New tow vehicle - yipee

[shwah]

Well I managed to get by with my Jeep Cherokee for a while, but finally took the step of getting a dedicated race/tow vehicle.

Just picked up a 95 GMC 3/4ton conversion van. It has a tow package and 5.7 motor with the 3.45 rear end.

I was planning to add an additional trans cooler, but have been advised by some that just keeping it out of overdrive when towing will keep fluid temperatures in check. They also mentioned that for this reason the 3.45 final drive is a benefit over the also available 3.73 - keeps the rpms reasonable at highway speeds. Anyone else have experience/advice about that I should keep an eye on or consider adding/changing to keep this a reliable tow vehicle?

Just did a trans fluid/filter change, coolant flush, and all the basic stuff that you do when picking up a used vehicle (filters/fluids/plugs). I tow an ITB Golf with a small open trailer. I will be installing a brake controller shortly, and hope to change from the current single axle trailer to a tandem with brakes on both axles over the winter.

Seems to be in good shape for a 123k mile truck. I feel like it was a fair deal at $4200.

Really looking forward to the extra space and wheelbase when travelling to events next year.

Chris

[racer-025]

You simply can't beat a full-size van (budget minded of course) for going racing. I've been using a one for over a decade.

[Dick Elliott]

NEVER ever tow without a cooler. Too cold is much better than too hot. Heat is the killer of tranies. Big tranie oil pan helps to. 278000 miles on my C-6 tranie and never out of the car. Cooler of course! Trust me on this one and yes, leave it out of OD when towing. DICK.

[shwah]

Thanks.

Just for clarity it does have a front mounted cooler as part of the towing package. I was just considering adding an additional one in series with it.

I figured that it couldn't hurt, and will probably go ahead with it.

cheers,
Chris

[spnkzss]

*** NEVER ever tow without a cooler. Too cold is much better than too hot. ***

That is not completely true. It is not a good thing to keep the tranny too cool. The fluid has an operating range that you need to stay in. That means too hot and too cold are bad on the tranny. Heat is definitly the main fear of trannies, but if you ever notice on some of the older vehicles they never seem to shift "right" until they get warmed up.

[lateapex911]

You know, now that you mention it....

I have a 2001 GMC Sierra pickup with the 5.3 and the tow/haul feature.

I have never looked for a trans cooler, but I highly doubt it has one.

Towing an enclosed trailer can be hard on it, esp the hills. Lots of downshifing...

So....how would I know if my trans was too hot? And...how do you addd a cooler? Are there plugged inlet and outlet ports on the trans? Are there better brands of coolers to use? Size?


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Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]

[SamITC85]

Jake,
If you have the towing package from GM it came with the tranny cooler. I have basically the same truck 02 Silverado 5.3 and it has the cooler as well as a temp gauge for the tranny as well

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Sam Rolfe
TBR Motorsports
#85 ITC VW Rabbit being converted to LPHP
#85 GP Scirocco

[Eagle7]

I've got a '96 Silverado K1500 5.7. Is there a way to disable overdrive? No switch that I can find. My last two outings (the only long tows I've made), it started making funny noises after a couple hours in OD. Shifting to 3rd gear cleared it up. 3rd gear was 2600 RPM @ 70 MPH. I'd try 4th if I knew how to prevent the shift into OD.

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Marty Doane
ITS RX-7 #13
CenDiv WMR

[lateapex911]

Interesting....I have the factory tow set up in the back, but no guage.

So, if the cooler is there, where do they put it? Time to crawl under the truck, I see....

------------------
Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]

[Bill Miller]

Marty,

4th gear on that tranny (700R4 or 4L60E) is OD. Both my '89 K1500 and my '98 K2500 say " O, 3, 2, 1"

shwah,

I had essentially the same engine/trans/rear setup in my '89 K1500. You'll do ok w/ a light car and a small, open trailer w/ that setup. While the taller (lower rpm at highway speed) rear may keep the revs down on the highway, the shorter ratio will be better if you have a lot of hills to deal with. Definately don't use OD. As I said in another thread, tow capacity is very dependent on rear axle ratio. All else being equal, a shorter axle ratio will have a higher towing capacity. Check the mfg's rating on that rig, but IIRC, it's ~6500-7000 #.

The other problem w/ that era ('88 - '96, pre-Vortec) Chevy is head gaskets. Those motors are known to blow head gaskets. And absolutely put a trans cooler on it.

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MARRS #25 ITB Rabbit GTI (sold) | MARRS #25 HProd Rabbit
SCCA 279608

[ITSRX7]

Jake,

As you know, I tow with a 5.4L Expedition. Tow package on that includes full C3 wiring and adapters, load leveling rear suspension and a tranny cooler.

I added some autometer pillar gauges (tranny temp and oil temp) to keep my eye on things when I pull. After we tapped the tranny case for the temp sender, I refilled with Swepco brand fluid. Suppsed to be the ultra good stuff the truckers use. Runs cool and shifts nice.

AB

------------------
Andy Bettencourt
ITS RX-7 & Spec Miata 1.6 (ITA project)
New England Region R188967
www.flatout-motorsports.com

[kennyr7]

Jake,
You only get a trans temp gauge in the 3/4 ton models.

Ken

[shwah]

Thanks for all the response guys.

I will go ahead and put an additional cooler on it, and a temp gauge, just to be safe.

Also in response to a few other comments - Light car and small open trailer perfectly describes my rig, and mountains are far from Chicago.

Chris

[apr67]

Most GM products that don't have tow packages use the radiator as the tranny cooler.

If you add an after market cooler, and live in a place where it gets cold, make sure you hook the new cooler up before the radiator and keep the radiaitor cooler. It acts as a warmer during cold weather..

At least that is why my transmission guy said.

[shwah]

Not sure if that was a comment in response to me, but if it was I'll clarify.

I have a factory external cooler. I was considering leaving it as is and never tow in OD, but based on suggestions above, plan to add a second external cooler in series with the OEM (I still won't tow in OD).

Chris