Another front anti roll bar query

[Les Millington]

I'm in the process of trying to identify a clonk on the TR4A at low speeds on very bumpy roads. As part of that I tested the security of the front arb which seems not to be loose but the geometry looks a bit strange to me.  The bar itself is about 5/8" diameter. If someone could cast an eye at the photos of each side and come back with a more educated opinion I would be grateful. I'll get the car up on a friend's hoist hopefully in the next few weeks to look for the clonk. 

 

Les

[Drewmotty]

Those links should be vertical. Maybe the brackets will fit on the centre wishbone bolt with the offset outwards. 

[Lebro]

+1

Bob

[Les Millington]

Thanks chaps, I'll see if that works. I certainly don't find the car's handling that brilliant to be honest, but maybe that's too many years of sticky tyres, front wheel drive and power steering.

 

Les

[Bfg]

Have you tried driving the car without an AR bar at all ?  

Pete

 

[trchris]

Hi Les 

The link brackets should be fixed to the middle bolt test fit first so you get them the correct way round also there’s a spacer the goes between the bracket and spring pan and the bolt is slightly longer. Looking at your picture the links don’t look good you may have to replace if you refit the arb

Chris

[Les Millington]

Hi Pete No, I haven't tried it without, but reading other stuff I am tempted, but 

Chris Thanks for that, I think I'll try moving it first as you and others suggest. At least it may add to one's knowledge, or lack of.

 

Les

[BlueTR3A-5EKT]

Is this a Suzuki Swift front ARB?

is the wrong shape for a SAH bar or Triumph or Addco.

Yes the links should be vertical.    Moving the pick up will change the rate of the bar.

I have removed my ARB which was a TR6 orig on a TR3 and am pleasantly surprised by the removal of sawing with the steering wheel on long corners and the lighter feel to the steering.    The car runs Triumph orig spec uprated front springs ie SAH 606 or TT4006 in todays copy market.

I have raised the rear tyre pressure to 30 psi

Edited July 26, 2023 by BlueTR3A-5EKT

[Malbaby]

That looks to be the wrong bar...Remove completely or obtain the correct length/profile one.

[Les Millington]

Thanks everyone, much appreciated, I shall report back in due course.

 

Les

[Bfg]

a question to those who have greater experience than I ... 

Behind my asking the question of whether Les had tried his Tr4A without an ARB - was my wondering if there is a discernible benefit from fitting an AR bar to an all independent suspension sports car (i am supposing with otherwise close-to-standard specification) intended for general road use, and particularly fitting just one across the front.? 

My thinking is independent  suspension surely facilitates geometry design and (progressive rate) springs / dampers which negated any benefit of an AR bar.  I can imagine there's a benefit to be had in fitting an AR bar to the front of many live-axle cars, and of course to saloon cars with their high centre-of-gravity & comfortable suspension ratings, but a Tr4A  ..which as a seat-of-the-pant type sports car was already designed for fast-road-use ?

Les doesn't say whether he has an AR bar on the rear suspension of his car,  but don't those who race a production car on smooth-surfaced track usually fit AR bars to both front and rear ..and then experiment with those to achieve a front-to-rear balance, with regard to their torsional stiffness, possibly even for different race tracks & conditions.? 

Just asking

Edited July 26, 2023 by Bfg

[Lebro]

No ARB = reasonable cornering, but body roll

Front only ARB = less body roll, but more understeer

Front & rear ARB = even less body roll, & excellent cornering

In my opinion !

Bob

[Tr4aJim]

My TR4A has a solid rear axle and no ARB. I run with 165/15 tires (tyres) with 26 front and 28 rear. Typically the car tracks very well, but in tighter corners, at speed, it tends to oversteer. 

BFG brings up an interesting point. While solid axle TR4s had ARBs, were ARBs deleted from the TR4A due to the addition of IRS, then Triumph apparently changed there minds and added them to the TR6?

So given the oversteer, and the solid axle, should I think about fitting an ARB, or would I have better results fiddling with tire pressures?

Jim

[stuart]

1 minute ago, Tr4aJim said:

My TR4A has a solid rear axle and no ARB. I run with 165/15 tires (tyres) with 26 front and 28 rear. Typically the car tracks very well, but in tighter corners, at speed, it tends to oversteer. 

BFG brings up an interesting point. While solid axle TR4s had ARBs, were ARBs deleted from the TR4A due to the addition of IRS, then Triumph apparently changed there minds and added them to the TR6?

So given the oversteer, and the solid axle, should I think about fitting an ARB, or would I have better results fiddling with tire pressures?

Jim

As you know Jim I also have a solid axle 4a and I found that just by stiffen up the suspension made a huge amount of difference to the handling. I have Spax adjustables on the front and they are wound up just over half way and I also have uprated lever arms on the rear. The rear springs on these cars are similar to the late TR4 where they added the ally blocks and deepened the dish on the spring, I found the rear springs to be too soft as well and so I added spring clamps and this has made a huge difference. It now goes just where I point it with minimal body roll and pretty much neutral steer. I do run 195 Yokohamas so the added grip helps.

Stuart.

[Tr4aJim]

Thanks Stuart! Do you have a source for the rear spring clamps?

Jim

[stuart]

39 minutes ago, Tr4aJim said:

Thanks Stuart! Do you have a source for the rear spring clamps?

Jim

Unfortunately not as they were given to me many years ago by a sadly now deceased member of our local area.

Stuart.

[Motorsport Mickey]

Might help if you can post a photo of you leaf spring stiffening clamps Stuart. Old school suspension tuning, effectively just a strap clamp across the bunch of leaves… and just tighten up. Easily made I’d have thought.

Mick Richards

 

[stuart]

16 hours ago, Motorsport Mickey said:

Might help if you can post a photo of you leaf spring stiffening clamps Stuart. Old school suspension tuning, effectively just a strap clamp across the bunch of leaves… and just tighten up. Easily made I’d have thought.

Mick Richards

 

Very old stock picture here then Mick pre Alfins and when it still had wires fitted. Top and bottom plate needs to be basically a channel shape to give it strength. I removed the one nearest the drum as it made it bit too stiff. Two clamps are just right..

Stuart.

[Tr4aJim]

Excellent! Thanks Stuart, it shouldn’t be too hard to come up with something similar.

Jim

[Andy Moltu]

On 7/26/2023 at 12:01 PM, Lebro said:

No ARB = reasonable cornering, but body roll

Front only ARB = less body roll, but more understeer

Front & rear ARB = even less body roll, & excellent cornering

In my opinion !

Bob

Agree. Had a rear antiroll bar on the 6 for years, took it off temporarily when a bracket needed replacing and it rolled more. Put it back and less understeer and flatter cornering when I put it back. 

My 4A came with a front one fitted and understeer more than the 6. Have got a rear one but yet to fit it.

But that's my preference. I don't like understeer. 

Progressive springs might help roll without an ant roll bar. Got them on the Stag but not aware of them for the IRS TRs. Perhaps the springs/travel is too short to practically manufacture?

[BlueTR3A-5EKT]

On 7/27/2023 at 12:45 PM, Tr4aJim said:

Excellent! Thanks Stuart, it shouldn’t be too hard to come up with something similar.

Jim

Closer to home for you Jim   There might be something here.   Try the Hot Rod parts sellers.   They still use leaf springs.

https://www.summitracing.com/search/part-type/leaf-spring-clamps

 

Edited August 1, 2023 by BlueTR3A-5EKT

[Tr4aJim]

Thanks Peter! I have been looking at suppliers like Summit. One thing Ive noticed is they seem to offer two types.

One type is a flat U plate where you have bend the ends over a receiver plate. This seems a bit finicky to me, as keeping the tightness uniform, while also bending the tabs over, might be problematic. Also once fitted, moving/adjusting tightness would be problematic.

The other type uses a U bolt and flat plate. This is closer to what Stuart used. It allows for easy movement/adjustment, but the flat plate seems susceptible to distortion under clamping pressure.

So I’m also searching for some appropriate U plate (similar to what Stuart has) and perhaps fabricate my own clamps.

Jim