gear swap and engine swap

[hoss]

alright i have a 84 bronco with a 300 I6 engine and the front axle is a dana 44 ifs and rear is a ford 8.8 i currently have a 3 inch body lift on it with 1.5 inch taller front leveling coil springs with 36 12.50 Super Swamper TSL/SX tires i still have the stock gears in both the front and rear axle and i know the transmission is either a T-18 or T-19 not sure which need help identifying it anyways any suggestions on which gears i should put in the axles until i can perform the task of changing them to rockwell 2 1/2 ton axles with deuce and a half suspension and can i swap the motor for a 400M?

 

[Seabronc]

Welcome to the Zone > . I know you will find some 400M fans here, but the 351W has more aftermarket support and if you want to go for BIG why not a 460. /emoticons/[email protected] 2x" width="20" height="20" /> That 300 I6 ain't no slacker if you want a off road machine.

Good luck,

>-

 

[hoss]

i agree the 460 has more power but i have had many dealings with that engine and do not like it at all we have a f350 with a 460 and it gets 4 miles to the gallon. i agree the 300 I6 ain't no slacker but recently me and some friends went down to our usual mud pit and i had to pull one of them out and she was strainin that i didn't like. with 400M it has big block power in a smaller package but i still want to can it be done and how easily?

 

[Justshootme84]

As for the tranny ID, look for a code in the door jamb sticker or a tag on the tranny housing. There is also a recent link to Novak Enterprises in a post with some pics onhow to ID your tranny (just do a search or browse the forum).

Running 36" tall tires with your stock 3.08 gears is putting a real strain on the motor and putting it out of it's powerband. To correct that, I would suggest at least 4.56:1 or possibly 4.88:1 as the new ratio. You will need a new carrier for the front axle for that large a swap difference.

The 400M is a decent powerplant as is the 300 I6, but the bolt pattern for the transmission is different (big block vs. small block). If you want to do the swap, it's possible, but you'll also need new motor mounts and do alot of work. Just depends on what kind of deal you can find on a 351W or 400M or 460 or 429, etc. There is also a link to engine specs (HP & torque) if you do a search. You'll be surprised by the lack of HP and the relative similarity of the 300 to the 351's. IF you plan to run Roclwells-I'm looking at that mod, too-you might want a 350-400Hp motor like a Stroker 351W.

 

[hoss]

well i'm having a 400M given to me versus purchasing a 351M to be rebuilt but i'm not sure about what the door jamb will tell me because i'm not entirely sure this was the stock engine and or transmission this engine was rebuilt about 20,000 miles ago acording to the odometer and the man i bought this truck from i do agree on the exceeding the power band thing but it takes off fine and has no problems running 70 down the interstate the transmission as i said is a four speed with first as a granny gear if that helps any. i talked to a person who used to do this and he said if the transmission would bolt up i would most likely just need a new bell housing and clutch and new mounts whether thats true or not i don't know

 

[ocalabronco]

tranny wise, you probably either have a T-19 or NP435. do you have to double clutch in or out of first gear? NP435's weren't synchro'd (well, most werent), so you had to double clutch first gear. T-19's were synchro'd. thereinlies your answer. and why do you need to go all the way to rockwells? planning on runing 49's or bigger? youre gonna been alot of lift to clear those toploaders

 

[Justshootme84]

engine specs

Found the link for engine specs. Looks like 32 more HP for the 400 over the 300, but only 149HP for the stock '78 400M, and the torque peak is at a really low RPM. if the engine is a freebie, you can't complain too much!!! You will still need the bellhousing with the bigblock bolt pattern, but your T-18/T-19 should bolt up since they were offfered on that motor. You need to find the ID tag or look for any numbers on the tranny to properly ID it. Also look for the axle ID tags while you're under there and ID your t-case. Whatever that model is will bolt up to any Ford tranny, but you may want to know the modlel to figure your final drive ratio.

 

[hoss]

thanks for the advice one more question if i did swap for the 400 would i still have to change my gears in the axles

 

[hoss]

ocala to answer your question about the 49's yes i do plan putting those axles and tires on asap after i get out of school with 10 inches or better plus the 3 inches of lift i already have. we have some deep mudholes out here where i live. any more questions?

 

[Justshootme84]

thanks for the advice one more question if i did swap for the 400 would i still have to change my gears in the axles

31419[/snapback]

​

YES.

 

[hoss]

i have identified the transfer case its a New Process 208 and i'm working on identifying the transmission where would i look for the serial number identification plate on it all i can tell you about it is that its a 4 speed with granny gear internal linkage transmission

 

[hoss]

i looked in the door jamb and all it told me under transmission was A whatever thats worth and whats the easiest way to tell what spline my axles are

 

[ocalabronco]

chances are very good your 9" rear is 31 spline

 

[ocalabronco]

and the tranny sounds like an NP435

 

[hoss]

i checked the door jamb and looked up the code for the transmission and it says it is a NP435 what is the difference between that one and the T-19? it's an 8.8 open differential according to the axle code with 3.08 gears

 

[ocalabronco]

an 8.8 in an 84? thats a new one to me.do this for me, crawl underneath and look at the axle. does it have an access cover bolted to the back of it, or is the housing one big unit with a 3rd member bolted to the front with ~12 bolts? the difference between the NP435 and the T-19 is all T-19's were synchro'd first gear, whereas only the newer NP435's had a synchro'd first gear. can you engage 1st gear with only one push of the clutch, or do you have to engage it twice between first, nuetral, and second?

 

[hoss]

yeah it has an access cover as far as i can tell the third member is non-detachable and yes i only have to push the clutch one time to get into first. why does it surprise you that it has an 8.8 i was under the impression that was stock

in all broncos from that year

 

[Justshootme84]

Ford started putting the 8.8" in Broncos in 1983, but some up to 1986 still had the 9". And it does look like you have a NP435. Look on the passenger-side of the tranny for the NP logo, it looks like a sunburst, similar to the NP208. ON the tranny it's a raised casting but still will say "NP". Back to your original question, the 3.08 gears should definitely be changed out for 33" or larger tires to improve performance.

How did I know the ratio in my original post? :-" :-"