Higher ratio diff

Post Sat Jun 04, 2005 6:19 pm

Guys I need yet more advice please.
I bought 3.73 diff for the Touring this morning. I wasn't sure if I ought to go this high or if 3.91 would've been better. But, it was only Ãƒ”šÃ‚£35 and 30mins drive away, so I thought what the hell.........
I've just been having a clean-up, and the diff's not a 3.73 but a 3.64. What do I do?? It's going to be almost like moving all the gears up i.e 1st will be similar to my 2nd as it is now. I've always felt that 1st is far too short - (and I could do with a bit more economy), but I don't want to totally wreck the 0-60.
What do you reckon? Bung it in and try it and hope for the best, or try to move it on again and keep looking for a 3.73 or 3.91???
HELP!

Post Sat Jun 04, 2005 7:40 pm

i think it might be too low. im going for a 3.91, as it gives good low down.

Post Sat Jun 04, 2005 7:44 pm

Go for it Steve.

I had a 3.38 in my touring, the fuel economy was great.

It's only quick standing starts where you suffer.

So unless you are going to Santa Pod, or racing boys racers off the lights it'll be fine.

Post Sat Jun 04, 2005 7:55 pm

Cheers for that Dudes.
I've been doing loads of calculations and I think I probably will go for it. 0-60 may even stay about the same, as with a 3.64 it will do over 60 in second - cutting out time wasted in changing to 3rd (and dropping out of the power band) at 54 like I have to now!!
It's going to need a pair of tyres on the back soon, so if I'm not happy with the 3.64, I'll get 50 profiles put on which will drop the effective gearing to nearer to 3.77.
Stuart.

Post Sat Jun 04, 2005 7:56 pm

Good plan.

It will be fine.

Post Sat Jun 04, 2005 7:57 pm

davetouring wrote:I had a 3.38 in my touring, the fuel economy was great.

As a matter of interest Dave, what were you getting on a cross-country run? Was this when you were still running the '20?

Post Sat Jun 04, 2005 8:03 pm

Yeah, I had the 3.38 with the 2.0 engine.

I would get >30mpg on a run easy.

Which was up from about 23-25 with the 4.1

Then with the 3.91 it would be about 24mpg.

A 3.64 would be fine.

Great for motorway cruising.

Post Sat Jun 04, 2005 8:07 pm

Wooow! I can easily get 28-30 cross-country now, so it's looking good. If I can get a 10% better figure I'll be happy enough, 'specially if the acceleration doesn't suffer too much.

Post Sat Jun 04, 2005 8:10 pm

I don't think the acceleration will suffer much at all.

The only place it may suffer slightly, is literally off the line.

Once you are moving, the difference is minimal.

Bit more slipping of the clutch off the line is you are trying to go quickly.

Post Sat Jun 04, 2005 8:14 pm

Cheers for that Dave.

:thumb:
When I get 'round to doing the job, I'll let you know my feelings on the result.

Post Sat Jun 04, 2005 8:16 pm

essbee wrote:0-60 may even stay about the same, as with a 3.64 it will do over 60 in second - cutting out time wasted in changing to 3rd

yes but thats a "false" time if u see what i mean.

the acceleration WILL be slower, even if the time remains the same.

Post Sat Jun 04, 2005 8:20 pm

Chaos wrote:yes but thats a "false" time if u see what i mean.

the acceleration WILL be slower, even if the time remains the same.

Point taken, Chaos. Not so much of a push in the back, but the same time on the stopwatch!

Post Sat Jun 04, 2005 8:34 pm

Dave.... One more question. How long to change the diff? (Bearing in mind that I'll be doing it with the car on stands & laying on my back!!)

Post Sat Jun 04, 2005 9:01 pm

If you've not done one before, it will take at least an hour I would think..

Probably two, to be safe. Un-doing the mounting bolts is the hardest part, as they are pretty tight.

If you have the right tools, it will be a four hour job max from start to finish.

Get help on here if you need it!