3-speeds 4 speeds and more

A man asked if a chevy 4 speed would bolt to a BOP bell housing and I responded yes as he had a buick 350 engine. when GM began using OD transmissions that bolt pattern changed and the rear main seal also changed to a one piece design.as did the Flex plate and or the Flywheel for awhile the bolt pattern at the block remained the same but the trans did not. then it turned to what constituted a 3 or 4 or 5 speed trans and what or where OD began, I say it begins after the 1to1 is acheved regardless of how many gears are in the case and that any seperate housing or gears is another unit so tell me my misconception and I will learn something new,as a day without learning somthing New is a wasted Day,I did not intend to PO any one and was only trying to help.

Paragraphs. They help.

I will try that. But no matter how many spaces I put in between sentences it all jams togeather. there are at least 3 spaces after each period but it post's with none

My understanding is the BOP (Buick, Oldsmobile, Pontiac, silent Cadillac) shares 4 holes and the pins with Chevy but an adapter or different bellhousing is needed to make it work.

if you hit the enter key twice after a paragraph, it spaces out nicely.

Thanks Evan I will try that.

Stampie that is true, the Bell from a chevy to a BOP Doesn't Bolt Straight to it but the Tranny's ( Manual)are the same I may have Mis-read this But thought that was the Question.

Thanks Evan

By your logic, a Tremec TR-6060 6-speed is a 4-speed (It has 2 overdrive ratios) and a T-5 is a 4-speed as well. Sorry, unless it's a separate bolt-on overdrive unit (Like a Chicago Mark E or a Gear Vendors) then you count all forward gears. Underdriven, overdriven and direct-drive, they are all FORWARD ratios, which is what you are counting. Even the weirdo A-833 is a 4-speed, because despite the swapped 3/4, it still has 4 forward ratios and they are all within the case, it's not a 3-speed with an overdrive unit bolted to the back. The Corvette/Doug Nash 4+3 is a 4-speed, it just has an overdrive unit bolted to the back that can be engaged in 2,3 and 4

In reply to NickD:

Im with Nick. X forward gears=X speed transmission. A t5 is a five speed, not a four speed plus overdrive. A sm465 is a four speed, not a three speed plus creeper gear.

How many forward ratios can you select in the main gate with one lever?

Would an old Chrysler Feather Duster 4-speed gearbox be a 3-speed under your system? It was mechanically identical to their 3-underdrive + direct four-speed, but they put an overdrive gear in it for 3rd and flipped the shift linkage so you selected the gears in the normal order - 1st, 2nd, 3rd (direct), 4th (overdrive).

In reply to NickD:

I think you misunderstood his statement about overdrive. If I understand it right he means that overdrive gears start once the gear ratio is below 1 to 1 not that the gears below 1 to 1 are the only ones that count. And that it's only an overdrive transmission if the overdrive gears are inside the trans case. Neither of which do I think are controversial statements.

Again I am Old, when transmissions became capable of dividing the forward motion into 4 forward raito's to Improve acceleration it was a big deal but 1 to 1 was the final drive raito,and back then an OD unit was mounted behind. Splitting the gear box into multiple forward gears is done to get them up to speed and OD's are mostly a crusing or fuel saving device not a performance option,you can get a less powerful car to perform better by adding gears BEFORE the 1 to 1 and using lower rear gear numbers then adding Od to put the engine into a zone where you can stand to drive it on a public road. but Hey The smallest engine I am using is 7 Litre's, But That just changed Today as I just Bought A 5.3 powered car, with 12 Cylinders .

In reply to GTXVette:

The cylinder count offsets the smaller displacement. Congrats.

I'm kind of aware of what GTX is talking about. I remember when trucks (especially) had all manner of transmission choices.

There were 3-speeds, of course. But there were all manner of transmissions with 4 forward gears - 3 normal + a granny low, straight 4-speeds, and 3 + o/d. There were 5-speeds in some heavier-duty trucks that had granny gears and overdrives, too.

Coming from the world of RWD Volvos, we certainly made the distinctions. The M46 was the old M45 4-speed with a Laycock overdrive on the back. We always called that a 4+OD, whereas the M47 had all 5 forward gears in the case, so that was a 5-speed.

I drove a MACK Dump Truck w/a 5speed trans and a 2 speed rear,it wasn't called a 10 speed.but they would Go like Hell I reverse Hi