I have a 85 carb 300 with a 4 spd with od 4x4. it is geared too high so im thinkin im gonna swap it out for a 5 spd out of a later model efi 300 4x4 will it bolt up? and is this a good idea?

 

It'll depend on the transmission you get. If it's the Mazda 5 speed, it'll have the same gearing as the one you currently have, just spread out to 5 gears instead of 4. If you get the ZF-5 speed, it'll be the same transmission you currently have, except it'll have an additional granny gear.
Either way, neither will really change your overall performance unless your only issue is off the line (in which the ZF will help.)

The biggest factor you'll run in to is whether or not you currently have a hydraulic or mechanical clutch. If you have a mechanical, you'll have to convert it over to a hydraulic setup to use either of the trannies. Other than that, they're pretty direct swaps with minor issues like crossmember location and driveshaft length.


All in all though, if gearing is your issue, you may just be better off regearing. If you have a 3.08 final, go with a 3.55. If you have 3.55, go with a 3.73, 4.11, etc.

 

Note quite on the ratios.

The 4OD: 3.25/1.92/1/.78
The Mazda: 3.91/2.24/1.49/1/.80
The ZF: 5.72/2.94/1.61/1/.76

Mostly road, no heavy towing or loads? Mazda. Will still be ok off road due to low range in the tc if needed. 3.91 is a bit better than 3.25, and you get rid of the god-awful 2nd to 3rd gap in the 4 speed OD.

Heavier loads, towing, lots off road? ZF. Still fine on the hwy, now you have a real creeper gear, and you still reduce the 2-3 gap.

My '85 had a juice clutch with the 4 speed OD. Not sure how that set up will match up with the ZF or Mazda set up, but it will be closer than a mechanical set up!

IMO, the gearing idea is sound, but the 4 speed OD will still have the gap issue and a tallish first. Heck, do both.

 

Mine has a hydralic clutch and i dont think the tranny i found is a mazda. Where i need the low gear is off the line pulling. first gear in my current 4 spd is just too tall. its about right when im not hauling or pulling but when i am it just dont work. is there an easy way to tell the mazda from the zf?

 

I guess I meant more that the 4OD and the Mazda both had "street" 1sts (no granny). They aren't as close as I remembered.




If your issue is mainly off the line with heavy loads, the ZF will do you great, that and it's a bit more heavy duty than the Mazda.

There should be some identifying numbers on the casing, but from what I hear, the ZF actually has a "ZF" cast onto the side of it.

 

What year did they start makin the bell housing and tranny in one piece?

 

Go with the ZF. I swapped a ZF in place of my mazda. The mazda has too many problems and is a much lighter duty transmission. And you will be thankful for the lower first gear in the ZF, it isn't quite a granny, but its close.

 

'87-'88 for these transmissions to go to integrated bell. Pics here:

Domestic Truck Tranny Guide

You'll see the difference between to two--big enough diff to spot from a distance. Look for the ZF in F250 and above vehicles with the 300 or 351W.

 

well the transmission i found is in a 150. doesnt that mean it wont be a zf? if so what would it be (besides a mazda?) i guess the slave cyl is in the bell on the zf?

 

Unless it's been swapped in, it won't be a ZF in an F-150. If it's a 5-speed, it's most likely the Mazda.

 

ok ill check. thanks for tellin me about that. will it say mazda on it?

 

ZF 5 speed manual – | ClassicBroncos.com Tech Articles

 

What is the first gear ratio for one of these mazda transmissions? and what is the first gear ratio in my transmitission (4od)?

 

You got the guys in post #3 and #5 both kill-filed, or what? ;)

Butthead in AZ
NP435 = 6.69 3.34 1.74 1.00 r8.26
T18 === 6.32 3.09 1.69 1.00 r7.44
4OD=== 3.25 1.92 1.00 0.78 r=?? (from "83's" post)
Mazda = 3.91 2.24 1.49 1.00 0.80 r3.39
ZF ==== 5.72 2.94 1.61 1.00 0.76 r5.72

 

Is the 4od a better transmission than the mazda?