Pro Tips
STRETCH DAYCAB I have a 2004 Pete 379 that had a new cab put on it prior to me buying it. The shop doing the work put a pre-1993 sleeper cab and used the daycab conversion kit to com-plete the daycab. With little interior room, I would like to convert the old cab to a Unibilt daycab conversion. It is my understanding that I will need the Unibilt conversion panel and also a stiffening ring of some sort for struc-tural integrity. However, how can I make the interior look factory during this conversion? Can I purchase just the interior upholstery that goes around the Unibilt opening? Any help would be greatly appreciated. Matt Bullard, Bull Run Farms Matt, easy enough to do and a common custom upgrade these days on older Petes. What you need to give yourself about five inches more legroom is to purchase a Unibilt walk-through ring (#20-16786; $300) from the Peterbilt dealer, which provides the needed cab support. Lay the ring up against the back of your cab's rear wall with the pre-drilled rivet holes aligned with those on the bottom of your cab, mark the opening, and rough cut it in. Then purchase Daycab's fiberglass Unibilt XL cab extension kit ($1,675), which has the matching upholstery, reinforced window, and bracing all factory installed. Our kit also comes with factory-style hucks or rivets; everything is pre-drilled and aligns perfectly. What you end up with is a 59-inch-wide opening that allows both seats to slide/lean back some five inches. Give me a call anytime if there are more questions. BEING CLEAR ON CLEARS What is the difference between Delfleet urethane clears and the automotive versions? Why does the industrial version provide better chip/scratch resistance? Steve Sanders, Pocatello, Idaho As far as the clears being more durable in the fleet world, I believe it should be looked at as a paint system from undercoats to the topcoats. Everyone sees the clear coat and its advantages for its aesthetic purpose, but the chip resistance and flexibility comes from all of the paint prod-ucts working together. In the Fleet world, the basecoats are typically dif-ferent from automotive coatings. The basecoats are high solids and are completely catalyzed, much like a single-stage. In the automotive world, most basecoats are not catalyzed, and are thinner in film build. Lynn Engmark, Fleet Coatings Specialist, PPG Training FRAME STRETCHING I own an '05 Peterbilt 379 that is currently 244 inches. I want to stretch it out to 280 inches. I have spoken to a couple of companies about doing this and seem to get different an-swers every time. If you can help with this, it would be great to have your opinion. Fleming Carlsen, via web No problem with integrity, just takes a lot of work to do the stretch. First, make the frame cut at the second crossmember back from the sleeper. Make the cut in a < shape so it stays between the crossmember's bolt patterns. (You want to use the factory cross-member boltholes to reinforce the welds when the new section is added.) Cut the extended frame rail of the same thickness and size as the existing rail to mirror the cut in the frame. Once the new sec-tion is aligned and welded in, the frame has to be reinforced. This is done by having a steel fab shop bend a ¼-inch piece of plate steel into a U channel that fits inside the factory frame. (If it's a 1/4-1/2 inch shorter in height than stock frame rail, no problem. Upper and lower ears should come out flush with factory frame rail.) The re-inforcement section should be at least 8 feet long and extend from the first crossmember behind the sleeper all the way to the cross-member just forward of the front driver. This way you don't have to fool around with dismantling your rig's rear axles and suspension. DO NOT WELD the inner frame in place bolt it in using the OEM crossmember holes and new ones that are drilled. You must add a new crossmember mid-way in the splice and at the rear splice so there's a crossmember about every 24 inches from sleeper to fifth wheel. You'll also need to add a carrier bearing to that new aft crossmember and have custom driveshafts made to accommodate the new driveshaft geometry. If you don't there'll be driveline vibra-tion issues. Of course, you'll also have to extend air lines and wiring to accommodate the added length. Doing the stretch in this manner is the least time consuming and least expensive while giving a custom look because the welds can be ground smooth and frame painted to hide the stretch. If you have any other questions, give us a call. We can help you with new driveshafts and used parts. Or stop in and we'd be happy to handle the job if you don't want to tackle it yourself. Brian Shaggy Schwartz, Chrome Shop Mafi a UNIBILT CONVERSION I would like to convert a 1990 Peterbilt 379 into a Unibilt. I see 359s at shows that have been done. Do I have to reinforce the cab and sleeper or just bolt the brackets in? Ryan Judd, via web Ryan, the simplest way to get the Unibilt effect is to get the VIN should be looked at as a paint system from undercoats to the topcoats. should be looked at as a paint system from undercoats to the topcoats. CUSTOM RIGS' Pro Tips H ave a question for the custom rig builders out there or a tip or trick to share with readers? Send it to us and we'll slip it into Pro Tips: crtechtips@rrpub.com . Or go to our web site, www. customrigsmag.com , to take advantage of special links we've added to these Q&As and others The Editors CR 14 CUSTOM RIGS Fall 2009