4.30 Rear Axle - Page 2 - Alfa Romeo Bulletin Board & Forums
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post #16 of 47 (permalink) Old 03-16-2010, 07:28 PM
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WOW Thanks Darren this is great.
Now I am sure about going to a 4.10


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[SIZE="2"]David Munro[/SIZE]
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post #17 of 47 (permalink) Old 03-16-2010, 07:29 PM
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No problem.
Glad to be of service.




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post #18 of 47 (permalink) Old 03-16-2010, 09:28 PM
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When changing the effective diameter of a tire it is worthwhile to consider the amount of ground clearance.

Also, with the 101 Spiders and Sprints a better appearance (as in filling the wheel well) is provided by the original tires, which are tall. As in 155/80/15. I think the 165/80/15 is close to 25 inches in diameter and gets around 815 revs per mile.

Then, the 2 L in a 101 hangs down by at least an inch lower than does a "normale" engine.

So there are fewer problems with standard tires on 101s, and to make the set up happier--a 4.3 diff, with an Alfaholics LSD.

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post #19 of 47 (permalink) Old 03-16-2010, 10:04 PM
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Yeah, sounds about right. I've been tooling around in my 2L Super with undersized tires (175/70/14) and it's revving way up there at freeway speeds.

-Jason

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post #20 of 47 (permalink) Old 03-20-2010, 10:24 PM
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Yeah, sounds about right. I've been tooling around in my 2L Super with undersized tires (175/70/14) and it's revving way up there at freeway speeds.

-Jason
This post got me thinking, so I took the Super onto the freeway to see exactly how bad it is. In 5th gear, my GPS tells me I'm going:

2500 RPM: 45
3000: 54
3500: 63
4000: 72
4500: 81

Anybody have a spare 4:10 rear end sitting around?

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post #21 of 47 (permalink) Old 03-21-2010, 04:53 AM
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But are you sure of the tachometers accuracy?

I mean you're prolly still spinning it up, but it may be better or worse than indicated.

If you wanted to get all goofy about it, there's a formula that takes into consideration tire rollout, rpm, final drive ratio and trans gear ratio to spit out mph. (or mph to revs if you prefer)

I've not found it online yet, just in printed text, though it must be around somewhere out there if you wanted to spook around.




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post #22 of 47 (permalink) Old 03-21-2010, 05:16 AM
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Well, they are out there if one looks hard enough I guess LOL

Here's three. The first is kinda quick and dirty, the second allows for each gear ratio to be entered but doesn't work out tire diameter, the third does everydamnthing at once.

Precision Gear
Apex Garage
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post #23 of 47 (permalink) Old 03-21-2010, 09:07 PM
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Quote:
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But are you sure of the tachometers accuracy?

I mean you're prolly still spinning it up, but it may be better or worse than indicated.

If you wanted to get all goofy about it, there's a formula that takes into consideration tire rollout, rpm, final drive ratio and trans gear ratio to spit out mph. (or mph to revs if you prefer)

I've not found it online yet, just in printed text, though it must be around somewhere out there if you wanted to spook around.
I've checked the mechanical tach against an old tach / dwell dealie and it was pretty much spot on. This 2L does NOT need to be buzzing around at 4k RPM at 72 MPH. Great for passing power, not so good for MPG...

-Jason

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post #24 of 47 (permalink) Old 03-21-2010, 10:27 PM
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Sure, suck the fun out of it




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post #25 of 47 (permalink) Old 03-22-2010, 11:13 PM
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Thanks for the chart and info, Darren. I've also been dreaming of a 4.30 for my GTV, to replace the original, non lsd 4.56. With 195/60-14s, it seems that the easy to find 4.10 would be fine. Might even get to use 1st once in a while.

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post #26 of 47 (permalink) Old 03-23-2010, 10:13 AM
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Hey guys!

A friend of mine is going to swap his Giulietta gearbox by a LSD 75 TS one.
This new gearbox has a 4.1 final drive and the Giulietta has a 4.3.

We want to retain the Giulietta final drive and the 75 ratios and LSD. I was thinking in swapping just the ring gear because the pinnions have the same number of teeth (10) therefore the gear Module is the same and there won't be any problem.

Am I thinking right or am I about to destroy a gear set?

Thanks for any help!

Joćo Vale
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post #27 of 47 (permalink) Old 03-23-2010, 03:41 PM
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Quote:
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A friend of mine is going to swap his Giulietta gearbox by a LSD 75 TS one. This new gearbox has a 4.1 final drive and the Giulietta has a 4.3. I was thinking in swapping just the ring gear because the pinions have the same number of teeth (10) Am I thinking right or am I about to destroy a gear set?
I think your question is: Is the pinion gear the same for a 10:41 differential as it is for a 10:43? If I had to guess, I would say "no" - that even though both pinions have 10 teeth, the shape of the teeth is slightly different to accommodate finer/coarser ring gears.

Can anyone who knows more about this topic chime in?

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post #28 of 47 (permalink) Old 03-26-2010, 07:03 AM
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R&P Gears

They are totally different gear sets. You cannot use different pinions with different ring gears. As well the Giulietta transaxles have smaller carrier units with smaller bearings. Won`t fit in LSD type cases.
I have a close ratio gearset that can be had with either a .95 or .83 fith gear. (for fitting in Large bearing late 75 LSD boxes.)
Send email if interested

Richard Jemison
RJR Racing

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post #29 of 47 (permalink) Old 06-16-2010, 08:35 PM Thread Starter
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SO anyone have a suggestion of a capable mechanic for rebuilding my rear dif and installng a 4.30 ring and pinion and lsd pack? Southeastern USA preferably then east cost to mid west if not.
Thanks
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post #30 of 47 (permalink) Old 06-17-2010, 07:09 AM
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Alfar7 is in Florida and I imagine he might know how to do it and have the specialty tools on hand.




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