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(Post Link) post #1 of 31 Old 03-01-15 Thread Starter
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6 speed 20 valve jtd gearbox on a 10 valve jtd?

Hi people,happy new year,to you all !
Out of curiosity does anyone know if the 156,2.4 20 valve 6 speed gm gearbox will fit onto the 2.4 10 valve engine?
Obviously(I think?) flywheel,clutch and concentric slave cylinder from the 20v would have to be used,if the bolt pattern of the flywheel is the same? Would probably have to use the 20v's allegedly chocolate driveshafts,too.
Also is 6th a taller gear than 5th on the five speed?
I know the 1.9 16v six speed fits,but is too long on the five pot engine,so you lose a little steering lock . . .and there ain't much to start with so to overcome that you need different offset wheels and possibly spacers,but think that may put extra strain on the wheel bearings and bushes/balljoints . . . .

Any ideas/thoughts,folks?
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Speed range (max speed on gears in km/h / mph):

I: 43 / 27 ....... 38 / 24
II: 72 / 45 ....... 71 / 44
III:119 / 74 ...... 110 / 68
IV:166 / 103 ...... 152 / 94
V: 212 / 132 ...... 192 / 119
VI: -- / -- ...... 232 / 144

speeds at 4500 rpm for 140 bhp 10v and 175 20v

pretty comparable to the speeds a 1.9 16v box would give you (1st to 5th 10% shorter, extra 6th 10% longer than old 5th gear)
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yeah it fits , but i'm not sure the centre part of the right axle will fit the engine , but probably yes.
You'll also need the subframe and gear linkage
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(Post Link) post #4 of 31 Old 05-01-15 Thread Starter
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Thanks guys,
Looking at those ratios,either six speed box will give better acceleration with the bonus of a longer top gear for economy,
I think I understand why no one puts the 20v gearbox on a 10v. It needs too many parts changing,so it is easier just to use the 16v six speed and just change wheels!
I have also heard that the gear change quality of the 20v is not so good.
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a good c630 or 530 is just a very nice gearbox, imo.... hard to beat
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F40 gearbox in a 156 is not great at all in my opinion. It is better in the 159, marginally. I just don't like how it feels to use, doesn't feel natural.

5-speed 10v box or 6-speed 16v box are so lovely to use in comparison.

If you're going to use the 6-speeder from a 1.9 16v then try and get yourself a 156 GTA gear stick/shifter mechanism, not only does it have a nice 6-speed gear knob but its also shorter in height with a quicker throw. I put one of these in my old 10v when I fitted a GT Q2 6-speed box.

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(Post Link) post #7 of 31 Old 09-01-15 Thread Starter
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I have been wondering if there was a short throw gear stick assembly,the standard one always felt slightly out of keeping with the rest of the car.
Thanks Pud237, the only trouble is that my shopping list is growing . . . . !
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Add a Quaife diff to your shopping list too!
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(Post Link) post #9 of 31 Old 09-01-15 Thread Starter
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Well,if I go down the Quaife route,I think Eibach arb's (or more realistically GTA's?) need to go on the list,too . . . .
This list is growing . . . .
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Garage
... and neverending
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(Post Link) post #11 of 31 Old 09-01-15 Thread Starter
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Yan.ko you are not wrong! If I ever got to the end of the list(there's no chance!),I would be bored!
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I had Eibach ARBs on my 2.4 10v with 6speed box, Q2 & KW V1 coilovers, at the same time I had just the rear Eibach ARB on my 156 GTA, also with Q2 and this time with Eibach Pro system shocks & springs. The GTA was definitely less fidgety over rough surfaces despite the 10v having 40kg taken out of its engine bay. I put that down to the stiffness of the Eibach front bar vs the stiffness of the GTA bar.
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Cornered flatter with the pair of Eibach bars though, but steering felt sharper with just the rear bar, almost a 'steer from the rear' effect. Hard to say what I preferred, but both cars felt amazing to drive.
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do you think the missing 40kg of the diesel means the GTA bars are slightly to thick on the diesel but work better on the GTA V6
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I would have thought dropping 40kg out of the front of the JTD would put it roughly in line with the GTA, the V6s typically feel lighter on their feet than the 5cyl diesels.

I have a full set of Eibach bars on my current 156 GTA but I haven't done enough road miles in it to really get to know it yet, plus the roads up here are very different to Bedfordshire.
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Just a short side-question.

do you guys think a C630 with Q2 would fit the 1.9 JTDM TwinTurbo?
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Quote:
Originally Posted by Black-Sheep View Post
Just a short side-question.

do you guys think a C630 with Q2 would fit the 1.9 JTDM TwinTurbo?
In what car?
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Delta TwinTurbo.... it's not something i am planning but the shift feel on that f40 is like driving an old truck, even with m-tech short shifter.....
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(Post Link) post #19 of 31 Old 08-02-15 Thread Starter
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Six speed box,from a 1.9 16v,fitted yesterday,sadly no quaife(yet!). The old box was getting noisier very quickly and would not have much longer,judging by the two year old oil,that came out black and full of bits!!!
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If I'm not mistaking you would also need 10mm wheel spacers to widen the front track, because the 6 speed gear box is a little bit longer compared to the 5 speed and on full turn, the tyre rubs against it.
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(Post Link) post #21 of 31 Old 09-02-15 Thread Starter
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You are not mistaken,Pyle,spacers are needed. I used 12mm hubcentric spacers,on the advice of Pud,as he has seen 10mm ones cracking!!
I also had to grind a few mm off the chassis leg flange,(close to one of the plastic inner arch attachment points,there is plenty there,still!!)as under hard acceleration in first or second,the box was just touching the body work.
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Sounds like you probably need a new engine mount I'd say, 10v engines do chew through them. Is yours remapped?
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(Post Link) post #23 of 31 Old 10-02-15 Thread Starter
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I fitted new mounts(all four of them) about 18 months ago,as the passenger driveshaft was knocking on the lower arm bolts on the subframe!I think it was you who said it was the rear gearbox mount,you were right,it was falling apart,but all of them were well past it.
There was only about 2mm clearance between the end of the box and one part of the body,with the five speed the end of the box followed the contours of the inner wing,but the six speed is slightly different and was very close,in just one spot.Strangely,with the old mounts,there would have been more clearance,but not much! Maybe its because mine is a pre face lift interior model,the inner wing is shaped slightly differently?
At the moment I have a tuning box fitted,but having driven a remapped one,a remap is on the ever growing shopping list. . . . . . .
Thanks Dan,for all the advice,it really is a straight swap and well worth it. Car feels much livelier and more refined(even with the smf) and the spacers give it a much better stance!
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I ground a bit of mine away when I did the job but after it was all fitted, there was so much room I was thinking that I needn't have bothered, and that if I'd jacked up the engine a little higher before jacking the box end up it would have just gone in without any grinding. I'll know soon enough, I'm doing the job on another next month.
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(Post Link) post #25 of 31 Old 10-02-15 Thread Starter
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There was plenty of room to fit the box,with as you suggest a little careful jiggling,but on mine there was one little bit,about two maybe three inches in front of the brake flexi hose where it was very close,but not touching until the loud pedal was used in first or second. For such a worthwhile mod,removing literally a few mm of metal,is well worth it. First drive with the new box,I just thought that it should have come out of the factory with it! I was just going to fit another five speed,but glad I didn't. The six speed was a lucky eBay find,it was advertised as a five speed,from a 1.9 16v 156 with 80k miles. . . .with a five speed price
Have you got yourself another 10v or is it for a customer? If it's for a customer,they won't be disappointed.
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