Tangent Technologies, Inc.

Special Kits Designed for your Factory Five Build

Roll Bar Kits
Kits for MK4 cars with 1-1/2 roll bars that allow you to install your roll bar downtube without drilling through the joint and inserting an exposed bolt. It makes for a very clean look.


 One kit required for each rollbar, dual roll bar cars require two kits.......... Price $89.95

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Below are the drawings, a copy comes with each kit. MK4 Kits are similar in design but have six locking wedges each.

Below you see the parts that make up each re-designed kit. Parts from 1018 cold rolled steel plate, laser cut to .005" tolerance. This new design truly eliminates drilling. Two different size wedge-locks are supplied for each connection.

 Below is a picture of the original style, it required a drilling and insertion of dowel pins, The new design is much easier to install.

The resulting joint is extremely strong and gives no visual clues as to how the attachment is made. The remaining bolts supplied by FFR are then used to attach the lower portion of the tube to the chassis below the body line. Since the kit requires no welding, it is safe to use on painted, powder coated or chromed roll bar sets. It is demountable at all times and reinstallation of bars is no problem. The wedge-lock is designed to grip tighter as the force to remove it increases. Tested to 20 tons of pressure without moving. A simple and strong solution to the Frankenstein through bolts. If nothing else, your Roadster is certainly worth this small upgrade. Good luck with your build! Don 

Below are pictures of the new MK4 roll bar kit design, all parts are laser cut to very close tolerances.



Blind Roll Bar Attachment Kit (instructions, a copy comes with each kit) (modified 7/22/10 to include MK4 1-1/2 bars)

Installation Instructions – Please read all and understand the drawings before jumping in. 

Determine which end of your roll bar down tube (third leg) mates up with the male section of the upper section the best.

The inside of this end needs to be cleaned to a depth of about 8-9”. Remove chips, flakes of paint, oil, dirt, etc. This end also needs to have the inside filed or ground to remove the burr that is probably present from being cut. A bit of a chamfer here is helpful. MK4 downtube is chrome moly DOM tube and is very slick and smooth inside, see below method for roughing up the inside of this material for added holding power.

Now, assemble the large lock using the large disc and large wedges. Place one of the 3/8 x 1-1/4 bolts flush with the back of the wedges, slip on a lock washer and then screw on a coupling nut. This assembly should fit easily into your downtube. Wiggle/slide the assembly down six inches, the measurement should be from the end of the tube to the face of the disc. MK4 same as above but there are six wedges and the bolt is 38 x 1-1/2 long, use the supplied O-ring to secure together until the assembly is inserted. Slide the assembly into the downtube a distance of 4" as measured to the end of the coupling nut.

Finger tighten with a socket on the end of an extension until the affair is seated and you can check the measurements.  If you need to reposition the lock; back off on the coupling nut several turns and drive down with a sharp rap or two. The assembly will stick if you pull on the bolt at all, gravity is your friend here, turn the tube upside down and push the bolt up, it should now slide freely.

(For perfectionists only) For extra holding power make sure that the welded seam inside the tube is ground down in the area of the lock. Radial scratches made using some emery cloth on a stick inside the tube and around the perimeter of the lock are good as well and needed on the MK4 downtube. You can also make some cross scratches perpendicular to the faces of the wedges, the edges that mate with the tube. None of this is really necessary though, (except on MK4 downtube)  you’ll find it grips pretty tight quick. The slightest amount of grease between the sliding surfaces of the wedge-lock  and bolt is a no brainer.

Tighten the nut to about 30-35 ft. lbs. You may want to use a strap wrench to hold the tube.This will be a bit tough to do, find a way to secure the downtube to make sure you make the spec.

Now take the supplied threaded rod and screw into the end of the coupling nut, there should be about 1/8” to ¼” of stud sticking out past the end of the tube. Finger tight is fine here, we don’t want to foul up the threads on the end of the stud with pliers or vise-grips.

Now, repeat the procedure for the upper stub on the hoop. The coupling nut should be flush  with the end of the tube on this assembly. Previous customers of the kit had to drill in a threaded stud, so you’ve got it easy. MK4, you make find that the coupling nut sticks out past the end of he stub and 1/8" or so, that should be fine. Take a break.

Once you’re satisfied with the installation of the kit, test fit the down tube on the roll bar. It is a good idea to coat the mating members with a little grease. The part should screw together fairly easily. The threaded stud length is meant to give some “wiggle room” if things are a little off center.

Next step is to check the down tube mounting post on the chassis. It should be free of paint or powder coat. If it is not you will find that when the down tube is screwed into position the paint may gall and freeze up your turning.

After the down tube mount is clean, slip the open end of the down tube in place; position the roll bar hoop in place. Bring the down tube up into position, align the stud, and simply screw upward until tight. A strap wrench may be used for the final tightening. Builders with chrome or powder coat may want to be careful not to over-do it. It may be possible to apply too much force and chip or flake your edges.

The finishing touch is to drill and install the lower mounting bolts as supplied and instructed by FFR. 

The wedge lock is designed to be primarily a cosmetic replacement for the through bolt. It is up to each person to determine the suitability of their installation for their specific purposes. The wedge lock is designed to grip tighter as the pressure to remove it increases. A wedge-lock, carefully installed, cannot be moved using a 20 ton press.

Naturally, no cars were flipped upside down and slid backward at speed to test whether or not the joint holds as you pass over a tree stump. At this point I would think you have other problems as well. Let’s hope none of us ever find ourselves in that situation.

As always with any Tangent Kit, if you feel the design does not suit your purpose, your money will be cheerfully refunded.

Good luck, hope you are happy with the good looking results.  

All the best, Don Wright

e-mail with any problems, concerns or suggestions (or praise) – e-mail     ver. 8/08 

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