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View Full Version : gearbox problem... doh!


Eternal
6th July 2010, 04:32 PM
As i knew it would be a massive bellhousing. I cant cut the rails as the chassis as is not fully welded yet. and i cant do any tunnel work or U3 or U4 till i know how far back i can get it.
Also its looking real high at the moment any ideas?

http://img443.imageshack.us/img443/7579/img0212r.jpg
http://img339.imageshack.us/img339/2617/img0213y.jpg
http://img251.imageshack.us/img251/6858/img0214ek.jpg

Eternal
6th July 2010, 04:33 PM
http://img824.imageshack.us/img824/7924/img0215pi.jpg
http://img4.imageshack.us/img4/9008/img0216ql.jpg

also i guess i will have to mount the diff higher as well to have a straight prop?

HandyAndy
6th July 2010, 04:54 PM
don,t forget that the middle section of BR10 gets cut out ( between U7 & U8),

cheers
andy

Eternal
6th July 2010, 05:01 PM
the bottom of the gear stick( black rubber thing) is 330mm from the table. center of the prop shaft is 185mm from table top. top of the gear stick is 525mm. gearbox is 840mm long. and gearstick center(at base) is 100mm from rear.

would love to know some of your measurements from type 9 and mt75 would give me a good idea on where to put it. I have given myself self 60mm from the back of the gearbox to the firewall.... this will allow the pully to clear the BR7 but it might sit above it im unsure yet lol

Eternal
6th July 2010, 05:07 PM
I might have to cut the top bit of TR8 out as well and add another bit above it. Anyone done this before?

dan_g8
6th July 2010, 05:08 PM
I might have to cut the top bit of TR8 out as well and add another bit above it. Anyone done this before?

Thats what i did to mine. dont think it will cause problems later on.

Eternal
6th July 2010, 05:23 PM
Thanks just seen your v8 height thread. dude that engine is massive. Im really worried about the dif to be honest. its going to be a nightmare to mount. =( the skyline dif is a 4.1 ratio do you think i can get away with a 3.9 sierra one instead or maby a 7.5inch cossy one? (RB25DET - twin-cam turbo (T3 Turbo) ~245 to 250 hp and 319 N·m) ~wiki) my one will be old so not that much power. it would save sooooooooooooooo much trouble,

Also can someone measure how high the center of the dif shaft center is from the table top? just so i can get the gearbox inline.

Thanks again all

Edit found out my gearbox ratios i dont have a clue at all about this kinda stuff all those cogs are confusing. So can anyone who knows whats what, advise me to the best dif for this 'RP71C #2', the ratios are 3.32, 1.9, 1.31, 1.0 and .838.

http://cgi.ebay.co.uk/SIERRA-SCORPIO-GRANADA-3-91-7-5-INCH-REAR-DIFF-KITCAR-/390211222449?cmd=ViewItem&pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item5ada66bbb1 Found that but duno how hard it would be to fit as its a bit wider. i presume the shafts will need to be modded/shortened

twinturbo
6th July 2010, 06:12 PM
Sierra 3.9 will be fine, acceleration will be down a bit. Will handle the power fine.

TT

dan_g8
6th July 2010, 06:13 PM
I would probably try and get a lower ratio diff than the 3.9. ive settled with the 3.6 ratio diff as i couldnt afford a 3.3. I have been told that the sierra diff will handle the power of my engine (200 bhp 210 lb·ft 280 N·m).

Hope this helps

Eternal
6th July 2010, 06:14 PM
I guess later i can get a quaife diff 4.1 when i got the cash. Would it be a load of work to put a 7.5 inch diff in? as i saw that the 7.5 inch 3.9's cost less than the 7inch versions.

Btw thanks for all the help guys

alga
6th July 2010, 06:18 PM
Keep in mind that the standard design has the lower flange of the bell housing hanging 25 mm below the bottom of the chassis. So it makes much more sense to cut the bottom rail that will have to be cut out anyway, and maybe make a hole in the table as well.

By the way, I did cut out and moved back a section of my top rail in order to fit the Zetec thermostat housing.

Eternal
6th July 2010, 06:22 PM
ahh i see i thought the bottom of the bell housing was flush. i guess what i need to do is build the back end first and put a dif in there so i can line things up. problem is this engine has a massive sump rofl. chop chop chop

twinturbo
6th July 2010, 06:47 PM
You can grind the mounting lug down on the 7.5" IIRC.. I should realy compare my 7" and 7.5" units..

Do you realy think your going to need a 4.1?

Are you going for an LSD?

I am going to be running a 7" Non LSD 3.6 diff to start with on the roadster and may go to LSD..

TT

Eternal
6th July 2010, 07:32 PM
ohh did not know that cool :D are the drive shaft flanges the same distance appart as the 7inch? if thats the case then game on!

Edit: just did a search on sierra owners forum....
"2wd diff top mount is 7.5 inch, 4x4 is 7 inch..... you can lop the difference off of the diff casing or cut and re-weld one of the mounting tags on the beam. As you look at back of the car it's top right hand mount you need to mod.

2wd saph arms are same as 4x4 arms so you're fine there...only ones that are different are 3dr arms (arb mount in diff place).

HTH
Dan"

happy days can use the standard rear end now. Thats makes life so easy. Man i could kiss you guys :D but i wont! so dont panic. Im saving that for then its passed its iva lol

snapper
16th July 2010, 06:23 PM
What wheel & tyres are you planning to use?
I have a V6 type 9 with similar ratios and find 1st and 2nd low even with a 7000 rpm red line, with the amount of power you have, the 3.9 will be fine, the 3.6 probably better on the road

snapper
16th July 2010, 06:26 PM
Another thought, on most 7 's the bottom of the bell housing is a couple of inches below the lowest point of the chassis

baz-r
22nd July 2010, 01:47 PM
Thanks just seen your v8 height thread. dude that engine is massive. Im really worried about the dif to be honest. its going to be a nightmare to mount. =( the skyline dif is a 4.1 ratio do you think i can get away with a 3.9 sierra one instead or maby a 7.5inch cossy one? (RB25DET - twin-cam turbo (T3 Turbo) ~245 to 250 hp and 319 N·m) ~wiki) my one will be old so not that much power. it would save sooooooooooooooo much trouble,

Also can someone measure how high the center of the dif shaft center is from the table top? just so i can get the gearbox inline.

Thanks again all

Edit found out my gearbox ratios i dont have a clue at all about this kinda stuff all those cogs are confusing. So can anyone who knows whats what, advise me to the best dif for this 'RP71C #2', the ratios are 3.32, 1.9, 1.31, 1.0 and .838.

http://cgi.ebay.co.uk/SIERRA-SCORPIO-GRANADA-3-91-7-5-INCH-REAR-DIFF-KITCAR-/390211222449?cmd=ViewItem&pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item5ada66bbb1 Found that but duno how hard it would be to fit as its a bit wider. i presume the shafts will need to be modded/shortened

the ratios are for each gear so (1st) 3.32 means for every one prop rev there is 3.32 crank revs.
1.0 is one in one out (like most 4ths are)
and .838 is a over drive where the prop spins faster so every .838 crank rev you get 1 at the prop
take this into account with your dif ratio and your rear tyre dia and you can work out speeds to revs
engine revs/gear ratio= prop revs, prop revs/ diff ratio = wheel revs and times this by wheel dia to get road speed
simples ;)

snapper
22nd July 2010, 08:02 PM
The gearbox ratios you have are very similar to the V6 type 9 and I find 1st low 2nd better and third the gear off much fun.
I run 185/60/14 if you have bigger rolling radius and big power available I think the 3.6 will be much more like it.
Remember the car the gearbox came out of was a lot heavier and designed to move of from standstill with 4 people and luggage