Over Drive Issues

[beast runner]

My 88 Eddie Bauer doesn't like the Over Drive gear...it shakes and chugs and carries on when the trans shifts into o/d. Any ideas? Would it be because I'm running 33's on it which are larger than factory issue? I plan to change the filter and fluid which I'm hoping will help it, but is there anything else I can do to remedy this problem? Thanks in advance!

 

[Rons beast]

Has this just started since you put on the 33s, or have you had the 33s on and been running with them and now the problem started.

I have heard alot of guys on here run 33s without problems. Personally I have 31s with no OD problems, but under a load, the engine is happier with the OD off.

here's an idea. The secondary part of the ignition system, (plugs, wires,cap, rotor, coil) is fickle. It can be sufficent for igniting fuel under normal load.

If there should be a weak point in a wire, or plug or such, it will show up under heavier load.

Try applying power while in gear but the brakes on, (old school... we called it power braking) this simulates a heavy load on the engine, and can make week points in the secondary show up, as the engine will start to miss and bog.

If that happens, replace the correct part and drive.

If not guess you have to look at the gearing. Someone posted a table on here for the proper gear for your tire size.

If someone knows where to find it please help me out.

Good Luck

 

[Seabronc]

I think Ron is talking about this chart that came from an old JBG catalog. Keep in mind that is ti calculated for a 55 MPH cruise speed. Also, it is intended for vehicles that are mostly used for highway use. The formula for calculating RPMs is above the chart. Basically you want to calculate based on what your normal cruise speed is to keep the engine in the 2000 to 3000 RPM range, 2000 being on the best fuel economy ( :lol: ) end and 3000 being on the best power end, ( you can't have your cake and eat it too . The optimum range given on the chart is the best compromise between the two.

This chart would be pretty close to a 65 MPH cruise if you crossed off the tire sizes and moved all the tire size numbers to the left about 5 positions. ie. first column tire size would be 29 instead of 24. In other words if I were to have 29 inch tires with 3.08 gears at 65 MPH I should have an engine RPM of about 2320 RPM which is a little less than the chart has calculated for 55 MPH with 24 inch tires. So the chart wouldn't be exact but it would be close.

Also, the chart RPM is also calculated without OD and in 3rd gear which is a 1:1 ratio of engine RPM to Drive shaft RPM. OD would reduce the RPM to about 83% of the calculation, which is fine for unloaded cruise like flat highway. OD is not normally suggested for running on roads that have a lot of hills that will cause a lot of down shifting into strait 3rd gear or less.

Good luck,

 

[beast runner]

Has this just started since you put on the 33s, or have you had the 33s on and been running with them and now the problem started.

I have heard alot of guys on here run 33s without problems. Personally I have 31s with no OD problems, but under a load, the engine is happier with the OD off.

here's an idea. The secondary part of the ignition system, (plugs, wires,cap, rotor, coil) is fickle. It can be sufficent for igniting fuel under normal load.

If there should be a weak point in a wire, or plug or such, it will show up under heavier load.

Try applying power while in gear but the brakes on, (old school... we called it power braking) this simulates a heavy load on the engine, and can make week points in the secondary show up, as the engine will start to miss and bog.

If that happens, replace the correct part and drive.

If not guess you have to look at the gearing. Someone posted a table on here for the proper gear for your tire size.

If someone knows where to find it please help me out.

Good Luck

the 33's were on it when I bought it and this has been an ongoing problem. I've noticed it's harder on gas when it runs in OD (when it is working properly). It's a higher mileage vehicle (308,000 km/ 190,000 mi) so I was wondering if it could just be getting old and worn? I am going to look into the plugs/wires/cap/rotor issue as well. This truck has some issues, mostly minor and I'm slowly working them out. I bought it from a family friend for a song and dance so I guess it won't hurt to put a little money into it. Thanks for your help!