drill and tap the center of a t-bar?

andyt11 · 08:24 AM

After installing my new neatrix bushes, and reassembling EXACTLY as it was (I managed to get the t-bars back in exactly the same splines with some careful paint marks during strip down) and the car is sitting exactly the same height it always was.

However, now before it goes for alignment, I've decided I want to drop he car half an inch at the rear. Unfortunately in my quest to assemble the car exactly as I found it, I also attached the spring plate to the torsion tube cover in the same place I found it. Maxed out in the low direction.

So now the only way to lower the car further is to re-index the torsion bars. This is the problem, the new neatrix bushes are so tight in the side of the car that I cannot disassemble and re-index. No amount of prying will get the spring plate off the side of the car, and I cannot get a bearing puller on there.

I had a brainwave though. If I drilled and tapped a small screw in the center of the t-bar, I could unload the suspension and pull the bar out with a slide hammer. Everything is greased up good, it would slide out easy. I'm fairly sure the center of a t-bar doesn't see any stress either, but I thought I'd pitch the idea to the Pelican brain trust. I imagine the t-bars are made from quite hard material?

andyt11 · 05-05-2014, 08:22 AM

The tightness of the bushes is what is preventing me pulling the torsion tube cover and spring plate from the side of the car. I cannot disassemble and start again.

My new idea is to leave everything in place and just pull the t-bar. I would of course do this with the suspension unloaded so I don't think the screw would snap.

My question is really whether it is a terrible idea to drill the end of the t-bar.

ClickClickBoom · ClickClickBoom's Garage

Hardened steel, extremely hard to drill, you are talking about a spring.

Shaun @ Tru6 · 05-05-2014, 08:40 AM

I talked with Clint at Rebel Racing about this when I asked if he could groove my springplates like the Elephant Racing style. He said it won't effect the torsion bar to drill and tap making them quickchange style.

boyt911sc · boyt911sc's Garage

Quote:

Originally Posted by andyt11

The tightness of the bushes is what is preventing me pulling the torsion tube cover and spring plate from the side of the car. I cannot disassemble and start again.

My new idea is to leave everything in place and just pull the t-bar. I would of course do this with the suspension unloaded so I don't think the screw would snap.

My question is really whether it is a terrible idea to drill the end of the t-bar.

Andy,

How do you expect to re-index the torsion bar/s correctly if you have the spring plate cover installed and bolted to the chassis?

Tony

andyt11 · 05-05-2014, 09:20 AM

I must be missing something! I don't see a problem, but you obviously do and I know there are many knowledgeable people on here. Why do you think I wont be able to to index the bars correctly?

Jeff NJ · 05-05-2014, 09:48 AM

I recently re-indexed my Tbars and replaced the bushings too. It was very tight, but I was able to pull the spring plate out to make the height adjustments necessary. I guess you could pull the tbar out the end of the spring plate (I see your dust cap is off), but man that would be difficult IMO. You would have to place the splines on both sides of the tbar in at the same time. I had a hard enough time indexing when I was able to insert the inner splines and then put the spring plate on to insert it into the outer splines.

Also, the instructions warn against even scratching the paint off the surface of the Tbar as that will adversly affect the Tbar performance over time. I can't imagine that drilling a hole in it is a good idea, but I am not a metallurgical engineer.

Why not let the alignment shop do it? My shop offered to do it, but it was quoted at 4 hrs in addition to the alignment, so I did it myself and let them align it. At some point, that $400 cost may be worth it?

Driven97 · 05-05-2014, 10:56 AM

I'm no engineer, but the center of a t-bar doesn't do much. Hence why you can get hollow ones that only need a slight diameter increase to have the same stiffness as a solid one of slightly smaller diameter. The surface is where the most stress / strain is. I would think a small centered threaded hole wouldn't have much of an adverse effect, especially if it doesn't extend past the splined section of the bar.

Again, not an engineer, so huge grain of salt.

andyt11 · 11:51 AM

Quote:

Originally Posted by Driven97

I'm no engineer, but the center of a t-bar doesn't do much. Hence why you can get hollow ones that only need a slight diameter increase to have the same stiffness as a solid one of slightly smaller diameter. The surface is where the most stress / strain is. I would think a small centered threaded hole wouldn't have much of an adverse effect, especially if it doesn't extend past the splined section of the bar.

Again, not an engineer, so huge grain of salt.

That's what I was thinking, but I'm not an engineer either. Maybe I should find one!

Jeff NJ, I would love to find a shop to do this. I'm tired of messing with it and I want to hand the car over to someone and get it back next week just finished and ready to drive. I'm having a hard time finding anyone in town who is familiar with the setup though.

maybe I have to find a smaller bearing puller.

john walker's workshop · 05-05-2014, 03:21 PM

why don't you drive it around some and maybe it will settle 1/2" by itself.

andyt11 · 05-06-2014, 04:56 AM

Thankyou John. I had the same thought last night in bed. I've been on one trip in the car, but only for 5 or 10 miles. I'm going to take it out again and see what happens. I'm also working on modifying a bearing puller, I'm thinking if I can use a puller and a pry bar together I might get it.

I also got a PM about a guy in town who may be able to help with this. Will post an outcome when it is resolved.

andyt11 · 05-06-2014, 06:33 PM

Well Mr Walker. Thankyou.

I took it out for a 2nd ride, this time though I hit up the grocery stores and petrol stations for speed humps. Ten or twelve speed humps later and we have settled down another 1/2".

I now have 25-3/4" on the drivers side and 25-3/8" on the passenger side. I was shooting for 25-1/2". When I sit in the drivers seat I get 25-3/8 both sides. I'm pretty happy with that.

It needs to go for an alignment, I think I'll leave it as is and ask them to stick a 200lb lump in the drivers seat during the alignment. Seems like the correct thing to do. This is just a road car though. I imagine they wont bother, I also imagine it wont make any difference to the alignment either!

Thanks for the advice. I'll put my custom fabricated bearing puller away for another day.