BUGA Community
Technical => Driveline => Diffs => Topic started by: hotrod on September 13, 2008, 04:05:48 PM
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Righto I know about diff ratios and for every turn of the wheel the driveshaft rotates the number of turns to match your diff ratio!
heres the thing, have managed to snag some time to work on the van I picked up 4 months ago and thought I would check out the diff ratio while I had the arse off the ground, as when i bought it and was bebating wether to trailer it home or drive it, matey I bought it from said it was good for 80 k so I assumed it was a standard diff ( have since bought a modified one, just waiting for it to come from sydney on the cheap). Wheel rotates 10 times and the driveshaft rotates 20 & 1/2 times making me think what the!
Put the van on axle stands (as the van is unreg) and at reasonably high revs the speedo said 80 k, gave it one big rev and got it to 100k but wouldn't want to do that for an extended time period especially when you add in the aerodynamics of a brick outhouse.
Am I looking at things correctly? ??? ??? ???
and what the ??? ??? ???
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going by thosr figures Hotrod its aprox 2.05 ratio doesnt seem right.
I think the original diff ratios were in the 4.00 4.5 range for the 80 kmh thing.
Have a look at the diff, where the pinion shaft goes into the diff, there should be a disc (large washer) there with the ratio stamped on it.
Warren
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the easiest way ive found.. cause i do it a bit lol.. love diff ratios! (only works on non lsd diffs which is almost all of em in beddys) is to jackup one wheel.. get someone to watch the wheel spin twice while you spin the tail shaft counting the no of turns.. so if the tail shaft turned 3 and a half to 2 turns of the 1 wheel then its a 3.5:1 ratio..
the reason for 2 turns not 1 is cause usually you would be turning the other wheel at the same time so it would be one.. this way you only have to jack up one wheel rather than 2!!
hope this helps..
hey hotrod what running gear you planning on running in front of that bargin of a diff?
ben
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So going by Bens theory I have a 4.00 (ish) to 1 ratio
Thanks Ben, am putting that bargian diff behind 173 3 speed at the moment, have done the v8 route but am at the stage of life where looking good is 9/10s of the enjoyment, and in a beddy how can you do anything but! 8)
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sorry fella you wont be able to run that diff behind a 173.. not enough power to get ti moving moving! thats one of the reasons why it went cheap.. the average joe cant put it behind his holden 6 cause its too tall!! sometimes i think the 3.25:1 is too tall for my 173. and wasnt yours a 2.9:1?? definatly need a v8 to run that puppy!!
ben
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probably 4.2:1 then i think the swb came with..
post up a pic of your centre we will know exactly what it is by the look of it..
ben
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If your going to take of the back cover to have a look count the number of teeth on the crown wheel and the number of teeth on the pinon gear and divide the pinon into the crown wheel this will give you your exact ratio
For example on my beddy my crown wheel has 49 teeth and the pinon gear is 11
49 divided by 11 = 4.45
cheers snow
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hey hotrod what hjave you come up with regarding the diff and all??
cheers ben
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nothing yet!
as
wife broken
car broken
dog broken
New house (mortgage) broken
Too friggen scared to touch anything else this week
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bummer that doesnt sound so good..
hope it gets better fella!!
ben
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hey HR, hope ur week gets better bro .....
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any clues on this fella???? i will have a look for those numbers tomorrow, but i take it some of you will know it by sight...
(http://www.buga.com.au/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=6282&g2_serialNumber=2)
(http://www.buga.com.au/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=6322&g2_serialNumber=2)
and while we are at it do these look familiar?
(http://www.buga.com.au/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=6312&g2_serialNumber=2)
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original bedford diff :( very slow on hwy..
holden discs.. holden calipers.. by the looks of things
blue stub axels.. owww not too sure.. if knew what holden ones looked like i would know lol.. but not bedford orig. could be drop axels i suppose!! that woiuld be a score and a half!!
ben
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Definately look like Holden Calpiers and Rotors to me. HQ - HZ ;)
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bugga on the diff!!!!!!!!!!
the add said highway diff!
will crack it open and count its teeth...
when you change to highway do you change the entire diff or can it be just the center?
i think the fella said HQ disk conversion kits (memory isn't the best these days)
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Had a highway diff in my last Beddy and I loved it ;D It was a slug to get movin, but it loved 140k. Anything below that and it had no boogy. I was happy to slug around town though with my feet up on the dash 8) From memory it was 2.78:1 or there abouts.
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i will be sticking this in... it was a free part... and with the heavy steering im thinking auto is the go go.
(http://www.buga.com.au/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=6327&g2_serialNumber=2)
im guessing a three speed auto?
so what ratio would be ideal (186 motor) might be looking at a 202 black down the track
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I doubt they’re drop axles as the stubs too low it would be more in the middle whack the rotors on them and see if the callipers fit id guess they’re from the same car the callipers and rotors are off
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those stub axles look like holden (hq-hz)
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Stubs look like Holden. Auto is a trimatic 3 speed auto. In my opinion 3.36 or 3.08 or somewhere around them would be best. More than 3.36 and no top end less than 3.08 no power down low.
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gday! why is it that i cant see the photos posted here? all im getting is a box with a cross in it? i run a 3.08 diff behind a 202 on gas. im not sure if its the best for fuel economy but it takes off alright and cruises at 100 at about 2700 rpm. ill be swapping it for a 3.36 soon and comparing it with the 3.08 to see which has better ecomony, then sticking with the best one. take it easy.
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where is this ratio stamp meant to be???? or do i have to drop the tail shaft?
i have looked everywhere and i can only see the make.
(http://www.buga.com.au/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=6815&g2_serialNumber=2)
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able
get a wire brush and clean the disc that the black arrow is pointing at, that is were it normally is
Warren
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the easiest way ive found.. cause i do it a bit lol.. love diff ratios! (only works on non lsd diffs which is almost all of em in beddys) is to jackup one wheel.. get someone to watch the wheel spin twice while you spin the tail shaft counting the no of turns.. so if the tail shaft turned 3 and a half to 2 turns of the 1 wheel then its a 3.5:1 ratio..
the reason for 2 turns not 1 is cause usually you would be turning the other wheel at the same time so it would be one.. this way you only have to jack up one wheel rather than 2!!
hope this helps..
ben
their is no stamp on mine but i just followed bens advice and i got exactly his example.
i put tape on the top dead center of my wheel and top dead center of the tail shaft.
i turned the wheel 2 turns and the tail shaft spun 3.5 times.
so that is a 3.5:1 ratio? like bens example?
if it is... is that highway or the stranded i need to change type?
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you may have a beddy housing with a different centre.. rumors tell us the cresta gears fits straight into the centre of the beddy centre..
3.5:1 is good!!
ben
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i cannot find a smiley face big enough! ;D
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Hi guys I hate to throw a spanner in the works but I have camper with a 202 and a trimatic, and a chev 12 bolt with a tall ratio of 2.3. On the freeway no problems, runs beautifully. Around the suburbs, a little sluggish off the the mark. I have used this set up for a number of years and the guy who owned the car before me found it OK as well. I am going to change it to a 2.78 just to help with take off but otherwise very happy.
Phill
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hey catcher are you sure its 2.3:1? i have never herd of anything that low. the lowest i know is the salsbury 2.6 something :1
the tallest diff i ever herd of being used behind a 202 is morgans 2.92. and thats pretty tall. 2.3 would be insane with nothing in the van.. with all the camping gear you wouldnt get anywhere.
ben
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Hi guys. 3.5 behind a 202 is great, you won't get much better for low down and top end. Have had many ratio's but after saying that I do run a overdrive on the trimatic for the higher end on the open roads but more than not the overdrive stays off.
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I have a SWB 78 camper fitted out with cupboards, water tanks etc on gas and petrol, 186 with trimatic and 3.55 HZ diff OK around town but a bit sluggish on the hwy. At 100 klm 3000 revs, 60klm 2000 rpm when the van was a manual revs about 400 less at 100 klm. I have a 2.78 to try out but I am concerned that it will be too tall around town
Joe
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Hi Ben, I am sure it is 2.3. The guy told me and I did not believe him he showed me the receipt of when he paid to have the diff ratio put in. I spoke to a few diff places about changing it and I was informed that Chev did make a 2.3 ratio.
catcher
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far out man!! man lucky ya got the trimatic to help out!
must be very economical ay?
ben
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I'm putting 3.45:1 (11/38) diffy in mine. The engine is an LD28 diesel with a Jatco 4N71B 4 speed auto which has a 0.6:1 overdrive.
Tyres are 185/70x14
So..
14" x 25.4 = 355.6mm
185 x .7 = 129.5 tyre hight
129.5 + 129.5 + 355.6 = 614.6mm wheel diameter
I dont know how much the tyre squashes with a load so I will say 600mm diameter
600 x 3.14 = 1884mm circumference
1000 / 1.884 = 530 rev/km
530 x 100 (km/h) 53000 revs per hour @ 100km/h
53000 / 60 = 883 wheel rpm @ 100km/h
883 x 3.45 = 3047 drive shaft rpm @ 100km/h
3047 x 0.6 = 1828 engine rpm @ 100km/h
I think I have got the maths right.
That means that before the overdrive I will be doing 3000 revs at 100k which sounds ok to me. That will drop to 1800 revs with the overdrive.
The old diffy was 5.286:1 (7/37) which would have been 2700rpm at 100km/h which is what it sounded like.
One day when I get the driveshaft back in I'll go for a drive and see what its like.
This link http://www.expeditionlandrover.info/enginePwrSpecs.htm (http://www.expeditionlandrover.info/enginePwrSpecs.htm) gives some usefull info on a few engines for Land Rovers including
LD28 Diesel 6 cyl, no turbo 93 Hp @ 4400rpm 148 ft/lb @ 2000rpm
Auda