Need help- haveing 4WD issues

[Sublimewind]

Hi all,

I don't often visit this section of the forum, silly me....

Anyhow, my GF has a GMC Jimmy (and I only ask here cause some know me here, and the jimmy and Astro are cousins) and the 4wd is not working properly and she keeps getting stuck in the snow...

The odd thing is 4 LO works sometimes, but not 4 HI.... It's the early/mid-90's version with the buttons on the upper left of the dash.

Is there a direction someone could point me? I do much of my own maintainence, but i'm a total noob when it comes to non-subaru 4wd systems... Could this be a solenoid problem or something completely different....

I know you guy work some magic here, so please, if you have any input, i'm all ears...

thank you very much,
Aaron

[LiftedAWDAstro]

In reality the Astro and S-10 systems are totally different! The S-10 has a front axle disconnect and my guess is that is where the issue is. You will probably need a new actuator. I believe they use an electrical element to heat up and shift the fork. These are noted to go bad or get weak. Some of the older ones are vacuum operated.

When the Jimmy is stuck, does the front drive shaft spin along with the rear? If it does, the issue is up front. If not, the problem lies in the t-case or electrical circuit.

[Sublimewind]

Ok, thanks mang... I guess i'll go get a Chiltons or something tonight...

[coolen]

I don't know nuttin' about 4wd's. However i DO know that some of the earlier chev's were vaccum operated. GOOD LUCK!!!!

[1996astro]

Sounds to me that it's going to need a switch or an encoder. I have seen a few of these come through the shop with the same complaint. For some reason I think it was the switch. The if it will shift into 4lo and back to 2hi then the encoder is working to shift the transfer case. Try playing with the buttons. When you press 4hi does it just blink and go back to 2hi?

[knucklehead]

hey guys i might not be in the right topic but i was wondering if you could answer some questions for me to help me out. i have the opportunity to get a 1975 chev 4x4 with front and rear dana 60's. the only thing is the front one happens to be passenger side diff housing and i am just wondering if i can make this work under the front of my 89 safari or should i find a driver side diff. also it comes with a 350 turbo tranny and a 203 transfer case but its lver style would these be good choices? um what else i was told 4.10 gears would be good but then im also told that 4.10 gears would make the engine rev quite high at 100km/h so maybe a 3.77 gearing would be better? lefted i see you have 33's on your van now how much trimming had to happen to make them fit? also any problem with the slliding door opening? what kind of rear tire mount did you use? sorry for all the questions but ive been thinking about this for 6 months and im trying to get everything ready for the summer so i can bolt it all together.

[LiftedAWDAstro]

The GM drive train parts will work but it will be a much tighter fit due to the offset of the Safari drive train. The TH350 is only a 3 speed auto so with 33's, the rpm's will be too high for high speed runs in the 70+ mph range. At 65 mph you will be turning almost 2900 rpm's. So yeah a set of 3.73's would be better unless you are willing to use the 700R4 tranny. The 203 t-case should bolt up to the 700R4 with only slight mods needed. I am not 100% sure on that though.

I only trimmed for the 32's I ran before the SAS was done. Once I went solid axle up front, I got enough lift that I didn't trim any more. I ran a set of stock H2's on all 4 corners and there is plenty of sliding door clearance.

For more info on the SAS, look over the extensive information on http://www.pirate4x4.com. Be careful though...they are hardcore and have no problem flaming a newbie!