Avenger Diff ratios to give better top speed?

[1300super]

Hi Guys, my Avenger runs out of puff at about 100kph, just like most old school cars. I was wondering is there any Higher ratio diffs fitted to other models of Avenger? Mine is the good old 75' 1300 super so its no rocket ship by any means, But it would be good if I could just drop the revs a bit at cruizing speed without having to do any major gearbox conversions. Any suggestions? Cheers.

[JoKer]

Chapter 8 page 132 of Haynes manual lists about 5 different ratios from 3.54 up to 4.37
Crown wheel 35/37 and 39 teeth mated with pinion wheel 8/9/10 and 11 teeth

4.37 37/9
3.54 39/11

apart from reguritating that I have no idea wich gives better topend or acceleration - suspect the lower is Auto and give better acceleration

4.37 found in early 1250 Models

[avenga]

I just did a 5 speed conversion on mine which was awesome for dropping the revs. Dropped them from 3,500RPM@100KPH down to 2,800RPM@100KPH. But yeah that is a pretty expensive route to take.

Have a read of this topic, we discussed different diff and gearbox ratios.

http://www.avenger.co.nz/forum/index.php?topic=32.0

Gear ratios (to chassis number R4 184358)
4th 1.000:1
3rd 1.366:1
2nd 2.029:1
1st 3.317:1
reverse 3.680:1

Gear ratios (to chassis number RH 184359)
4th 1.000:1
3rd 1.387:1
2nd 2.165:1
1st 3.538:1
reverse 3.680:1


4.37:1 35 crownwheel teeth, 8 pinion, road speed= 25KPH per 1000RPM, 4,000RPM@100KPH
4.11:1 37 crownwheel teeth, 9 pinion, road speed= 26KPH per 1000RPM, 3,846RPM@100KPH
3.89:1 35 crownwheel teeth, 9 pinion, road speed= 27KPH per 1000RPM, 3,704RPM@100KPH
3.70:1 37 crownwheel teeth, 10 pinion, road speed= 28KPH per 1000RPM, 3,571RPM@100KPH
3.54:1 39 crownwheel teeth, 11 pinion, road speed= 30KPH per 1000RPM, 3,333RPM@100KPH

And you can change the cruising speed a bit by tyre size. Read this post. Ross (Oldschool) said changing his tyre size made it better on the open road.

http://www.avenger.co.nz/forum/index.php?topic=96.0

Also have a read of my 5 speed gearbox conversion.

http://www.avenger.co.nz/forum/index.php?topic=60.0

[JoKer]

personally I would not go to that effort, of swapping Gearbox unless it was my Daily and I was traveling long distances

plug and play /diff / tire sizes sound simple

try the below for playing with tire sizes

For all sorts of car related data and is not guaranteed 100% perfect but is capable of your general needs



Please accept the ZIP file download 21KB filesize (TINY!)

Full credit to Stephen Penney [Author] and original link (I have lost) from NissanSilvia forums in AU for file origin

please report any problems with the file to me

[hunted]

Hey Sam. Sticking they factory wheels back on will help a bit, as the 185/60s on the car now are relatively small

[1300super]

Cheers guys, all great suggestions. I did stick the standard rims & tyres on for a day and it helped, but they look terrible so they promptly came off again lol. I think the 3.54:1 ratio diff would be the go. Now Ive just got to find one. Ill stick up a wanted add. Also I think its about time I throw that 1600 in 

[avenga]

Good luck finding a 3.54:1 in NZ. Most diff's are 3.89:1 or 4.11:1. I use a 4.11:1 estate diff in my race car and a 3.7:1 in my '75. I used to scrap late model Chrylser Avengers which had the 3.7:1 diff but all the hillmans are 3:89:1

Rear axle ratio...
All NZ 1500 had 3.89.
1300 had 4.11 along with the Estate.
1600 had 3.89 until the last mk2's that changed to 3.7, so 3.89 is most common.
4.375 was never fitted to NZ built Avengers, it was standard in UK 1250 and 1300? and also 930cc Sunbeams.
I am sure that 3.54 was never used for NZ Avengers and I am not sure what it was used in.

[hunted]

Also I think its about time I throw that 1600 in 

this haha.

also, another one of my plans for it was to get some 14 or 15" steels of a citreon (same stud pattern) and get them widened. then could run a semi low profile tyre on it so it looks lush, but still retain a decent rolling diameter.

[JoKer]

i have to pull my diff out as I am 1 wheel drive.. will count crown wheel (was welded-locked diff)

same with the spare/original in the shed

[avenga]

Just don't weld your diff like this.

[JoKer]

hahha yea thats where i went wrong! awesome windup that was...

[avengertiger]

see how the 1600 goes sam before you change diffs etc my old 1500 at home would sit at 90mph flat out back home so 60mph shouldnt be that stressful on the running gear,have no idea what ratio diff was in the 1500 super will get a look later

[1300super]

Yeah thats not a bad idea Dave. Ill chuck it in and let you guys know how it goes.

[oldschool]

Once I got the speedo and tacho working on my 1979 1600 GLS it told me I was doing 3000rpm @100 km/h. It has 165/80-13 tyres. It probably has the 3.70:1 diff, the lowest ratio one you can get in NZ Avengers. My other 1600 Hillman Avenger with a 3.89:1 diff and 175/80-13 tyres works out to the same 3.70:1 ratio, so you can make quite a difference to the revs by fitting bigger rims/tyres. There's lots of 3.89:1 diffs around (saw a few at Smash Palace) and it would be heaps better than the 4.11:1 one you have at the moment, whether you're running a 1300 or 1600 motor.
 

[avenga]

Your speedo must be wrong or something Ross because a 3.70:1 gives you 3,571RPM@100KPH and because the speedo picks up the speed from the gearbox it doesn't matter what tyre size you have, It won't effect what your gauges are reading unless you are using an external speed sensing device like my GPS speedo.

Even the 3.54 is only 3,333RPM@100KPH so to get 3,000RPM@100KPH indicated on the speedo you have to go down to like a 3.2:1 with a speedo cable to suit.

If you want to do some testing Ross we can go for a drive with my GPS speedo plugged in to each of your Avenger.

And the difference between 165/80/R13 and 175/80/R13 is 2.6KPH @ 100KPH and the difference between the 3.70:1 and the 3.89:1 is only 3.7KPH difference @ 100KPH so neither are going to make a huge difference. I worked out the tyre swap between those sizes will drop the engine by 107RPM and the diff swap from 3.89:1 to 3.70:1 would drop the engine speed by 133RPM so bugger all change really.

Compare this to my 5 speed conversion with 5th being 0.82:1 which with standard tyres would drop a 3:70:1 Avenger from 3,571RPM@100KPH(28KPH/1000RPM) to 2,928RPM@100KPH(34KPH/1000RPM), dropping the engine speed by 643RPM at 100KPH. In my Avenger with the combo of my tyres and 3.7:1 diff I get ~2,800RPM@100KPH going by my GPS speedo saving me ~771RPM @ 100KPH.