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restoring Merkur- solid T5 driveshaft....yay or nay?

Posted by Clayto 
Clayto
Clayton McCrary
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restoring Merkur- solid T5 driveshaft....yay or nay?
February 08, 2015 01:13PM
Ultimate goal is Gravel spec once cage is in.
Have any of you XR guys used one?
I have a chance to get it local for $100
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fiasco
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Re: restoring Merkur- solid T5 driveshaft....yay or nay?
February 08, 2015 06:53PM
For $100, I'd snag it for the parts to make a two piece! Or as a spare.



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Clayto
Clayton McCrary
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Re: restoring Merkur- solid T5 driveshaft....yay or nay?
February 08, 2015 08:04PM
I have a stock spare already and its in great shape.
Was thinking of getting the straight one piece for durability and no guibo to fiddle with.
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MarkHille
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Re: restoring Merkur- solid T5 driveshaft....yay or nay?
February 10, 2015 01:37PM
Quote
Clayto
Ultimate goal is Gravel spec once cage is in.
Have any of you XR guys used one?
I have a chance to get it local for $100

What is the diameter? I have one going from a t5 to a supra diff. Its not really interchangeable with the stock diff so if you have a stock diff and want to change it you might have to make some changes to the driveshaft. Is it custom ($350ish new?) or is it just a mustang shaft with spacer? I wouldn't mess with the mustang one. Either way, you should expect a ton of scary vibration noise from the driveline that seems to be notorious in an XR with a solid shaft but longevity doesn't seem to be an issue. For a daily driver I'd say don't do it. For a race car it seems the best/strongest option.
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Clayto
Clayton McCrary
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Re: restoring Merkur- solid T5 driveshaft....yay or nay?
February 10, 2015 09:16PM
Quote
MarkHille
Quote
Clayto
Ultimate goal is Gravel spec once cage is in.
Have any of you XR guys used one?
I have a chance to get it local for $100

What is the diameter? I have one going from a t5 to a supra diff. Its not really interchangeable with the stock diff so if you have a stock diff and want to change it you might have to make some changes to the driveshaft. Is it custom ($350ish new?) or is it just a mustang shaft with spacer? I wouldn't mess with the mustang one. Either way, you should expect a ton of scary vibration noise from the driveline that seems to be notorious in an XR with a solid shaft but longevity doesn't seem to be an issue. For a daily driver I'd say don't do it. For a race car it seems the best/strongest option.

Not sure on diameter....It's a custom driveshaft. Fits to a stock housing.
I think I'm gonna get it and put it in my parts pile.
Previous owner had it 60,000 miles with no vibration problems.
Wife is going back to work after 8 years raising kids.... Stoked for her new job and for some of my Budget backsmiling smiley
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john vanlandingham
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Re: restoring Merkur- solid T5 driveshaft....yay or nay?
February 10, 2015 09:41PM
Quote
Clayto
I have a stock spare already and its in great shape.
Was thinking of getting the straight one piece for durability and no guibo to fiddle with.

No Guibo right next to a cat is good... One piece SEEMS to make sense in a car that the motor sits still and the diff is fixed like in IRS.

However.

We can review known knowns
Seems like every IRS car I can think of in rally use---and that's EVERY AWD car since beginning of time---and a lot of others retain the 2 piece design...
I don't understand why but they do. Group N they must by rules, Group A they can do whatever they want---and they all retain 2 piece....Probably a good reason..

We know they all retain 2 piece....we don't know why they do or if its know big deal (and certainly if it were BETTER-er to have 1 piece for any reason, all these works cars in last 30 years would have one piece..

There's something in driveshaft design called "critical speed" and length and rpm are factors, so I think it MIGHT be smart to look into driveshaft critical speed before making any decision...

The other thing is: you wanna pay twice? What box is going to be in this? Might be nice to nail that down before deciding on propshaft design.

But as I said i don't know anything about propshafts..


this might be a help in thinking ^



John Vanlandingham
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MarkHille
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Re: restoring Merkur- solid T5 driveshaft....yay or nay?
February 11, 2015 08:44AM
I would love to have a two piece.

But...when I was pricing them out it was going to be well over double in price. Then there is the maintenance involved (guibo and that bracket thingy). Then there is properly fitting the bracket. Then there is you run over one big rock and your out of the rally and need to spend the same $$$$ on the replacement.

I could see if it was a safety issue but I have never heard anything about a one piece failing in a Merkur. I specifically asked some of the auto x guys who have been running them for years. The vibration only presents itself as a noise and not an actual vibration so it doesn't affect the drive and it mostly seems to come from the transmission. The more solid your transmission is mounted the louder it seems to be. If you still have all your sound deadening you may not even notice.

My shaft is 3.5" and 48" center to center. If you don't get a 0.80 5th gear you will never use 5th gear. In 4th that puts the ratio at 1:1 and with a stock rev limit of 6500rpm it falls well under the 8700rpm critical speed in the chart. No?

I paid $300 out of the door for mine. I could have gotten two of them and had a spare for less than what I was getting for quotes on a two piece. Some people were modifying their stock two piece shafts for not a ton of money but of the 4 stock drive shafts I've seen they all would have been more likely to fail than the one piece I have. Didn't Sean have a two piece that failed during a rally?
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Clayto
Clayton McCrary
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Re: restoring Merkur- solid T5 driveshaft....yay or nay?
February 11, 2015 11:20AM
Of course this seems to make sense. But , I had to bring it to the forum before I decide to buy this and keep it for awhile. I will run the stock one as long as possible and either throw spare stock in or go custom if I get it.
I'm waiting on exact length from seller.
Here's the ad info.....

"Looking to sell my 1-piece T5 XR driveshaft. It is steel
The pros:
-No guibo
-No center support bearing to align
-No vibrations (personally tested up to 145mph)
-No adapters necessary
-Good u-joints, although regreasing is recommended as it's been sitting for a few years.
The cons:
-Paint has worn off from rock chips and the sort. Could be repainted if this is something that concerns you.
-A little too long, requires loosening the trans mount and front sway bar to install
located in Vancouver, WA. Would rather not ship due to size."

Straight and simple is what I'm looking for and if the length is good I'll grab itsmiling smiley
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Re: restoring Merkur- solid T5 driveshaft....yay or nay?
February 11, 2015 12:42PM
Why is there no difference between mild steel and chromoly? Same modulus?



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john vanlandingham
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Re: restoring Merkur- solid T5 driveshaft....yay or nay?
February 11, 2015 01:25PM
Quote
Rallymech
Why is there no difference between mild steel and chromoly? Same modulus?

Yeah. all ferrous metals--even cast iron--have the same...(iron just doesn't have the fatigue resistance...ya snows bend it CRACK!)

What ever since it is clear theres a relationship tween dia, length and critical speed and for a given dia the speed goes down maybe the whole deal with retaining 2 piece on like fast IRS cars is each piece is kinda short..
Whatever the case it sure is spoooky thinking about sumpin only 035" of sheetmetal away is spinning at 6 or 7 thousand rpm right next to my butt. Yikes








John Vanlandingham
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MarkHille
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Re: restoring Merkur- solid T5 driveshaft....yay or nay?
February 11, 2015 03:45PM
Quote
john vanlandingham

Whatever the case it sure is spoooky thinking about sumpin only 035" of sheetmetal away is spinning at 6 or 7 thousand rpm right next to my butt. Yikes

And here this whole time I was more worried about those big trees going by outside the window at 0 rpm!!! eye popping smiley Yeah, I don't want anything up in my ass like timmo either....





In all seriousness, thanks for the input john. smileys with beer
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Robert Culbertson
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Re: restoring Merkur- solid T5 driveshaft....yay or nay?
February 11, 2015 04:51PM
Quote
john vanlandingham
Quote
Rallymech
Why is there no difference between mild steel and chromoly? Same modulus?

Yeah. all ferrous metals--even cast iron--have the same...(iron just doesn't have the fatigue resistance....)

Mostly correct. I'm not trying to be a dick and correct you, just making sure that accurate information is conveyed.

Grey cast iron has a Young's Modulus range of ~10,000 (about 6061 aluminum)-25,000 ksi, while almost all carbon steels and cast steels are 30,000 ksi.

The yield and ultimate strengths are what set different grades of steel apart the most. With mild steel being about 12% weaker than 4130.

Source: http://www.engineersedge.com/manufacturing_spec/properties_of_metals_strength.htm
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NoCoast
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Re: restoring Merkur- solid T5 driveshaft....yay or nay?
February 11, 2015 05:23PM
Quote
Robert Culbertson
Mostly correct. I'm not trying to be a dick and correct you, just making sure that accurate information is conveyed.

Precision and accuracy are optional around here.

I don't know what my shaft was other than it had two U joints and a center support bearing. No guibo thank god. Or did it have a Guibo. I don't recall. Regardless, Mark will have it in two weeks.



Grant Hughes
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Re: restoring Merkur- solid T5 driveshaft....yay or nay?
February 12, 2015 06:46AM
I had one of the Rapidooo 2 piece shafts (no giubo) that I got from a forum guy. There were no vibrations at all with it (other than 'normal' shit). I had the flange drilled for the Supra diff (and machined off the "hub" part) - no problems. I thought the U-joints seemed a bit small - I forgot what size they were now. I'm currently running some 1 piece unit (no giubo either) that was already on the car when I got it. I put a new Supra flange on it, changed U-joints while I was there, and had it balanced at a shop, and it's fine. I think I have more vibration/noise from the solid mounted exhaust than anything else.
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Re: restoring Merkur- solid T5 driveshaft....yay or nay?
February 12, 2015 11:55AM
Just put some unlubricated nylon bushings in the rear STA and you'll never notice another vibration as the noise from the bushing will distract you from all else.



Grant Hughes
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