K FRAME

[gf7cuda]

Hello Mopar friends, I was installing my engine this past weekend and had an issue with lining up my K frame bolts (3 ok \ 1 not ok). I built a jig and installed from the bottom with transmission attached. The main question is, with the weight of the engine/ trans already on the K frame, alter the bolt holes line up? This is a recent K frame I purchased and had it restored and had no damage to it. To take it one step further, the original one I had to put back in because my new purchased one wouldn't line up also gave me a hard time lining up until I took the weight off K frame with a screw jack. Has anyone experienced this problem?? Thanks in advance.

 

[Xcudame]

The factory K-Frame wasn't the most rigid piece! That's why people weld gussets into them and weld all the seams. So yes, your engine/trans weight could very well be distorting your K-Frame. You could try disconnecting the motor mounts and jacking the engine up with a floor jack a piece of plywood between the jack and oil pan. The removed weight may let you get all four K-Frame bolts in.

 

[Rich Followell]

Hello Mopar friends, I was installing my engine this past weekend and had an issue with lining up my K frame bolts (3 ok \ 1 not ok). I built a jig and installed from the bottom with transmission attached. The main question is, with the weight of the engine/ trans already on the K frame, alter the bolt holes line up? This is a recent K frame I purchased and had it restored and had no damage to it. To take it one step further, the original one I had to put back in because my new purchased one wouldn't line up also gave me a hard time lining up until I took the weight off K frame with a screw jack. Has anyone experienced this problem?? Thanks in advance.

As a retired frame tech the first thing that comes to mind when I hear something like this is bent frame! Have you tried a diagonal measurement between the bolt holes? they should measure exactly the same. try this on the body and on your subframe. if you have a slight difference of 1/8 I wouldn't worry about it but because you have to divide that number by two leaving only 1/16 of a difference. But if you find a 1/4 or greater you could have a problem. also measure the length between the holes on each frame rail they should be the same if not ergo an issue!

 

[pschlosser]

The only time I've had issue with K-member to frame alignment, was when the K-member came from another car. In those cases, I may have been guilty of bolting just the K-member to the frame rails, and doing what I can to get them to align, such as loosen/remove fender, bumper, etc. Only AFTER it's bolted and torqued, will I add the motor-trans and suspension.

From the bottom, like the factory does with the motor-trans and suspension, I'm confident they have supports in place on the trans and wheel hubs to evade undue stress on the K-member.

If you're K-member came from this same car, it may not be that far out of whack.

Once your K-member-engine-suspension assembly is between the frame rails, lifting the engine-trans by carb plate (for example) may remove enough stress or "tweak" to get things aligned enough to bolt together.

While it's a PITA, as others suggest, see if you can find where the "tweak" is.

1. compare bolt hole cross measurements on the frame rails.
2. compare bolt hole cross measurements on the K-member.

If things are pretty straight, they should be within 1/4-inch more or less.

 

[gf7cuda]

As a retired frame tech the first thing that comes to mind when I hear something like this is bent frame! Have you tried a diagonal measurement between the bolt holes? they should measure exactly the same. try this on the body and on your subframe. if you have a slight difference of 1/8 I wouldn't worry about it but because you have to divide that number by two leaving only 1/16 of a difference. But if you find a 1/4 or greater you could have a problem. also measure the length between the holes on each frame rail they should be the same if not ergo an issue!

Thank you for your advice. I will check this out. Appreciate it

 

[gf7cuda]

Thank you for your advice. I will check this out. Appreciate it

It did come from a B body , but b/e body should be the same I believe, I could be wrong. Came from a 71 Roadrunner

 

[HooToTheCore]

It did come from a B body , but b/e body should be the same I believe, I could be wrong. Came from a 71 Roadrunner

B body k-frame will have a 2 degree angle difference in the steering gear to steering column alignment. It will also not support an e-body sway bar. Other than those items, it can be used on an e-body.

 

[gf7cuda]

The factory K-Frame wasn't the most rigid piece! That's why people weld gussets into them and weld all the seams. So yes, your engine/trans weight could very well be distorting your K-Frame. You could try disconnecting the motor mounts and jacking the engine up with a floor jack a piece of plywood between the jack and oil pan. The removed weight may let you get all four K-Frame bolts in.

I had to do that and it worked to get the old one back in. The jig I made supports the outer edges of k frame. So the middle under engine is open and not supported.

 

[gf7cuda]

B body k-frame will have a 2 degree angle difference in the steering gear to steering column alignment. It will also not support an e-body sway bar. Other than those items, it can be used on an e-body.

So they are different? My build sheet has 52 for frame and this K frame has a 52 coin on the front. I thought I seen somewhere 71 e/b body is same. I could be wrong...

 

[Challenger RTA]

This might help. Install K frame bolts that line up and check to see where it is out. Use a tape for these measurements. 38 1/8" and 54 3/8".

 

[Mr Cuda]

The answer to the question asked twice, is yes, they are the same.

 

[gf7cuda]

This might help. Install K frame bolts that line up and check to see where it is out. Use a tape for these measurements. 38 1/8" and 54 3/8".
View attachment 128238

Big help RTA, measurements help, thank you!

 

[gf7cuda]

The answer to the question asked twice, is yes, they are the same.

Thank you Mr Cuda..

 

[HooToTheCore]

B body k-frame will have a 2 degree angle difference in the steering gear to steering column alignment. It will also not support an e-body sway bar. Other than those items, it can be used on an e-body.

This may be the case for '70 and earlier B-body k-frames. I know my '70 Challenger had a k-frame that should not have been on the car. I tried to add a sway bar and the k-frame required the bar to pass in front of the k cross member, not through the cross member. I swapped the k-frame for an e-body frame and the sway bar installed correctly.

 

[Xcudame]

Someone with more knowledge than me may know for certain, but I think 71 and 72 B bodies share a K-Frame that can interchange. 70 and prior, the B-Body had the different steering box attachment angle and sway bar mounted different as mentioned above. 73 and later B-Bodies had the weird biscuit rubber suspended front suspension that changed geometry again.

 

[brotow]

Two k frames I have available both from Challengers

 

[aussiemark]

The frame rails, firewall, cowl and inner fenders are the same on 71 B bodies /E bodies the K frame should be the same I would have thought.

 

[brotow]

this how
i installed my drive train. Lowered the car to the k frame which was on a custom dolly, fit perfect. Originally a /6 now 340 6pak.

 

[Xcudame]

Gf7cuda, were you able to confirm the measurements supplied by Challenger RTA?

 

[gf7cuda]

Gf7cuda, were you able to confirm the measurements supplied by Challenger RTA?

Not yet, next time I get it up on lift.