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Cross member from 1995 Roadmaster in 37

9K views 31 replies 7 participants last post by  enjenjo 
#1 ·
I'm exploring another option for the front suspension & steering for my 1937 Roadmaster.
I have a 1995 Roadmaster donor car and I'm considering cutting the front cross member out of that car and grafting it into my 1937.
Virtually all the 95 steering, brakes, and suspension could then be used.
I'm already using the power train and rear axle out of this 95, so this would make all replacement parts from the same model car and will also save money.
This would change the 37 to a front steer set-up.
I would not be able to use the 95 steer box because it normally resides where the 37 frame passes through and supports the front bumper.
I have a 77 Scout 2 box that may work because the box sits on top of the frame and the pitman shaft goes down to the bottom of the frame.
The first picture shows the cross member I would cut from the 95. The other pictures show the cross member installed in the 37 frame.
My question for anyone who has grafted cross members:
1) Will it work for me to cut rectangular slots half way up from the bottom of the 37 frame and half way down from top of the 95 cross member so it can be slid up into the frame?
I could then have the cross member welded to the frame.
Thanks
 

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#2 ·
You can use any steering gear you like as long as the pitman arm is the exact same length as the original Buick unit and moves on the same plane. It must run exactly parallel to the idler arm or bumpsteer will be the result. Some of those older steering gears have a much slower ratio than modern units, so be aware that the steering may be slower than with the original Buick gear.

As for mounting the crossmember, it certainly can be notched into the original frame, but make sure to mock the chassis up at ride final ride height and rake and then mock up the front suspension, level it and set it at ride height. Utilizing the radius of the tire/wheel combination you plan to use you will then see how high the suspension will need to be when installed in the frame. It is vital to set everything up accurately so it all will be correct when the car finally hits the road!

Regards,

Andy
 
#3 ·
Thanks for your help.
I plan on using the 95 pitman arm with the 95 spindles and idler, so everything will be matched. The 95 pitman arm will fit on the 77 Scout 2 gearbox because they are both saginaw.
1) Would it be better to:
a) knotch the 95 cross member and the 37 frame and then weld in a piece of angle that would become the mating surface (like an aftermarket crossmember), or
b) would it be better cut slots in each part so the pieces slide up into each other and the weld every slot?
2) Does anyone have pictures of a grafted crossmember similar to this?
Thanks
 
#4 ·
suspension swap

I have looked at putting in a jag IFS in the 36 olds and 37 pontiac. on those I would have to cut off the original spring pockets and adding flat plate to the side of the frame, then put the jag Crossmember under the rails. It depends on how much of the original frame you have to cut to get the new crosmember in place. sometimes you need to make a temporary bolt on bird cage locating fixture for keeping the front sheetmetal-bumper clip mounting locations.
 
#5 ·
The 95 cross member would actually reside for the most part behind the 37 cross member.
The 37 spring pockets may interfere a little bit and I could remove them for a better finished look. May leave the 37 cross member in place to support the radiator. The 95 frame will actually fit on the outside of the 37 frame so I plan on cutting the 95 frame in front of the anti-sway mount and behind the spring pockets.
I think I will have to notch both the cross member and the 37 frame to get the car to ride at the desired height which is lower than stock. See the attached cross section that shows the interferance between green 95 crossmember and grey 37 frame.
Thanks
 

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#6 ·
I have done many installations such as you describe, and my inclination is to leave as much of the new crossmember intact as you can to protect the integrity of the geometry. I would notch the frame until you can tack the crossmember in place, then make filler plates and gussets as required to make it structural. Sounds like you have it well in hand, and with the cad drawings, that makes the process much clearer.

Good luck,

Andy
 
#9 ·
Over the years I have installed Volare, Pacer, Mustang II, Corvette and countless aftermarket IFS and straight axle front ends. What I have discovered as the key to success is that if you take your time and ACCURATELY mock up all components at your desired ride height and rake and have the tire and wheel combination figured out before anything is welded in place, you will be successful.

Also, make certain that the frame you are grafting onto is square, level (not twisted), and true to a centerline.

My last bit of advice is that unless you really know what you are doing, don't alter the factory geometry of the crossmember, control arms or the steering. The factory geometry is usually pretty good for a car that is used for cruising. You can play with spring rates, shocks and alignment settings later to fine tune your car.

Regards,

Andy
 
#11 ·
Andy,
I apologize if these seem like simple questions, but this is the first project car I've built:
1) I assume I will set up the front suspensionwith the engine and frontmetal removed.
If so, then how to you take into account the weight removed weight when setting up the height of the front cross member in the frame?
2) I have been told it is preferred to remove the body to weld in the rear suspension in the frame. Similarly, how do you take into account the weight of the body when setting the height of the rear suspension?
3) Do you set up the front suspension, or rear suspension, first or do you set up them together?
Thanks
Mutt
 
#12 ·
compare weights.

compare the weights of both cars, and try to check the lower a arm angle and spring compressed length a the new car on its wheels.. then either remove the spring and make a spacer bar to set up the new suspension or compress the new suspension with a long piece of 3/4 all thread. when you have the new crossmember blocked at the right heigth you can determine where your frame should be to get the ride heigt you want. If it rides too high with the new suspension you can go for different springs.
 
#13 ·
#14 ·
Looks pretty close to what I planned except I would like to keep more of the original frame intact for radiator and fender support.
Thanks


Oh puhleeeze do not copy this. This has to be one of the scariest front clip swaps I have ever seen. All I can say is that as an aerospace engineer who has designed and flown a bunch of structures, this is wrong on so many levels that I can't even begin to list them.
 
#17 ·
The problem I have with that graft is the gross mismatch in the width of the frame rails. That was a very poor selection of a crossmember for that application and the actual execution of the splice was horrible from a load transfer standpoint. I'm also guessing that the track width was substantially wider than stock. It was a complete waste, since there are MANY better front suspension swaps for those early trucks. I can't speak to your Buick application, but I'm going to guess that the B-body suspension is substantially wider than your stock track width, as are the frame rails.
 
#19 ·
i recently assisted a fellow employee to strip down a 40 Buick Special. These cars have a chassis that would make a F350 blush with embarressment. No wonder the US steel industry was once so huge...:D
What sort of chassis does the 1995 Roadmaster have? Is it the same as the GM A bodies of the 70's?
How about using more of the chassis if that is the case and having the join as far back as possible?
Look under most 1970 through 80's GM midsize cars and you can see the front sub frame goes right back under the front seat area. This gives a better load distribution and less strain on the mounts.
The same could be said for your chasis join.

Simple is best... and the hardest to achieve.
 
#21 ·
Look under most 1970 through 80's GM midsize cars and you can see the front sub frame goes right back under the front seat area.
The "sub frame" keeps going all the way to the back bumper on those cars - they're full frame cars...

The 95 Roadmaster is a Chevy Caprice wagon with a different grille. It's the same chassis as on the 1977-1996 B-body wagons.

Back to the original question. Again, as a structural engineer, you REALLY want the frame rails on the old and new frames to be as close as possible in spacing. The fact that you happen to have a Roadmaster and a torch is NOT the reason to use it. What is the spacing on the Roadmaster rails where you plan to splice in to the 37 frame? If the mismatch is like the ones on that Chevy pickup, it's a bad choice.
 
#20 ·
You are right that the frame on the 37 is very significant, plus it's allready boxed in. The 37 frame is narrow at about 31" outside at the firewall and it narrows to 26" at the front axle. The problem with changing the subframe behind the firewall is that the front fenders and front radiator shell bolt directly to the outside of the 37 frame (see picture) and the radiator is also supported by it. That is why I would like to keep as much of the existing frame in place as possible. All I really will be removing is the old spring pockets and creating a notch for the 95 cross member. There is room in front of the side mount spare tire wells for the 95 cross member shown in green at the beginning of this thread.
Thanks
 

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#22 ·
Thanks everyone for your feedback and insight. All of your advice is exactly what I'm looking for in a post like this.
You are correct that my 95 Roadmaster is a full frame.
I was describing the descrepency in frame shape, and why using more of the 95 sub frame was not an option.
I also understand that when joining a front sub frame that the rails should match up.
If anyone can show me a subframe or stub frame that will fit inside the 37 Roadmaster fenders and front shell, I will be glad to consider it.
I have not found such a subframe, which is why I'm considering grafting the 95 cross member.
Think of this as a building an ifs kit out of the 95 front suspension & steering.
I would guess you would not be as concerned if I was using a Jag cross member.
I contend that the biggest difference between my approach and using a Jag ifs is there will be added work to remove it, fittment and reinforcement.
I do not have your experience, because this is my first custom car, but I am a professional mechanical engineer with 35 years experience, so this modification will be made in a safe way.
If anyone has other approaches that I've missed, then I'm open to suggestions.
Thanks
 
#23 ·
Ahh ,I see now. Yes I agree,using the 95 front cross member is a good way to approach this but i would be unpicking the whole 1937 Buick front of the chassis and then adding the 95 cross member to a pair of bare chassis rails . You can fabricate a new radiator mount which could be lighter,stronger and better looking I think. If you use the original front crossmember and the the later unit you run the risk of having a chassis that looks like something from mad max.
The founder of lotus cars, Colin Chapman , had a great moto.."add lightness" .:welcome:

here in Australia, a few guys use the jag front end or the mitsubishi L300 Van front end to get around our restrictive laws but i feel they are missing out on a real gem and that is the Ford Falcon AU alloy front crossmember. i think thunderbirds and lincoln town cars in the USA had them too.
Re the GM B body Chassis ,it was used in Australia in the HQ holden Ute as perimeter chassis unit , and I put one under a 1955 Ford mainline ute . The mainline had the1955 Fairlane convertible chassis and was grossly obese with pitiful handling. I have seen a 1948 Buick with the same chassis too.
 
#27 ·
mercmad63: Now I see the suspension you meant. Checked them out before and would work well for pick-up (A friend of mine put one in his F150). Problem is they have a track of 64" with high offset wheels. My 37 Roadmaster has a stock track or 60.5. Not sure I can fit in my car. Found a rod shop in the states that narrowed one, but seemed like a lot of effort and risk to cut and weld the aluminum cross member.

1) Has anyone used one of these set-ups from Fatman
1928 - 1933 Buick Independent Front Suspension (IFS) Kits - Fatman Fabrications Fatman Fabrications
My concern with this if it uses a rear steer chevy citation r&p combined with Chevy pick-up spindes then there will be limited 6" throw and a very large turning radius. For a car like mine with a 131" wheelbase this may be a deal breaker.
Thank
 
#28 ·
Looking at that,he seems to sell a "one front cross member fits all " type of deal . A 33 Buick chassis is a lot different to yours. Yours resembles most Detroit chassis right up to the roadmaster you have now where they followed the time old engineering principle of "if in doubt...go bigger..."
Thinking about thisd,you will be ahead of the game by removing the 37's front crossmember completely ,and as i mentioned before, just keep the Chassis side rails.
The idea being to adapt the 95 crossmember as cleanly as possible and leaving remnants of the original crossmember will make it look ugly :) .
 
#29 ·
If I was to cut the 95 Roadmaster clip (Green Frame) a little farther rearward than is shown in this picture, then this could be a more traditional front clip swap.
My concern is still that the 37 fenders bolt to side of the original frame (Gray Frame).
1) Is keeping the 37 rails in tact as mercmad63 suggested still the the better way to graft in a different suspension?
Thanks
 

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#30 ·
Have you considered a jag front end from an XJ6 or XJ12? they are very compact and will support the Buick.
If you have a look at what you propose,you will be adding a lot of unnecessary weight to the car,basically carrying two chassis around .
As for the Jag front ends , I am not sure of the width but i have seen a lot of these added to Chevies of the 30's.

The USA was big market for these jags so you should be able to pick up the parts for very little money .
 
#31 ·
Timohale has suggested that solution several times as well. Track fit is a match. Does like a real nice ifs and has r&p as well. My only hang-up was the 4.75" x 5 bolt pattern requires me to buy a different set of wheels. Already have a complete of 5" x 5 wheels had planned on using. Would also have to buy a new rear brake drums, but they are available for my rear axle.
Jag ifs would handle weight and may ultimately be best choice.
 
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