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Gearbox for road and trackdays


Garth

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Planning to swap/re-build my standard 5 speed box as part of some upgrades this winter. Will be running about 195bhp and plan to change 1st and 2nd to make them slightly longer and closer. Have a 3.62 diff (I am told!).

Have been trying to get hold of SPC but think he may be on holiday? Also plan to speak to Road and Race? BGH Geartech's website is useful giving some 'standard' boxes with slightly different ratios. Should I speak to them - most of the posts I have read suggest either SPC or R&R?

Cheers

 

Garth

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SPC works well for me, this one - here

 

Tracsport Type 9 rocket ratio helical gear kit .

 

These gears have been developed with the Duratec user in mind. The gear tooth profiles are much larger than ford original spec and are similar to a typical S/cut gear.The amount of engine torque this gear kit can be used with is about the same as a typical s/cut gearset. The gears are cut to an angle of 25 degree's this means there is more than one tooth driving at any one time which is stronger than one at a time as in s/cut gearboxes,and also 95% quieter. They are also gear shaved after gear cutting to perfect the gear form. First and second gear are bored out larger than standard which saves weight. In other areas we have also lightened the gear train, the benefit of this is enhanced syncro life and a potential faster gear change. First and second gear are fitted with caged needle roller bearings to reduce friction.

 

The gear ratios are as follows 1st 2.482 2nd 1.61 3rd 1.225 4th 1.1 5th .87 or .82 The .82 5th gear pair have an increased helix angle and finer pitch teeth for quieter cruising.

 

I haven't compared it with anything other than a standard Type 9 but I am very pleased with it. Road and Race weren't interested in building me a 5 speed when I asked, it might depend on how busy they are.

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I think you'll find that those ratios are optimised for a 3.92 diff and 1st could be a bit long, although it does work out about the same as a Quaife pro box long first. Not great in traffic. Unless you're sure, it might be worth checking your diff ratio first as 3.92 was the standard and 3.62 used with 6-speed boxes with a direct 1:1 rather than overdrive 6th gear. You might find a metal tag on the diff with the ratio stamped on it. Mind you, that doesn't mean that the internals haven't been changed. Alternatively, jack the rear end up, rotate the road wheels lots of times (40), counting wheel and propshaft revs to calculate the ratio.
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Mines using a 3.92 diff and yes it makes 60 in 1st if I rev it hard enough. It take a little getting used to when pulling away but it's never been a problem and I've not stalled it. Close ratio vs long ratio always provokes a bit of debate, personally I like mine the way it is, it suits how I use the car and the way the power is delivered. It looks like there are 2 great suppliers in SPC and BGH, I doubt if either would be a disappointment, I went with SPC because that's who I called to discuss the options and I just made the decision based on that conversation. To see how it looks in use there are a couple of 'Dunsfold Runway' videos on my channel where you can see the speedo and therefore the gearchange points - it accelerates a lot faster than it sounds because of the time spent in each gear IYSWIM.

 

A 3.62 final drive might just make it a bit long though - get that confirmed if you can before making a choice.

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I cannot find any tags or stamps on my diff. CC say they supplied me a 3.62 with my kit. If i jack it up and rotate a wheel I assume I need to stop the other wheel from spinning? - otherwise they will just rotate in opposite directions? Does the propshaft then rotate at double the speed??

 

Will use gearcalc to check what the revs etc will be like with a 3.92 diff too. Was planning to convert mine to a LSD, so could change ratios at the same time (except my budget was not going to stretch that far this winter!!

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BGH here - despite SPC only being 10 miles down the road (I think) when I did the upgrade... Mines a heavy-duty sporting-close with tweaked 1st, 5th (and maybe 2nd) ratios. Also has the alloy top-plate with dipstick/filler.

 

Rob G has a BGH too - has been using in his Duratech for some years (much more power/torque than my k-series!). I expect he'll be along soon.

 

 

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