Jeep J20 stock height

[eldudderino]

Hi, could anyone tell me what the stock measurement is from the front axle to the fender on a J20? This would tell me lift height correct? It has 35s on it and they do not rub. No cutting has been done. Also the rear has a spring over axle set up not sure if thats stock. The rear springs are like flat but they have a good 6in spacer between the axle and the spring. I assume they are stock springs just spaced. Any thoughts?
Thanks

[joe]

The factory TSM will have stock dimensions measured at various point. Overall height, height at drivers sill plate, cargo deck height. That's with stock wheels and tires.

[eldudderino]

where do I find that at? I have search for stock dimensions and height a lot I cannot seem to find anything.

[77Deepj20]

Is the front still spring under?

I was able to fit 35's with a spring over conversion on the front with a dana60. It was about a 6" lift from stock

[joe]

May vary by year but usually in Chapter A "General Information". In there you'll find a chart "General Dimensions".

[Cecil14]

where do I find that at? I have search for stock dimensions and height a lot I cannot seem to find anything.

There's a sticky at the top of the "tech" section with links to the TSMs.


aa

[eldudderino]

The front is still spring under. Can someone just give me a link to the TSMs. What are TSMs anyway?

[eldudderino]

I found what you are talking about but I do not see in any of the manuals on that site the measurement I think I need. To tell suspension lift you take the height of the center line of the axle to the fender and subtract that by the stock measurement correct? Or is there another way?

[joe]

If the factory didn't measure the locations you want, just use the locations and measurements the factory used. Measure yours...compare. Don't forget to allow for the tire dia differences cause the factory measured using "stock" tires.

[eldudderino]

If the factory didn't measure the locations you want, just use the locations and measurements the factory used. Measure yours...compare. Don't forget to allow for the tire dia differences cause the factory measured using "stock" tires.

So I measured and I assume its a 6in. The factory measures 12in from floor to bottom of the front part of the frame. Mine measures 24in, but I have 35in tires. The stock tires are about 28 inch so thats +7in. So then if you subtract 7inches from 24 and get 17 then 17-12 you get 5inch. I assume its a 6in I could be wrong but the ground may not be level or what ever. Is my math correct? Does that make sense? Also in the rear its spring over axle...is that stock? They put a pretty high spacer in looks like 6+inch I have not measured yet. Do you think the stock springs are in the back still? They are flat I am trying to figure out what springs to get for the rear end.
Thank you!

[Cecil14]

Stock front (after '74 or so) is spring under, this was done to accommodate moving the spring hangers from the side of the frame to under the frame. Stock rear has always been (to my knowledge) spring over.

When taking your tires into account, remember the difference is only half. You are only gaining half of the total tire diameter in height between the ground and the axle. I would encourage you to measure your tires to be 100% sure what size they are. A "35" is rarely truly 35" tall. A good, true, way to measure for this purpose is from the center of the hub to the ground. That's going to be the most accurate measurement you can really take. Then you'll just have to assume that the same measurement on a stock vehicle was 14". Does the TSM specify which tires were on the vehicle for those measurements? I know 31s were a pretty common option on the J-trucks.


aa

[eldudderino]

Stock front (after '74 or so) is spring under, this was done to accommodate moving the spring hangers from the side of the frame to under the frame. Stock rear has always been (to my knowledge) spring over.

When taking your tires into account, remember the difference is only half. You are only gaining half of the total tire diameter in height between the ground and the axle. I would encourage you to measure your tires to be 100% sure what size they are. A "35" is rarely truly 35" tall. A good, true, way to measure for this purpose is from the center of the hub to the ground. That's going to be the most accurate measurement you can really take. Then you'll just have to assume that the same measurement on a stock vehicle was 14". Does the TSM specify which tires were on the vehicle for those measurements? I know 31s were a pretty common option on the J-trucks.


aa

It does say the size and it converts to a 28.3in or something mine are 33inches tall on the vehicle.

[tgreese]

This may be too straightforward, but if it's lifted, and you have blocks in the rear, isn't the height of the lift equal to the height of the blocks? The blocks are used on the rear because it's spring-over (so it's possible), and because it's cheaper than new springs. The front is spring under, requiring new springs. You'd expect the front and rear to match.

[Cecil14]

This may be too straightforward, but if it's lifted, and you have blocks in the rear, isn't the height of the lift equal to the height of the blocks? The blocks are used on the rear because it's spring-over (so it's possible), and because it's cheaper than new springs. The front is spring under, requiring new springs. You'd expect the front and rear to match.

I have seen cases of people using a combination of springs and blocks, ie: 2" blocks and 4" springs. The less lifted springs tend to flex a little bit better, and are usually cheaper. Not my personal preference, but then neither are large lifts.

I would say the block is probably a decent place to start, and you're obviously getting at least that much lift in the rear. If it's sitting level, then the front springs are likely at least matching that lift block.


aa

[eldudderino]

I have seen cases of people using a combination of springs and blocks, ie: 2" blocks and 4" springs. The less lifted springs tend to flex a little bit better, and are usually cheaper. Not my personal preference, but then neither are large lifts.

I would say the block is probably a decent place to start, and you're obviously getting at least that much lift in the rear. If it's sitting level, then the front springs are likely at least matching that lift block.


aa

So the rear block is exactly 6 inches from the bottom of the leaf to the top of the axle. I can post a pic to show you what I am talking about, but both leafs in the back are flat...like more then flat they are bending the other way slightly. Even being spaced this should not be happening correct?