Frame Cross Braces from RATCO

[Magz]

Hello all, got around to  installing the frame cross braces from the RATCO frame into my 1976 TR6 frame. A while back, I noticed that their frame has additional cross braces under the floor pans, between the frame rails. RATCO agreed to send me two of the brace pieces for a nominal fee and today they were welded in place. See pictures.

 

Edited July 2 by Magz

[Magz]

After installation I drove around for about 30 miles and didn't really notice much difference in feel, but I have one interesting observation: prior to installation my rear wheel camber was -1 degree on both sides. After installation, both sides are now at 0 degrees camber!

So, perhaps the bracing does help prevent frame sag under load. I'll check again tomorrow, but it remained more positive after 30 miles of back roads and highway driving, so it seems to be a real effect.

I have adjustable trailing arm brackets, so dialing it back slightly negative is no big deal.

Edited July 2 by Magz

[Magz]

Tomorrow I will POR15 the braces, spray cavity wax inside and Waxoyl on the exterior after the POR15 cures.

[harlequin]

Is there a weld between the top of the new box sections and the chassis Magz?

[PodOne]

I wonder if they had been welded with the weight through the wheels what effect it would have made to the door gaps at the top as they open slightly. It would have been interesting to see if they were reduced or stayed the same.

[Magz]

52 minutes ago, harlequin said:

Is there a weld between the top of the new box sections and the chassis Magz?

No, they are only welded on 3 of the 4 sides including the two wider sides, only the narrow top side is not welded. To do more I'd have to have the frame off or cut holes in the pristine floor pans. On the outside rails it's actually a little more since the braces follow the indented surface of the outside rail.

[Magz]

25 minutes ago, PodOne said:

I wonder if they had been welded with the weight through the wheels what effect it would have made to the door gaps at the top as they open slightly. It would have been interesting to see if they were reduced or stayed the same.

The weight was actually on 3 Jack stands under the main frame rails at the far ends of the car. The lift pads shown were only lightly touching the frame (could be moved by hand) as a safety measure in case the stands gave way. 

I thought lot about how best to support the car pre-welding since I didn't want to "weld-in" any distortion. When the car was supported from where the pads are you could see a noticeable change in door gaps that decreased using the jacks. The door gaps post-weld look good and the doors open and close easily.

[Magz]

Gaps.

[PodOne]

Interesting, so if you jack up the car using the pads in the same positions do the gaps still change?

[Magz]

12 minutes ago, PodOne said:

Interesting, so if you jack up the car using the pads in the same positions do the gaps still change?

I didn't check that but when I put it up to paint the braces I'll take a look.

[Malbaby]

Those braces do assist....But the weakest part of the IRS chassis is near the rear of the "sandwich" plates.... That is where the chassis twists and bends under load....Top of the door gaps open when the rear of the car is suspended.

[harlequin]

1 hour ago, Magz said:

No, they are only welded on 3 of the 4 sides including the two wider sides, only the narrow top side is not welded. To do more I'd have to have the frame off or cut holes in the pristine floor pans. On the outside rails it's actually a little more since the braces follow the indented surface of the outside rail.

Did you consider cutting an access hole in the side of new box section for the top weld? And then welding a patch over the access hole. I ask because you have introduced stress points where the welds end and ofcourse water access across the top of the box is a possibility.

George 

[John Morrison]

Think this is very interesting.

What would be the thinking on fitting similar to a non IRS TR Chassis?

John.

[stuart]

4 hours ago, John Morrison said:

Think this is very interesting.

What would be the thinking on fitting similar to a non IRS TR Chassis?

John.

Are you talking non IRS 4a or a 4 John. 

TBH I would be very wary of any extra welding done to an IRS chassis unless it was done as a bare chassis. The braces above arent really going to do much, theyre designed to fit a Ratco chassis which is a completely different kettle of fish.I reckon the best bit of re-enforcing is as per the ones built by a guy who used to work for Rubery Owen and are very beefy indeed, like this one.

Stuart.

 

Edited July 3 by stuart

[Magz]

Looking at the RATCO frame (attached), the layout is similar to the stock TR6 frame, albeit of heavier gauge, stronger sections. The parts that jump out as different are those two cross-braces under the floor pans. So...I contacted RATCO for a chat and they said they put them in as a frame strengthener, and they'd be happy to send me a pair. Now they're in my car, too.

[Magz]

By the way, I took this job to a local professional welder, even though I welded in the diff mount and bridge reinforcements myself earlier. I wanted a pro's expertise to join the heavy guage braces to the lighter guage frame without blowing through the frame rails. I'm happy with his work.

[Magz]

13 hours ago, harlequin said:

Did you consider cutting an access hole in the side of new box section for the top weld? And then welding a patch over the access hole. I ask because you have introduced stress points where the welds end and ofcourse water access across the top of the box is a possibility.

George 

I did not. It would be difficult to get a full bead through an access hole, anyway. I'd estimate about 85% of the perimeter is welded. The section is primed internally and will be filled with cavity wax, so I'm not worried about moisture...plus, my baby doesn't see rain, ever - I'm kind of crazy that way. 😉

[stuart]

43 minutes ago, Magz said:

Looking at the RATCO frame (attached), the layout is similar to the stock TR6 frame, albeit of heavier gauge, stronger sections. The parts that jump out as different are those two cross-braces under the floor pans. So...I contacted RATCO for a chat and they said they put them in as a frame strengthener, and they'd be happy to send me a pair. Now they're in my car, too.

I can see why they put them in the Ratco frames as its just in front of the angled section out to the end of the trailing arm section, The original chassis curves out to that point so wouldnt have the same stress point. 

Stuart.

 

[Magz]

1 hour ago, stuart said:

I can see why they put them in the Ratco frames as its just in front of the angled section out to the end of the trailing arm section, The original chassis curves out to that point so wouldnt have the same stress point. 

Stuart.

 

Point taken. They do seem to make a measurable difference in chassis sag, however, based on the change in camber angle observed on both rear wheels, which I have verified again today both visually and with an inclinometer.

[stuart]

1 minute ago, Magz said:

Point taken. They do seem to make a measurable difference in chassis sag, however, based on the change in camber angle observed on both rear wheels, which I have verified again today both visually and with an inclinometer.

Im always wary of noticing even the slightest chassis sag when jacking up as to my mind and from a lot of years of working on these that its an indication that there is corrosion somewhere inside as when doing restos with brand new chassis there is zero sag no matter how you jack them up.

Stuart. 

[Magz]

1 hour ago, stuart said:

Im always wary of noticing even the slightest chassis sag when jacking up as to my mind and from a lot of years of working on these that its an indication that there is corrosion somewhere inside as when doing restos with brand new chassis there is zero sag no matter how you jack them up.

Stuart. 

Not to belabor the point, but I think most folks here would say that when their TR is up on a 2-post lift with the pads under the frame that their door gaps change, an indication of chassis flex/sag. Just on this thread there are two such other members who stated so. 

In any case, I thought I'd share my findings for others to do with as they please. Not recommending for or against, simply sharing data.

[Paul Hig]

@  $7k (thats £5240 at todays exchange rate) for a complete new chassis, I wonder what shipping and taxes would add?

[Richard71]

2 hours ago, Magz said:

Not to belabor the point, but I think most folks here would say that when their TR is up on a 2-post lift with the pads under the frame that their door gaps change, an indication of chassis flex/sag. Just on this thread there are two such other members who stated so. 

In any case, I thought I'd share my findings for others to do with as they please. Not recommending for or against, simply sharing data.

+1

[harlequin]

3 hours ago, Magz said:

Not to belabor the point, but I think most folks here would say that when their TR is up on a 2-post lift with the pads under the frame that their door gaps change, an indication of chassis flex/sag. Just on this thread there are two such other members who stated so. 

In any case, I thought I'd share my findings for others to do with as they please. Not recommending for or against, simply sharing data.

Magz I must apologise if I appeared to be critical of your modification, that certainly was not my intention.

George 

[Magz]

9 minutes ago, harlequin said:

Magz I must apologise if I appeared to be critical of your modification, that certainly was not my intention.

George 

No offense taken. A healthy discussion is the way we all learn.