kensprin
|
| posted on 22/5/11 at 07:23 PM |
|
|
Over geared
Getting fed up with 1st and 2nd. 1st limited to 20 mph 2nd limited to about 40 mph.
Without messing about with the gearbox ratios and getting a quife setup could I change thd diff from a 3.64 to the 3.14? Would this help?
I'm running a bob - v6 type 9 and I think it a 3.6 diff using 185/60/14 I have been trying to find a serial number list on here For diff codes
but can't find it. I did see it on here before.
What I really like is to hit 60 in second. At the moment I rearly use 1st gear it's just pointless.
|
|
|
|
|
mcerd1
|
| posted on 22/5/11 at 07:39 PM |
|
|
what kind of diff have you got now - sierra 7", 7.5", etc.... ?
as far as the type 9 goes have a look at BGH gear kits: linky
-
|
|
|
jacko
|
| posted on 22/5/11 at 07:50 PM |
|
|
quote:
Originally posted by kensprin
Getting fed up with 1st and 2nd. 1st limited to 20 mph 2nd limited to about 40 mph.
Without messing about with the gearbox ratios and getting a quife setup could I change thd diff from a 3.64 to the 3.14? Would this help?
I'm running a bob - v6 type 9 and I think it a 3.6 diff using 185/60/14 I have been trying to find a serial number list on here For diff codes
but can't find it. I did see it on here before.
What I really like is to hit 60 in second. At the moment I rearly use 1st gear it's just pointless.
If you look in my photo archives there is some info on diffs
Jacko
|
|
|
Steve Hignett
|
| posted on 22/5/11 at 08:01 PM |
|
|
diff codes
http://locostbuilders.co.uk/forum/9/viewthread.php?tid=85080
|
|
|
snapper
|
| posted on 22/5/11 at 08:03 PM |
|
|
The big problem with standard gearboxes is 1st and second tend to be to low and 4th, 5th to high.
If you change diff to make 1st, 2nd work, 4th is to long to achieve max engine revs.
It's a conundrum that only a close ratio box will solve.
Having an engine that revs will extend the early gears as will going for bigger wheels, it's well worth having a good look at a gear ratio
program.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
|
|
|
scutter
|
| posted on 22/5/11 at 09:04 PM |
|
|
 
I had a play with gearcalc, 60 should be achiveable, but you are going to have to rev the nuts off it.
A 3.14 diff ratio would 60 being easier to achive but you'll be geared for 160!!!
ATB Dan.
The less I worked, the more i liked it.
|
|
|
Chippy
|
| posted on 22/5/11 at 10:57 PM |
|
|
I have the same problem with my BOA, which just mildly tuned gets 238 BHP and 250 lb's ft. The engine will pull 6250 without grenading, but I
have my rev limiter set at 6100, those rev's in top will see me well over the 145 mph mark, and then I hit the limiter, so I will be fitting the
3.14 diff, which I have ready to go in fitted with a Quaf ATB, just a matter of getting around to it. I feel that fitting it will not only get over
the problem of first and second gears being too low, but should also give better fuel figures, (very low 20's at the moment), as 70 mph
presently is around 3500 rpm, and with the 3.14 it should be 2600. Cheers Ray
Edit to say fitted with a modified MT75 which has slightly different gear ratios.
[Edited on 22-5-11 by Chippy]
To make a car go faster, just add lightness. Colin Chapman - OR - fit a bigger engine. Chippy
|
|
|
snapper
|
| posted on 23/5/11 at 05:14 AM |
|
|
The MT75 has worse 1st & 2nd than the type9, I have just fitted the V6 type 9 I bought of Chippy a couple of years back, the difference with my
setup is that I now have a Pinto that will rev to 8,000 rpm.
May have the old box built up with a close ratio set but in all honesty I have spent far, far to much and should look at building another car.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
|
|
|
kensprin
|
| posted on 23/5/11 at 07:18 AM |
|
|
Yes Chippy at 70 I'm doing 3500rpm in 5th. Anyone have a 3.14? oor know which vehicle they were fitted to? Jaco had some good info on his
photo archive and that gear software looks great is it freeware to download somewhere ?
|
|
|
mcerd1
|
| posted on 23/5/11 at 08:27 AM |
|
|
3.14's were only really in the 2.3D sierra's - so they are like rocking horse poo and everyone wants one..
(plenty of old threads about finding one)
there are normally a few for sale, but you won't like the prices that most of them go for 
3.38's are a little cheaper if you can find one
[Edited on 23/5/2011 by mcerd1]
-
|
|
|
mark chandler
|
| posted on 23/5/11 at 11:02 AM |
|
|
I have a 3.38, its an odd one as its from south africa so has a steel housing and needs putting back together, one crown wheel bolt missing.
I stripped as I was told the internals were the same as UK spec, the pinion is different and never bothered reassembling.
A couple of KG heavier that a UK spec, same mountings as a 7" diff, its the front one in this picture
If you are interested U2U me.
Regards Mark
[Edited on 23/5/11 by mark chandler]
|
|
|
Xtreme Kermit
|
| posted on 23/5/11 at 12:23 PM |
|
|
Are you sure it's a 3.6 diff? The figures in gearcalc indicate that 62mph is 6000rpm in second and that 70mph should be 3100rpm.
What red line are you using?
With a 3.38 diff it would look like this:
Gear Mph per 1000 RPM Mph @5500 RPM Mph @6000 RPM
--------------------------------------------------------------------------------
1 5.96 33 36
2 11.06 61 66
3 15.89 87 95
4 20.02 110 120
5 24.26 133 146
With 70mph in fifth being 2885rpm
edited to say 'that formatted well' 
[Edited on 23/5/11 by Xtreme Kermit]
|
|
|
mcerd1
|
| posted on 23/5/11 at 12:41 PM |
|
|
quote:
Originally posted by Xtreme Kermit
With a 3.38 diff it would look like this:
Gear - Mph per 1000 RPM - Mph @5500 RPM - Mph @6000 RPM
--------------------------------------------------------------------------------
1-------5.96-------------------33----------------------36
2-------11.06-----------------61----------------------66
3-------15.89-----------------87----------------------95
4-------20.02----------------110---------------------120
5-------24.26----------------133---------------------146
With 70mph in fifth being 2885rpm
[Edited on 23/5/2011 by mcerd1]
-
|
|
|
kensprin
|
| posted on 23/5/11 at 07:30 PM |
|
|
I'm redline at 6250 and that's the standard boa ecu limiter. Peak power 6000.
I'm wondering if I have some stupid 4.2 or more diff it is 7". I'll get to the garage when I'm back home and have a look.
The calc dose not seem correct for me. We are missing a variable somewhere. Wonder if the type 9 v6 ratios are correct. Cant find a lower diff
anywhere !!!!!
|
|
|
mcerd1
|
| posted on 23/5/11 at 07:39 PM |
|
|
the lowest standard gear for a 7" is 3.92
anything lower geared than than (i.e. higher number) is an expensive custom one.....
[Edited on 23/5/2011 by mcerd1]
-
|
|
|
Chippy
|
| posted on 23/5/11 at 09:54 PM |
|
|
quote:
Originally posted by snapper
The MT75 has worse 1st & 2nd than the type9, I have just fitted the V6 type 9 I bought of Chippy a couple of years back, the difference with my
setup is that I now have a Pinto that will rev to 8,000 rpm.
May have the old box built up with a close ratio set but in all honesty I have spent far, far to much and should look at building another car.
Ermm! maybe you didnt notice the edit on my post, it's not a standard MT75. Made up from combining the 4 X 4 box with a diesel one. Cheers Ray
To make a car go faster, just add lightness. Colin Chapman - OR - fit a bigger engine. Chippy
|
|
|
