View Full Version : Gearbox...
I'm starting to collect bits.
I'l either be buying a new shell soon (something like Dans/Ash's spec) or i'l just cage/weld mine ! I'l also be uprading everything else like Suspension, Brakes and Polybushing it e.t.c e.t.c
Finally, It comes down to the engine.
As i see it, i either go the whole hog and spend my cash on Getting a mega decent head done with a cam to suit... or i look into a gearbox.
What's everyones opinions on a SCCR. i've seen a couple of F13's with the ge****ts and a Plate diff in for about ?800-1000 second hand. The same price as a new head/cam/lifters would cost me !
Surely it'd be better to not stress the engine anymore, run a mildish spec, keep the reliability ? Plus i'd gain a couple of HP through the transmission losses but mainly have alot better Gearing/Acceleration !
I'd imagine it'd make it alot quicker than it would by spending the money on 20hp more !
Id leave the engine spec as it is now.
And just fit a diff in the box.
Bearing in mind it hardly ever gets driven anymore, and i'm going to rape it severly round tracks during my year-in-industry this year !
Would there be no real benefit in buying a secondhand SCCR box/Diff for ?900 than buying a Diff for 500ish ?
I don't like buying things second hand, so i'm reluctant to. but i'd risk it for a whole box i think .. But if not i'd probably go for a New Diff. It may sound stupid to some people, but i've had so much bad luck with 2nd hand stuff in the past !
Ive never had a problem with 2nd hand stuff, luckily.
Up to you, personally i wouldn't pay that much for a box/diff.
But thats just me,Lol.
Is Dans box still for sale?
Personally id just get a brand fire new diff for around ?500 and stick with that
Hmm not sure about Dans box ! Could be just what i need !
Incidently, what are the transmission losses in % compared to normal Gears ?
I thought your engine was all up together? What were you looking to do spec wise?
Personally I'd spend the money on a geabox/diff, better to put the power down and carry more speed thought the corners. It would make the best use for what you've got at the moment plus if you did spend the money on the engine then you'll want the gearbox/diff any way.
If you did want a head theres been a few B+ heads for sale recently, I payed about ?250 for mine and ?80 for it to be checked over, valves relapped, new stem seals, skim, etc
EDIT: wish Dan left that 'box in the shell when he sold it lol
Well... i've got a really good head at the moment, but it's got standard size Valves in it. Which is the let down..
That aside, i was just going to go get a custom job done but spend some cash on it - and then run a Cam on solid lifters !
I was massivly impressed with Dar's car @ Llandow, but i don't know exactly how much of that was the Gearbox. It just seemed to be On the power constantly !
I have heard that the only real benifits are seen from increasing the exhaust (poss. inlet :/) side. Autosprint seem to be the people to speak to at the moment, seem fairly cheap too... BTW have you got double valve springs? Probably need them with solid lifters/lairy cam.
But i like the reliability/driveability it has now.
I.e i drove 300 miles to llandow, two of us went out all day, then drove 300 miles home. I only used 3 Tanks of fuel..
Hence why im not so keen on changing it. And apart from Suspension/Brakes/Loosing Weight/Stiffening i'd be interested in the gearbox route...
tom_beverley
14-01-08, 10:10 PM
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
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.
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 !
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...
mikeoxford
15-01-08, 08:28 PM
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
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.
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.
how often are you in 5th dar?
Got in to 5th around Llandow on both the straights (Just) and I hit 5th 3 or 4 times around Castle Combe.
see sig link site for gearbox info mike.
swapping the 5th pairs is V easy, I dont even think you need the cassette out!
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