Gearbox...

If you're going to get a SCCR its wise to go for an F15 as they are slowing in the production of spares for the F10 and F13 and I know Quaife have ceased production of F10 spares altogether.

I bought a cheap SCCR box with a damaged input shaft and was lucky enough to get the last HH replacement shaft. I asked wether they would be getting anymore made and they said its unlikely.

IMHO its money well spent as you're gaining power by minimising your losses. Also as you've said, you also gain improved acceleration and gearing whilst if you get a diff too you will dramatically improve the handling characteristics of the car.

Do you happen to know the actual realistic % of improvment in the gearbox ?

I.e Standard box 25%. SCCR 20% !?

it varies with engine speed ;)

but generally straigh cut boxes are less power loss, and also wear the bearings less. BUT also can potentially have a lower power/torque rating due to smaller gear contact patch.

The only problem with a SCCR box comes when you are using the car to drive to events. With the gear ratios tuned for acceleration you will be running the car at higher revs along the motorways.

With the Quaife gear set (Syncro) the gear ratios are set but you have a choice of two final drives.
Using my Quaife catalog and Stu's gear ratio calculator spreadsheet.

F13/F15 5 speed synchro

Code:

---

Rev Limit set @ 7,000rpm
Using 195/45R15 tyres
 
    MPH in gear
    -----------
    4.533  4.857
    -----  -----
1st 41mph  38mph
2nd 60mph  55mph
3rd 74mph  69mph
4th 88mph  82mph
5th 100mph 94mph
 
@ 8,000rpm 5th with FD 4.533 = 115mph
 
70mph in 5th
------------
4.533 - 4,863rpm
4.857 - 5,257rpm
 
Gear ratios
-----------
1st 2.54
2nd 1.76
3rd 1.42
4th 1.19
5th 1.04

---

That should be enough information on the box.

I guess you could always fit a std WR 5th pair to keep m/way cruising nearly sensible.......

how often are you in 5th dar?

I know it sounds stupid that i'm thinking about getting such a gearbox but yet still want to drive 100's of miles on the motorway !

Simple fact is i don't want nor have a trailer !

Thanks for the infomation Stu/Dar. Can you not give a very rough indication on the improvment on losses ? i know it's not going to be be 30hp !

lets for SnG say the losses are approx 5% less.... depends on gear oil used.

Thanks ! :)

Quote:

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Originally Posted by Nick

I know it sounds stupid that i'm thinking about getting such a gearbox but yet still want to drive 100's of miles on the motorway !

Simple fact is i don't want nor have a trailer !

Thanks for the infomation Stu/Dar. Can you not give a very rough indication on the improvment on losses ? i know it's not going to be be 30hp !

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Just as a note, the gearbox im putting on mine till I save for a SCCR is an F13CR with a 4.18FD and F10WR 5th gear (im hoping its longer) mainly due to driving to, and around the 'ring this year. Both the FD and 5th will be coming from my standard 1.2 F10 gearbox. You could pick up a suitable F10 for about ?0-?40 and do the same plus a diff of your choice. Much cheaper than a SCCR with something similar to what your looking for, minus the transmission loss...

Theres some good write-ups on gearbox oil and additives here:
http://www.bobistheoilguy.com
Talks about foaming and losses etc.

Dans box looks sold, worth a PM though?...
http://www.pngclub.com/forum/showthread.php?t=91297

Quote:

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Originally Posted by Ash

Just as a note, the gearbox im putting on mine till I save for a SCCR is an F13CR with a 4.18FD and F10WR 5th gear (im hoping its longer) mainly due to driving to, and around the 'ring this year.

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Im running a F13CR with 4.18FD and am very happy with it. May not be ultimate spec but does what I want it to do.

Is there anyway to find out if the 5th from a WR box is any longer? I replaced the gear casette and diff with CP many moons ago, would it be much hard work to do this? I can imagine im going to drink fuel on a ring trip myself and i didnt know you could do such a thing.