Rear Live Axle for a Custom-built Car

[nrg500]

Where can I find a suitable rear live axle that I can use on a custom-built car ? Also, what is the price range for a rear live axle ?

I thought of using a rear live axle from a Hyundai Starex but my officemate said that I should look for a live axle that is designed for high speed. I need a relatively long rear live axle, the ones I see in owner-type jeeps is short

According to Chassis Engineering (by Herb Adams), the chassis should be designed around the type of suspension that will be used. I can't start the ladder chassis design coz I don't have measurements of the rear live axle that I'm going to use

I know many will disagree with using a rear live axle but this is my first build and I want it to be less complex and less expensive

Thanks

[jick.cejoco]

Where can I find a suitable rear live axle that I can use on a custom-built car ? Also, what is the price range for a rear live axle ?

I thought of using a rear live axle from a Hyundai Starex but my officemate said that I should look for a live axle that is designed for high speed. I need a relatively long rear live axle, the ones I see in owner-type jeeps is short

According to Chassis Engineering (by Herb Adams), the chassis should be designed around the type of suspension that will be used. I can't start the ladder chassis design coz I don't have measurements of the rear live axle that I'm going to use

I know many will disagree with using a rear live axle but this is my first build and I want it to be less complex and less expensive

Thanks

what engine and transmission are you going to use? for starters, you need a third member that has different gear ratios available to tailor to your needs. what are you going to use this for, quarter miles or stretch or daily commute?

[nrg500]

for city driving and track use

I'm going to use Toyota 4A-GEU engine if I can still find one

[niky]

Use an axle that goes with the engine. Easiest way to go.

[nrg500]

Use an axle that goes with the engine. Easiest way to go.

Thanks for the input but I think cars using a rear live axle is very rare now

If I'm not mistaken, manufacturers abandoned the dependent rear suspension design for cars in the 70's or 80's

Almost all cars now use an independent rear suspension


Do you think it is viable to salvage rear live axles from vehicles like Toyota Fortuner and Mitsubishi Montero ? Those vehicles have a width of ~1800mm



Also, are drive shafts universal ? What I mean is, can a drive shaft be coupled to any rear live axle ? Is it the same case with the engine ? Can I couple a drive shaft to any FR engine ?

Thanks

[nrg500]

Can I just fabricate my own trailing arms ?

What is the effect of trailing arm length on the car's handling ?

[niky]

Drive shafts can be adapted. Your big problem is whether the axle-ratio on your rear differential is compatible with your gearbox... i.e.: will give you usable road speed in top gear.

Trailing arms will affect handling, but it's not as big a deal as the panhard bar and anti-roll bar orientation.

You might be better off recycling a live axle from a 70's Corolla or Corona...

[nrg500]

Drive shafts can be adapted. Your big problem is whether the axle-ratio on your rear differential is compatible with your gearbox... i.e.: will give you usable road speed in top gear.

Trailing arms will affect handling, but it's not as big a deal as the panhard bar and anti-roll bar orientation.

You might be better off recycling a live axle from a 70's Corolla or Corona...

Do I need to dismantle the rear live axle to know the axle ratio of the differential ?

I checked the specs at the manufacturer website of the sample vehicles I mentioned but it does not go into specifics of the rear live axle

For the panhard rod, I have read that it should be as long as possible to minimize lateral movement. Is that correct ?

[niky]

Yes, typically.

Most Manufacrurers don't publish the data. That's why it's better to stick with axles designed for the engine or for similar sized engines.

Trust me, you DO NOT want a rear diff for a big, slow-revving diesel for your small gasoline motor.

Look for a scrapped car or buy the whole rear assembly to minimize fabrication. If you don't know much about the parts you're using or suspensions in general, don't try to half-ass it and fabricate your own.

[nrg500]

Yes, typically.

Most Manufacrurers don't publish the data. That's why it's better to stick with axles designed for the engine or for similar sized engines.

Trust me, you DO NOT want a rear diff for a big, slow-revving diesel for your small gasoline motor.

Look for a scrapped car or buy the whole rear assembly to minimize fabrication. If you don't know much about the parts you're using or suspensions in general, don't try to half-ass it and fabricate your own.

Thanks for the advice

I did some searching on Google on how to find the live axle gear ratio (ring & pinion ratio as some call it)

I found this Axle Gear Ratio Identification - GETAHELMET.COM

The easiest way to determine your ring & pinion gear ratio (sometimes called axle ratio) is to check the tag that's bolted to the front differential cover. On the tag you should see some numbering such as 3.07, 3.73 or 4.11. Any of these numbers are common for a Jeep stock axle ratio. If you want to double check (perhaps a previous owner regeared, wrong factory tag, etc), here's what to do:

Jack up the rear axle and support it with jack stands. Put the transmission in neutral and then rotate the rear drive shaft by hand. While turning, count the number of drive shaft revolutions required for one revolution of the tire. If the drive shaft turns approximately 3-3/4 times, you have a 3.73 ratio, etc. It may help to use a piece of chalk mark a reference point on both the tire and drive shaft.

Number of Turns --> Approximate Gear Ratio
2 - 3/4 --> 2.72:1 or 2.77:1
3 - 0 --> 3.07:1
3 - 1/2 --> 3.54:1
3 - 3/4 --> 3.73:1
4 - 0 --> 4.10:1
4 - 1/2 --> 4.56:1
4 - 3/4 --> 4.88:1



My question now is what is the ideal ratio I should use if the it's a live axle that will be used for a car ?

Thanks