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Thank you my Engineer friend for helping me with the correct name clap:

Only aluminum is extruded not steel. tube hydroforming is the prefered method for fully boxed rails.

Ah. Finally a practical use for OTR trials!

(With apologies on how to do laundry in a Land Rover)
Drill and tap two holes in the box section, one at bottom, the other at the top. Half fill section with grit/ sand/ aluminium oxide/ silicon carbide/ whatever. Then drive it in an OTR trial till your teeth fillings come out and eyeballs pop out of their sockets. Should result in a clean inside box section. Repeat process with paint. :D

Regards
Sutripta

We all have heard this term and are quite familiar with it. I have discussed about this with several mechanics and even had a short talk about it with Jeep guru U.B.S.

According to Uday Sir, if the chassis is cut and welded properly, it can withstand the abuse when taken off-road.

Though I have no intention of getting my JEEP shortened, I thought it would be a good topic for JEEPers to discuss and gain knowledge.

Lets consider a 90 M.W.B like CL500.

a. From where should the chassis be cut ?
b. How would the chassis be welded back ?
c. What about the body tub considering that it would still be a 90.
d. How to ensure that the strength and rigidity of the chassis would be retained considering that the JEEP would be taken off-road ?

Gurus please enlighten

It can be possible. But where it is cut & how it is welded is important. May be some experts should help.
(In some offroading forums I have seen box section rails cut & shortened/extended with the help of a welded Fish plate for additional strength)

Those offroading vehicles were used in more extreme conditions than here's.

In India you can check chassis of Mahindra Bolero Storm or Thar (Pic Below). The joint is just below Windshield side (Red Arrows).
Also check the Blue & Yellow Arrows for Un-even chassis rails as front is Scorpio's & Rear is Bolero's. Just FYI.

But still a clean chassis rails should be preferred for offroading for better integrity.

here are some pics:




After market rear frame for wheel base extending:




Source: _http://www.colorado4x4.org/vbb/showthread.php?t=156763_



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although gussets have been added, those welds (near the bends) act as huge stress concentration areas, i hope they do some stress relieving there?

Spike

Stress Relieving? How is it done?

Why there is this extra plate welded on every Gypsy Chassis (Red Arrows)? Is it also to take the load away from the bend there (as it did not have a arch like rear, more like step up rear) or is it simply for strengthening?

(Coming back to previous pics of modded jeep, how can they survive all that rock climbing with ultra low ratio t-Case + Lockers + BIG *** wheels? :Shockked:Wouldn't that chassis suppose to break at the welded point?)

Yes, it is to distribute the suspension loads on a wider area and not load the bend which happens to be the suspension mounting area too. Also seen that the extra plate or the reinforcement is quite large to cover both the bends.

Offroad maniac, the pic itself is self explanatory, if you see the chassis drawing, you may notice that the red arrow region houses the spring mounting pivot, the spring must be mounted in a particular orientation in order to comply with the drive line angles, you can achieve this by shifting the chassis mounting position downward along the 'Z' axis, also this member helps in transmitting the suspension loads towards the chassis. It acts as a gusset too.

Spike

Thanks ranjit, Spike for replies.
It also helps to spread the load/ stress due to leafs mount point? The road forces (?) acting against gravity... Please mind my stupidity in drawings:D

There is such joint (orange) in SWB Samurai as well. may be thats there in the rear side because the rear side of frame is parallel (straight) so the forces (X) must be concentrating on that particular joint (Green) only.
While as the front side has a little arch so its not needed there? I dont know just learning......stupid:

The arch, in technical terms is referred to as "crank", this is provided to accomodate the wheel travel during articulations.

Spike

Yes. thats what I know. but again the Gypsy's rear dint have it so all the arrows & circles....:D. Japanese Design. A little Hatke from everything else?

BTW, That extra plate can be found in center side of Chassis rails of many pick up trucks eg. Tata 207 & Mahindra Maxx etc. I have seen chassis flexing vertically (Dont know the technical term) when these loaded trucks passes through a speed breaker. (Mostly in the case when such extra plate is not present). This is found mostly in Tata & Force/Trax pick ups as the chassis rail's Height is less in such trucks.

Do you mean the extra plate is found on the chassis is at a location between the load tray and the cabin? While braking or apllying brakes the complete load (Load tray weight + the Pay load) gets transferred in forward direction due to inertia. The forces can be very high in case of urgent braking depending on the pay load. (Hence chassis flexing vertically is seen). In such conditions as the load tray is not connected to the Passenger cabin and mounted separately on chassis the load gets concentrated on the chassis long member in the portion between the load tray and the passenger cabin. Hence to bear this extra force due to braking, reinforcements are provided.

Thats the exact reason & a very sound explanation. Thanks:thumbs up.