Who needs money?

I think I have decided on a new transmission. After some forum research and talking with the guys at Novak Conversions I am going to go with the Heavy Duty AX-15. All the forums seem to suggext going with the NG3550 or the NV4500. The 3550 is basically bolt in, but really is no better than the standard ax-15. The 4500 is a good off road transmission but requires some adaption to make the conversion. I am looking for a simpler option to get her on the road faster, plus I do not do a lot of off-roading, so the hevy duty ax-15 makes sense to me. The quoted $1740 plus shipping for it.

I am posting the email discussion between me and Novak Conversions for reference:

ME:

I am pretty sure I need a new transmission. I have a 91 jeep wrangler, 32" tires 4"suspension lift, 3" body, 4.1 axles. It has a rebuilt inline 6 4.0L engine, ax15 trans and np231 transfer case.

I just replaced the clutch, cover, plate, throwout, pilot and master cylinder (not flywheel), because it is not shifting properly. It is very difficult to get into gear, unless I hold the clutch pedal in and wait for the rpms to drop then I can usually get it to slide in without grinding. With the new clutch, it operates the same. I have not had a pro look at it, but I am not hopefull, it has 177000 miles on it.

I am trying to decide on rebuilding my existing transmission (by a shop, not me), buying a rebuilt ax15 or going with a new transmission altogether. Can you make a recomendation and give me some prices? I want to stay with a 5 speed transmission. Some time down the road I will convert to a chevy small block v8 or v6, and will go with 35" tires on my next purchase, likely in the next year. I am not a serious off-roader but would like one capable of doing some rockcrawling if I decide to.

NOVAK:

Thanks for checking with us regarding your Jeep. Sorry to hear about your transmission. This is so common for the AX15 transmissions. Because of this and the unsuccessful rate of rebuilding these, we only recommend installing a new transmission. We have been rebuilding transmissions for years and are extremely comfortable doing so. Even with this experience, we have a hard time successfully rebuilding the AX15's. We do not like to encourage our customers to spend the $$ on rebuilding theirs, only to have it not work or go out again in just a short time.

We carry new, heavy duty AX15 transmissions. These again are new and have heavy duty upgraded internal components. This would work really well in you Jeep now behind the 4.0, and in the future behind a potential V6 or V8.

We have these in stock, price on the new transmission is $1740.00. Let me know what you think. Let me know if you have any further questions, I'll be happy to answer them.

ME:

Will the heavy duty fit on the bellhousing I have? Is it the same throwout bearing or is it avail with an external slave? Will it require any other changes to the clutch or pilot bearing? Will it bolt to the transfer case I have? Does the cost include shipping? if not what is shipping to zip 23235? Is there a core charge? Will my short throw shifter fit on it?

What is different between the standard ax15 and the heavy duty, or what parts have been upgraded to make it heavy duty? In looking on the forums I do not see a lot of experience with the heavy duty ax15, most seem to recomend the nv4500. but there are adaption issues and costs that I do not think I want to deal with. I am more interested in dropping the old and putting the new in and getting back on the road without a lot of adaption and conversion cost and time.

NOVAK:

Yes, this transmission will bolt right to your existing bellhousing and transfercase. This transmission typically takes the newer style external slave and clutch system. But, we can make a simple change here before it ships to accommodate your internal hydraulic clutch system. Cost does not include shipping. Shipping to you at 23235 is $126.25. Yes, your short throw shifter will work just fine. And yes, the different required pilot bushing is included.

As for internal upgrades, there are multiple components including the reverse idler shaft, cluster gear, and other hard parts that have been specifically heat treated to handle the additional strain. There are factory aluminum synchro hubs that are notorious for warring out that have been upgraded to steel. There are also sections of the case, being aluminum, where shafts are pressed in that now have steel inserts to prevent ware.

Hope this helps and answers your questions. Let me know if you have any more. I can assure you this will be the best route for your Jeep in comparison to the NV4500 for the exact reasons you mention. This will be the direct bolt-in you are looking for.

ME:

How does the HD ax15 compare to the nv 3550? This seems to be a popular swap on the forum sites. Will this handle the larger v6 and or v8 engine?

NOVAK:

The heavy duty versions of the AX15's are far superior to any NV3550. The NV3550 is no better than any AX15, and again, it certainly won't hold a candle in the wind to the HD-AX15. We have numerous customers running these behind their 5.3L, 6.0L, and LS1 V8 engines. I have no reservation what so ever in recommending this for your Jeep now for ease on installation and for future use with a potential V8.

Keep me posted

Unbelievable

After all the effort, new clutch and all, no improvement. It still does not shift correctly. I am going to have to take it somewhere and find out what is wrong with it.

urgh, grrr, frustration

I got the pilot bearing out and the new one in, sort of. I ruined the first one trying to tap it in with a socket, so i pulled it back out (with much effort) and used the "sleeve" (not sure what its called, amy be the pilot bearing seal) from the original and bought another new bearing. This time I used a wooded dowel to tap it in, it went in pretty easily.

So then I discover that the flywheel I bough is the wrong size, so I re-used the orginal, it looks in good shape. So now I have the flywheel, pressure plate and cover back on...

Went to redo the gasket seal on the transmission, of course spilled fluid and oil all over the floor, to realize the transmission housing does not come apart easily. I am a little worried to beat on it to get it off, so I am at an impass. The options I have are, live with the leak, and get it fixed later, or take it in next week and have the shop do it.