Monday, November 28, 2011


The passage of time produces interesting contrasts. One of the most notable is how we use our cars. When I owned a Saab dealership (1967-1974), V4 Saabs were used as daily drivers. Twenty years later, only a few were in daily use, and the emphasis was on keeping them running.
Fast forward another 20 plus most of the V4 powered Saabs are driven on weekends or occasionally and almost never in any inclement weather.
Restoration continues on some of the "lucky" V4 cars still intact and with that there is an almost anal emphasis on "originality."

A number of owner/restorers "beat their chests and rend their shop coats" over fuel pumps. We're talking about an item that is mounted low and almost out of sight in the engine bay.
"That's not original! It's not like the one I took off my engine!" claimed an owner. The logical response was "Is the pump you took off original? Do you even know what was original?"

I'll confuse you with some facts: Ford used at least THREE different series of Pierburg fuel pumps on the V4 engines sold to Saab on contract.

As the years went by and the supply of "original" pumps dried up, Saab contracted with various manufacturers for replacement fuel pumps and sold them to dealers and customers.
So, does this make them "not original"? They DID have Saab part numbers and were sold by Saab dealers...

HELLO? We're not talking vintage Packards or Duesenbergs here...But if having a hissy-fit over a part that you can barely see when you look in the engine bay makes your day, then go for it. But do compare that greasy, drippy lump of a pump with the pumps shown here...just to make sure that the bucks you spend on rebuilding it are for an "original."

Sunday, November 27, 2011


The VDO folks tried to make one basic speedometer fit a whole batch of applications. For Saab alone, this basic speedo worked for 10 or so different cars!
Different transaxle final drive ratios meant that they had to have different ratios INSIDE the speedometer so any one car had the correct speed and miles recorded. This photo shows the left side of a Saab VDO speedo with the little side transfer gear set removed.

At the bottom of the photo you can see the transfer gear set.
I did the exploded view drawing below to show the side transfer gear set at the extreme right. The lateral transfer gear set is just to the right of the main speedometer body. The ball is used to retain the lateral gear set. You need a special, very small, puller and press to push out the ball so the lateral shaft can be removed without damaging it.

The exploded view also shows the trip register reset mechanism [extreme left in the drawing]. The tiny cog wheels at the top and bottom advance the number wheels at the appropriate time.

This is a close-up drawing I did of the main speedo body, with the side transfer gear set still in place. This gear set must be adjusted for the correct mesh with the gear on the end of the top [primary] mileage register.

The four arrows show the worm drive gears on the two shafts and the two gears--that are selected for a given transaxle ratio. The gears are different diameter and have a different number of teeth. So a single speedometer "main frame" can work for a 2-stroke with 5.23:1 final drive as well as Sonett V4 with a 4.67: final drive, by changing the gear sets. Clever, eh?
My next blog will be about some special tools and why I needed them.

Saturday, November 26, 2011


Now the fun begins. The knurled, round knob secures the big "U" bracket that holds the speedo into the instrument panel. The thin hex nut holds the speedo "innards" to the outside case. I have to be careful with the relatively delicate gubbins from here on.

I built a holding fixture [in red, below] to hold the speedo securely in my vise so I don't slip and bust some tiny part while I'm trying to replace damaged bits.Then I clean and re-lube the working gizzmos. The 40 year-old grease in these babies gets real stiff. I use a dentist's pick [AKA "torture tool"] to clean the old grease off the gears!

The gear train for resetting the odometer trip meter register is on the lower left on the speedo inner frame. The round drum is where the magnet and speed needle cup are located. At the top is the main odo register [with numbers] and above that the advancer sprockets that allow only the correct number wheel to rotate.

I reversed the mount fixture [red] so I can get to the "innards" easier. See the wee gear train on the side.... these gears are changed to make the speed and miles read correctly for the different transaxle final drive ratios that Saab used over the years.The rest of the "innards" are the same.
My next blog will be more about taking it all apart, with more special tools, steady hands and a lot of TLC.

Friday, November 25, 2011


The Saab VDO speedometer is a good quality instrument. But like all of us, some parts get tired and gummed up after many years, and...uhh...some parts quit working. My drawing shows a dual register VDO speedo with the internal gubbins phantomed in.

MILEAGE recording--on the odometer registers--is accomplished through a double set of transfer gears. My phantom drawing shows the SIDE set of transfer gears. Interestingly, SPEED indication is done magnetically--there is no physical connection from the speedometer cable input to the speed indicating needle. The input shaft is connected to a small magnetic drum that rotates inside a sort of cup that is connected to the needle. The faster the speedometer cable turns, the faster the magnetic drum, and the farther around the speed dial the needle moves. A tiny hairspring insures that the needle always returns to rest at the "0" peg. So now you know, generally, how the thing works.

Next is how to get it apart so what DOESN'T WORK can be fixed/replaced.
I designed and built a fixture [clamped in my vise] that holds the speedometer firmly in place. The ring removal tool [with the green handle] has a specially ground tooling tip that just fits under the stainless ring, that, as I move the tool around the speedo, gently stretches the stainless ring until it pops off the speedometer. CARE and PATIENCE are vital here, but the ring does come off with NO DAMAGE!

I've got the ring off--NO DAMAGE! Below it is the glass, and below the glass a painted trim ring. Now I can get on with the work on the speedo's "innards".

A look at the special fixture that secures the speedometer. Without this fixture it is REALLY EASY to booger up the very soft stainless steel outer retaining ring. I've completely rebuilt a number of these VDO speedo's now--for Saab, VW and Porsche--so if yours is AWOL in the function department, I can rebuild yours, too. Give me a shout---541-499-0246 or email me at
Next---I take you into the VDO "innards". I know---you can hardly wait....