1992 argo magnum 8x8 Transmission Question

[reiddo1]

My transmission will not stay in gear in reverse unless I apply pressure with my knee against the selector lever; also in low range it is fine at low speed but when I increase the speed to about 5 mph and when coasting at that speed the selector will move out of that position as well. High range is fine in all respects. I have greater noise from reverse and low range than high range. I am considering an overhaul of the transmission. What gears, bushings and bearings am I likely to have to address? I'd like to have these on hand when I dismantle the gear box rather than have long downtime from slow deliveries. Any help is greatly appreciated.

[Roger S]

If you have broadband, here is a 60 meg manual with detailed transmission overhaul. It is for '92 and up models other than the magnum. On pages 368-9, I think, you'll see what detents hold the shifter into position. I assume the spring behind the ball gets weak. There are a lot of updates and changes,like a nylon spacer on the shifter linkage, a reverse gear w/ a split bushing and an oil hole.. etc.

That's about all I can suggest as I havn't had one apart yet. Probably need to use your VIN# or maybe there's #'s on the trans case, etc for exact part #'s and updates. You can right click and "save as" on the link below.


http://www.beaverdamargo.com/Documen...e%20Manual.pdf

[eightwheeler]

or the shaft with the detents is worn around the holes, i just fill with weld and remacine, then it like new again

[Rock Doctor]

I have one apart on the bench right now, it had exactly the same symptoms that you describe.
I will replace all bearings and seals. I will also replace the Primary input shaft (It has the drive gears for Hight, Low, and Rev) The gear for High is perfect, the gears for low and reverse are worn (Rounded) Costs about 175 Bucks.
I will also replace the "Double Gear" which is the one that slides side to side and actually shifts you from High to Low, to Rev. Teeth are chewed a bit. Cost.......Not sure, but probably about 100 Bucks. The detents on this shaft, where the steel ball locates the gear seem to be fine.
Also replacing the "Idler Gear" which is part of the reverse Gear train. Costs about 65 Bucks. MIGHT just turn it around instead of replacing it. The teeth on the side that engages are chewed up a bit.
I had to damage one "frost plug" over the end of the shaft that carries the "Double Gear", you might want to have a spare for that. Cost 5 Bucks

Hope this helps a bit.

RD

[reiddo1]

I am told by other 8 wheeler owners for the magnum series that it is not uncommon to have noise in low range and given the additional speed the low range gearing would be turning, additional noise would be expected. My real concern is the difficulty keeping it in reverse. I had the transmission apart once before because I could not shift at all and found after replacing some bearings which either had unusual play or were plain shot, my shifting problems disappeared. The oil lite bushing for the reverse idler seemed to me to be worn and being higher in the transmission probably starved from lubrication prior to me acquiring the machine. I did not replace it then because I was anxoius to get her back running again. Actually my first transmission oil level check after purchase revealed no oil whatsoever. My gears as I recall don't seem worn at all and I am hoping that mere replacement of the reversing idler gear and bushing will do the trick. As was suggested by eightwheeler in a reply above, I will check the springs and balls for the detents. I think that when I had it apart before there was a ball that dropped out but am unsure whether I re-installed it.

[mike bar]

Hey reiddo1,just want to let you know I have the same problem with my 1990 magnum with a MA tranny. After having it to an argo dealer to fix he only fixed the reverse from jumping out.At this point My reverse works ok but the shifter has to go a long ways to the left to engage, I have to leave the firewall loose so I can pull the corner of it out so the shifter will slide in behind it P.I.T.A. Low range works only when going easy, if I apply to much gas it will pop out and have to slow rpm's to almost nil to get it to engage again, also very noisy in both F and R. Works great in high range. What is the purpose of the balls and detents?would this be the reason mine has to travel so far left to engage? Just wanted to let you know you're not alone. Keep us posted on your progress and good luck $ Mike

[eightwheeler]

yes Mike you have the same problem, over time from going gear to gear selection the ball wears down the slide shaft on the sides of the detents, too much torque on the gear and the spring loded ball pops out of the detent, ill take a pic of a bad one tommorrow to show a bad one

[reiddo1]

Hey reiddo1,just want to let you know I have the same problem with my 1990 magnum with a MA tranny. After having it to an argo dealer to fix he only fixed the reverse from jumping out.At this point My reverse works ok but the shifter has to go a long ways to the left to engage, I have to leave the firewall loose so I can pull the corner of it out so the shifter will slide in behind it P.I.T.A. Low range works only when going easy, if I apply to much gas it will pop out and have to slow rpm's to almost nil to get it to engage again, also very noisy in both F and R. Works great in high range. What is the purpose of the balls and detents?would this be the reason mine has to travel so far left to engage? Just wanted to let you know you're not alone. Keep us posted on your progress and good luck $ Mike

I would take the gear linkage handle, place it in a vice and make the appropriate bend/s so that it does not have to go all the way to the left; if you bend too much there is a possibility that when in high range the gearshift lever may contact your left turning lever. As to why you have noise, my comment is that they may have changed a couple of gears and it is possible they may require some wear in time to become quieter.
Good luck...................Don

[mike bar]

I would take the gear linkage handle, place it in a vice and make the appropriate bend/s so that it does not have to go all the way to the left; if you bend too much there is a possibility that when in high range the gearshift lever may contact your left turning lever. As to why you have noise, my comment is that they may have changed a couple of gears and it is possible they may require some wear in time to become quieter.
Good luck...................Don

When I get around to fixing it I will probably have to do that to my shifter, but it couldn't have been that way from the factory. What would make it be this way now is what i am wondering? When eightwheeler posts the pics. I will get to see what these detents are.
Buy the time the argo dealer supposedly fixed the problem and when I got it back in and found out it wasn't completely fixed, he had closed shop and left the province.

[Roger S]

Where the spring and ball goes to hold the shifter in gear(s).

The pic with the shim washer on the shifter fork is an update, I imagine to keep the fork engaged if the bushing should get pushed up.

RD, it says the chamfered side goes down onto the dowel pin. I guess your chamfers are worn off. Thought you might want to chamfer the other side to ease engagement if you turn that reverse gear around. I use a narrow 1/4" grinding wheel dressed with a 45* on one side to do stuff like that.