Should I change diff or gearbox?

[mk1sooty]

Hi all,I`m after some advise. The engine i`ve built spins up very quick and i`m through the 4 gears very in no time when driving hard.So would I get away with just altering the diff or is it best to change either, ratios in the gearbox or do away with the 4 speed and move to a 5 speed?

Any advise would be appreciated.

[ZetecVan 2.0]

You've probably got a 4.1 or 4.4 diff in. I had a 4.1 in my van for a short while, and it quickly ran out of steam. At 3500rpm I was only doing around 60mph. I reverted back to the 3.54 until I got a 3.54lsd. at 3,300rpm you're doing 70mph.

 

Change the diff. It's an easier job.

 

Jack up the back of the car, and turn one of the rear wheels one full revolution, and count how many times the prop turns round. From that you can work out what diff you have.

[bigglesmk2]

 

Jack up the back of the car, and turn one of the rear wheels one full revolution, and count how many times the prop turns round. From that you can work out what diff you have.

 

Thats a clever bit of info

 

Once you've counted the amount of prop turns,what do ya do with that figure to work out what diff ya got ?

[ZetecVan 2.0]

Well, if you've got a 3.54:1 diff, for every one turn of the wheel, the prop turns 3.54 times.

 

A 4.1 diff would turn the prop just over 4 time for every turn of the road wheel.

[bigglesmk2]

Oh yeah,makes sense now

[mk1sooty]

You've probably got a 4.1 or 4.4 diff in. I had a 4.1 in my van for a short while, and it quickly ran out of steam. At 3500rpm I was only doing around 60mph. I reverted back to the 3.54 until I got a 3.54lsd. at 3,300rpm you're doing 70mph.

 

Change the diff. It's an easier job.

 

Jack up the back of the car, and turn one of the rear wheels one full revolution, and count how many times the prop turns round. From that you can work out what diff you have.

Thats sounds easy enough,as far as im aware its a standard mk1 RS2000 set up which is 3.54.At 70mph its doing 4000rpm.

[Vista]

What size tyres are you running on the car?

 

Using the standard 1:1 4th gear ratio on an RS2000 with standard 175/70 tyres and a 3.54:1 final drive ratio, you should be doing nearer 80mph at 4000rpm (a fraction under 77 to be exact)

 

I use a type 9 with a 3.54 final drive ratio and from memory 70mph is around 3100rpm though it's still very comfortable at 80/85 at around 3600rpm

[mk1sooty]

What size tyres are you running on the car?

 

Using the standard 1:1 4th gear ratio on an RS2000 with standard 175/70 tyres and a 3.54:1 final drive ratio, you should be doing nearer 80mph at 4000rpm (a fraction under 77 to be exact)

 

I use a type 9 with a 3.54 final drive ratio and from memory 70mph is around 3100rpm though it's still very comfortable at 80/85 at around 3600rpm

Its on 185/60,I think half the problem is I went for too lighter flywheel which wont help.next job is to see work out what the diff ratio is by spinning a wheel,cheers all for the advise

[Toby]

Its on 185/60,I think half the problem is I went for too lighter flywheel which wont help.next job is to see work out what the diff ratio is by spinning a wheel,cheers all for the advise

 

I don't think the flywheel weight will be too much of a problem, it's just a bit annoying for passengers as it's hard to drive smoothly cos you get more engine braking when you let off. I don't think you'll really notice any problems by the taller diff.