Autocrawler
Latest Web Update
by David Kennedy
Photography: David Kennedy
(Photos are the same as in the magazine story)
We’d like to apologies to those of you who came here to the website looking for this update weeks ago. We ran late and didn’t get this update online as quick as we’d promised. We screwed up and we’re sorry. We won’t let it happen again!
Since the February issue went on sale we’ve come further with the Autocrawler's development. Unfortunately the engine in our test vehicle has had a terminal failure that will delay further testing for at least a few months but we wanted to share what we’ve learned so far. If you have questions about anything we’ve done here, or are interested in bouncing your transmission ideas off the author e-mail
david.kennedy@primeida.com.
Captions:
131-0302-TRAN-02
The 30,000-pound GVW cooler from Flex-a-lite’s (PN 45951) has proved to be more than what our Blazer has needed. But it’s still winter in LA and we haven’t hit the dunes yet so for now we’ll just enjoy the extra capacity this cooler has. In our application the electric fan on the back of the cooler has never had to come on so now we know we didn’t have to put the transmission cooler where it restricts airflow through the radiator. There’s no harm done, and we may just restrict airflow through the cooler with some tape until it gets warmer outside.
One thing we don’t like about our installation is the way we’ve plumbed the fittings on the bottom of the cooler. Our configuration may be trapping air pockets at the loops in the top of the cooler and causing less than peak performance. There’s no way for us to know for sure- and we don’t even know if it matters-but next time we’ll flip the cooler around 180 degrees to put the fitting on top and make sure there’s noting in the system but ATF.
131-0302-TRAN-03
This was the author’s first experience with making braided stainless steel lines but now he’s sold on it. Orme Brothers in Northridge, CA hooked us up with the Goodrige hose and aluminum fittings. We installed the fittings and measured the length of hose required to connect the cooler, pressure gauge, and Accusump. When you’re routing your own lines you’ll want to make sure to support them every few inches with some rubber clamps. The lines will stand up to a lot of abuse, but can wear through whatever they rub against so keep that in mind.
131-0302-TRAN-04
Our shifter is still mounted to floor, but we’ve since positioned it further from the firewall. We still intended to make a mount that will locate the shifter up high to the right of the steering wheel like the versions we’ve seen in some professional rally racing cars. But until we do we’ve moved it to a more conventional floor mounted location. The beauty of the Art Carr cable actuated shifter is that it will work well in any position as long as you don’t kink the cable.
131-0302-TRAN-05
The 72-inch braided Kevlar hose from Auto Meter turned out to be too short to connect the pressure gauge to the transmission if we mounted it on the dash. We moved the 2 5/8 inch Pro-Comp temperature and pressure gauges to the bottom of the dash where they are less visible, but don’t restrict our line of sight out the windshield either. It’s just as well because we don’t need to monitor transmission pressure/temperature too often- but if the TH700R4 were to start acting up the gauges will give us a better idea of what is going on inside before any damage is done. We also learned we could have gotten away with a 300psi transmission pressure gauge instead of the 600psi version we’re running. We’ve never seen our Autocrawler get close to 300 psi.
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Due to engine problems with our Autocralwer-equiped Blazer we didn’t get to wheel in any situations extreme enough to starve the 700R4’s pump and test the Accusump to see if it could maintain line pressure in the transmission. What we have done since last time is refine our installation by removing the Accusump’s pressure gauge and release valve and plugging them so we don’t find out the hard way if they can handle over 200 psi of ATF. For now we’ve basically overfilled the transmission with 3 quarts of ATF and supplied 12-volts to the electric valve on Accusump the to keep the valve “open” or automatic mode to feed pressure to the transmission if the 10-vane pump in the transmission should suck air. We’ve also wired a toggle switch into the valve so we can store 200 psi of ATF in the Accusump to give the transmission line pressure without the engine running. We know we can use the pressure inside the Accusump to apply the first gear clutch pack but we don’t yet know for how long. We believe the 3 quart ATF supply provides enough fluid to keep the first gear clutch pack applied (as determined by our Pro-Comp pressure gauge) for about 60 seconds but that’s still a guess because it’s hard to know for sure as we can’t turn the transmission’s pump on and off to test our theory. Even without knowing how long the 3-quart supply will last we feel confident in saying that it will be enough to keep you driving until transmission’s pump can take back over. If you plan to park your rig at an extreme angle and want to have ATF pressure when you start wheeling again we recommend you cut power to the electric valve to store the pressure inside the Accusump until you start driving again.
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As you read this there are at least three TCI Autocrawler full reverse manual valve bodies with compression braking undergoing off-road testing. Ours has the hardest shift you can get out of a 700R4 valve body but a softer shifting version is possible. To build your own Autocrawler talk to Lowell or Will at TCI and they’ll be more than happy to sell you the valve body they developed for this article. This trick valve body will also route ATF fluid pressure to the torque converter clutch solenoid while in first gear (something that the stock valve can’t do) so that you can activate the converter clutch via a 12-volt switch whenever you choose. This makes for hill descent control that matches any manual transmission, and when combined with the artificial line pressure provided from the Accusump it is theoretically possible to turn your engine over without using the starter. Just like guys with manual transmissions can do.
Sources:
Art Carr
888/526-5868
www.artcarr.com
690
TCI
662/224-8972
www.tciauto.com
Flex-a-lite
800/851-1510
www.flex-a-lite.com
Auto Meter
815/895-8141
www.autometer.com
Orme Brothers
877/ORMEBRS
www.ormebros.com
Canton Racing Products
203/481-9460
www.accusump.com
Daystar Products
623/907-0081
www.daystarproducts.com