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#1
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Are my rpms too high? Speed to rpm chart?
Are my rpms too high? Speed to rpm chart?
Hi folks, I had a 2nd replacement differential put in by Enrique. this one seems to be smoother than the first one he put in. the other one had a lot of noise from being worn out. this one makes less noise, but it still appears to be louder than my original that went out. That said, my rpms seem higher than I remember w/ my original differential. I can't quantify the original, but here's the rpms at 60 and 70 mph of the current diff: 60mph = 2500-2600 70mph = 2700-2800 Is this about right for a 87 300D? Is there a reference chart that anyone knows of? It just seems a little noiser and higher than i remember. it too could be the $50 tires that I put on a few weeks ago. Or (gasp), could it be the transmission? |
#2
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thats normal
__________________
1985 300TD Turbo Euro-wagon 1979 280CE 225,200 miles 1985 300D Turbo 264,000 miles 1976 240D 190,000 miles 1979 300TD 220,000 GONE but not forgotten 1976 300D 195,300 miles 1983 300D Turbo 175,000 miles http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg |
#3
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79:
those rpm number are normal for your 79 too? Or are you saying thats normal for my vehicle? |
#4
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Here. Add a few hundred RPM for torque converter slippage.
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#5
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Forced,
Thanks for the chart. If I am reading this correctly, the white boxes at the top are diff gear ratios. The colored bands correspond to some sort of strata like 'best, good, average, etc". But what does 1. Gang, 2. Gang, etc mean? I looked up Gang in German and it says "to be the usual thing, to be quite usual". So which Gang column do I look at? I'm assuming 5. Gang. Is that your understanding? |
#6
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Gang=speed. 1st gear, 2nd gear, etc.
For an automatic you will need 4 Gang. |
#7
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That chart can't be right. Im turning 3300 at 60mph. 3.58 rear end, 195/70 R14 tires.
EDIT: never mind, I wasn't pay attention to the Km/h, I was thinking mph.
__________________
1985 300TD Turbo Euro-wagon 1979 280CE 225,200 miles 1985 300D Turbo 264,000 miles 1976 240D 190,000 miles 1979 300TD 220,000 GONE but not forgotten 1976 300D 195,300 miles 1983 300D Turbo 175,000 miles http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg |
#8
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The chart doesn't have the 2.65:1 gears of the '87 300D.
Mine turn 3,000rpm right around 77mph so your numbers look about right.
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Gone to the dark side - Jeff |
#9
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It's fine....It's normal...for the 2.65 and 195/65/R15's and non-locker 722.3x.
__________________
1987 300SDL (324000) 1986 Porsche 951 (944 Turbo) (166000) 1978 Porsche 924 (99000) 1996 Nissan Pathfinder R50 (201000) |
#10
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My 86 300SDL with unknown rear diff runs 3000 rpm straight up in the 70-80 mph range. Sounds perfectly normal to me.
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#11
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forced and other 300DT owners: thank you for posting your rpm numbers. now that i know the rpm range is normal, i'll need to figure out why it seems that there's more noise. is it the replacement diff? or perhaps the new tires?
Jeff: how noisy is it inside your cabin when you're driving between 70 and 80 mph? i know its subjective, but is it drony and loud? |
#12
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probably your ties if they're cheapo's.
__________________
1985 300TD Turbo Euro-wagon 1979 280CE 225,200 miles 1985 300D Turbo 264,000 miles 1976 240D 190,000 miles 1979 300TD 220,000 GONE but not forgotten 1976 300D 195,300 miles 1983 300D Turbo 175,000 miles http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg |
#13
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Quietest about 80mph-up, around 110 the wind noise around the mirror gets annoying, 130 it seems to quiet down again.
If you're getting a 4x4 tire type sound, it is usually a wheel bearing. If it's engine noise, probably either a bad engine mount, or mis-aligned mounts (pre-stressed), alignment and stress-relieving the mounts is outlined in the FSM.
__________________
Gone to the dark side - Jeff |
#14
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79 and Jeff,
Again, thanks for your advice and insight. I'm ruling out wheel bearing because they were done 10k miles ago and they were fine b/f all the suspension work. I'm going to push it up to 80mph tonight to see if it gets louder or not. probably will. I'll have the misses sit in the back to see if she can identify where the noise is the loudest. Bob |
#15
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Decide also whether it is:
Speed dependant only, Speed and load dependant (on/off throttle changes it), Engine RPM dependant, Load and direction dependant (swerve from side to side gradually to see if it changes), or does it change if you touch the brakes.
__________________
Gone to the dark side - Jeff |
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