17 years and counting...

[svono50]

Rear End Rebuild #2 of 5

Pulling the axles out revealed the damage to the axles where the bearings ride and certainly one source of the whine from the rear end. I also noticed that the c-clip ends of the axles were both burnished and discolored, as well as worn down a bit. I am guessing this is from my HPDE track days, where the axles are side loaded for much longer periods of time than street driving. That also increases end play slop in the axles and rear brakes, so new axles were in order in multiple ways.



My plan was to replace all the seals, bearings, axles and rebuild the differential clutches…simple, right? Well, I noticed that the spider gears in the differential looked like a beaver had been working on them. I checked out the prices of replacement spider gears and almost fell out of my chair. It was cheaper to buy a complete new differential than purchase new clutches and spider gears…YIKES!



Luckily I hadn’t ordered the new clutches at this point, only a Ford Performance ring & pinion installation kit and a bottle of friction modifier. I happened to have a brand new Eaton posi differential sitting under my workbench collecting dust for ~10 years because it was a 31-spline unit and not compatible with my stock 28-spline axles. I got it as payment for a side job I did for a friend. He had it for a Fox Mustang project, but sold the car and just gave it to me as part of the payment. Hmm, I was replacing my axles anyway, so I could opt for 31-spline axles and use this ‘free’ differential…love it when a plan comes together, even if it is pure luck!

[svono50]

Rear End Rebuild #3 of 5

In my research for finding a suitable set of replacement SVO axles, my head really started to spin and hurt, as it seems nobody out there wants to publish our axle length. Why…I have no idea, but it is 30-7/16”, from the inside tip of the axle to the outside flange surface. I ended up finding Dutchman Axles in Idaho, who have a listing for our SVO and also the fact that it shares axles with the 82-84 Continental and 84-91 Mark VII vehicles. Dutchman’s axles get mostly good reviews and their tech line was very helpful and knowledgeable when I talked to them, so they got the nod.

Another twist in my rebuild saga is that Eaton differential. Turns out the Eaton’s differential cross-shaft, the shaft that sits between the axles, is a different diameter than the stock differential. Eaton uses a 0.875” shaft, while Ford used a 0.750” shaft, so a stock length axle would result in a rear track width increase of 0.125” (1/8”). Good thing is Dutchman makes axles to order and can create a custom length axle for the same cost as a stock length unit…hurray! I spec’d my replacement axles 0.0625” (1/16”) shorter than the stock length (30-3/8”), placed the order and waited. I got the axles in less than 2 weeks, not bad for a pair of customized axles in my book.



Only 'issue' I would say I have with the axles is the hub nose height/depth. It is just tall enough to capture the brake disc and not really out to capture the rim's hub. My hub-centric rings of my TSW wheels did seem to be OK (i.e.- no rear wheel vibration from off-center), but I would have preferred more depth like the OEM axle. I did feed that info back to Dutchman, but unsure if they will change their design. The silver part of the OEM hub is what protruded from the brake disc, which was ~4x what the Dutchman hub protrusion.

[svono50]

Rear End Rebuild #4 of 5

Next came benchmarking my current ring gear backlash and checking the gear mesh pattern, so I had something to reference or shoot for when reinstalling everything. My current backlash measured 0.0108” and the pattern was showing a ‘competition’ contact pattern (i.e.- shifted a bit toward the toe/inside of the ring gear). The mechanic that set up these gears knew I was going to be drag racing at the time, so I wasn’t surprised to find the pattern as it was. It was good to see that the backlash was still in spec after all these years, which is 0.008-0.012” for my 4.10:1 FMS gears.



An easy way to ‘lock’ the pinion for checking backlash is to use one of the driveshaft bolts and run it through the pinion flange against the housing. Don’t go nuts on tightening it, just enough to hold it in place.



It was time to pull out the differential/ring gear and the pinion…no turning back now. Marked and unbolted the diff carrier bearing caps and pried out the diff. Paid special attention at the orientation/position of the shims on each side. Pulling off the pinion flange went easier than expected and the worn seal surface was indication of just what was causing my leak. I read online somewhere that any wear in that seal surface on the pinion flange is the end of its useful life even with a new seal, drats! I found repair sleeves that you can press onto the flange, but they were finicky to install and so everyone recommended purchasing (2) of them in case you damage the first one. I kept looking and found quite a few folks on Ebay and Amazon selling brand new pinion flanges for less than even one repair sleeve. I found a Motorsport flange (M-4851-C) for ~1/2 the cost of the OEM Ford flange, so shop around. Once the pinion was out, the use of a drift punch and hammer took care of getting the bearing races out of the housing.



I took this opportunity to spray out the internals of the housing with brake cleaner to remove any old contamination/remnants left behind. I didn’t plan on it, but I also cleaned the outside of the housing to remove all the leaked fluid residue from the pumpkin housing and axle ends. I then tossed on a quick coat of paint on the pumpkin and outer axle tubes that had some surface rust once cleaned. Nothing fancy, but it did clean things up a bit.

Next steps were to get the new pinion bearings installed and pinion back in the housing with the correct bearing preload. Luckily we have a hydraulic press at work where I pulled the old pinion bearing off without damaging the shim that is between the bearing and pinion. I kept the same shim in the hopes it would give me the proper backlash/gear pattern. I also borrowed a 3’ piece of uni-strut to use as a torque arm to hold the pinion during collapse of the new crush sleeve, along with an inch-pound dial torque wrench for measuring the bearing preload. The only socket I had to fit onto the pinion nut was a 1/2” square drive and the inch-pound torque wrench was a 1/4” square drive, so I had to purchase an adapter set that was a 1/4 to 3/8 adapter and 3/8 to 1/2 adapter that I stacked together. I read in the Ford shop manual that the minimum allowable torque to collapse the crush sleeve was 140 lb-ft of torque. Let me say, I would estimate my crush sleeve easily required 200 lb-ft of torque based on the force I applied to it. The 3’ uni-strut backup bar was absolutely needed. The new crush sleeve was 0.510” long and the one I removed was 0.435” long, so I had a good 0.075” to crunch down the new sleeve. I was able to get the preload torque to 23 lb-in torque, right in the specified range of 16-28 lb-in for new bearings…hurray!



Moving onto the differential, I started by knocking the ring gear off the old diff and installing it onto the Eaton diff with the new ring gear bolts from the Ford Performance kit. The Eaton diff already had new bearings on it, so it was now ready to go into the housing. I put the left-hand shim pack in, dropped the diff in and pushed it over. I was expecting to have to install new shims, but to my surprise, I was able to tap in the original right-hand shim and everything was snug. But, what was my resulting backlash and gear pattern going to be?? The backlash checked out slightly tighter at 0.0095” and spot on in the allowable range of 0.008-0.012”! Painted the gear pattern grease on the ring gear and did a coast and power pattern check. It was spot on to the normal recommended pattern, so slightly more toward the center of the teeth. Ok, where is the Candid Camera crew…I certainly couldn’t believe my luck that the original shims worked at getting me within allowable specs with new bearings and differential. I actually walked away from the rear end at that point for the night, since I felt I had used up all my available luck for that day!!

[svono50]

Rear End Rebuild #5 of 5

Next day I popped in the new axle bearings and seals, then installed the new Dutchman axles. They were a perfect fit and gave me the exact same axle flange-to-flange measurement as my stock setup…which is 61-5/8” (another ‘mystery’ measurement).



I decided to hold off installing the calipers and rotors onto the rear axle till I got it bolted back up into the car, since it would make it a little lighter. I ended up filling the rear differential with Lucas synthetic 75W-90 gear oil and 1/2 bottle (2 oz) of Ford friction modifier. Why only 1/2 bottle? Eaton’s instructions recommend using 4 oz of a GM friction modifier, so a call to their Tech Line was made to confirm if the Ford friction modifier was allowed. The tech noted that the Ford FM is just fine, but to only use 1/2 the recommended amount with the synthetic gear oil I had and if I had any diff clutch chatter, just to add an additional ounce and check operation again. That way I would keep as much differential bias as possible, along with smooth operation.

My first road trial went perfectly, without any issues noted. I have a 5 mile loop I run from my house with speeds varying from 25-55 mph and the reduction of driveline noise was incredible. At 55 mph, you couldn’t easily hold a conversation with a passenger and now you barely had to raise your voice…it really was that much of a difference. My rear suspension is all Heim joints, so any rear end noise is transmitted into the cabin. The 2 oz of friction modified seemed to be enough, no chatter. As of this writing I have participated in a Track Day event, an Auto-x event and made a road trip down/back to Alabama from Chicago and the rear end is still ‘quiet’ and working great with ZERO leaks! Next project to document will be the upper torque box reinforcement install I did at the same time as the rear end rebuild.

[svono50]

Upper Rear Torque Box Reinforcement Kit Install

A few years ago after installing my Fays2 watts link, I discovered that it didn’t play well with the other (4) suspension links and there was a pretty severe bind that it would encounter when going through the corners on an auto-x or road course. Enough so that it would unload the inside rear tire and limit how much I could start to accelerate out of a turn…not fun. I thought that running spherical bearings in all (8) connection points was the ‘proper’ solution, but I was wrong with my assumption. Through some investigation work I found that removing one of the rear upper control arms was the only way to eliminate the bind and allow ‘free’ movement of the rear axle (i.e.- Poor Man’s 3-Link/PM3L).

When you run the PM3L on our chassis, all the initial acceleration ‘hit’ is now concentrated into that single upper mount, where the axle’s rotation is trying to pull that upper link backward, away from the floor pan. Add in the fact I have all spherical bearings in the suspension links and now there is virtually no ‘cushion’ to absorb the shock of a clutch drop. Being a former drag/street racer, I know what can happen to torque boxes over time.

It was time to get a set of reinforcement plates in the uppers BEFORE I heard any clacking from a torn upper mount. I ended up purchasing the UPR brand upper kit to install while I had my rear axle out for a rebuild. While not necessary, I highly recommend removing the rear axle to install the uppers, so you can get good drill clearance and elbow room.

Install starts by drilling the inside/upper vertical 1/2” bolt hole first and bolting the lower bracket and floor plate in place with this first bolt/nut. Instructions suggested drilling the second vertical bolt hole from inside the car, but I found it was much easier to drill it from below using the lower bracket as a guide for the location and it did align to the floor plate hole just fine. Once the second vertical bolt was installed, then you move to drilling a smaller 3/8” hole through the horizontal holes using the lower bracket as a guide. I found using a 1/8” bit to pilot the holes and then stepping up to a 3/8” bit worked very well.



I found that the inner floor plates were a bit oversized on the top and bottom, so I ended up marking the floor plates to a size that would still offer great support and better fit the contours of my floor pan. A quick zip on the band saw took care of the excess, then I re-bolted them into place and hammered them down to fit flush and pulled them back off one last time to give them a quick coat of primer and paint to hold off any corrosion. The vertical bolts bulge up the felt floor cover a bit, but they don’t interfere with the floor panels at all with the rear seat backs down.



I installed both upper reinforcement brackets, even though I only use one upper arm…passenger side in case you are curious. If for some reason I find the need to go back to using both upper arms or that the driver’s side is the ‘better’ side to use, I can do so without having to install the other bracket. Now if I ever want to perform a drag race launch, I can do so with a sense of comfort that it shouldn’t create any damage to the upper torque box…$50 well spent IMHO!

[gbeaird]

Those in-lb torque wrenches DO look funny with two adapters and a 1"+ 3/4" drive socket on them, don't they? They get the job done, though!

Not being into DEs, or drag racing the SVO, I knew about the torque box reinforcements, but have never seen them installed. Interesting. So the box itself can take the shear, but the spot welds pull out?

I used similar shoulder harness mounts on our 86 (and even have a set installed on our 95 Imp. SS). Not ideal for road racing, and some sanctioning bodies don't allow them, but they're quite functional in an autocross setting.

[svono50]

I don't think anyone manufactures a socket that would have a hex that size and a 1/4" square drive, since the normal torque on a fastener that size would well exceed what the 1/4" drive could take. It did give me an excuse to purchase the required adapters, so now I have the full set for most anything I should need it for.

Yep, the ears of the upper box can handle the pull, in all but the most extreme drag racing cases, it is the spot welding to the floor pan that fails. There is another brand upper torque box reinforcement style, that ties the flanges to each other and over to the frame rails with round tubing and flanges, but that is well overkill for anything I am going to put into the car and its one mount would interfere with my watts link bracket.

Those are the Schroth Rallye 4 ASM units and I love them. Perfect for holding me in place on both the track and auto-x courses. Since I don't 'compete' on the road courses, they have never been questioned and certainly allow me to concentrate more on driving than holding myself in the seat. I had to install them on the passenger seat too, because no instructors will allow a 'better' restraint method on the driver than the passenger (i.e.- them). I can't blame any instructor for wanting to be restrained as well as the driver.

[gbeaird]

You always drive better when you get to use the wheel to turn the car, and not hold you in your seat. Since I don't autocross the SS anymore, I should probably look at transferring the harnesses from it into our '10 Caprice. The CG-Lock we put on it, though, seems to do a decent job, though.

[svono50]

First time using the harness on an auto-x course, I almost completely blew out the first corner by entering too fast, as I had to totally re-calibrate the 'feeling' of a corner now that my arms and legs were no longer stabilizing devices...

[gbeaird]

First time using the harness on an auto-x course, I almost completely blew out the first corner by entering too fast, as I had to totally re-calibrate the 'feeling' of a corner now that my arms and legs were no longer stabilizing devices...

And you don't run the windows up and down during your run like you used to do, too, right?

[svono50]

And you don't run the windows up and down during your run like you used to do, too, right?

...or turn signals or horn blasts...

[svono50]

Door-Hatch Striker Bolts #1 of 2

With aging cars comes aging plastic components that can become hard, brittle and crack/break. The bushing sleeve on our door and hatch striker bolts fall into that category and can happen at any time as I found out at the 2015 SVO Reunion. On the last evening of the weekend, I started to prep my car for the trip home and upon closing the passenger door, I noticed it wouldn’t close completely as if it would only partially latch. After trying to close the door a couple more times I finally noticed some plastic pieces on the ground by my feet…parts of the plastic bushing sleeve on the striker bolt…great! I put the large pieces back onto the striker shaft and wrapped them with several wraps of wire harness wrapping tape (basically electrical tape without any adhesive on it). This actually worked pretty well, so I now could finish closing up my car. Not so fast, the driver’s door now did the same thing…uugghh!! So some more harness tape to the rescue on the driver’s door. OK, now to close the hatch and catch some sleep…not so fast, the hatch now decided to spit out its sleeve. Are you kidding me!!! Yep, all three at the same time. I should have bought a lottery ticket!



The temporary tape fix worked just fine for the trip home as well as for the rest of the 2015 season. I started researching my options and found some Dorman HELP! products that looked like they should work. I found that the Dorman website only listed the #38448 door striker bolt that looked different than the one I had. The #38448 had an additional loop of steel off of the washer, similar to the later Fox Mustangs I had seen, but certainly not like the original just post. Concerned about that style working with our door latches, I took a trip to my local auto parts chain store to see what they had on the shelves. I found the #38421 striker bolt that was basically an exact match to the stock one. The back of the package showed it was for, “Various Ford Models 1986-73”. I purchased the only one they had on the peg, confirmed it looked right, put it on my bench and didn’t get to it before storing my car for the winter.

On the SVOCA forum here there was some discussion on striker replacement this winter started by SvoScott, which I participated in and learned that the hatch striker had other differences other than a larger washer, it had a different thread as well…doh! Glad I hadn’t purchased three of the #38421 strikers. Now knowing the hatch striker threads were metric, I hit the Dorman site again and found only the #38445 striker that had the correct M10x1.5 threads. It had the steel hoop off the side of the striker like the #38448’s also had. With no other options from Dorman, I bought another #38421 for the other door, the #38448 for the hatch and picked up a #38424 kit that had (4) replacement bushing sleeves (just in case).



The driver’s side door replacement went cleanly and quickly with only a couple adjustments to get the new striker in the correct position. You have to get the door to close to the right distance and also the correct vertical height, nothing too difficult.



The passenger door decided to throw a couple of challenges my way. First the nut plate the striker threads into decided to fall into the rear fender when I removed the original striker. A quick loosening of the interior body panel gave me access to find it and hold it up the hole to thread the striker into it. I got the striker in the approximate position, but could not get the door to close past the partial latched position…hmm, didn’t have this issue on the other side?? If I really slammed to door it would latch, but I had to yank on the door to get it to pull off the striker and open. Closer inspection showed it was hanging up on the bushing sleeve making you have to slam to door closed onto it and having to yank it back off the striker. I removed the striker, its washer and bushing sleeve. The bushing sleeve measured the correct outer and inner diameters, so what gives. It turned out the bushing material is what didn’t ‘give’. It was very hard/firm as if it was dried out or of the wrong material. Luckily I had bought the #38424 bushing sleeve kit, so I compared the flexibility of the replacement bushing sleeves to the one on the striker bolt. The kit bushings were softer and more compliant. I put one of the kit bushing sleeves on the striker bolt and reinstalled it. The door closed/latched/opened easily like the driver’s door now…whew! The original bushing sleeve went into the trash.

[svono50]

Door-Hatch Striker Bolts #2 of 2

Onto the hatch striker replacement. After some measurements, I discovered the bushing sleeve outer diameter was much smaller on the #38445 compared to the original (14.9 vs 18.0mm). The smaller diameter didn’t allow the hatch latch jaws to tightly hold the striker like it should…rats! I then closed the hatch latch jaws to check the I.D. of the jaws and sure enough the #38445 bushing sleeve O.D. was too small. I took one of the bushing sleeves from the #38424 kit and it fit perfectly in the jaws. Only issues being that the I.D. of the kit bushing sleeve was just a bit larger than the latch bolt shaft (12.5 vs 12.0mm) and also longer (23.5 vs 22.4mm). I decided to use the (2) ‘short’ bushings out of the #38424 kit to make up a new bushing sleeve. I wrapped the striker bolt shaft with my wire harness tape to make up the difference between the shaft and bushing sleeve I.D.’s. I used one full ‘short’ bushing sleeve and cut off a 6mm slice of the other ‘short’ bushing sleeve to make up the 22.4mm overall length needed. I put the new modified striker bolt into position and did a test close, which proved to be successful! I did have to adjust the striker once to get the ‘right’ close distance on the hatch, but it ended up working great.



Kind of a shame you can’t just put in a replacement set of strikers, but all in all, it wasn’t too bad getting these in. Now I have ‘fresh’ strikers and bushing sleeves that will be good for the next 30 years, eh?!?

[gbeaird]

I seem to remember some issues with replacing that bushing on our 86, too. Maybe it was because the replacement part was so different. IIRC I removed that new bushing off the replacement bolt and installed it on the OEM bolt. Don't remember the exact details anymore, since I've slept since then, but yeah, I remember some oddities.

Since we replaced the hatch with a glass one, everything needed fitting/adjusting anyway, so I made it work, adjusting the latch so it held the hatch firmly against the bumpers.

[svono50]

I have no idea why the hatch bushing O.D. doesn't match the stock one, doesn't make any sense to me, as our hatch latch/striker is the same as all other Foxes from what I remember. I wonder if the 87-93 Foxes had a revised latch setup that used the smaller diameter bushing.