low cost hydraulic puller needed

Harbor Freight has both pullback rams to go with the hand pumps that may work as well as a clone of the Greenlee hydraulic punch puller with the separate pull cylinder and hand pump.

We used to call them "porta power", but a google search on that now yields rechargeable batteries, etc.

Take this link. There's bound to be some of what you need in the kits:

Pete Stanaitis

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David Lesher wrote:

At many times the price. That's the issue. A bottle jack is $10-20. The pullback ram kits end up being $100-$150...

Surely if you're skilled and capable of doing that kind of work, your time is worth far more than it would take to improvise a pullback ram out of a bottle jack.

Given that attitude; I'd pay someone to fix my car, etc. Few hobbies make sense from a pure dollar aspect.

I was hope the smart folks here could conceive of a new approach; one we had overlooked.

We are not necessarly looking to make such from a bottle jack. We could, we think. Connect "cap" to piston, build a saddle _ _ | | | | | | | | ---

for the jack to sit within, with tabs to the die that does the pushing. The saddle must reach around the frame rail, of course.

Here's a homemade one:

A frame around the jack to reverse the direction of force would be the cheapest, I think.

Don Young

Can you use a c-frame screw press like those for handling ball joints and control arm bushings? Those can take a lot of use before they wear out, and you can use an air ratchet or impact gun to drive them. Just keep the screw well-lubed. Something like

for $33.

----- Regards, Carl Ijames

You might be able to do something with a couple of brake calipers or drum brake wheel cylinders from the junkyard. Use the "pump" from a small bottle jack.

The demotivator here is that folks can probably think of many approaches that you have rejected because they didn't meet criteria not mentioned here: available space, available tools and skills, expectation of time to make, how much force is needed, etc etc.

It's real hard to beat a long lever if there's room to deploy it.

Nothing wrong with a hobby approach. I assumed this was some kind of job. But even in hobbies, make-or-buy ought to be a cold calculation. Not like getting your car fixed, which I do myself as an oath-bound duty, after suffering swindles and gouges in my earlier days, and swearing never-again.

There's nothing to pry against. And you'd pull the car off the jackstands.

We do want something easy to make; the idea is to come up with an open source design other BMW owners/clubs can replicate. (The E30 owner is a Linux developer...)

The factory tool is who knows, maybe $800-$1000. Aftermarket ones are a few hundred $, and require a new jackscrew every few uses. Homemade ones with a bolt/all-thread are one shot or two.... if they work.

If it is possible to use the pump in a bottlejack; we can buy a pull cylinder.

The H-F "C clamp" would be a good installer but we need to pull:

-------- ---- body w/ hole NUT _|_ -|- die with shaft... | ======|| | ||===== ======|| | ||===== ======|| | ||===== ======|| | ||===== subframe with long donut within ======|| | ||===== ======|| | ||===== | \--|-/ Cup | NUT

You need to pull the die through, forcing the || || donut down & out ahead of it. You can't push it out like a ball joint; there's an upper lip, and no clearance.

I think the last flyer from Harbor Freight had the Greenlee clone at $70. Looking on the website it was $90. ITEM 96718-3VGA

Dan

You could cut the chain links off to shorten it.

Jim Wilkins

What you need is a hollow ram cylinder for a porta power. Unfortunately I've not seen any cheap imitations of the name brands in these. Sometimes you can get lucky on ebay or at a auction (where I got mine).

The Specifications for this item are not currently available online, or the item has been discontinued

I think you would be okay using the thread method as long as you include a thrust bearing. Like this Harbor Freight punch:

Note the thrust bearing by the head of the bolt. I've used this type before (not by HF though) and the thrust bearing makes a world of difference.

Get the largest bolt practical and/or thrust bearing to go along with it. If it don't work well enough you can keep your eye open for a hydraulic method that fits your budget (shrug).

Leon Fisk noted the benefit of a thrust bearing. Note that it would need to ride on a hardened disc or surface.

Now, consider a bolt inside a bushing that is threaded both inside and outside. The bolt might be 18 TPI while the bushing on the outside might be 16 TPI riding in a threaded collar. In use, you use two wrenches, simultaneously rotating the bolt clockwise and the bushing counterclockwise, effectively screwing the bolt "in" as the bushing screws "out" (for RH threads). The result is a differential motion of

1/16 - 1\18 inch per turn, or 1/144 inch (.00694) net. You get the benefit of thick, robust threads while the differential action provides enormous mechanical advantage. Lube the threads with high-pressure lube.

For pulling use a hollow ram with a pull rod through the center, powered by a hydraulic hand pump. No C-frame required. Like this:

From Enerpac site: Neither Northern Tool nor Harbor Freight seem to offer a comparable one for hobby use.

David Merrill