How To Do The Electronic Speedometer

1. How To Do The Electronic Speedometer In the event your Astro/Safari didn’t have it…and change out the 86 era dash to the 92 while you are at it… Advance the show by mouse click or hit your spacebar.

2. By 86astro • This is the way of adding the 92-94 Suburban gauge cluster into your old fashioned cable driven Astro/Safari. • I will show the proper way to hook up the electronics, as well as where to obtain the parts.

3. Go from this…UGH!

4. To This… BIG Improvement!

5. Lets Begin!!! • The new cluster has a tachometer, which I wanted for the looks, and besides, I hate the “graph paper” look of the astro cluster. • Some of big differences are… • Size of the clusters – The Astro/Safari cluster is a little bit smaller in every direction than the new tach cluster. Many people have chosen different ways to mount the cluster, such as removing the lexan, boring out the dash, or even mounting it to the bezel itself. Different strokes for different folks…

6. Oil Pressure Gauge - You need to pay attention to this because some of these clusters had 0-40-80 psi, and others had 0-30-60. There are 2 different senders for these, so make sure that you get the appropriate sensor for the cluster. The Astro I have uses the 0-40-80, and the cluster I obtained uses the 0-30-60. I will be changing sending units…lol Cable VS Electric - In my case, I had one other big hurdle to overcome. I had the issue of the cable driven speedometer, and this new tach cluster is electronic. This is not as big a problem as it would seem. I like crawling under greasy cars piled 2 high at my local yard. I have found 2 different schools of thought on how to do this job, I simply had to choose which school I wished to go to… Let’s look at each one.

7. School 1 – The Magnetic VSS • Some folks get the magnetic type of VSS from the donor truck, and also get the little white DRAC box that goes with it. Then you can proceed to mount the VSS sensor and wire it to the DRAC. You MUST also remove your cable driven ring gear from the tailshaft, and replace it with the 40 tooth reluctor ring from the donor truck, or any other RWD GM truck, van, or car with electronic speedometer. If you do not use the 40 tooth reluctor ring, you will NOT get a signal. REMEMBER! If your Astro/Safari is a 89 or newer, this is what you should have, unless you have all wheel drive, then it looks a little different. I was going to use this, but I changed my mind…

8. The Ring • This is the 40 tooth reluctor ring. I opted NOT to use this because I understand these are VERY brittle, and a real PAIN to install on the tail shaft without destroying the internal bearings in the transmission. The are made of pot metal and could possibly break too.

9. Magnetic Sensor • This is the magnetic VSS sensor that you would use if you were going this route. It installs the same way the cable driven gear did.

10. The DRAC • This picture shows the DRAC unit that is needed for the swap as well. Bear in mind, that you should look for a truck that has the same gear ratio that you have and remove the unit from that vehicle, otherwise there is some complicated jumpers that need to be installed and reset. If you get the correct one, it just makes the whole job easier. I found my DRAC in a truck equipped with 3.73 rear gears…Just what the doctor ordered! • The DRAC usually resides behind the glovebox area, and is generally velcro’d to the top of the glove box itself. Simply remove the glovebox and you should be able to peel it off. Remember to get as much wire as possible, you will be glad you did.

11. DRAC Wiring • This is one of the wiring diagrams used for the DRAC…Use caution, and look into the shop manual for the exact diagram, they may be different according to truck and options. • Class Dismissed from School 1.

12. School 2 – The Gear Driven VSS • Another way to add the speed sensor to your system is to use a VSS speed buffer module that was used on the 1986 to 1992 4 cyl. and 6 cyl. Firebirds and other GM makes such as the mid 80's mid size Delta 88 and similar. The yellow speed buffer is usually mounted behind the glove box on the passenger side. Be sure to get the connectors that go with it. • I will explain the whole thing as we go along…

13. Removing the Tail Shaft Cover • My transmission was already out and on my workbench. The 4 red arrows show the bolts that you will need to remove to remove the cover.

14. Sensors 101 • These are the two speed sensors together. The magnetic one (school 1) is on the bottom, and the gear driven (school 2) one is on the top. The gear driven one is the one that we are concerned with now. This simply compares the two of them.

15. Gear Choices • Various replacement gears for the VSS. Pick the color that best matches the gear driven speedo gear you removed, then use it on the VSS. These gears can be had for like 6 or 7 bux. I called Mary at Performance Transmission Center in Louisiana and she was very helpful. • HOT TIP!!! A 3.73 ratio will require a 15 tooth drive gear in the trans, and a 44 tooth driven gear. The driven 44 tooth unit is the grey one below. This is what I needed and we calculated to get the proper speedo reading. You will also need the tire HEIGHT.

16. 4 Output Speed Buffer • This is a picture of the speed buffer that you will need to use to hook this system up • Make sure that you get as much of the harness as possible, it will benefit you in the end when you wire things up.

17. Wiring Pinout • The pinout and wiring is shown in the following diagram, and the picture on the next page.

19. The main concern with either school of thought is to get the speedometer to work. If you can accomplish that, then you are gold. My attempt will be with the 2nd School, and the gear unit and the little yellow 4 out buffer. Seems like a good way to go. • Lets go finish the gear and VSS install on the workbench.

20. Drive gear removal and installation • There is a little black clip under the gear that must be depressed, then simply remove the drive gear from the tailshaft. Installation of the new gear is the reverse.

21. Sensor In… • The speed sensor will push in exactly like the old one came out. The gear will be loose on the sensor, but this is normal. Tighten down the 10mm bolt, and plug in the wires and this part of the job is done!

22. Mild Change of Plans! • I decided to take out the WHOLE entire dash from the 86, since I found a mint condition one from a 91. I always did like that style better, so lets follow along as we rip, er, remove the old dash. • My understanding is that the new cluster fits better in this dash anyhow. • For details on how to remove this old 86 style dash, there is no better source than this on the astrosafari.com board…just do a search for this…A hwtc2002 HOW-TO: Dash Removal . He documents it very well with pictures…saves me time taking pictures! With his permission, I am using his pictures here, they are numbered in the order they are in…

23. Don’t be intimidated by what you will see here… • It is actually much easier than it looks. I was downright scared at first, but it actually quite easy. I did my removal in under 2 hours… • The tools you will need are a 7mm socket or nutdriver, a 10 mm socket, and a small blade regular screwdriver to aid in plug removal. • Grab a phillips head in case…

24. Removing the dash, step 1-4

25. Steps 5-8

26. Steps 9-12

27. Steps 13-16

28. Steps 17-20

29. Steps 21-24

30. Steps 25-28

31. Steps 29-32

32. Steps 33-36

33. The last step… • Please don’t let this intimidate you, It is easier than it looks. • When it is all said and done, It will be worth it.

34. It should look like this now…

35. Another shot…

36. This is the old VSS unit…This can be discarded…ONLY this end!!!

37. This is the other end that plugs into the old VSS. You will splice these three wires into the yellow speed buffer to match the colors.

38. The buffer revisited • The remaining wires on the buffer are easy, the green is Speedo, the red is cruise, and the separate plug with the yellow and purple go to the trans sensor. • Be careful not to run either of these wires near spark plug wires or the tach lead, or you will end up with the speedo acting like a tach! • I mounted my buffer under the brake padal on the firewall with self tapping screws. Works nicely there.

39. Fortunately, GM uses mostly the same color wires in their harnesses between vehicles. In my case, all I did was re-wire the new plug from the existing one. • It’s really easy to match the colors. • Give yourself a little extra wire, you can electrical tape the wires together as a loom. • Test your connections and if all is correct, you will get what you will see in the next slide…

40. Got to love it! • I like this cluster much more than the other one. • I also installed wedge base illumination bulbs, Sylvania # 2825. These are rated @ 5 cp each. Significantly brighter! • I chose not to install the 2825 lamp in the shift quadrant…was just a bit bright, so I substituted a 194 bulb there. • Lets move on to installation…

41. The Painful Ductwork… • This is what the new ductwork for the new dash should look like… • Like anything else involved in this project, a little “modification” was needed… • Trim here, trim there, then it fits…the lower left bolt will screw into the existing hole, but the right side will need to be “created”.

42. You need to seal this hole…I used duct tape

43. I had to duct tape this yellow area as well… perhaps I got over excited with the cut off wheel…

44. The screw holes seem to line up on top, just need longer screws…

45. Some helpful hints… • When you install the dash, remember to bring it in from the top down…seems to fit better that way… • I am finding that mounting is going to be trial and error, with a little “engineering” tossed in for good measure… • Don’t get too carried away with the cut off wheel…it can be your friend, but it can screw things up too…for example, I accidentally cut away the mounts for the steering column support…whoops! Had to rebuild! • In any event, it looks a whole lot better than the old dash, which was all cracked and torn…

46. I am going to have to make a slice in the dash (yellow) to mate with the bracket (green)

47. Part way in from the passenger side…Still has to get up closer to the windshield….

48. And the view from the drivers side… • Obviously, the wiring is not all complete, and the dash is not bolted in yet, but what a difference… • Now is a excellent time before you do this job to decide if you wish to change the interior color.

49. Lets continue… • The dash bezel needs to be trimmed a bit to fit the new cluster. I would recommend having a spare one or two from the yard for this part of the task in case one gets messed up. • I took about ½ inch on the sides by simply running the whiz wheel directly along the side curves.

50. The cluster gets a shave too… • I then took approximately ½ inch off the top of the cluster too, in order for the bezel to “snap” into place. • I then used black electrical tape to seal the opening in order to prevent the dust from rolling in.