Im still in the hunt for higher ratio diff. I have found potential what is my best bet but. .
I have a 7" push in non LSD. The new one is 7.5" bolt on non lsd.
Now, is there potential to change the output type? I know my chassis needs to cater for the wider diff. I was also told that they are longer, can this
be confirmed.
I don't want to change my drive shafts or prop. Simple is best for me right now.
What Ratio do you have now and what are you aiming for?
I have a 3.92 and i want higher. Im looking at a 4.27
The nose on the 7.5" diff is 10mm longer (not a lot at all). When I changed up to the 7.5" in my car the 10mm difference was catered for by the prop slider.
I think you mean a Lower ratio diff. You get lower number of output turns for the one turn of the input shaft. And so the gear ratio of the diff is
Lower. In the same way that 1st gear is a Lower ratio that 5th in your gearbox.
1.6 MX5 differentials are 4.3:1 apparently, it would be a much more involved change but it will give you what you want. Also they do a 4.1:1 &
3.9:1 as well so you would have some choice to change back to Higher ratio if it wasn't what you wanted.
The easiest but not the cheapest would be to fit either a 4.1 or a 4.4 CWP to your 7" diff.
Quaife direct or Raceline supply
quote:
Originally posted by Doctor Derek Doctors
I think you mean a Lower ratio diff....
Still does not answer my question.
Can i take out the bolt flanges and put in my push in ones?
quote:
Originally posted by bi22le
Still does not answer my question.
Can i take out the bolt flanges and put in my push in ones?
Hmm. So its seems to me that i cant change the bolt on for push in half shafts, the nose of the diff so to long and its not going to bolt easily in to
my chassis.
Boo
I had this same problem a few years ago and couldn't find a good solution for the diff I'm afraid.
I broke the 3rd gear synchro on my standard type-9 box and was looking at ways to sort out the gear ratios at the same time as replacing it.
One option was a bgh box and shorter diff to bring the overall gearing down. In theory custom 4.4 and 4.7 cwps exist for the 7" diff, but
they're expensive and nobody actually seemed to have one or know when they might be able to get one.
In the end I left the 3.92 diff and fitted a Caterham 6 speed box instead. 6th is a 1:1 ratio, same as your 4th. It's not cheap and it's
an engine out job, but I couldn't find a practical alternative at the time. It did completely transform the car though, the ratios are spot on
now - it's definitely worth sorting out one way or another.
I would of thought it would of been cheaper to fit the 4.27 diff and change all three drive shafts!
You do get obvious other benefits from fitting the 6 speed if your pockets are deep enough.
What engine do you have in your striker?
It's a 20v Silvertop 4AGE in my car. Rev limit is 8000 rpm and it develops most of its power at the top end of the rev range. It was geared for
170 odd mph in 5th before I changed it and about 140 in 6th now.
My gearbox was broken so I had to change it anyway and the cost of a bgh box and aftermarket diff ratio to make the ratios right was about the same as
the Caterham box and bits and pieces to do the conversion. If you've got a close ratio box already then the diff will be much cheaper (if
they're available) and should work well. I'm not sure a normal type-9 will work as well with the shorter diff though.
Nice work, cheers for the info.
I have a 20v blacktop in mine with a 8250 limit and it sings!!
As you know these, even with the VVT, have quite a narrow power band. I only use 5th on in and out laps so anything the wrong side of 1:1 is no good.
The scorpio 4.27 seems a lot of work to get in. I would rather go for a more modern lighter diff that is cheaper and gives the same ratio.
More to think about i guess.
Yes you definitely need to keep them revving to make them work 
I found the rev drop between 2nd and 3rd the most frustrating thing before I changed the box - I'd be trying to use every possible rev in 2nd (to
the point I'd frequently hit the limiter) to try and get somewhere near the power band in 3rd.
Be interested to see what you come up with, something from a Subaru Impreza / Legacy might be an option too if you're going to be changing
mounts, driveshafts etc.
quote:
Originally posted by bi22le
Im still in the hunt for higher ratio diff. I have found potential what is my best bet but. .
I have a 7" push in non LSD. The new one is 7.5" bolt on non lsd.
Now, is there potential to change the output type? I know my chassis needs to cater for the wider diff. I was also told that they are longer, can this be confirmed.
I don't want to change my drive shafts or prop. Simple is best for me right now.