fairlycrass

Hoping someone can give me some ideas here...

1991 Cherokee Sport, 4.0, 4WD, 5-speed. Has about 210k miles on it. When I bought it in early September (and while it was warm out), it shifted just fine. Now that it's cold, it shifts really hard--especially before it really warms up. Once it's warm, it's not too bad, but at first, it's all you can do to get it downshifted into 2nd or 1st when slowing down. You have to be going really slow.

I'm wondering whether I might just have dirty, or old, fluid, or if there's something bigger going on...? I am pretty much a novice mechanic. I've done things like shocks, tie rod ends, FPRs, stuff like that, as it comes up, but don't really know where to start looking for this problem.

Thanks!

Hommersimpson

I am in florida.. and when cold my 5 speed in morning dont like to shift to well eather.. once warmed up its lot better but could be better... im thinking of doing a rebuild on it..mainly the shifting stuf that wears out..
I did change fluid and added a quart of lucas oil treatment.. that did seam to help a TAD.. not alot tho.

fairlycrass

It gets cold in Florida? I reckon the coldest day ever in FL is about like our cool summer mornings here in Wyoming...

I haven't looked at the fluid yet, but I was hoping that might be it, since it sounds cheaper and easier than rebuilding something.

Dsandine

Almost every manual vehicle I have owned has done that, pretty sure alot of it depends on the viscosity oil you are running, like if you are running straight 75 weight it is going to be really thick when cold. (ever try filling a tranny with mt-90 in the winter, it takes forever because its so cold and the oil is so thick) Then once the gears get turning and things height up it thins out a bit and shifts easier, as far as I know (not 100% sure) that is normal. I run motor oil in one of my cars and it does not do that but it has very low viscosity so I think it is all about the weight of the oil in there.

Cherokee

yeah man, i just changed mine and it looked a little dirty.
was doing the same thing as you described, but now its much smoother even when i start it in below freezing weather.

i used conventional 10w30 motor oil in the AX15, which is fine to do.

if youre going with a gear oil, make sure you don't get anything GL5 rated as it contains too much sulfur to mess with youre brass syncros (AX15). GL3 or GL4 rated are good.


if that doesnt help it just might be your clutch or maybe the syncros are already wearing down.

fairlycrass

That's good to hear. I am hoping to squeak by with no major, expensive repairs for this thing for awhile. How much work is it to change this? Mostly just a mess, I assume. Did you use the Mopar stuff from Quadra-tec, or any ol' conventional oil brand?

whowey

If you are going to use motor oil, you will need to decrease the amount of time between changes. Motor oil contains a much lower levels of the additives to protect the gears and anti-shear additives than gear oil contains.

Hommersimpson

what would be the BEST to run ? money no option kinda thing ? royal purple syth motor oil ? gear oil lower weight ? the very best to help shifting .. and life of transmision

Cherokee

yeah, I just couldn't afford to spend my money on redline mt 90 at 11 dollars a quart.

temporary fix in my opinion, but it needed a change of any sort.

whowey

Best to run is going to be one of the high end full synthetic GL-4's gear lubes. I know what I recommend to my customers and in the past I have run the Red Line MT-90 with very good results.

The main point is to avoid gear lubes that are GL-5 rated. GL-5's contain sulfur. Sulfur is what is damaging to the bronze synchro's in AX 5/15 transmissions.

Another potential issue is the fluids that offer the claim, that they use sulfur.. but its okay because its not elemental sulfur. Sulfur is corrosive to yellow metals regardless of what form.. that includes magic pixie sulfur....

Royal Purple gear oil is GL-5 rated. Using their motor oil would have exactly the same guidelines as using the cheapest farm store brand oil... Motor oil simply doesn't have the additives to stand up to long term use in manual transmission applications.

whowey

Absolutely...

I can't stand the fact the Chrysler started recommending this.. I understand the need to cut the costs of carrying another fluid in their line-up vs. the small amount of these transmissions that are being serviced in their dealerships. But this has really carried it too far in my opinion.