F13 box and a 4 speed diff..

[01dleigh]

I have heard a few guys talking about the diffs out of a 4 speed box being handy in a F13 box is there any truth in this?

[bazil]

4.18 diff into a F13 CR box yes

[01dleigh]

well i have got the 4 speed box in the car at the moment and have the f13 as a spare and someone said to me to use the f13 with the other diff..
well thats my weekend planned now :)

[bazil]

Make sure the F13 is a CR box and not a WB box

[01dleigh]

will that be stamped on the gearbox?

[bazil]

Yes, I have wrote and article on how to identify your F13, on e a mod approves it you can view it.

[bazil]

Look here

http://www.pngclub.com/forum/showthread.php?182786-*INFO*-how-to-tell-F13-ratio-s

[Jack]

once a mod approves it you can view it.
Oh how fast we work round here. lol

[bazil]

lol that's what I call good service lol,

I got my hands dirty getting that picture :(

[01dleigh]

thats great cheers mate off to the shed to go find out! Great help cheers!

[bazil]

No probs,

[01dleigh]

what diffrence will it make putting the diff from the 4 speed box? is it a worthwhile procedure? :S

[bazil]

On a cr box it will improve acceleration

[01dleigh]

Thats what i wanted the answer to be :) cheers

[matthew172]

how will it improve acceleration? larger crown wheel on the 4 spd diff? if so does the pinion not need changing too ?

[bazil]

I thought that would have been obvious, but yes CW and pinion need changed

The 4.18 ratio is higher that 3.74 the CR box ratios are shorter than WB ratios so overall acceleration is improved.

[Dan]

Its been donkeys years since i faffed around with all this stuff but please dont forget the stamp on the box isnt always true, remember these box's have been around for an age and even if it says 4.18 its not a done deal. Out of everything to be done a MUST do job is to double check by counting the teeth on the pinion and then dividing it by the amount of teeth on the crown wheel, thus giving you the final drive figure of that pair.

[bazil]

True, but I have a REALLY ****ed up box,

It's stamped C374 so should be a gsi/gte box BUT 4th and 5th gear are the same? Wtf I thought ?

Turns out that the gearset is a WB 5 speed with the 5th gear from a CR box and 3.74 diff

So it turns out 4 th on a WB and 5 th on a CR are the same ratio giving me a 4 speed box with 5 gears lol

[phazer]

^^ Velos said to me a few times about boxes being a bit random. It's obvious if you think about it but on the production line it seems if a part ran out Vauxhall/Opel just bunged on what would fit from another model/part. Most times no-one would be any the wiser and it's probably cheaper to pay a dealer to rectify later than hold up the line.

[mowgli]

but you wouldn't factory build a box with 4th & 5th the same..... they would have used a different sub assembly line to make cr boxes, as the main wr box was way more common... bazils suffers from someone wanting economy and swapping the 5th gear from a wr to a cr... then making a box up with what was left & selling it on...

[phazer]

I wan't commenting on that specific box, I was more commenting on the fact that the boxes are hit and miss and don't necessarily have inside what the stamps suggest. That said it's not impossible it was factory build that way.

I have to say, why would they run two lines to build in essence the same thing? Even then manufacturing processes were quite mature. You have seen a modern production line I assume? Each car is different, different model, different spec, different engine. The parts arrive just in time for the build of that specific item. The same goes for the suppliers that build that large sub components. Kanban and the Toyota models is what you need to look at if you're interested.

[mowgli]

production lines haven't been that special for a very long time, they just use new names for stuff...... they use computers & barcodes these days, before that, they just used storemen & clipboards to get the same result....

i worked at unipart when they were pioneering the 'just in time' principles & they did training courses on the subject.... i'd been working in small stores and there was nothing new being taught by this bloke in a suit.. ...BL put this country back about 30 years by having 6 months of stock in a warehouse next to the plant, but they did that because of the risk of strike action, seriously.....

i'm saying that the main production run on f13 5 speed boxes would have been wr, for economy cars.. the cr would have been a bit more of a special build, so would have been made on a different sub line. then they would have been labelled up & taken to where the engines were joined & the front suspensions were fitted up.

[faker]

Am I missing something here? I thought the initial question was - any benifit fitting the diff from a 4 speed into an f13? are all 4 speeds not a 3.98 or 3.74??? Only early 1.3 sr and sport came with 4.18s. Any f13 from a mk3 astra 1.4 come with a 4.18 as standard.

[bazil]

I assumed the op was talking about using a f10 4 speed diff into a F13 box as that's the usual conversion.

[mowgli]

and if you can find one, the old mk1 astra estates had a 4.4 diff & then there is the 4.53 that was fitted to some mk1 astras & also to some 1.0 12v corsa b/c's