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Author Topic: Overdrive  (Read 17878 times)

Offline 76_Scottsdale

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Overdrive
« on: March 30, 2008, 06:31:56 pm »
After having had my 700R4 installed for a few months, something's been bothering me. With the new overdrive, my final drive RPM at say 50 miles per hour only dropped a couple hundred RPMS. If it has a .7 overdrive it should've dropped almost 700 RPMS. Now before anyone asks, yes I'm sure it is in overdrive, and yes the torque converter locks up once it shifts into 4th gear. I can feel the torque converter unlock if the brake pedal is pressed slightly, so I know the tranny is in overdrive. I'm extremely disappointed with the overdrive if this is all it has to offer. It is a brand new tranny under warranty from Bowtie Overdrives, so if something is wrong with it's covered. Does anyone have any ideas why I can barely notice an improvement in final drive rpms? If iI calculate the rpms if should be around 1470 at 50 mph in overdrive. It is actually at 2100 which is the 1:1 ratio, so obviously the tranny is not engaging in overdrive. The TV cable is adjusted correctly also.


I'm running 4.10 gear ratios and 305/70/16 tires if it interests anyone.
« Last Edit: March 30, 2008, 06:36:34 pm by 76_Scottsdale »
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1976 Scottsdale K20
350 C.I.D.
700R4
NP205
2 1/2" Lift
305/70/R16 BFG MT
True Dual 3" Flowmaster 40 Series Exhaust

Offline VileZambonie

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Re: Overdrive
« Reply #1 on: March 30, 2008, 07:40:53 pm »
Manually shift the transmission to verify each shift. If you shift from overdrive to drive does it shift into 3rd or does no shift occur?

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Offline 76_Scottsdale

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Re: Overdrive
« Reply #2 on: March 30, 2008, 08:04:27 pm »
I can feel it shift into 3rd, but the RPMS only rise slightly, like only of the torque converter unlocking, about 200 RPMs or so. If I accelerate smoothly manually shifting into each gear, then from 3rd to 4th i feel it shift but it only drops about 200 rpms, which I believe is just the torque converter locking.
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1976 Scottsdale K20
350 C.I.D.
700R4
NP205
2 1/2" Lift
305/70/R16 BFG MT
True Dual 3" Flowmaster 40 Series Exhaust

Offline 76_Scottsdale

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Re: Overdrive
« Reply #3 on: March 31, 2008, 02:42:04 am »
bump
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1976 Scottsdale K20
350 C.I.D.
700R4
NP205
2 1/2" Lift
305/70/R16 BFG MT
True Dual 3" Flowmaster 40 Series Exhaust

Offline zieg85

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Re: Overdrive
« Reply #4 on: March 31, 2008, 05:21:32 am »
I get about 1800
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Carl 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
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Offline zieg85

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Re: Overdrive
« Reply #5 on: March 31, 2008, 05:28:35 am »
Here is the 50 mph set.  If you are getting 2100 rpms you are not seeing OD
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Carl 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
https://www.facebook.com/groups/248658382003506/

Offline VileZambonie

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Re: Overdrive
« Reply #6 on: March 31, 2008, 07:49:17 am »
In fourth gear converter locked you should be around 1750 RPM's give or take a few...

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Offline 76_Scottsdale

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Re: Overdrive
« Reply #7 on: March 31, 2008, 05:12:57 pm »
That's exactly what I'm thinking. The converter is definitely locked but I don't think I'm seeing OD. I've made contact with Bowtie and it's covered under warranty, now I think I get to take it out and put a new one in >:(
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1976 Scottsdale K20
350 C.I.D.
700R4
NP205
2 1/2" Lift
305/70/R16 BFG MT
True Dual 3" Flowmaster 40 Series Exhaust

Offline VileZambonie

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Re: Overdrive
« Reply #8 on: March 31, 2008, 05:53:47 pm »
Did they wire it up to lock the converter in drive? So if you shift in and out of overdrive there is no change? Just unplug the connector for the converter clutch so you aren't confused by it. Manually shift each gear.

Did you adjust the TV cable properly?
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline 76_Scottsdale

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Re: Overdrive
« Reply #9 on: March 31, 2008, 11:12:18 pm »
The TV Cable is adjusted perfectly. I wired in the torque converter. It is wired so it automatically locks the converter in 4th gear. I'll try unplugging it so it doesn't lock and i'll see if there's any change shifting into 4th.
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1976 Scottsdale K20
350 C.I.D.
700R4
NP205
2 1/2" Lift
305/70/R16 BFG MT
True Dual 3" Flowmaster 40 Series Exhaust

Offline Leevon

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Re: Overdrive
« Reply #10 on: April 01, 2008, 06:07:45 pm »
just a thought, was the speedo gear matched to the gear set and tire size? 
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Offline 76_Scottsdale

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Re: Overdrive
« Reply #11 on: April 01, 2008, 11:23:54 pm »
It's a 4 wheel drive application there are no speedo gears.
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1976 Scottsdale K20
350 C.I.D.
700R4
NP205
2 1/2" Lift
305/70/R16 BFG MT
True Dual 3" Flowmaster 40 Series Exhaust

Offline 76_Scottsdale

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Re: Overdrive
« Reply #12 on: April 02, 2008, 01:09:33 am »
I unplugged the TCC wiring so I wouldn't feel it lock at all. It doesn't shift into a 4th gear at all, automatically or when I manually shift it into 4th from 3rd.
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1976 Scottsdale K20
350 C.I.D.
700R4
NP205
2 1/2" Lift
305/70/R16 BFG MT
True Dual 3" Flowmaster 40 Series Exhaust

Offline VileZambonie

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Re: Overdrive
« Reply #13 on: April 02, 2008, 06:17:42 am »
You have 1-2-3 with normal shifts? Not late shifts?
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              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline 76_Scottsdale

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Re: Overdrive
« Reply #14 on: April 02, 2008, 04:06:31 pm »
No late shifts. The TV setup feels just perfect, it shift right when it should. Just no 4th gear.
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1976 Scottsdale K20
350 C.I.D.
700R4
NP205
2 1/2" Lift
305/70/R16 BFG MT
True Dual 3" Flowmaster 40 Series Exhaust
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