fbekholden.com

Hi guys Im new to the forum & Im having trouble with my ute.Well not trouble but when I get to about 50mph it seems as if I need another gear.I want to leave the old girl reasonably stock but she does have a bit of work done to her,like extractors mild 25/65 cam & twin zeniths,the car runs great but I think I need to change the diff ratio.Can anyone help me?What is the standard ratio & what ratio is recommended to give me a better cruise?Cheers Mick1964

What ratio does it have now ????
Mine has a similar problem, sitting on 50mph and revs pretty hard. The ratio I have now is 3.36, so Ive been thinking of dropping it to 3.08 and see if it makes a good difference on the freeway. Around town its fine, its on the open road where it struggles a bit.
Either that or change your wheel diameter.

Dave.

Thanks Dave I dont know what ratio it is all I know is that its standard.Cheers

Your standard diff is 3.89, I wouldn't go any more than 3.36 with a grey motor.

Dave, with your 138 Red motor I would have thought the 3.36 would be spot on, 3.08 might be a bit sluggish off the line.

What Trev said.

We just put a 3.36 dif in our car and i wish i did it years ago

3.36 you won't regret it

Mick

Thanks guys all your help has been great I really appreciate it.I got my answer in the same day as I posted the question, hows that? Just goes to show that this sight is the place to go Cheers Mick1964

Hi guys anyone know were I can buy a 3.36 diff Im in Windsor NSW.Cheers Mick1964

Trev wrote: Dave, with your 138 Red motor I would have thought the 3.36 would be spot on, 3.08 might be a bit sluggish off the line.

First gear is pretty short in mine, although its still sluggish as well. Had it out last weekend on the Monash and got it up to 60mph and was to too scared to take it over that as it was revving its ring off.
Sorry Micheal for hijacking your thread.

Dave.

You need a taller tyre Dave. 3:36 is what I run too and it's pretty much perfect. Any taller and you're gonna have to rev the rig out of it to move.

Thanks DR, was actually looking at that last night. Got a set of stockie rims here which I might play around with.
I think the proflie on the Dragways are pretty small, I'll have a look when I get home to see what they actaully are.

Dave.

Thing is, if you put a larger wheel the speedo will still be showing the same speed, at the same revs, although the car will physically be going faster. So Devilrod's right, a larger rim or taller tyre will help. but you may get the illusion that nothing's changed.


Coz you have a lower wheel/tyre combo than standard, the speedo may be showing 60mph, but the car may be only doing 50mph. I dont know the profile of Dave's tyres, but his smaller tyres with a 3.36 diff will probably be no different to mine with the stock ratio and 80 series tyres.

Easy way to explain it. If you had a tacho and your speedo was showing 60mph at 4000rpm, you could put 2.7's in the diff and truck tyres on it...........it will still show 60mph and 4000rpm on you dash, although the car itself is going faster. That has to do with the speedo working off the gearbox, with the whole thing calibrated to the stock diff and tyres



Mick, if I'm not wrong most diff centres up to HJ Holden should fit, and the majority of these were 3.36. Many wreckers would stock them

I'm running 3.36 centre, 14" rims 235/60/14 tyres = 2850rpm at 105kph (Checked with Navman) and stock crash box.

Mick

Hi Guys, is the 3.08 rear diff a direct bolt in replacement?

Now I have the 5-speed the dif needs to be changed....I'll try the Holden wreckers if it's an easy swap.