Ford 4spd to Sierra 5spd gearbox conversion

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hamhonda, Jan 13, 3:18pm
Anybody know much about this conversion!Have just bought a project that has a Cortina 1.6litre mtr & 4spd (motor is a cross flow, push rod type) but would like to convert it to 5spd if possible.Have been told the 5spd is longer so will need to shorten the drive shaft but would like to know if theres any other differences, ie is the gearlever in the same position etc.

bill-robinson, Jan 13, 3:40pm
what is the car!
what do you hope to gain with a 5 speed!
what diff ratio is it using!

supernova2, Jan 13, 3:43pm
I think the 5sp was fitted to the Pinto motor (ohc) not the Kent (pushrod).Not sure if bolt pattern is the same.

hamhonda, Jan 13, 4:05pm
Austin A40, I've got a guy looking into another diff head for me as well.Screams its guts out at top end so thats why I'm looking into it.I would prefer to just do a diff head but have been told getting a lower ratio head will be pretty hard to find

skull, Jan 13, 4:13pm
It will scream even more with a lower ratio, you want a higher ratio. More teeth on the pinion and/or less on the crownwheel. You may be better off trying to fit a whole Ford back axle and brakes into it, they are a lot more bullet proof than an Austin diff, possibly a few more ratio options as well.

unbeatabull, Jan 13, 4:32pm
A 3:1 Ratio will rev less then a 4:1 ratio.

hamhonda, Jan 13, 4:41pm
Yep, understand that.

kenw1, Jan 13, 4:58pm
Is it 13 or 14 inch wheels!To lower the ration on my MM I went to 13" wheels.

hamhonda, Jan 13, 5:01pm
Sorry, I meant to say higher ratio, not lower ratio

bill-robinson, Jan 13, 5:35pm
I would play with diff ratios and wheel and tyre sizes before fitting a 5 speed. The A 40 (farina I hope) should have a full floating axle which is great., and from memory a good selection of ratios was available. Spend time looking and searching before trying anything.Good luck with a great project.

skull, Jan 13, 5:48pm
He needs a higher ratio, it's already revving too high.

supernova2, Jan 13, 6:09pm
I auume the Austin box was a 1:1 top as would be the cortina so motor should not be reving any more than the old Austin one would have.When you say screams its guts out have you put a rev counter on it!

Just remember your 1600 is almost twice the size of the original engine so IMHO the diff wont last long if you cane the snot out of it.

Hope the brakes and front shocks have been sorted as well.

elect70, Jan 13, 6:11pm
Get the 2l pinto out of seirra with the 5 speedcompletediff& all , as the 5 speed doesnt fit thepushrod 1600be a good little Q car,Wont find any alternative diffs headsfor the A40. BTW ifwantrustybut completeFarina i know of 1 ina shed .

sr2, Jan 13, 9:02pm
Cross flow, 1.6, pushrod Cortina! If it's the 1.6 it should be OHC, otherwise could it be the earlier 1.5 pushrod!

skull, Jan 13, 9:09pm
There is a 1.6 pushrod crossflow Cortina, it's a continuation of the 120E motor block style with lots of improvements over the non crossflow motors. Next improvement was a completely different OHC motor, 1600cc and 2000cc.

franc123, Jan 13, 10:55pm
Huh! All the 67 on Mk2 Cortinas, Mk3 up to 74 all had 1.6 xflow OHV engines as an option, and of course all rwd Escorts. I'd agree with simply putting an 2L Sierra and five speed in there, its got to be recerted anyway so you may as well get some more grunt. Its also possible to mate a Zetec engine to a sierra five speed, the later type 9 one IIRC, although there may have to be sump mods and of course a fair bit of messing about converting to EFI.

snoopy221, Jan 13, 11:07pm
Have been told the 5spd is longer so will need to shorten the drive shaft but would like to know if theres any other differences, ie is the gearlever in the same position etc.

Quote

hamhonda (207 )10:18 am, Mon

Gear lever and rear gearbox mount BOTH need to go back roughly one or 2 inches.

Also the bellhousing is a bit fatter and firewall clearance may need modification

And yip the ole 711M 4cyl pushrod

Is the same bolt pattern as the 2/0 litre Overhead cam which had the five speed

sr2, Jan 13, 11:43pm
Woops; just goggled it you??

zetec, Jan 13, 11:58pm
x1
Just of historic interest now, but I don't think the 1500 Kent was a cross flow desigh - the cross flow head was intrduced in the Mk 2 Cortina in 1300 and 1600 Kent engine form, along with the bowl in piston, that was in 1968, I recall it because my father bought one new.

rob_man, Jan 14, 12:13am
That sounds about right. I'd hesitate before dropping a 2L into an A40 because they're so much heavier than a Kent. I'd be thinking of a Toyota 5 speed behind the 1600 if it was mine and possibly an LSD from a Terios.

quickstitch, Jan 14, 12:29am
the kent and pinto shared the same bellhousing pattern from memory, its been 26 years since my last escort repower but im sure i bolted a 2 litre motor into an escort using the escort box.moving the gearstick hole is an easy obstacle. Changing the clutch from hydraulic to cable is the hardest part but nothing that cant be overcome with some thought

snoopy221, Jan 14, 12:54am
Crickey Dick -Yup Quickstitch.
The ole mk2 was a 16hundy with a separate bell housing with hydraulic clutch.
The ecky's and go tina's had cable-

But what the heckeroonie was an

A40!
cable or hyd!-either way -one should be able touse the bellhousing that is existing.

jmma, Jan 14, 12:58am
A40 is hydraulic, like most of the old stuff(o:

hatchback, Jan 14, 1:15am
I was thinking Toymotor 5 speed too, a w55 not an old cast celica w50.did Ford make a good 5 speed!

rob_man, Jan 14, 1:29am
Probably but I don't know much about them, I'd be thinking about the power loss through too heavy a box as well, which the Sierra box might well be. If the ford box bolts up though it's probably the easiest route to go down.