Outer Limits 4x4 Board

Ok well I know a SD33 is not the best choice for touring but that is what I have to work with. Even worse I have the 4 speed. Ok now this past weekend at Son of Trials I had a bit of highway time with the old girl/ First time in the 6 months I've owned her save the trip back home when I bought her. At anyrate she travels along at 80k/hr per the speedometer (75k/hr per GPS) at about 2800 RPM on the tachometer. She feels like she has more go but I'm concerned because the adjustable redline in the tach was set at 3000 rpm when I bought her. There is a placard under the hood which says max rpm 3XXX I can't read any of the numbers except the 3 as the rest have been rubbed away. I have the original owners manual and it says to never run the truck faster than 125 k/hr but says nothing of the RPM. I'd have to think the motor would be screaming to even get to 100 much less 125. I have the original pizza cutter 7x16 splitties for tyres as well. Any help here? I love my old Betsy and I don't want to over rev her.

Thanks
Chris

ey mate when i got my sd33 i ahd just over 100 thousand on it, and it would hit 110-115 and it had no more, got zorst and few others mods done and now i can crack 125 with more to go but just run out of gear, i also have 4 speed and its a pain. Dw the old girl can handle it

dont worry bout the revs, it will happily rev out at over 3500. 125kph is easy enuf to do as standard. 110 is abit more comfortable else the engine just gets abit noisy

I'd be happy with 100 really much more in the old girl doesn't seem safe lol. I rekon that would be about 3100 rpm

vk2icj wrote:I'd be happy with 100 really much more in the old girl doesn't seem safe lol. I rekon that would be about 3100 rpm

i know what ya mean, i bought a 2nd truck for spares once and on the way home i felt i had to hold onto the door. anything over 80kph and i thought the door would rip off or id fall thru the floor... abit nervous for the 700km trip home

They have an inbuilt govener in the fuel pump. once the rpm hit this point the fuel delivery tapers off . Sort of like a rev limiter.

Itll sit on max rpm all day if you can keep it cool enough.

Had mine on the govenor in 5th gear and still couldnt keep up with a b double overtaking me.

pongo wrote:
Had mine on the govenor in 5th gear and still couldnt keep up with a b double overtaking me.

Damn! by my calcs, at 4000rpm in 5th gear, with a 4.625 diff and 31" tyres it'd be pulling 148ks/hr.
Ive got a feeling that the governor is set at about 4200 or 4300 rpm with no load, good motors the sd33, my car wore out before the motor!

vk2icj wrote:I'd be happy with 100 really much more in the old girl doesn't seem safe lol. I rekon that would be about 3100 rpm

Theyre really not a bad unit for touring in that they are as reliable as gravity! Should sit on 100 all day, just gotta be a bit patient, probably something that a lot of people aren't these days with all the emphasis on having power and getting everything done yesterday!
Better off touring a lower speed imo, get to see more that way, plenty of people have used similarly unrefined - and in a lot of cases less powerful cars for serious touring - expeditions e.g. Len Beadell - land rovers.
Have a look in the Mq/Mk bible it has gear ratios and you can work out what revs youll be doing at each speed - not that you need to do much as 4th is 1:1 and the diff will most likely be 4.625:1

Had my mates MQ SD33 Naturally Aspirated with extractors and exhaust with 5 speed fitted off the clock on 31's on the way back from getting the run around on buying another truck... they rev out to a bit over 41-4300 RPM - well the 30 something diesel patrols I have had did anyway.....

Patroler wrote:

pongo wrote:
Had mine on the govenor in 5th gear and still couldnt keep up with a b double overtaking me.

Damn! by my calcs, at 4000rpm in 5th gear, with a 4.625 diff and 31" tyres it'd be pulling 148ks/hr.
Ive got a feeling that the governor is set at about 4200 or 4300 rpm with no load, good motors the sd33, my car wore out before the motor!

I had 4.3's . For a while i was running 35's but got a bit too floaty at over 140.

If you can get the fuel into it itll do it. Try running a elec fuel pump as my cheap ebay one is better than the std lift pump.

Thanks for all the help so far fellas. I've been scared to take her over 3000 rpm

I have an 81 mq sd33 four speed, and 4.6 diff ratio
I converted to a 85 sd33t, with five speed and 4.3 diff ratio, much better at highway speeds, will now sit on 100 very happily.
I recommend changing the diff ratios to the turbo model ones, (4.3:1) and also getting the rear lsd at the same time the too best modifications I have done to my car, even better than the turbo motor swap.

I reckon the standard sd33 could prob spin the 4.3:1 ratio pretty happily on the highway with standard tyres...