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Uprating a 50 year old gearbox.


MightyJoe

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I am currently building a 1500 pre crossflow for my cortina and i'm looking at options for the gearbox. Its a 4 speed column change manual ( so quite rare and hard to replace i'd imagine) and the engine is going to be putting out about 3 times the original power, i dont want to be sweeping parts up off the road after the first donut. 

i know i could rip it out and fit a T5 floor change but i assure you thats not going to happen!  

 

i was wondering if anyone has any experience with fitting bigger / stronger bearings, to handle more torque and rpm. 

 

Am i mad? 

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I was actually thinking of having to machinne the box to fit bigger stuff. you reckon a like for like size will be a good enough upgrade?  i know gearbox upgrades usually mean a second mortgage too so yeah i was kinda hoping to avoid that area as much as possible ha. 

The toyota hiace thing was something i was looking at too tbh, and some 80's navaras were column change too. this is probably my best option if i grenade the ford  one but in my mind its alot more fucking around with linkage, bellhousing and driveshaft etc. 

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I'm not so sure that bearings would be what causes a failure due to tq. ( Please correct me if I'm wrong)

More likely in my opinion that you'd be breaking everything else.

i messed around with cvh turbos for years in the uk and went through about 9 or 10 BC boxes in that time, they'd shit themselves in 2nd and 3rd usually when thhey came on boost. first gear only got mullered if you were doing too many burnouts on the limiter. They'd start making a hell of a grumble first though, and it was always the layshaft bearings that took the hit first.  i switched to an IB5 box then which i fitted my lsd into and ran that one for 4 years no problems. its a common mod now for them, they're a 25 year younger design inside the same housing, with the main differnce being the bearings ( and different gear ratios but... i digress) so i thought that was a good place to start.   i'm a real novice with gearboxes though hence this post, i'd sooner wave a magic wand at one than crack it open tbh. 

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The bearings used in bearings now are much nicer tolerances so you probably won't need to use bigger. Polishing the Gubbins will go some way to avoid stress cracks and the insides becoming outsides

3 times the power is a fair wack tho, so if its a poor design you will have to lay off, or upgrade

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cool i think that'll be the go for the start anyway, its a weekend toy i just want to err on the side of caution. cos i'm skint lol.  and yeah 3 times output is an estimate as the engines still in bits, but the stock motor only put out 50hp and i'm hoping for about 120-130. it was also the increased torque and revs i was worried about. 

 

i'll get it stripped down and put up some pics anyway, should be next week sometime. cheers for the input. 

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  • 2 weeks later...

MK3 Zephyr internals in the Cortina box? or just run the whole thing?

 

The 6 cyl Vauxhalls  PA , PB etc had a pretty good box in them to as did the Austin A90, 95 and they had an overdrive option in the top two gears as well.

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Your solution needs to be cost effective and bullet proof while retaining the column shift. Yes?

 

All these solutions like "get the gearset ISF'd", "getting gearbox internals cryotreated", "Polishing the Gubbins", "Full syn 75w85 gl4 oil + all the other things everyone has suggested"  sound very expensive, more so than than a late model Toyota conversion?

 

Bell housing from a MK 2 Cortina (bolt on) won't be hard to find and also has the heavy duty 3 lug starter mount.

Linkages are just a matter of a few sums to sort and the basic layout of the current follows the same basic pattern as the Toyota five speed (double H patten).

Drive shaft, speedo cable and cross member are all easy if you talk to the right people or do your research.

 

One huge benefit that you will get is availability of parts once installed, if you kill a Toyota 5 speed a replacement is available and cheep unlike a modified factory one.

Not to mention a huge range of clutches straight of the shelf and because they are made in big numbers they won't be moon beams price wise.

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