Towing spec question - Chevy Impala SS Forum
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post #1 of 15 (permalink) Old 12-04-2014, 12:30 PM Thread Starter
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Towing spec question

Why is it that a Fleetwood with towing option is rated at 7000 lbs, and the Roadmaster with the towing option is rated only at 5000 lbs? The Fleetwood is around 300 lbs heavier to begin with.

What components allow for a higher rating on the Fleetwood? Is it because the rear-end and the transmission are more stout on a Fleetwood?
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post #2 of 15 (permalink) Old 12-04-2014, 01:12 PM
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Probably due to the higher numerically ratio gears available for the Fleetwood. On trucks the towing capacity is diectly related to gears. For example: 3.42 5000lbs, 3.73 7000lbs, 4.10 10,000lbs.
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post #3 of 15 (permalink) Old 12-04-2014, 01:23 PM Thread Starter
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That makes sense. Thank you.
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post #4 of 15 (permalink) Old 12-04-2014, 04:53 PM Thread Starter
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Very good!

My 94 Roadmaster has a 2:56 posi and my 94 FWB has the 2:93 gears. I am not doing any towing on either, but was curious about the different specs.
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post #5 of 15 (permalink) Old 12-05-2014, 12:18 AM
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"9C1 Caprices with LT1s had 3.08, a 4L60E built to a 'pursuit' spec, and unique shift tables and line pressures accounting for both MpGs at low throttle angles and the likelihood of pursuits.
I suspect their ratings were 17 City, 25 HiWay, and 3000lbs[, but I can't be sure]."

I am pretty sure it is 5000 for LT-1 9C1's and the owner's manual says to tow in D.

Jim B.

'95 9c1, pcmperformance.com 93 tune, Dynomax Ultraflo catback, K & N box filter, LT4 KM, 160 stat, 3.08 Posi.

Last edited by fbi9c1; 12-05-2014 at 12:21 AM.
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post #6 of 15 (permalink) Old 12-05-2014, 01:15 PM
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What I do is wire a switch on the electric fan cars so I can turn on BEFORE the motor gets hot such as a backup in the summer or getting ready to pull a hill.
When does the stock fan come on? Like 220 deg?

Why roast the motor then cool it down? With the mechanical fan it just stays cool.

Last edited by BQUICK; 12-05-2014 at 01:17 PM.
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post #7 of 15 (permalink) Old 12-05-2014, 01:58 PM
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Gm advertised the Fleetwood as being able to tow that and do it in overdrive.

1996 DCM SS 216k
1996 Black RMW 158k
1995 DCM Roadmaster Wagon 118K
1992 Olds CC 5.3l LS swap 181k
1994 Fleetwood 160k
1975 Impala Coupe

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post #8 of 15 (permalink) Old 12-05-2014, 02:25 PM
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Quote:
Originally Posted by BQUICK View Post
What I do is wire a switch on the electric fan cars so I can turn on BEFORE the motor gets hot such as a backup in the summer or getting ready to pull a hill.
When does the stock fan come on? Like 220 deg?

Why roast the motor then cool it down? With the mechanical fan it just stays cool.
Most of us have the good sense to have a 160 Thermostat and a PCM tune with lowered fan turn on temps and adjusted shift points and increased pressure for crisper shifts as well as an aux trans cooler(9c1). If you don't at least have the trans tuned, you should install a Transgo HD2 kit. There is a Sonnax kit also I think. I wouldn't start towing with the stock setup anyway. The trans is the weak link in all of this.

Jim B.

'95 9c1, pcmperformance.com 93 tune, Dynomax Ultraflo catback, K & N box filter, LT4 KM, 160 stat, 3.08 Posi.
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post #9 of 15 (permalink) Old 12-05-2014, 05:40 PM
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Quote:
Originally Posted by Marky Dissod, Dec 5 '14, 1:42AM View Post
Quote:
Originally Posted by SKATTERBRANE View Post
Why is it that a Fleetwood with towing option is rated at 7000lbs, and the Roadmaster with the towing option is rated only at 5000lbs? The Fleetwood is around 300 lbs heavier to begin with.

What components allow for a higher rating on the Fleetwood? Is it because the rear-end and the transmission are more stout on a Fleetwood?
V4P Fleetwoods had 3.42, a 4L60E built to a 'towing' spec, and shift tables and line pressures written specifically for towing, to the detriment of MpGs.
They were rated at 15 City, 23 HiWay, and certified to tow 7000lbs.
[The Fleetwood's longer wheelbase may have something to do with it.]

V92 Caprices and Roadmasters had 2.93, a 'standard-spec' 4L60E, and shift tables and line pressures written for MpGs to the detriment of towing, thus an advisory to put the shifter in 'D' if needed to avoid 3-4 hunt-shifting.
They were rated at 17 City, 25 HiWay, and certified to tow 5000lbs.

Fleetwoods with 2.93 had a 'standard-spec' 4L60E, and shift tables and line pressures identical to V92 B-cars, yet were only rated to tow 3000lbs.

9C1 Caprices with LT1s had 3.08, a 4L60E built to a 'pursuit' spec, and unique shift tables and line pressures accounting for both MpGs at low throttle angles and the likelihood of pursuits.
I suspect their ratings were 17 City, 25 HiWay, and 3000lbs[, but I can't be sure].

Don't know about B-cars with 2.56 or L99 …
Quote:
Originally Posted by fbi9c1 View Post
I am pretty sure it is 5000 for LT1 9C1s, and the owner's manual says to tow in D.
A 9C1 Caprice owner's manual would be a precious [comm]oddity …
While 3.08 is always better than 2.93 for these cars, I was under the IMPRESSION that the lack of a [email protected]$$ mech fan was the formal technicality that prevented the 9C1 from a tow rating of 5000lbs?
No matter, I'd rather tow with a 9C1 with electrical fans, than a V92 with a mech fan any day.
Quote:
Originally Posted by BQUICK View Post
What I do is wire a switch on the electric fan cars so I can turn on BEFORE the motor gets hot such as a backup in the summer or getting ready to pull a hill.
When does the stock fan come on? Like 220F?
Why roast the motor then cool it down? With the mechanical fan it just stays cool.
Reprogramming the fans' on thresholds does the same thing without additional wiring hardware.
OEM electric fans don't come on til 225F & 232F, which is bat$h!t ridiculous considering that the mechanical fan NEVER allows that to happen. Some people haven't figured this out yet [after 20 years].
Tuners usually lower the fans' on thresholds to 203F & 212F for use with a 180F thermostat, or 185F & 194F with a 160F tstat.
Quote:
Originally Posted by 95BRMW View Post
GM advertised the Fleetwood V4P as being able to tow that and do it in overdrive.
Amended.
Quote:
Originally Posted by fbi9c1 View Post
Most of us have the good sense to have a 160F thermostat and a PCM tune with lowered fan turn on temps and adjusted shift points and increased pressure for crisper shifts as well as an aux trans cooler(9c1).
If you don't at least have the trans tuned, you should install a Transgo HD2 kit. There is a Sonnax kit also.
I wouldn't start towing with the stock setup anyway. The trans is the weak link in all of this.
Adjusting the shift points and line pressures is the other critically important reason to have the pcm reprogrammed.
Some people haven't figured this out yet, either …

1g1bl82p7rr127841 Rust In Pieces, Rest In Peace
They are NOT Lying to You
You are NOT Lying to Yourself
You are Being Lied to - BY Your Self
Alone aka The Last Psychiatrist

Last edited by Marky Dissod; 12-09-2014 at 08:36 AM.
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post #10 of 15 (permalink) Old 12-09-2014, 01:26 AM
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The Roadmaster is rated for 7000 lbs if you disable the air shocks.

Ian - Portland, OR
1994 Roadmaster Wagon - Light Drifwood Metallic, tow pakage
1974 Alfa Romeo Berlina - daily driver
1968 Reinell 18' - 100hp Evinrude V4
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