Couple of quick questions

[canucksfan1]

1. What is the fastest and easiest way for me to tell what gears are in the rearend of my new car. Its an 81 Olds Cutlass Supreme Brougham, doesn't have any options that i am aware of, and the sticker in the trunk with all the RPO codes is no longer there. Should i just pull the cover and start counting or is there an easier, and possible cleaner way????

2. There is a little vaccum module thing on the passenger side exaust that i never noticed before and was not hooked up. It appears to open a valve in the end of the passenger side exhaust manifold. As far as i know it has not been hooked up since i own the car, i hooked it up last night but haven't really driven the car since. What is this for??? wat diff would it make as far as drivability???

Thanks all you guys and galls are awsome and a whole heck of alot of help!

 

[85 Cutlass Brougham]

There is a code stamped on one of the axle tubes that indicates where it was made and what ratio it has. I don't know them off the top of my head, but I have a book somewhere that tells what they are. The other way is to take off the diff cover and read it off the ring gear. It will have a ratio of the number of ring gear teeth to the number of pinion gear teeth. Take out a calculator and divide the ring gear teeth by the pinion gear teeth and you get the gear ratio.

 

[canucksfan1]

awsome thanks for the ery quick reply

any ideas for question 2???????????

 

[canucksfan1]

no one???

 

[clean8485]

The vacuum device is part of an assembly called an EFE valve, or heat riser valve. Its purpose is to help the engine warm up more quickly when its cold, by diverting exhaust heat up through the cylinder heads, and intake manifold, to help warm up the carburetor. Once the engine is warm, the valve is supposed to open, and allow exhaust gases to exit through the exhaust system normally. If you're going to render the valve inoperative, try to make sure that it is in the open position. The engine may take a bit longer to warm up, but you'll get normal flow through the exhaust system, with minimal restriction through the valve. Hope this answers your question.

 

[Uncletruck]

The heat risers used on these cars will remain open all the time if the vacuum hose is disconnected. The vacuum circuit goes through a coolant temperature sensor vacuum switch that closes the valve when the engine is cold. If you only use the car in the summer, it's unlikely you'll even notice if the thing closes or not and I would not bother reconnecting it. When these valves get old and wear, they devleop a nasty little rattle noise when they are closed, which is why most people disconnect it.

-UT-

 

[SBCregal]

you can jack up the rear end of the car and count how many revolutions the driveshaft makes as the wheel makes one complete revolution

 

[canucksfan1]

yeah thats what i ended up doing, 11.3 turns roughly, made the wheel turn 10 times. Any ideas what the gear is?? Somewhere around 2.20:1 or something???

 

[85 Cutlass Brougham]

The jack up the rear thing only really works with a limited slip diff. Otherwise, the spider and side gears render the count meaningless.

 

[canucksfan1]

thats what i thought too, cuz like i said the coun't was 11.3 turns of the driveshaft to 10 turns of the wheel. That would make the gear ratio 1.13:1 which makes no sense then i heard you times it by too if u don't have posi, which still doesn't make sense so i dunno i will have to pull the cover, cuz i can't fins the numbers