i have a 1981 f100 4.9l 300-i6 rwd srod manual trans shifts good and clutch feels good but everyone says trans is weak and wont last long so i am just planning on the future i am looking at a few transmissions the zf 5 or zf 6 both the big block versions have external slaves if i am correct i wanna keep my mechanical clutch so i am hoping i could convert 1 of them to mechanical clutch and use a adapter plate to keep my 300-6 has anyone done this if so tips advice and places to buy what i need

i have heard of people using a t5 but if i build up my 300-6 in the future or wanna tow with it would it hold up ???

 

I'm not sure if the srod was offered in 81... maybe its something close.

If it's a stock engine, doesn't see a lot of towing, and you din't drive it like a madman it will last a long time I'm sure.

A 5 speed will require a lot of parts: clutch, driveshaft modification, master and slave cylinder etc. Look through here: https://www.ford-trucks.com/forums/1...ion-swaps.html

Switching to a 4 speed with a low first and no overdrive is basically a bolt in deal except the driveshaft length, and the bellhousing can be swapped to the new one. You have the np435, t18, and t19 to choose from. All 3 are indestructible and pretty cheap usually.

 

i am 100% sure its a srod had to order special shifter saddle bushing to fix loose shifter

 

Trying to use a adapter on a trans with the wrong bell pattern is a very expensive and convoluted way of doing it.

I would get the proper small pattern zf or M5OD and install it the proper factory way. Hydraulic clutches have a good track record for longevity. All you would need is to drill some holes in the firewall to mount the master cylinder for the clutch.

You need to swap pedal assemblies over, but I want to say someone on here did this and they were able to use their old pedal assembly with a few modifications to accommodate the rod to the master cylinder on the firewall. Not sure though, maybe someone remembers this?

 

I found a 88 f250 has zf5 no engine guy said he would deliver whole truck for $1200 anything I need to know before I go look at it for a donar truck

 

RUG SR-OD Single Rail 4 speed overdrive: 1978/83 F100/150; 1978/89 E100/250.

RTS TS-OD Top Shift 4 speed overdrive: 1984/87 F150 2WD/4WD & Bronco.

 

I guess it was offered in 81. I got real confused trying to figure out what my 85 came with.

Anyway if origninal poster has a stock engine and uses the truck for light duty driving I'd just keep it as is, and enjoy the usable first and overdrive.

If swapping to a zf5 be sure that donor truck has a 300six, 302 or 351W. Also note if it is a 2wd or 4wd trans. Also... you have a gear driven speedometer so if you want to keep it working you need to be able to connect it to the trans or transfer case.

 

The later pedal assembly will not bolt in your 86 down truck. But eyeball it, it may have a part or two that would make it all work. Worst case, go to the junkyard and get the pedal assembly out of a 83-86 manual pickup.

If you part out the rest of the truck, your total cost to do this swap will go down dramatically.

 

I have one of those SROD's in my 86 F150 that is currently under rebuild. I drove the truck briefly and the transmission seemed to be pretty good considering the truck had been almost beat to death before I got it.

I keep hearing how weak these transmissions are supposed to be, but when you start to investigate, they are descended from the Ford toploader of 60's and 70's fame which is supposed to be about as bullet proof a transmission as you will find.

So, I have not yet had the pleasure of blowing one up. I'm putting it back in my truck and hoping for the best. One characteristic I noted was that the 5.0/SROD combination was getting incredible mileage in my 86 F150 SWB single cab 4X4 with 3.55 gears.

 

What engine was it? Only the small block ZF will bolt up. The 460 and diesel wont. The small block one has the internal slave.
Also fwiw, the 92 and newer do not have a provision for a speedo cable.

 

My 85 came with whatever the heck this "4 speed overdrive" or SROD transmission is. I got the truck from my grandfather, the trans had never needed work and shifted very well for me. The truck also was ordered with the "towing package", so my truck came with large shocks, large clutch, etc, and this supposed wimpy transmission. I drove it hard and never broke it....

I still have the trans in my garage and I'm itching to buy a second truck with a 300 and using it to make some serious gas milage.

People also complain "it has an awful gearspread"...hold my beer I'll take you for a ride with the np435 heck I'll even smack the dash going into first and the seat going into reverse.

 

It's not an SR-OD .. as it was not used after 1983, except on Econolines.

See post #6 for the RUG SR-OD & RTS TS-OD applications.

 

Been a while had some work done to the old ford and here's my problem I like the trans it shifts smooth no problem there but it's a overdrive transmission with 2.47 rear gears so I'm practically at idle down the road in overdrive I'm only getting 15mpg unloaded with new Carter yfa carb new filters plugs wires distributor cap rotor button and coil ??? Someone told me that with such low rpm I could actually get worse gas milage because I'm not in my motors power band plus I haven't towed anything with it most I would tow would be small trailer and mower or small aluminum boat but will I be burning clutches with them gears taking off ???

 

Most modern cars lope their engines along just like that. And your six is one of the few that can barely turn over like that and keep the truck going. Do not expect to get much over 15mpg, these trucks are heavy bricks running down the road. But after awhile if you feel you need a gear change, you could certainly go up in gear ratios. 3.50's are very a very common ratio.

 

After doing some research and pricing all the transmission options here is what I'm thinking of doing i wanna keep the 300 not planning on any other motor like the simplecity of the motor I'm thinking a close ratio t19 with a 4.02 first gear and somewhere between 3.00-3-55 rear its going to be a Sunday fun drive truck if I wanna save gas I will drive my s10 eventually I wanna get a small camper 5000lb or less gvwr won't be hauled more then once or twice a year other then that only thing I will be hauling is some fishing poles and my dog any suggestions would be great on the build I am really enjoying fixing up the old ford just got new rims and tires pacer bullet holes almost got Everything for power brakes that's next on the list