TH400 whining and grinding
Thread Starter
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Joined: Jul 2015
Posts: 31
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From: Dubai UAE
TH400 whining and grinding Hi guys,
I have a offroad racetruck bought from the US.
I think the gearbox is prepped by TCI, but i have no more information then the stickers on it.
it has done now about 100 miles since new.
if the gearbox is cold its runs quite alright.
soon as the gearbox starts to warm up its getting louder.
at operational temp its 1st gear is quiet over the whole rpm range.
shift to 2nd it sounds like there is a roots blower on the engine from 2000 rpm up.
shift to 3th and it sounds like an angle grinder, i cant hear anything else then the gearbox.
the builder says its cause the intermediate gearbox has straight cut gears.
I don't believe it since 6000 rpm in first is not making the noise as 2000 in 2nd.
The gearbox doesnt slip in any of the gears, fluid looks and smells good.
you guys have some ideas, I will try to measure the pressure of the gearbox this afternoon.
I have a offroad racetruck bought from the US.
I think the gearbox is prepped by TCI, but i have no more information then the stickers on it.
it has done now about 100 miles since new.
if the gearbox is cold its runs quite alright.
soon as the gearbox starts to warm up its getting louder.
at operational temp its 1st gear is quiet over the whole rpm range.
shift to 2nd it sounds like there is a roots blower on the engine from 2000 rpm up.
shift to 3th and it sounds like an angle grinder, i cant hear anything else then the gearbox.
the builder says its cause the intermediate gearbox has straight cut gears.
I don't believe it since 6000 rpm in first is not making the noise as 2000 in 2nd.
The gearbox doesnt slip in any of the gears, fluid looks and smells good.
you guys have some ideas, I will try to measure the pressure of the gearbox this afternoon.
Last edited by patrick335d; Nov 15, 2015 at 12:36 AM.
Thread Starter
Teching In
Joined: Jul 2015
Posts: 31
Likes: 0
From: Dubai UAE
you guys have an idea, I measured the pressures, see below.
can there be a cause?
manual spec measured
Neutral, brake applied @1000 rpm 55-70PSI 95PSI
Drive @ idle 60-85 140PSI
Drive 3th, brake applied@1000 60-90 125PSI
Drive 2nd, brake applied@1000 135-160 205PSI
Reverse, brake applied@1000 95-150 175PSI
Drive 1ST, brake applied@1000 90-110 205PSI
can there be a cause?
manual spec measured
Neutral, brake applied @1000 rpm 55-70PSI 95PSI
Drive @ idle 60-85 140PSI
Drive 3th, brake applied@1000 60-90 125PSI
Drive 2nd, brake applied@1000 135-160 205PSI
Reverse, brake applied@1000 95-150 175PSI
Drive 1ST, brake applied@1000 90-110 205PSI
Last edited by patrick335d; Nov 19, 2015 at 10:49 PM.
Thread Starter
Teching In
Joined: Jul 2015
Posts: 31
Likes: 0
From: Dubai UAE
Left 60-90 is gm spec, 125 is what i measured.
I found a movie on Youtube where the gearbox makes the same noise.
19 seconds and onwards.
Last edited by patrick335d; Nov 20, 2015 at 08:19 AM.
Thread Starter
Teching In
Joined: Jul 2015
Posts: 31
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From: Dubai UAE
Do you have a GM partnumber of this, Cause the People here in the Dealership dont know the difference between a filter and a sparkplug. They will ask me for a licence plate number which i dont have otherwise. Thanks for the help so far.
Thread Starter
Teching In
Joined: Jul 2015
Posts: 31
Likes: 0
From: Dubai UAE
I opened up the sump today, got the filter on order.
found just some small stuff on the magnet.
But i found vibrations marks all on the sump, from the filter.
i assume that the filter is solid against the sump, restricting the oil flow.
Got to fix my rear end first now, since that one is bust.
found just some small stuff on the magnet.
But i found vibrations marks all on the sump, from the filter.
i assume that the filter is solid against the sump, restricting the oil flow.
Got to fix my rear end first now, since that one is bust.
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