SM465 to D18 adapter, short or long?

Well,
I'm finally tearing into my engine/tranny swap, and have a few questions. I'm going to run a 2.5 mercruiser/sm465 to my existing dana 18. I realize the benefits of the short AA adapter, but for a DIY guy like myself, will there be any drawbacks with the longer adapter in my 3a? I just feel like this would be a simpler solution for those of us doing this mod, who have never torn down a tranny before (it makes me a little nervous to tear apart the freshly built 465 I acquired). AA's website lists the long (spud shaft) adapter at 4 5/8 in length, and short at 7/8". It seems like a small difference, but may make a big difference in a 3a.

Is anyone currently running the long adapter in a 5 or 3? If so, how's your rear driveshaft?

Thanks again for your help,
Jake

 

Nearly 4 inch difference? Yep that is significant. The SM465 is longer then your stock tranny to begin with so try to reduce the amount of loss of rear driveshaft.

 

I'm currently working on the AA short adapter for my sm465. You have to 100% disassemble the trans to replace the mainshaft with the new adapter one. The hardest part is pressing the bushings on to the new mainshaft. I'm stuck there. I'm considering taking it to a trans shop and having them reassemble it for me.

I know in my 5, that extra 4" of the long adapter would make this swap near impossible.

 

A trick on the bushings is put the shaft in the freezer and put the bushing in a toaster oven at around 350* until it's fully heated. Usually takes about 20minutes/1/2 hour. They usually drop right on at that point. I have a toaster oven in the garage just for that kind of stuff. You've got to be quick though because they contract very quickly when they hit the cold shaft.

Personally I'd do the short version even though it's more work and more difficult. You want to keep as long a rear driveshaft as possible and that's hard enough in a Flatty.

 

maybe I'll try that. It doesn't effect the heat treating?

 

Not at that temp.

 

I used the short one from novak and was able to use the stock drive shafts in the 3b

 

Thats how we do it at work all the time. Heat one side and freeze the other, heattreat won't be affected in most steels at all until the temp rises above 400-450 degrees, then it will need to be tool steel to be affected. The bushings are made of sintered iron so they are not really affected by temp until about 800*.

 

Looks like i'll be making a trip to the local tranny shop for the work. What should I expect to pay to have this adapter installed? I might consider installing it myself, just scared to mess up a perfectly good transmission.

On another note, being I'm going with the short adapter, do you reccomend AA or Novak?

Thanks Again

 

Where are you located? Maybe someone close that can help or do it for a better price. I would say that the trans shop would be expensive. I have never installed an Advance adpaters unit but have installeda Novak unit, quality was good on the Novak. I also think Herm the overdrive guy has an adapter, not sure.

 

Herm is an AA dealer.

 

Why not just use the long adapter? This summer I put an SM420 in my CJ3A and used the AA long adapter. I have had no problems.

 

both are good choices. I know Herm sells the AA. That's the one I've got. I think the AA allows a bit of t-case clocking.

 

I think I may just attempt the adapter install myself. Worst case scenario, I take a box of parts to the tranny shop and have it installed anyways. Not sure why, but transmissions scare me. Yankeefist, being you're running the long adapter, how long is your rear driveshaft? Do you have any pic's of your completed install?

Thanks

 

if you take your time its not that hard

 

My rear drive shaft measures 16 1/2" from center of u-joint to center of u-joint. I did what most guys suggest and mounted my motor as far forward, up ,and left as I could. Everything worked out great with no interferances from the saginaw steering or the front drive shaft.

 

I bought the short kit from herm, ($475 if i remember right). I had your same reservations so I carried it all to a transmission shop (in Dallas) and they charged me $75 to tear it appart and put it back together. Once I got it home I installed the adapter plate, no problems at all.