ok guys so here is a dumb question i wanna shorten my driveshaft tomorrow at work but i dont have a dial indicator i can get one but it wont be tomorrow so the question is can i eyeball the runout or do i absolutely need a dial indicator to do this thanks in advance please only answer if you have expirience i dont want a persons guess to cause me problems as i have a limited budget and even less time id like to do it right the first time but this is my only vehicle and its been down for way too long already so quickness in execution is the key here if its too risky ill have to wait for the tool but would rather do it tomorrow i am a good welder/metal worker just need to know how improtant the dial indicator is
shortening my own driveshaft
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I only tried it once and it didn't work out so I took it to my local machine shop and got it fixed. I watched while he did it and it looked like the dial caliper is probably critical to doing the job right. Only cost me $50 too, so not cost prohibitive.
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5,407 Posts
Actually taking a caliper or straight edge that you can supported in a fixed position and slide it to the shaft as it turns will indicate if you have run out. It just won't tell you how much. Even a dial indicator is not of value if you can't chuck up the assembly and turn it.
John L
John L
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9,050 Posts
You didn't state how or on what kind of machine you were going to use.
I have done driveshaft shortening for many years. Tho I always use some kind of runout indicator. It could be done in a lathe with a good eye and a three post steady rest.
Always shorten the end going to the rear. If you use a large lathe. Mark a line the length of the shaft for index purposes. Chuck up the yoke end in the headstock and use the steady rest tight on the shaft, to be cut end. cut the weld thru on the shaft and gently tap the end off the shaft.
Carefully trim shaft to length, try not to move any lathe settings. After cut, line up the marked line, tap end back into shaft. If the cuts were true. The ends will fit perfectly. Check for visual runout. Tack weld with a Mig in three places. Check again then weld up the shaft.
I have done driveshaft shortening for many years. Tho I always use some kind of runout indicator. It could be done in a lathe with a good eye and a three post steady rest.
Always shorten the end going to the rear. If you use a large lathe. Mark a line the length of the shaft for index purposes. Chuck up the yoke end in the headstock and use the steady rest tight on the shaft, to be cut end. cut the weld thru on the shaft and gently tap the end off the shaft.
Carefully trim shaft to length, try not to move any lathe settings. After cut, line up the marked line, tap end back into shaft. If the cuts were true. The ends will fit perfectly. Check for visual runout. Tack weld with a Mig in three places. Check again then weld up the shaft.
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5,407 Posts
Good clear explanation from Bob. I have seen my local drive line shop correct a slight run out in the tube by heating the "high" side of the tube with an acetylene torch about the size of a dime. By shrinking the high side it will pull the tube straight. This method only applies to run out in the middle of a tube. There is no fix for sloppy work at the ends.
I have been told that the center of the tube will get warm after a high speed run, if it is not true, due to the flexing. I wonder if Bob knows if this is correct.
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663 Posts
shorten drive shaft
it can be done,machine off 1end clean up the yoke that the u joint goes into.you then need a long flat surface,lay the drive shaft on the floor or flat plate,this whay you get the u joint circles lined up,this must be right on.when you are there tack weld the shaft to the yoke in 4corners. install on the vehicle withe the rear wheels up and in nuetral.rotate the drive shaft you mah have to wack it with heavey hamer check the runout with ablock of wood with a piece of round stock.when you ar close weld it in place,just small amout at a time,weld a heaveyer amount to keep it streight. when finished you can st it further with torch and cold wate.heat a small spot then cool with wet rag.the shaftvwill pull to the side heated nd cooled.have worked for me on 2 ocasions. cliff
it can be done,machine off 1end clean up the yoke that the u joint goes into.you then need a long flat surface,lay the drive shaft on the floor or flat plate,this whay you get the u joint circles lined up,this must be right on.when you are there tack weld the shaft to the yoke in 4corners. install on the vehicle withe the rear wheels up and in nuetral.rotate the drive shaft you mah have to wack it with heavey hamer check the runout with ablock of wood with a piece of round stock.when you ar close weld it in place,just small amout at a time,weld a heaveyer amount to keep it streight. when finished you can st it further with torch and cold wate.heat a small spot then cool with wet rag.the shaftvwill pull to the side heated nd cooled.have worked for me on 2 ocasions. cliff
ive cut em. i dont do much engine work but its just metal. you can do it with bout any thing. you got to get a good mark on it. i use a scratch all. a sharp one. hahaha. even a good pipe wrap will work to get close enough.a good square will after your first cut but you got know how to use them tools well.you can cut it with a dang sawsall near the mark and finish with some carefull grindin. but you got to get that mark rite. check it ever way you can. i'll proly get a lesson here from someone but i ben workin metal, steel all my dang life. not cars but its the same dang thing.im buildin a car.my first one. aint done nothin in a while but i asked a few questions on here and cut that sucker up and its together.i used my carpenter tools. hahaha
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1,782 Posts
Before you worry about removing any runout in the tube.. Focus on getting the tube yoke in the tube straight. And DO NOT butt weld!! You will have the best luck if the tube yoke is no more than .05 difference measured 180 degree from each other.
After your tube yoke is welded in straight then worry about removing runout in the tube.
After your tube yoke is welded in straight then worry about removing runout in the tube.
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663 Posts
drive shaft
take the shaft to a machine shop and have the yoke removed properly,it has a aria that fits snugley into the tube,if you are dum enough to think you can cut the shaft in the midel ane ever get the shaft to work properly,think again .Iwas that dum 1 time,learn from us old dudes. cliffthanks everyone ill probably just get a dial indicator or if i get adventurous ill try the straight edge thing and hack it up tomorrow I will let ya'll know how it turns out (no pun intended)
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5,030 Posts
If you go ahead w/this, before taking the car out on the street install a driveshaft loop. Cheap insurance and I would say that even if I welded it. A loop should be on every performance vehicle anyway, IMHO.thanks everyone ill probably just get a dial indicator or if i get adventurous ill try the straight edge thing and hack it up tomorrow I will let ya'll know how it turns out (no pun intended)
And you should have it balanced. You might be able to use the hose clamp trick if it's not too far out.
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11,051 Posts
Make sure your yoke's are lined up right,, AWAYS make you cut and weld's at the ends.. Never try to do it in the middle.. You will never get it right..
by the way guys i was talking about cutting off the yoke NOT in the middle and i did build my own driveshaft loop awhile ago nows the perfect opportunity to utilize the s.o.b. and just an update i ended up not shortening the shaft the way i planned and i cut the splined shaft (OMG!!!!!!!!ya i know) im cheap and when i get the funds im getting a chromolly shaft anyway so this one only needs to get me to work and back for a few months (tax time is my christmas) but if i were to do it myself like i was asking i've decided the dial indicator is a must as is a lathe im sure i could check runout on the vehicle with a dial indicator but with the speed and power soon to be in the truck i'm not too sure i would even want to take it down the strip so many thanks guys for your kind words of encouragement and advice but for now i got it sorted out........Happy Rodding!!!!!!!
yessir im not sure where this shaft came from (a few mysteries left from previous owners) but i know its not an s10 shaft and the slip yoke after pushed into the tranny all the way was still exposed about 2 1/2 inches so i cut an inch off instead of wasting money thanks for your concern tho ss:thumbup:
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9,050 Posts
Just today had a request from the business next to me.
They had an "old guy" shorten the shaft for a custom unitbody Ford pickup. They said 67" the guy heard 57". Now they want me to add 10" back into the shaft!!.. I don't think so...
They had an "old guy" shorten the shaft for a custom unitbody Ford pickup. They said 67" the guy heard 57". Now they want me to add 10" back into the shaft!!.. I don't think so...
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20 Posts
Hay man, my '54 3100 jus blew the 2-3 sprag on a 350 turbo and I switch to a 700r I had, was going thru the same dilama, have a Astro Van out back and wola, the driveshaft fit,problem solved. See Y-all in Daytona for the Turkey Run.
drive shaft cut
I have cut a lot using the farmer boy method. First find a drive shaft with no or very small factory balance weights. I lay the shaft on the steel table and use an angle iron next to it to scribe a straight alignment end to end . and spray some paint so you don't put it back together 180* out . I then chuck it in the lathe and make the first cut partially thru the rear, weld bead,, then measure the amount to be cut out and partially make that cut, then with the steady rest accurately adjusted, finish cut the end off, then finish the center cut, put it back to gether then as noted above tack weld, safety hoop.
I have cut a lot using the farmer boy method. First find a drive shaft with no or very small factory balance weights. I lay the shaft on the steel table and use an angle iron next to it to scribe a straight alignment end to end . and spray some paint so you don't put it back together 180* out . I then chuck it in the lathe and make the first cut partially thru the rear, weld bead,, then measure the amount to be cut out and partially make that cut, then with the steady rest accurately adjusted, finish cut the end off, then finish the center cut, put it back to gether then as noted above tack weld, safety hoop.
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