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[Grahampuk]

I purchased a 98 cherokee XJ, 4.0 ltr, manual, Dana 35 with 3.07 ratio, 4.5 lift with 32 inch tyres

The problem is the vehicle will only have a cruising speed of 65mph with a 2800 rpm and whenever I shift from 4th to 5th gear the vehicle does not have enough power and I must change back down to 4th and I know the engine power is ok.

My question is what do I need to do with the tyres, axles or gearing to be able to cruise at 75mph ?

Regards,

Graham

[bigjeepzj]

cheapest way 4.10 axles off a 2.5 petrol

[Grahampuk]

Thank you for the reply,

What would that give me a cruising speed of ?

[chrisjones]

Should return the gearing near enough to stock

[gazjeep]

Go & check out Randy's Ring & pinion website, if you cant get the axle's off a 2.5, price up re-gearing what you have, at a guess your looking at £1200 - £1500 to get the parts this side of the pond.

Depending on where you are, I know a man that can do the work for you 

[Grahampuk]

Thank you,

Don't think I can get stock axles from a 2.5 here in Middle East as all vehicles were 4.0, ordering is not an issue so what would you recommend I order ?

Regards,


Graham

[Bulldog67]

you jammy bastard, I bet you aint got frickin rain and cold assed wind 

[bigjeepzj]

contact these guys

http://www.ringpinion.com/

but you will need some one who knows what there doing

[Grahampuk]

Any idea which axles I should go for ?

[bigjeepzj]

http://www.jeep4x4center.com/jeep-tires/tire-gear-ratio-chart.htm

[isle of man]

Try ECGS they are very helpful.

[Bubba]

4.56 would be better but may need more axle work than just gear sets

[Jonny Jeep]

I ran 33 inch tyres on my Tj with 3.07:1 gears for a while. Cruising at 70mph wasn't a problem. 5th gear was useless and not used at all, but it would cruise happily at 70 in 4th unless it was very windy, when I had to use third. If you can only get to 65 I'd say u have other problems than the gearing.

[robsrotti]

Middle east, now that would explain the manual gearbox on a 4.0L.

[Mike Pavelin]

I ran 33 inch tyres on my Tj with 3.07:1 gears for a while. Cruising at 70mph wasn't a problem. 5th gear was useless and not used at all, but it would cruise happily at 70 in 4th unless it was very windy, when I had to use third. If you can only get to 65 I'd say u have other problems than the gearing.

He's probably doing more like 75-80 if he's running 32s on stock gears without recalibrating the speedo.

[bigjeepzj]

 Good point

[gazjeep]

The Doc speaks good logic  , double check that speedo with a satnav, the differences can be surprising 

[Jonny Jeep]

It is a point but I have had indicated speeds faster than 70mph in my TJ before swapping the speedo gear (Professional Driver on a closed course, do not try this at home). 
80mph shouldn't be an issue for an XJ with a rated top speed of over 100mph.

[Cockney Boy]

I'm running 35"'s and. 4.56 on my TJ and the speedo has be redone to accommodate the above and there is still a difference between my Sat Nav.

[JamesH]

The speedo should read 5-10% faster than actual speed when setup right.

For the original question I would say 4.10 gears would be perfect with manual box and a driver who wants a good top end speed but do check actual speed and don't rely on the speedo to tell you as the bigger tyres have a massive effect. You could go 4.56 gears but it would be revving a bit cruising at 70+. There are some calculators around on Randy's ting and pinion and other sites that will give you revs at given speeds.

[Jonny Jeep]

Here's a good calc for speed at given rpm or revs at given speed...
http://www.grimmjeeper.com/gears.html

[Lornaben]

Or even right here on this site

http://www.birtydastards.com/frm/index.php?action=ezportal;sa=page;p=8