I went with Federal Mogul bearings from my local parts store.






This is the axle after powder coating and reassembly.