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Sprite Technical Information

PDLJMPR Web Magazine
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Sections:
Engine
Electrical
Transmission/Differential
Suspension / Steering
Body
Misc

New:
Install a convertible Top

Engine:
Building a No-Leak Engine
Downflow to Crossflow Radiator Conversion
Temperature Guage Calibration

Building a No-Leak Engine, by Les Myer

Although I am a Sprite novice, I have built more engines than I can recall during my tenure as a professional mechanic for American automobiles in what seems like a previous life. Over the years, I developed many opinions as to how to successfully seal them against leaks. Recently, I performed a complete overhaul on the 1275cc in the 67 Sprite I acquired 6 months ago and applied my sealing techniques during the re-build. I am happy to say that after the first 400 miles, my engine has not leaked one drop of anything onto the white cardboard I have placed under the car when it is parked in my garage. I am not inferring that I am a Sprite expert in any way, but offer my opinions for your consideration. If I state something that is obviously stupid, let me know so I can learn.

Sprite engines are similar in basic design to American-made motors, except that they have no rear main oil seal. Instead, the rear-main cap / rear cap cover are machined to tight tolerances with the "sealing surface" (for lack of a better word) of the crankshaft. There are spiral grooves machined into the "sealing surface" to pull any escaping oil back into the crankcase. The fit of the cap and cover in relationship to the crankshaft is critical for oil control. If the block is line-bored, or if the cap/cover is allowed to scrape on the crank, this critical fit could easily be destroyed. There are kits available for installing a true rear main seal, - they are an option.

The 1098 and 1275cc engines have a PCV system that is supposed to maintain a vacuum on the crankcase. Air is drawn into the engine, by the PCV system, through a calibrated orifice in the oil filler cap. Maintaining such a vacuum certainly helps prevent oil from flowing through the tight tolerances of the rear main cap/cover. (The 948cc engine has a draft tube that creates a vaccum in the crankcase when the car passes through the air, but only vents the crankcase when the car is sitting still.)

The previous owner of my Sprite decided that a PCV valve was a "bad thing" and removed it as well as the hose leading from the oil separator mounted on the timing cover. Since the engine was in need of serious repair (2 exhaust valves leaking, >0.010 cylinder taper, flat cam lobes, etc), consequently there was considerable blow-by with no place to go except out the front cover, rear main, and every other seal on the engine. When pressure would build up, about a pint of oil at a time would blurb out the open orifice in the oil separator, all over the front of the engine and engine compartment. The moral to this story is that one should expect an engine to leak oil if 1) the crankcase ventilation system is not working properly and/or 2) excessive blow-by is present. On a 1098 or 1275cc engine, the idle RPMs should rise if the oil filler cap is removed (from my shop manual), thus indicating a vacuum on the crankcase was present before removal of the cap (assumed). If your car does not pass this test, you need to find out why and fix it or buy a big bag of oil dry and a case of oil to put in the trunk.

Converting a Sprite from a Downflow to a Crossflow Radiator - by Mike Harlan
Last year I converted my Bugeye from a downflow to a crossflow radiator to improve the cooling situation, since I was marginal on cooling with a built 1098cc motor. The procedure below is what I did for the conversion. Steps might vary for a non-Bugeye, but should be fundamentally the same. First, I bought a radiator shroud from a 1275 Spridget with a cross-flow radiator. You need to be very careful here, as some 1275 Sprites were downflow, and the Midget 1500 is a totally different design!! I got my shroud used from Faspec, Inc. in Portland, Oregon, along with a lot of other bits listed below for about $65. I have since seen that someone, Vicky Brit I believe, sells them new. It would have saved a lot of work in cleaning, straightening, and painting, but certainly would be more expensive. I also got the lower crossover tube, which runs below the radiator in front of the steering rack. These are also available new if used can't be found. An overflow tank is needed, as it is the source of filling the system rather than the radiator itself. The overflow tank is brass, so used is OK. The new parts I purchased were the radiator, all hoses (upper, lower, crossover, and overflow), and the radiator cap. Why bother with old, unknown parts which may or may not work. Mini Mania cut me an EXTRORDINARY deal for all that stuff, plus a 6 bladed plastic fan. The conversion itself is simple, once you have the right parts.

One additional note on the tank is that it is mounted by means of a metal strap with bolts on each end which wraps around the tank. This part could be fabricated, but is best purchased used from your friendly parts supplier. That's it! The conversion was easy and made a significant reduction in water temperature on my car. It was definitely worth the money and effort for me! Mike Harlan

Temperature Guage Calibration, by Frank Clarici
Temperature guage not reading properly on your Sprite? Fix it yourself in 20 minutes.
Items needed: 5/8" wrench, small pot, propane torch.

If you do NOT agree with these ideas, if you are "mechanically challenged" or are just down right "stupid" I suggest you perchase New parts from a supplier of your choice and have a local shop do this work for you.

Frank Clarici
may be copied

Electrical:
Alternator Conversion
Low Voltage Ignition Wire Problems
Tachometer Conversion, Positive to Negative Ground
Electric Tachometer Face Swap for Bugeye

Alternator Conversion - by Frank Clarici

Items needed:
1 Mitsubitshi alternator
1 GM swoop alt. bracket
6'' of 3/8 id steel pipe
3/8 X 8" bolt and nut
3/8 drill bit

This conversion allows the use of halogen headlamps, cd players, and ends your generator worries for good it also eliminates your Lucas voltage regulator. 2 hours is all the time it should take after you aquire all the needed items.

Now for the wiring

You can remove your regulator or use it as a junction box for the new wiring . If you use it as a Junction box you will have to cut out the guts, just be sure that the large brown, brown with blue, and brown with yellow wires are connected together, and that the small brown with yellow is connected to the small brown with green ( field to indicator lamp.)

If you do NOT agree with these ideas, if you are "mechanically challenged" or are just down right "stupid" I suggest you perchase New parts from a supplier of your choice and have a local shop do this work for you.
Frank Clarici (may be copied)

Low Voltage Ignition Wire Problems

Having had numerous Sprites thru the years, I have come across a simple problem that will drive you nuts if you are not familiar with it. The problem seems to be the rivets which hold the low voltage terminals to the ignition coil. They loosen up with age.

Symptoms:
Car sputters or dies for no appearent reason.
Electric tach acts erratic or quits.
Problem comes and goes without warning.
Car sputters or dies after hitting a bump.

Check the rivets that hold the terminals to the coil. A quick fix is to tap the rivets home using a small hammer and punch or the edge of a screwdriver. Replacing the coil will solve the problem for another 20 years.

If you do NOT agree with these ideas, if you are "mechanically challenged" or are just down right "stupid" I suggest you perchase New parts from a supplier of your choice and have a local shop do this work for you.

Frank Clarici

Tachometer Conversion, Positive to Negative Ground

Items needed: soldering iron & solder, electic tape or heat shrink tube

If you do NOT agree with these ideas, if you are "mechanically challenged" or are just down right "stupid" I suggest you perchase New parts from a supplier of your choice and have a local shop do this work for you.

Frank Clarici

Electric Tachometer Face Swap for Bugeye

BUGEYE TACHOMETER CONVERSION

Many Bugeye owners are confronted with the problem of sorting out a tach drive once they have converted either to an alternator or discover that they cannot find a mechanical tach drive at a reasonable price. Frank Clarici offers a great piece of advice on how to convert an electronic tack over to negative ground. I have taken his advice one step further. Many Bugeye owners do not want to give up the stock look of the original gauges, so I have outlined here how to solve the tach drive as well as the stock looking gauges problem.

You will need:

1 Hour labor Procedure:

It is that easy, drop me a line if you need more information,
Bob Magnotti
bob@itgonline.com

Transmission/Differential::
Universal Joint Replacement

Universal Joint Replacement

Having replaced universal joints on Spridgets several times, most recently helping a friend who was stuck, I thought I'd share a very easy tip for installing the propeller shaft after replacement of the joints. Installing the slip yoke into the transmission through the tunnel for the shaft can be frustrating if the joint flops around. To ease installation,simply wrap the joint with electrical tape (3m works best) and install the joint. The heat and rotation of the shaft will send the tape to the rear of the shaft with a few miles of driving allowing it to be removed. I refuse to believe that this is an original idea, being so low-tech, but no one I've told so far had ever heard of this trick. I hope this helps keep the B.F.F.(British Frustration Factor) Down to acceptable levels. Jerry Carroll

Suspension / Steering:
Drum to Disk Brake Conversion
Steering Wheel Modification (smaller diameter)

Drum to Disc Brake Conversion

This is the quick, cheap, down and dirty disc brake conversion. You may want to spend a whole lot more money by purchasing all new parts and rebuilding your front end while you are working in this area. This tech tip is NOT going into that kind of detail.

Items needed:
"A" arms from a disc brake spridget including rotors, calipers, and swivel axles. For quick and cheap disc brakes you will need to aquire a set of "A" arms from a later Sprite or Midget. 1964 on will work. Remove the complete "A" arm assembly from the body and the shock keeping all of the parts intact. Be sure you have the swivel axles, brake rotors, and calipers.
NEW brake pads
NEW brake hoses (disc). DO NOT use used rubber brake hoses, your life is not worth your saving $30.

If you do NOT agree with these ideas, if you are "mechanically challenged" or are just down right "stupid" I suggest you perchase New parts from a supplier of your choice and have a local shop do this work for you.

Frank Clarici

Steering Wheel Modification (smaller diameter)

In my continuing efforts to fit a large body into a very small car, I offer the following modification to the steering wheel.

  1. Remove steering wheel. My hub wouldn't come off so I just removed the spoke attachment bolts.
  2. Carefully remove original rubber grip material - a single edge razor blade works well.
  3. Cut spokes off flush with rim.
  4. Cut out section of rim to desired size. eg. to go from standard 15 to 13", cut 2 x pi or 6.3" from the rim.
  5. Now the fun part. Reshape rim to new diameter trying to keep it as round as possible.
  6. Shorten spokes by about one inch.
  7. Clamp together and weld rim and spokes.
  8. Refit grip material using 3M weather strip adhesive.

I also added a foam wheel cover to keep everything together. Advantages: cost no adapter to move the wheel even closer to your chest horn still works (well, as good as it ever did...) Next project: Modify seat backs on later cars to gain some more valuable real estate for long legs (mine is a 74 midget and the seat back cushion looks much thicker than it needs to be)
Rich Wagner

 

Body:
MKI Sprite Windscreen Replacement
Sprite Color Codes

MKI Sprite Windscreen Replacement

After a long and unsucessful battle to find a replacement windscreen for my car [1958 Mk1 Sprite] I eventually came up with a suitable solution that not only works, but is considerably cheaper then conventional means. I took a template of the existing windscreen [in my case it was perspex as the previous owner was equally unsuccessful it appears] and then had a 4mm float glass copy made which I then sent to our local glass toughening plant for the necessary processing. Albeit the output was a flat piece of 4mm toughened saftey glass it actually bends surprisingly easily, especially bearing in mind that the Sprite windscreen has but a gentle curve. Using the same gasket that is used in modern sliding windows [wrap around gasket] I was able to do the entire replacement unassisted and now have a new, clear curved glass windscreen. The fact that it is only 4mm thick is rather academic as the overall area is less than 0.35sqM and it's strength lies in the outer tensioned layer of the glass surfaces, in fact it is far stronger than the 6mm laminated glass that would normally be fitted. The reason for the choice of glass thickness lay in the fact that it would bend far more readily than 6mm glass and would not exert too great a force to return to the flat condition and thus causing possible stress damage to the metal surrounds. If my explaination appears rather simple please Email me and I will give full advise. Furthermore should any Sprite owner require a replacement windscreen as described above I can [from your template] make up a unit and crate it etc for approximately $70.00. ex Cape Town, South Africa. Once again Email me should any one be interested.

Regards, Martin Pedder
fastraq@iafrica.com
tel/fax +2721 557-8657

 

Misc:
Interior Panels for Side Curtain Models
Carpets for $30.00
Install a convertible Top

Carpets for $30.00 - by Frank Clarici

Have you seen the carpet kits available for Sprites and Midgets, they cost $100 and up and they do not fit properly. Here is the solution. Items needed:

If you have your old carpets you can use them as a template if not , no problem, just follow these simple instructions:

The carpet should hold in place for many years and can easily be removed with some mild pulling should you want to inspect your floors for rust. For a really nice touch try some carpet padding under the rug. You will not believe how much road noise this eliminates. Glue it in in the same manner. I have done this procedure to 4 Sprites now, 2 with padding , 2 without, and have had no loose carpeting at all. The first car was done over 4 years ago.
Good luck.

If you do NOT agree with these ideas, if you are "mechanically challenged" or are just down right "stupid" I suggest you perchase New parts from a supplier of your choice and have a local shop do this work for you.
Frank Clarici
may be copied

Interior Panels for Side Curtain Models - by Frank Clarici

Are your interior panels warped, ripped, or non existent? You can do it yourself for about $60 in a Saturday afternoon in any color imaginable including hot pink. The items you will need are:

The procedure:

Good luck,

If you do NOT agree with these ideas, if you are "mechanically challenged" or are just down right "stupid" I suggest you perchase New parts from a supplier of your choice and have a local shop do this work for you.
Frank Clarici
may be copied

Installing a Convertible Top - Steve Byers

NOTE: This procedure was written specifically while installing a top on a '73 Midget, but they can be adapted to other models.

1. Fold the top in half along a line from front to back. This locates the centerline. Mark the location of the centerline at the front and rear of the top with chalk.

2. Put the top in place over the rear fastener locations with the chalk mark lined up with the center hole in the cockpit pinch weld. Place the rear retainer bar in place with its lower edge lined up with the upper edge of the binding material on the top. It helps to have an assistant or two to keep the top properly stretched from side to side and located while you punch the holes for the fasteners in the top material.

3. From the cockpit side, using an awl or icepick through the center fastener hole in the rear cockpit pinch weld, punch through the top material to locate the fastener hole. Ensure that the awl comes out through the center hole in the retainer bar.

4. Install the center snap fastener through the retainer bar, top material, the outer lip of the cockpit rubber seal, and the cockpit pinch weld.

5. Alternating from one side to the other, repeat steps 3 and 4 to install the remaining six snap fasteners along the rear edge of the top, working your way out from the center. Be sure to check that the lower edge of the retainer bar stays aligned with the upper edge of the top binding, as in step 2, before punching the hole for each snap fastener.

6. Position the top material tightly around the curves at the rear corners of the cockpit. Use the Tenax stud holes in the pinch weld to locate the holes in the top for the Tenax fasteners. I preferred to do these one at a time, and alternate from side to side to make sure the top stayed even. The lower edge of the top should be almost touching the little ledge on the body as it goes around the corners. Punch the holes with the awl. Install the Tenax fasteners on the top, and the studs in the cockpit pinch weld, then fasten the top using the Tenax fasteners

7. When all the fasteners are installed at the rear, latch the top frame header rail to the windshield.

8. Determine the center point of the top frame header rail, and mark it with chalk. I used the windshield center rod as a guide.

9. Pull the top tight over the frame and down against the header rail over the windshield, lining up the chalk mark on the top (step 1) with the chalk mark on the header rail (step 8). Have a couple assistants keep the top tight from side to side over the frame. While keeping the top material stretched over the header rail, and feeling the edge of the header rail through the top material, mark a line on the top across its whole width indicating where the edge of the header rail is. Now mark a parallel line 1/2 inch back from the first. At this point, you can erase the first line. (NOTE: what you have just done is allow for 1/2 inch of stretch to make sure the top is tight when finally attached to the header rail and the top is latched)

10. Unlatch the top frame and partially fold it back. Apply contact cement to the outer surface of the header rail and the inner surface of the top material back to the chalk line.

11. After the contact cement sets up, attach the top to the header rail, aligning the chalk line with the edge of the rail. The remaining top material should be folded over the rail and secured with contact cement, trimming any excess as necessary. I preferred to let the material overlap the holes for the seal channel.

12. Now you are ready to install the seal channel and seal. I used self-tapping screws for the seal channel instead of rivets. Probe with the awl through the top material to find the rivet holes in the header rail. This will properly locate the seal channel. The seal has a foot that is stuffed into the channel with a screwdriver (or similar tool).

13. The various snap fasteners for the interior can be located by rubbing chalk on the mating male part on the windshield posts and top frame, stretching the material over the male fastener, and rubbing it to transfer the chalk. Use an awl to punch the holes in the center of the chalk marks. It takes a special tool to install the snap fastener female halves, but they are available and not expensive.

 

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