Overhauling the Differential (pt. 2)

All the pieces of the differential have been removed and separated, but many of them have years and years of gear oil and sludge. After doing some online window shopping, I decided not to get a parts washer. It would be yet another piece of equipment taking up valuable space in the garage and cost more money.

So I did it the poor man’s (read: cheap) way. I got a gallon of kerosene, a metal pail, some throw-away aluminum baking pans and went to work. I already had a box of nitrile gloves and several scrubbing brushes. It took about two hours, but I went through each piece, soaking it in the kerosene, giving it a scrub, and repeating until all the old sludge and muck was gone. Since I went the more hazardous (but more effective) way instead of using a water-based de-greaser, I made sure I was wearing long clothes, the nitrile gloves, and worked with the garage door open to get good ventilation. My skin is very sensitive to petroleum distillates from not protecting my skin when building cars in high school, so I knew I had to be safe.

The kerosene isn’t as fumey as paint thinner, but it does throw off a strong aroma. It was also very effective: I only had to dip, scrub and repeat two or three times on the internals, and even the outside case, with 50 years of dried gear oil and paint, cleaned up very nicely (considering it has been under a car for 50 years).

I made sure to change gloves every 20 minutes or so to make sure I was not getting any punctures in the gloves from the wire brushes or parts. The gloves held out just fine, and now the differential is shiny clean and ready for new parts and pieces. The kerosene is reusable many times, so I poured it through a paint strainer and back into the original container. I lost a few ounces to evaporation and drippage; it’s also a little darker now, but will work just fine for later projects. I am ordering replacement parts from a Triumph supplier out of Kansas City, so I will pick them up when I go up there later this week for work.

Here is a picture of my oh-so-classy parts washing setup. It may not be big enough to clean a crankshaft, but for most parts and pieces it is just fine and takes up very little room.


Lighting the Shop and Overhauling the Differential (pt. 1)

Lighting the Shop

I have done a lot to get the garage ready for this car project (and future projects, fingers crossed) but one that I had been putting off was installing lighting in the rest of the garage. Thanks to summer time, I could do most of my work with the sun up and just a shop light over my work bench. Shorter days have meant I didn’t have enough light to do any work, especially in the evenings, so I bit the bullet and installed some lights.

I located some used fluorescent four-bulb fixtures from a bank remodel. The ballasts were bad, but the frames were good. I installed new ballasts and, with help from a friend, got them installed. That was way more work than I expected. There was still some old wiring in the rafters of the garage, so I had to rip that out and run all new wiring for the lights. There is not a single strand of old wiring in that garage anymore, and hopefully that is the last side project I have for a long time.

I wish I had all those lights installed when I sealed the frame. I had no idea how much light I was missing in the garage, which is bright enough now that anymore light would be too much. Having that much light showed all the little areas that did not get a second coat and look dull instead of shiny. This may result in a complete second coating of the frame next spring. It also means I can work any time of day and have more than enough light to see what I am doing.

Disassembling the Differential

A couple months ago I took apart the differential to get an idea of what needed to be done. It was clear I would need a bearing splitter and a shop press to remove and install the six different bearings and multiple seals. I bought a bearing splitter set but left that project where it was, in the basement, until I could afford a shop press. I am glad I waited, because I found a 20-ton shop press for under $150. With those tools, I got started with pulling all the bearings and seals.

It was clear that the differential had never been overhauled. Most of the bearings had “Stanpart” and “Made in England” stamped on them. Interestingly, the differential carrier bearings showed “Made in USA”, so those may have been replaced. It was also clear that the seals were originals. It made me very glad to have gone through all that extra effort because when the differential is done it will be essentially brand new and hopefully not need to be touched again for another 50 years.

Most of the bearings came off fairly easily, but the inner axle shaft bearing were on so tight that they nearly broke the bearing splitter. I bent the bolts of the bearing splitter and stripped the threads of one, the bearings were stuck so tight. I replaced the original splitter bolts with Grade 8 hardware and cranked down hard, and they eventually gave. I could not believe they could be on so tight.

I got all the bearings and seals freed up, and the last step was driving out the old mounting bushings on the differential case. Like most of the bearings, the bushings were clearly originals and were dry, cracked and in there tight. It took me almost two hours to drive out the bushings. There was no way I could press them out, so I had to use multiple cold chisels and even a reciprocating saw. It did almost no damage to the differential case, other than a very small cut line from the saw. That was one of the most frustrating part of getting the differential ready for rebuild, and if I had to drive out old bushings like that every day for a living, I would lose my mind.

I did some looking online and I can get all the new parts for around $200, including all new bearings, bushings and seals. A rebuilt differential costs between $1,000 and $1,200, so it is clearly worth all the time this is taking, along with the cost of tools. But this is no small undertaking: I laid out all the parts for a picture, and counted 86 different pieces. I couldn’t fit all the parts into one picture, so here is a panoramic:


It’s kind of amazing that the differential, which is about the size of a volleyball, could have so much going on inside. I am going to finalize my parts list and place an order so I can get this finished and installed back on the frame.

Sealing the Frame

After four rounds of sandblasting, I got the frame cleaned enough for my liking. All the rust was gone, and the only thing left was some stubborn black paint in various corners. I did a lot of research online to try and figure out what primer and paint to use. It was very confusing. Self etching primer, epoxy primer, enamel, two-step paint, etc. I felt like I was getting nowhere. It seemed like every one had a benefit and drawback. I stopped by the local O’Reilly’s and asked the guy behind the paint counter. He was of no help.

My ultimate goal was to get the frame sealed enough that rust would not be a future problem should I decide to drive the car in the elements, which is not in my plan. I ended up landing on a product called POR-15. It claims to seal metal, even rusted metal, so long as you prep the surface and apply the product according to their instructions. You basically use their degreaser to get rid of any leftover gunk, use their etching phosphoric acid product, let the frame dry completely, and then brush or spray on the product. It claimed to be self-leveling so you won’t see any brush strokes if you go that way.

A local paint supply store, Car Color, carried the product so I got all three products. It was not cheap: a quart of each came to $85.

I wheeled the frame out that evening and got started. I noticed there was still some sand in the holes of the frame. I ended up spending an hour spinning the frame on the rotisserie to pour out all the sand and using the shop vac to suck out the rest. I had no idea there was so much sand left in the frame. Once that was done, I moved to the degrease and etch, with a thorough water rinse after each step. That took less than two hours. Then I dried off the frame as much as I could and spun the frame over and over to drain out as much water as I could. I left it over night to dry with a fan blowing on it.

The next day the frame was good and dry. The manufacturer says to wear long sleeves and gloves and have lots of ventilation. That is good advice. The sealer sticks to anything it touches, skin included, and throws off lots of fumes. I decided to brush paint the frame, since you need to have separate breathing air if you decide to spray it. It recommended two coats.

The first coat went on very well. It’s black in color so it was really easy to see where you were getting coverage and where you were missing. It seemed like the metal was soaking up the product when I brushed it on. The first coat took about 1.5 hours and used half the quart.

The manufacturer says to put in the second coat within 2-6 hours. Since I was doing this after work, I didn’t get the first coat done until about 7:00. I waited until 9:00 and started the second coat. It went on with much less product, although it was dark and even with a big halogen drop light I couldn’t tell where I was getting coverage and where I was missing. It all just looked shiny and black, both coats. I did the best I could and stopped for the evening.

The next day, in daylight, I could see I had missed some areas on the second coat but had gotten full coverage on the first coat. You could tell the difference because the first coat was matte black and the second coat looked very glossy. But the self-leveling claim was true: it looked like it has been sprayed on, not brushed.

No matter. I am going to paint the frame so I’m not worried about the difference in sheen. The product has no UV protection, so if you leave it in the sun it will fade to gray in a few weeks. This will be under the car so that’s not a concern, but there will be other areas that I plan to paint black that will see the sun, and want it to look uniform. If I was going to leave it without paint, I definitely would go back in bright daylight and make sure I got two coats so it didn’t look matte in some areas and glossy in others. I expect the gloss will go away some as the product fully cures, but that won’t matter for me.

The frame is now stable and ready for winter. Next spring I will paint it with the same paint I will use for the other chassis and suspension bits. Until then, I won’t need to worry about rust. Over the winter I will do the same thing to the suspension and other chassis bits so I can prime and paint them knowing they are well-protected from future rust.

Some photos:





Spit’ on a Spit

I decided that prepping the frame on sawhorses wasn’t going to be a good solution. I expect I will prime and paint the frame myself, so the best way to do that is to put the frame on a rotisserie. I had already built one I thought would work for the painting, so I tried it on the blasting part.

It worked pretty well, but wouldn’t let me spin the frame all the way upside down. The two hooks on the back of the frame stick back so far they were catching on the vertical post of the rotisserie. I also underestimated the weight of the frame. I can hoist it around with not much difficulty, but it put a lot of strain on the legs of the rotisserie. So much that the posts started dragging on the ground.

To fix that I put another caster right under the posts and gave the legs more support with additional bracing. I modified my eye-bolt setup to have the frame stick farther away from the posts, and that one allows the frame to spin all the way around. Problem solved.

I had been thinking I would not blast the frame completely clean because of the stubborn black paint, but I have not found a primer/paint setup that will be really good on clean metal, maybe some very minor rust, and paint. The close ones I found looked more like roofing tar than paint, and that’s not what I’m going for with this project. It probably will look cheap and won’t match the paint I hope to use for the suspension and other undercarriage parts.

So I decided to keep blasting the frame. The coal slag was not strong enough, and the garnet was too expensive, so I kept looking around. I found recycled glass media at northern tool for $9 per 50-pound sack. I bought two. That media is strong enough to cut through every layer on that frame, and seemed to work fine with the pot blaster. That may be in part because I also added a water separator, which helped quite a bit. But I ran through 100 pounds in a couple hours and am still not done with the frame. That’s kind of frustrating, but I’m assuming that a professional blaster I would have similar struggles with this project and charge me an arm and a leg to get the frame 100 percent clean. So I will buy another 100 pounds next weekend and keep inching toward a clean frame. If nothing else, it will make our driveway look event more like a beach (per Beka).

Pics of the recent work:








Getting Blasted

With the frame modified and refitted, the next step was sandblasting the rest of the rust and paint so it could get a fresh layer of primer and frame paint. I had bought a used 40-pound pot blaster from Craigslist and had to make some minor repairs to it to get it working right. On Saturday I picked up a line dryer, pressure regulator and coal slag and went to work. I set the frame on sawhorses in the backyard, put on a respirator, goggles, ear plugs and welding gloves and got started.

I quickly discovered two problems. First, the previous owner had apparently not used a line dryer and there was too much moisture in the pot blaster. The coal slag kept clumping and fouling the lines and nozzle. I wasted probably half a 50-pound bag of slag just trying to future out what was wrong, and when I did get things somewhat working, I realized the coal slag was no match for the remaining paint in the frame. I had bought the coal slag because it was $9 for the 50-pound bag. It was not worth it.

I did some more research on how or tune the pot blaster for better results and on Sunday bought 50 pounds of 80-grit garnet media. It cost $25, but man did it work better. I think part of the problem was residual moisture in the blaster pot, which the coal slag helped drive out. With a dry blaster and good media, I went to town on the frame, but even the garnet was not strong enough for some of the remaining frame paint. I decided that if a sandblasted couldn’t get rid of it, then I could probably leave it without much worry.

Once I got the frame to a point that looked acceptable, I cleaned the remaining media off the frame with compressed air and prepared a phosphoric acid solution to treat the metal and any remaining rust. There are several companies that make such a product, which you spray or brush onto the metal and let it sit for 30 minutes, then rinse with fresh water. I worked quickly to get a first coat on with a brush, and realized that was not going to get into all the nooks and crannies, so I loaded up a pump sprayer and finished the job. I flipped the frame to get all surfaces and let it sit, and then rinsed and dried the frame as much as I could. I had to flip the frame a couple more times to get all the drain water out of the frame boxes.

It seems like a lot of work so far, but the frame is now ready for primer and paint. The phosphoric acid created a protective layer on the steel so it won’t rust again before I can hit it with primer next weekend. Here are some pictures of the frame:







Next week will be primer time. Can’t wait.

Waiting for Blasting and Painting

This would’ve been a good weekend to start sandblasting and painting the frame. Unfortunately, my budget is making me wait. I need to buy a sandblaster and paint gun, which aren’t all that expensive, but other things like an air compressor and welder have taken up quite a bit of money. This is giving me time to think about the project overall, and what I want the car to look like when it’s done.

I want this car to be able to travel 1,000 miles at a time without a problem, but also be able to hit the race track when inspiration strikes. I also don’t want the exterior of the car to look like a race car, other than perhaps a rollbar.

Upgrading to CV axles is probably going to be one of the most expensive upgrades on this car (other than electronic fuel injection), but I think it will be worth the price long term. I don’t want the car to require a lot of ongoing maintenance once it is finished. The CV axles should help accomplish that goal. Fuel injection should help as well. These will help on the open road and the track. But they also mean more cost, which means a longer time frame.

Hopefully the next couple weeks will free up some dough so I can get this frame ready for parts. That will feel like a real milestone.

Catching Up

Last time I was figuring out what differential I had. With all that has happened since then, that seems like the easy part.

I got the frame down to bare bones and started thinking how I was going to handle Phase Two: putting it all back together. With all the old paint and minor surface rust on the frame, I decided a good sand-blasting would do the frame some good before repainting. But before doing that, I needed to make sure the frame was ready to go. I didn’t want to go through the effort of blasting, priming and painting the frame just to learn that I had to weld on something new.

I took a hard look at what else I needed to do to the frame and how I was going get there. The list seemed simple enough:

  • Weld any needed material onto the frame
  • Sandblast
  • Paint

As I made this list, I remembered I had no electricity in my garage. It had been disconnected when we removed our old back deck (the electricity to the garage went by suspended wire from the corner of the deck to the corner of the garage). So I needed to get electricity out there. But just 120v? I looked at several different sand blasters and paint guns to find out how much air I would need. Based on those tools, I needed a big air compressor. So big that 120v would not be enough. I had to go to 240v. Same with the welder: to get one with the guts to do real welding, 120v just didn’t cut it.

I looked at my electrical panel: no additional spots. To return 120v and add 240v to the garage, I needed a bigger electrical panel.

This felt like falling dominoes: before I could take the next steps on the project, the preliminary steps kept adding up. And each domino represented lots of dollars. I took a deep breath and went to work.

I hired an electrician to install a bigger electrical panel in our house. A friend helped me dig a trench (by hand) and run underground conduit for electricity out to the garage (no more suspended wires). I wired the garage for 120v and 240v. The electrician signed off on all of it. Whew.

Next: air compressor and welder. No small-ticket items there. I scoured online for the best prices, and then waited for sales. I also trolled Craigslist. I ended up getting a 240v welder with MIG capacity for $170 new at Harbor Freight. I found a 60-gallon air compressor at Menards for $420.

With those home and installed, I first set to work on the welding. Someone had cut a notch by the transmission mount on the frame, so I had the same friend help me get a piece of metal cut to size. I gave him a template traced and cut from a manila folder and the metal, and he had it cut to shape.



 I got it welded in place from both sided and ground the welds on the top to make them flush, then polished it up with a lap disc. It turned out really well.

I then welded up the upper suspension bracket. (http://spitlist.info/Shock.Mounts.htm). Same buddy had gotten the pieces water-jetted and mandrel bent for me, so all I had to do was knock off the water-jet rust and weld the pieces. Check, check.

Having decided to convert the rear suspension to GT6, I purchased the brackets from Canley Classics (http://www.canleyclassics.com/?xhtml=xhtml/product/rearwishbonemountingbracket.html&xsl=product.xsl) and got those welded in place.

That all done, I went back to the diagrams to make sure I was all set for the rear suspension. I started doing more research on the Roto-flex and thought harder about Canley’s CV conversion (http://www.canleyclassics.com/?xhtml=xhtml/product/cvkit1.html&xsl=product.xsl). I also thought about trying to build my own cv assemblies, but the helpful websites on that topic scared me off.  Too much parts-sourcing.

Everyone has their own particular way of building a project car, and my way used to be to get it done as soon as possible with the least cost. That’s how I built my cars in high school and college because I had little money and no spare ride to let my project car sit on blocks for who knows how long.

Those days are past. I learned the hard way that if I’m going to do it, I just need to do it how I want to do it, the way that seems best, and if it takes more time because it costs more money, then so be it.

Soul-searching done, I decided to go with the Canley system. I don’t have the money to buy it right now, but it can wait. In the mean time, I am going to find a good, used sand blaster, blasting cabinet and paint gun, and get to work on the frame and associated parts. While I’m rebuilding my war chest I can blast and repaint to my heart’s content. And when I have the dough to drop on the CV system, I’ll make the buy and be able to get the car back on four wheels.

Solving the Differential Equation

The car is down to the bare frame and I’ve needed to make some fundamental decisions about the rear suspension setup before I send it out to be sandblasted. This process had been brought to a screeching halt because I had not been able to positively identify the vintage of the differential. When I bought the project car I knew it came with a roto-flex setup, but I did not know if that had been scabbed onto a Spitfire differential or if it was on a GT6 differential. Having figured out that the chassis and frame were likely a matching set from the factory, if the differential was also from a Spitfire I had been inclined to toss (read: sell) the roto-flex system and go back to the swing-arm suspension with a camber compensator. Even though that was not the best design in the world, it would make the car more true to its original setup. In addition, that would save me the trouble of making sure I had correct brackets on the frame for a GT6 rear suspension.

Having pulled the differential apart and confirmed it was a 3.27:1 gearing, I was confident it was indeed a GT6 rear end based on the research of Paul Tegler (http://www.teglerizer.com/triumphstuff/spit_and_gt6_specs.htm). But when I started looking at the parts catalogs to order parts for the rebuild, I saw there were two different versions of that rear end (http://www.rimmerbros.co.uk/ItemList–Triumph-GT6-Rear-Axle-Differential–m-689). That put me back to trying to find a positive ID for this part.

There were some pretty obvious numbers and letters cast into the case, but those lead me nowhere. I had tried to find any other identifying marks on the case, but was not making any progress. I tried to remove the pinion nut to see if there may be some markings between the case and plate bracket, but did not have the right socket so I let that idea go in frustration. I went back online to see what I could find, and located this diagram from Rimmer Brothers:


I looked back at the differential and saw absolutely nothing in the location referenced in this diagram. I scrubbed that area for a couple minutes with a brass wire brush and the flat of a screwdriver, and managed to see one faint straight line that didn’t look like a natural corrosion line, so I added some apple cider vinegar to my toolkit and went to work with elbow grease.  I painted vinegar on that area, scrubbed with the brass wire, scraped with the screwdriver and repeated for about 30 minutes. Slowly but surely a couple more faint lines started appearing, so I then used some dentist-like pick tools and ran them over the faint lines, repeating the process over and over and over.

After all that work, I found some faint stamp lines that had not been obliterated from 40 plus years of being under a car and exposed to the elements:


The stampings are still tough to make out from a photograph, but they say “KC1348″. I could not find a fifth digit, despite even more scrubbing. Based on this stamp, this differential came from a 1966-68 Mark I GT6. But roto-flex was not used on the Mark I cars, so I truly have a hodge-podge of pieces from different cars of different years.

I am going to submit this to the wise folks at http://www.triumphexperience.com and get their input on what rear suspension setup is best for the long haul and make a decision from there. I don’t like getting bogged down, but I also want to have a solid setup when I plop the chassis back on the frame.

Getting Down to the Bottom of Things

Having figured out the vintage of the chassis, frame, engine and transmission, the last mystery was the differential. I had not been able to get a good calculation of the gear ratio by spinning the pinion, so I cleaned it up and brought it inside to have a look at its insides.

Once I had the case apart, I inspected the gears and everything looked fine, although there was a smell of burned/old gear oil that I hadn’t smelled since I was working on my Capri in high school. I counted the ring and pinion teeth, which had 36 and 11, respectively. Looking back at the reference guides, this could only have come from a GT6. I still was unable to find any meaningful stamps on the differential to tell me what year of GT6 it came from, but it confirmed that the differential, along with the half-shafts, did not come from a Spitfire. With that information, I think I’m going to bite the bullet and go with what I have. This will require the addition of a frame bracket to accomodate this suspension system, but I can order those and weld them on with not too much trouble.

Here is a picture of the differential after being opened up:



Considering the smell of the inside of the differential, I think it has never been rebuilt and I’m assuming it’s 40 years old or more. As a result, I am going to take the time to completely rebuild the differential with new bearings, seals and shims. It needed new seals at a minimum based on the buildup of gear oil on the case.

Over lunch today I picked up some steel stock to repair the notch near the transmission mount on the frame. I’m going to have a friend shave it down from 0.1875″ to 0.150″ to match the thickness of the rest of the frame and then go to work on tacking it into place and cutting it down to fit the correct contour. Using a piece of folder paper, I traced out the right side of the frame and matched it up to the left side so I know what the new piece needs to look like. Here are a couple pictures of the cleaned up frame area and tracing of the paper:


I’m going to get this piece welded in and then add the suspension mounts for the GT6 rear end. Once that’s all done, I will send it out for sandblasting and then prime and paint it myself. I have decided not to go with powdercoating for reasons that will probably get explained later.

The process of figuring out where these parts came from has been a pain, but at least I know what I’m dealing with. The combination of the bigger displacement engine, four-speed transmission and relatively low rear-end gearing means this should not have neck-snapping acceleration, but should be a blast on the highway.


A Close Look at the Frame

With the vehicle stripped down the frame and a reasonable idea of its vintage, I took to work getting it down to bare metal so it could have a proper prime/paint job. the first things I noticed were two notches that someone had cut in it. One was just behind the right outrigger on the inside of the frame, and the other was forward of the transmission mount on the left side, including the left-front transmission bolting area.



The first notch will be left as is. The second notch will get retrofitted to be as close to original as possible. I don’t understand why anyone would think it was a good idea to cut out one of the transmission mounting bolt areas. That makes no sense. I will have to clean up that cut, fit a new piece of metal, and borrow a welder to weld it back in place.

Other than that issue, the frame looks good. I could find no rust other than minor surface rust. Much of the black paint job was done apparently without primer, so the twisted wire attachment on the angle grinder made short work of it. That made me glad I was going to the effort of redoing the paint, as no one could expect such a paint job to last.

On the front third of the frame under the black paint, I discovered what appeared to be original green paint of the same shade as the chassis. No one will ever know for certain, but it makes me think the chassis and frame are a match from the factory. If that’s the case, I feel even better about going with this car for a restoration project. The green paint and primer underneath did not go easily, and was clearly a better job than whoever had shot the black paint some years later.

Standing over the frame for a few hours running an angle grinder, I got a very good idea of all the nooks and crannies in this frame, and I’m wondering if a full paint removal is realistic with just an angle grinder, or if a media blaster or other method will be needed to get in those tight corners. Especially toward the front of the frame there is obvious surface rust in some of the areas an angle grinder will not easily reach, so I’m going to have to do something to get that rust off the frame before priming and painting.

After about two hours of running the twisted wire attachment I got through most of the top surfaces of the frame. I flipped the frame over to give it a good look and did not see any welded ID plate, so that may have gotten removed at some point. An observer at http://www.triumphexperience.com thought the outriggers did not look to be factory, but they had the same green paint and primer underneath, so I think they may indeed be a factory piece.

Tomorrow I have to diagnose a refrigerant leak in one of our cars but hope to spend a couple more hours with the angle grinder to continue working on the old/bad paint. I think it will probably take about 10 hours of grinding to get the frame to a point that it’s ready for final prep. Even though most people will never see this finished work under the car and it will probably never be driven in rain or snow (to cause rust), I will know that this frame is set for another 50 years.