Single Rail/ 4.1 '86 XF questions

[Anonymous]

Good evening gents,

I'm taking this opportunity to pick your brains a bit. The XF that I'm currently driving is fitted with a 4spd single rail. To late it is begining to become quite stiff to put into 1st and 2nd gears. I.e. on the slow down for a corner the car has to be almost completely stopped before second can be selected. To get to my question, as an estimate how difficult/expensive would it be to change the selector/syncros in my gearbox?

In recent weeks I've been a little spoilt driving a mates MX-5, whilst I will never get use to draging my ass on the ground I did enjoy playing with gearbox, what options do I have with single rail to reduce/increase/whatever the motion of shifter so that I can get a little closer to that feel?

On a different note, different people have mentioned using 250 cranks, 200 conrods, with suitable pistons. My question is what change in performance are you expecting to gain from this combination, won't this reduce the cubes and what options are there for pistons with this combo.

I'll leave it at that for now.

Cheers

Arch

 

[Anonymous]

Arch,
Noel here.
What is your gearbox doin as you try to downchange into second and first?
Is it just difficult to select the gear (baulking) or is it making a grinding noise?
I will hazard a guess and say that there is no noise just a stiff down change.
Try once on the down change to release the clutcch in neutral aan dblip the throttle and see if the gear is easier to select.
If that does help both first and second gears.
Then either the old oil is too thick or the syncro assembly is weak/slow.
A simple fix!
Drain out the oil.
Look in it for sparkles.
Metal shavings indicating wear/damage.
If there is metal particles then the gear box must come out and be rebuilt.
If there is none and the oil is clear.
Add one litre of automatic transmission fluid and top up the rest with the correct oil.
Road test this combination and see what happens.
This could fix the problem or reduce it.
If it has made no difference then the gear box has an appointment with a rebuilder.
Hope this helps.
Noel.

 

[xctasy]

pjarcher said

On a different note, different people have mentioned using 250 cranks, 200 conrods, with suitable pistons. My question is what change in performance are you expecting to gain from this combination, won't this reduce the cubes and what options are there for pistons with this combo.

This is all secrete society stuff for people with more dollars than cents. (Well, at least thats what I think having done almost the same thing myself!). Lots of termino;ogy here, sorry.

The block, bore and basic depth of the piston is the same with Aussie post 1970 200/3.3 and 250/4.1 cross-flow engines. Oh sure, there is a bigger trough in the bigger engines piston, and a smaller one in the 200, but they are just the same aside from that. Only difference is the rod length and crankshaft.

The stroke is 99.314 mm in the 250, and 79.400 mm in the 200, a difference of 19.914 mm. ( The 250 had 149.352 verses the 200's 159.309mm). The rods are exactly half that shorter on the 250..9.957mm. The deck of the engine is about 240.513 mm. Both pistons are about 40.64 mm tall. The pistons stop about 0.86 mm short.

What ACL did back in 1999 after the AU came out, was take some over size OHC six cylinder pistons, which are about 30 mm tall, and added them to there list.

What you do is take these 'shallower' pistons and just add the post 1970 200 con rods. Capacity, static compression ratio, that is, the amount of squeeze in the cylinder, doesn't change at all, and all is the same at rest.

But when its run, you get extra rev range and power. But it's not a lot of power, and is only accessable if you are using the engine hard. The engine will be smoother, carries a slight loss of dynamic compression, and this makes the engine more reliable. Piston carries 6 to 7% less side thrust, and the rod angularity is less at maximum piston speed. And that's it.

As an example, Ford spent over 50 million on retooling the AU Falcon for its 154 mm rods, and reduced the side loads by a tiny 3%. The swapping of the 200 rods into the 250 can be done for a rebore, rebearing, a set of ACL Race pistons and a set of 3.3 con-rods...easy to find, one quarter of XC,XD,XE and XF engines were so equiped. Bonus is you get a much better rod length the stroke ratio than any 4.1, 3.9 or 4.0 Ford.

 

[aussie7mains]

In my experience its more likely that the clutch isnt relaesing fully, check your clutch adjustment.
A7M

 

[Anonymous]

Thanks Gents,

I put the car on ramps on Sunday to drain the gearbox oil only to find that the previous owner has rounded the drain plug off. I'll drop it into the mechanics to have that ripped out later this week. Will I was at is I checked the oil level and it was low. 1 litre oil later(50% of the capacity according my workshop manual) and the gearbox is shifting a little easier. I don't hold a great deal of long term hope for this gearbox as I have no idea how long it has been running low on oil.

XECUTE,

Thanks for the response on the 250 crank/200 conrod combo. To summarise by using 200 conrods I should be able to improve my rev range whilst reducing wear and tear. Sounds like I have a new project.

Arch

 

[Anonymous]

We have a single rail in the Transit, and it baulks going into first. More worrying is that when you change quickly from first to second there is a crunch. It is not there if you change slowly. What oil are you supposed to use? I have been told 20/40 and EP80/90, which is what it has now.