SM420 vs. SM465

[Doug Krebs]

Any reason not to run a 420 over a 465? I already have both, so that isn't a factor.

Pro's of the 420:

135ish vs 175ish pounds
shorter in length ~2 inches
smaller overall
reverse is near granny gear (down and left)
7.0 vs 6.55

Cons of the 420:

I'll have to machine an adapter to use a 465 bellhousing
Parts are more scarce and more costly (if needed)
I think the shift throw is longer

With either tranny I'm going to have to make an adapter for the rear and a new main shaft.

[uglyota]

don't you already have like 4 threads about this?

[Doug Krebs]

don't you already have like 4 threads about this?

truthfully i searched

[Fredo]

why wouldn't you just use a small-bore SBC bellhousing instead of a large bore 465 bellhousing?

[Doug Krebs]

why wouldn't you just use a small-bore SBC bellhousing instead of a large bore 465 bellhousing?

School me, I don't know much about 420's other than what i've read recently.

[robertf03]

yeah no kidding. theres probably 20:1 of sm420 compatable bellhousings to 465 bellhousings.

sm420 is "normal" bearing retainer OD, the diameter that indexes into the bellhousing. sm465 is bigger. That adapter you are talking about would be a spacer ring of a pretty big OD. I doubt you'd have any stock sitting around that would work.

by the way, thanks for the safety glasses hookup.

[Doug Krebs]

you'd be surprised what we have laying around at work.

I'm assuming people are using 465 bell housings because they can be aluminum and have the hydraulic slave cylinder mount.

[Fredo]

I guess. Mounting a slave isn't that hard. You just have to build or buy a bracket. Man we are such old men. 11pm on a friday night and we're on here discussing ****ing transmissions and bellhousings.

[Doug Krebs]

I guess. Mounting a slave isn't that hard. You just have to build or buy a bracket. Man we are such old men. 11pm on a friday night and we're on here discussing ****ing transmissions and bellhousings.

I know sad. If it makes you feel better, I continued cleaning the garage for a couple hours tonight.

I built a ghetto bracket for my blazer a few nights before we went to Las Cruces. It's still under there...

[Fredo]

Well there ya go! The bracket is already figured out!

[Doug Krebs]

The real reason I started looking at the 420 was I thought it might be easier to slam into reverse in a roll situation. I'm not sure that would be the case as you still have move over, but you don't have to skip over 3rd.

I started liking it better when I figured out it was 40 pounds lighter, smaller, and shorter.

[robertf03]

It is lighter, but you still have to eat right and stretch before installing one


There is some deal with the sm465 that I read about years ago where two sets of gears are located by c-clips and smart transmission shops will machine a spacer to replace the c clips and the result is supposed to be a quiter and easier to shift transmission. If you do consider keeping the 465 you might want to knock some parts out for it while you have access.

[robertf03]

I guess. Mounting a slave isn't that hard. You just have to build or buy a bracket. Man we are such old men. 11pm on a friday night and we're on here discussing ****ing transmissions and bellhousings.

I just got cable modem, so no more downloading porn at 14.4

[jerryg79]

your not going to roll the parts on the garage floor



































sorry i was channeling mike

[davido]

They're essentially the same. No big pros & cons outside of having to make custom parts (if that's really necessary, that's a huge con in my book). It's not hard to get over into R on a 465, I know from experience. Your reaction is going to make the difference, not the gear location. You'll be fast at both once you're use to using it. I like the R in the bottom right just because that's where it typically is anyway, if you're use to driving another stick. The biggest pro of the 420 is probably the gearing. Does it have a backup light switch though?