Author Topic: F25 to F28 gearbox mod  (Read 31805 times)

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Offline V6-ER

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F25 to F28 gearbox mod
« on: January 21, 2007, 18:38:14 PM »
If in the future i decide or can get my hands on a turbo F28 gearbox apart from the 2wd conversion needed would i still be able to use this gearbox with my courtenay billet lightened flywheel for my V6 ????

I have heard different things on the subject so im now unsure so if anyone can confirm for me cheers.
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Re: F25 to F28 gearbox mod
« Reply #1 on: January 23, 2007, 08:21:17 AM »
I've eard that you need to do a small flange to instal the gearbox on the motorblock and need to use turbo flywheel but I don't know if V6 and Turbo engine have the same flywheel.

Offline MarkV6

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Re: F25 to F28 gearbox mod
« Reply #2 on: January 27, 2007, 00:20:42 AM »
The F28 will mount in the same place as the F25 but the F28 is shorter so it is easier to move over the engine so you don't have to faff about finding different length driveshafts.

F28 Gearbox - There is a mechanical speedo version and an electronic speedo version. Blanking plates can be bought or speedo drive holes drilled but it makes sense to buy the right version to start with.

Spacer kit - I got mine off migweb for

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Re: F25 to F28 gearbox mod
« Reply #3 on: January 27, 2007, 00:30:54 AM »
Nice one MarkV6,
                     A good detailed guide there, it will come in handy for me when i put an F28 6 speed box on my V6. Cheers chap! ;D

Offline V6-ER

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Re: F25 to F28 gearbox mod
« Reply #4 on: January 27, 2007, 10:26:03 AM »
Cheers mate karma added. Nice description.
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Offline mircea.armeanu

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Re: F25 to F28 gearbox mod
« Reply #5 on: February 28, 2012, 14:18:01 PM »

Note that none of the bolt holes will line up around the bottom of the bellhousing as the oil sumps are different between a tubby and a sixer.


I know the post is quite old, but I'm going to fit an F28 to a C25XE and I am researching the procedure... and this alignment issue, can it be fixed (drilling needed?) or just fit it without those screws?
Thanks!
Opel Calibra V6 1995 C25XE + F28
Wanting : 3.0L V6 & 4x4

Offline archiebroge1

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F25 to F28 gearbox mod
« Reply #6 on: February 28, 2012, 17:11:49 PM »
I know the post is quite old, but I'm going to fit an F28 to a C25XE and I am researching the procedure... and this alignment issue, can it be fixed (drilling needed?) or just fit it without those screws?
Thanks!
Seem an expensive mod for a c25xe bud f20 it a good mod an more than capable of handling the power. Plus will bolt straight in
Cant stop got 2 300bhp turbo projects to build

Offline Butcher

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Re: F25 to F28 gearbox mod
« Reply #7 on: February 28, 2012, 17:21:34 PM »
Seem an expensive mod for a c25xe bud f20 it a good mod an more than capable of handling the power. Plus will bolt straight in

Only problem with the f20 as I'm thinking about going down this route is you loose the wider ratio 5th that the f25 has so motorway cruising will be at higher revs for the same road speed, but you can get round this by fitting the wide ratio final drive from an f18wr to keep the 5th gear revs down and hopefully mpg on a run won't be too affected.

Offline mircea.armeanu

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Re: F25 to F28 gearbox mod
« Reply #8 on: February 28, 2012, 23:23:06 PM »
Seem an expensive mod for a c25xe bud f20 it a good mod an more than capable of handling the power. Plus will bolt straight in

I bought a F28 gearbox in may 2011... I have the gearbox... so don't need F20... if I'd wanted 5 speed I'd get another F25.
I want F28, 6 speed and in the future 4x4, so... how about the original question? Do I need to drill holes for those bolts, or the other ones will hold?
Thanks!
Opel Calibra V6 1995 C25XE + F28
Wanting : 3.0L V6 & 4x4

Offline Martin.

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Re: F25 to F28 gearbox mod
« Reply #9 on: February 29, 2012, 00:00:15 AM »
I bought a F28 gearbox in may 2011... I have the gearbox... so don't need F20... if I'd wanted 5 speed I'd get another F25.
I want F28, 6 speed and in the future 4x4, so... how about the original question? Do I need to drill holes for those bolts, or the other ones will hold?
Thanks!

Like you say...you have a F28..... your fitting it......you don't want a F20 because you want 6 speed.......how about you fit it and answer your own question and if it needs drilling...then drill it... (all your going to need is a drill, so not allot to get prepared for!)
good luck with fitting 4x4 to a non 4x4 car...oh yeah all you need is a angle grinder.
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Offline Butcher

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Re: F25 to F28 gearbox mod
« Reply #10 on: February 29, 2012, 00:14:43 AM »
Like you say...you have a F28..... your fitting it......you don't want a F20 because you want 6 speed.......how about you fit it and answer your own question and if it needs drilling...then drill it... (all your going to need is a drill, so not allot to get prepared for!)
good luck with fitting 4x4 to a non 4x4 car...oh yeah all you need is a angle grinder.

LOL ;D

Can we have this in the guides section ;D

Offline mircea.armeanu

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Re: F25 to F28 gearbox mod
« Reply #11 on: February 29, 2012, 00:46:29 AM »
Dear Martin,

I needed some answers, and I thought I could  find them on " Biggest Calibra forum", no bad manners (BM) intended, just presenting the situation to avoid further useless discussion .

If you fitted an F28 on 2.5 V6 and knew the answer, you could just answer...
The purpose of my question was to find out if the whole thing will hold, it is pointless to drill out the gearbox without any need.  And furthermore, I like to do a job well prepared, and in Romania NO ONE did this before, so I cant ask anybody.
So... no need to pollute this thread with childish discussion!
I'm sorry if I offended someone!

"All you need is an angle grinder" seems like an answer... no need to drill?

Off topic: Don't need luck to fit 4x4 on non 4x4 shell, this could be discussed on another topic.

Sorry if I offended  any  of you, if you were in Romania I'd invite all those offended  to  a beer (my treat) ;D

Kissez! U guys are the best! 
Opel Calibra V6 1995 C25XE + F28
Wanting : 3.0L V6 & 4x4

Offline Martin.

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Re: F25 to F28 gearbox mod
« Reply #12 on: February 29, 2012, 01:01:51 AM »
Dear Martin,

I needed some answers, and I thought I could  find them on " Biggest Calibra forum", no bad manners (BM) intended, just presenting the situation to avoid further useless discussion .

If you fitted an F28 on 2.5 V6 and knew the answer, you could just answer...
The purpose of my question was to find out if the whole thing will hold, it is pointless to drill out the gearbox without any need.  And furthermore, I like to do a job well prepared, and in Romania NO ONE did this before, so I cant ask anybody.
So... no need to pollute this thread with childish discussion!
I'm sorry if I offended someone!

"All you need is an angle grinder" seems like an answer... no need to drill?

Off topic: Don't need luck to fit 4x4 on non 4x4 shell, this could be discussed on another topic.

Sorry if I offended  any  of you, if you were in Romania I'd invite all those offended  to  a beer (my treat) ;D

Kissez! U guys are the best! 

I'm afraid no I can not tell you if you need to drill new holes. If I new I'd most certainly let you know.
You may find some one, but from the way I read your post it seemed like that box is going in one way or another. and I'm sure as in most cases if you or anyone put enough effort into it anything can be possible. I don't think you ll find all your answers to this in a box so to speak. so in the politest way. make a start on and over come each step and hurdle as it comes.
even do a guide as you go.
yes fitting 4x4 to a non 4x4 is another topic. been covered many times be for.
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Offline mircea.armeanu

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Re: F25 to F28 gearbox mod
« Reply #13 on: February 29, 2012, 01:17:11 AM »
I'm afraid no I can not tell you if you need to drill new holes. If I new I'd most certainly let you know.
You may find some one, but from the way I read your post it seemed like that box is going in one way or another. and I'm sure as in most cases if you or anyone put enough effort into it anything can be possible. I don't think you ll find all your answers to this in a box so to speak. so in the politest way. make a start on and over come each step and hurdle as it comes.
even do a guide as you go.
yes fitting 4x4 to a non 4x4 is another topic. been covered many times be for.

I'll make a complete guide as I go on, this was planned a long time ago, even if this topic was covered before (I think I can make a positive contribution to this awesome forum).
I'm very excited about this mod... hence my desire to know all the facts and finish the swap in 2-3 days (I have a feeling it will take longer) but it will be done (F25 gearbox is ruined/broken)!
Cheers!

Opel Calibra V6 1995 C25XE + F28
Wanting : 3.0L V6 & 4x4

Offline Martin.

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Re: F25 to F28 gearbox mod
« Reply #14 on: February 29, 2012, 01:25:52 AM »
I'll make a complete guide as I go on, this was planned a long time ago, even if this topic was covered before (I think I can make a positive contribution to this awesome forum).
I'm very excited about this mod... hence my desire to know all the facts and finish the swap in 2-3 days (I have a feeling it will take longer) but it will be done (F25 gearbox is ruined/broken)!
Cheers!



of course you can!!
There is nothing at all wrong with asking for advice or if anyone knows.
One one hand hope you get it all done in the 2-3 days, but don't go cutting corners in a excited rush chap. do a good job on it and keep us informed on your progress. and think one day. someone else will be in your shoes wanting this info and it will be there for them. 

your last comment is the attitude to have  ;)
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I have not failed. I've just found 10,000 ways that won't work.