TR5/TR250 Triumph TR250 Drooping Rear Chassis

[rustbuster]

Hello All,

I am a new Forum member, and I have recently acquired a Triumph TR250. I am reading through Roger Williams' book titled "How To Restore Triumph TR5/250 & TR6". I have been under the car several times, and the frame, floors and sills actually look pretty good. Not much rust.Williams mentions something in his book about "chassis hogging" that seems to be relatively common in the IRS cars. My car displays the symptoms; door gaps widening towards the top of the B-posts and rear frame rails visible beneath the rear valence. Williams describes in great detail the phenomenon of chassis hogging, and how it may be caused, but he does not mention how it is repaired. Is a drooping rear frame something that a home restorer can deal with during a body-off restoration, or would the frame have to go to a specialist for repair or replacement? How is the condition repaired?

Thanks Everyone. I appreciate any advice or input.

 

[Guest]

Hello Rustbuster, and welcome to the forum.
You say that the car "looks pretty good" and "not much rust". Since you know where the problem might emanate from causing the chassis to buckle, have you looked at this area closely yet. I believe the consensus is the area of the frame where the swing arm attaches and pivots is usually the culprit. It doesn't necessarily mean that this area has to be eaten out in rust; these frames are flexible and are made of fairly light gauge steel. The torquing effect over 38 years can cause this area to weaken, rust can cause it to accelerate. If you are planning to pull the body, you can better assess the damage from the top of the frame. My TR6 demonstrates some of the classic symptoms of frame hogging but this is not really the case. A lot of these cars just have poor body fit and door alignment was never one of their virtues. Remember, these were built on a line that didn't use robots. No two are truly alike. I have gaps at the tops of my doors and after careful measurement over the 6 years I have owned this particular car, zero change. There is no rust on my frame and no cracks at the welds. If you are a pretty descent welder, you can make frame stiffeners to close in a few angles. Serious probing with a pick will tell you if the rust monster has actually done any damage. The body can be shimmed to close the door gaps, although the tail of the frame will show more. Another option, if the car has great value to you is go with a new frame from Ratco. Bottom line, straightening a frame and totally rewelding is beyond the scope of the average home restorer.
Summarizing, either the problem is not that bad and can be
rigged by you or go with a new frame. New frames from Ratco start at about $2,500.

 

[NickMorgan]

I agree with everything that Bill has said. My TR4A chassis rotted out on the outside of the cross-members where the rear arms attach. The rest of it was sound. I know of someone who put an engine in the boot of his TR4 and after a long drive noticed that the door gaps were wider than he remembered. It turned out that the two "U" shaped body mounts at the rear of the body had bent under the strain. If your car has been rebuilt in the past, maybe the number of body shims in various places are not as they should be. Maybe all you have to do is put in some more at the rear, or remove some just in front of the rear axle.
I think that you should be able to see the chassis just below the rear valance. I think there was also a stay from the bottom of the over-rider to the chassis here that ran below the valance, but I may be wrong about this.
Get someone to sit on each rear wing while you slowly drive around. They will be able to watch the door gaps for you. If they are fairly steady then your chassis is strong.