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MG MGB GT V8 Factory Originals Technical - Calling Kevin Jackson (Anti tramp devices)
I have been reading the archive from March this year regarding anti tramp devices. Kevin Jackson stated that he was going to try Bill Youngs method for this (as shown on the British V8 site - http://www.britishv8.org/Articles/Easy-Traction.htm).
Kevin, I just wanted to know how you got on.
Or anyone else out there who has tried this traction bar style solution.
|C J Bond|
|Chris, that article was written by Bill Guzman, want to give credit where it's due. I used a traditional style traction bar I fabricated that mounts under the front half of the spring. Nothing new in the technology, been used for years, but they work well and don't hang too low if you're careful how you make the brackets. Bill G's method works well also, but may have some tramp depending on how much space there is between the added leaf and the spring when installed. That distance is how far the spring can deflect under torque before the additional leaf stops it. It's a version of the old "slapper bar" traction bars used on a ton of muscle cars in the 70s. You can "tune" the reaction of the bar by adding a snubber to the end of the new leaf to take up some of the distance and make the bar react sooner. |
Photo of the bar I built and used on my midget, and yes it does do the job, no axle tramp at all.
Apologies to Bill G - it was late when I posted the message!
Thanks for the info Bill Y, yes I had Traction bars on my Dodge Super Bee in the 80's. But used that mainly for Drag Racing and straight lines. Now I want to go around corners as well!.
Your setup looks similar to the RV8 approach, which up until last night I intended use but some of the earlier posts said that it effects the handling - have you had any problems in that area.
|C J Bond|
|I'm not a road racer, so couldn't say about the handling at the finer limits those guys drive at, but no problems I've noticed on the street. I added a panhard rod and a small rear sway bar to my car due to the heavier V6 up front and the handling seems to be pretty neutral with oversteer at the blip of the throttle. I used the rubber bushings from Midget rear spring shackles in my bars for a bit of compliance so the ride wouldn't be harsh, but they give very little movement when called upon to reduce spring warp. I don't usually try any drag race type starts, but it will leave two pretty even stripes of rubber and that's with an open diff. It plants pretty good.|
Yes I was thinking of trying Bill Guzman's idea of the extra half leaf going forward from the axle, but in the end just fitted the new reverse spring eye 110lb GT springs when we fitted the 3.07 axle and removed the rear anti roll bar, but retained the Gabriel telescopic dampers which were part of the original Moss Hopkinson handling kit.
The rear suspension now works and no longer crashes over every imperfection in the road surface, the springs have transformed the handling and the grip level is very high and through a fast corner the rear sits down and you can feel the suspension doing it's job.
As far as axle tramp is concerned as yet I have not had a problem and with fairly spirited starts, the springs seem to cope with the torque of the V8 quite well, I'm sure if I dropped the clutch at 3000RPM I would get some axle wind up but the current set up seems quite acceptable.
I'm not a great fan of traction bars in their standard form because of the conflict of the fixed length bar and a leaf spring that wants to increase it's length under compression and can cause the supension to be less compliant than it should be, there is a cure for this and you could easily modify a standard anti tramp bar kit from Moss or MGOC to achieve this, see picture.
I would thoroughly recommend the reverse spring eye springs, they are more expensive than the standard replacement springs that are available, Moss say they are made to a higher spec and the quoted reduction in ride height was spot on at -2" which is ideal for a rubber bumper car, the rear is now approx 14.5" centre of wheel to chrome strip.
I also have a 7/8" front anti-roll bar and the car feels well balanced front to rear.
Hope that a help.
Thanks for your comments and yes it does help.
Just to put things straight, my project is a V8 MGA, with Rover 3500, LT77 and MGB tube axle with 3.07 gears (soon). So I dont think the reverse spring eye 110lb GT springs will fit. The front end is Hoyle coilover with 7/8" roll bar. Its a ground up rebuild, so very much in the development stage at the moment.
I like the bell crank idea for the anti tramp bars - thanks for the photo, it now makes sense.
Just out of interest, did you buy your 3.07 gears as a recon axle or have the ring & pinion fitted to your own axle. I'm looking at recon axles at the moment and would welcome any recommendations.
|C J Bond|
In my opinion it would be better if the bell cranks were the other way round with slightly longer radius arms, I would probably use a silent bloc type bush to sit on top the spring and using a an adjustable track rod end on the spring bracket end and the standard rubber bush on the other end, you can then pre-tension the bar to get the right effect.
If you use a standard kit you cut of one bush housing from each radius rod and have the tube threaded to accept a rod end, have 4 bell cranks cut and drilled for the correct bolt sizes and just bolt it all together.
Re rear springs you might get some good recommendations from the MG Experience board there are some helpful guys who regularly contribute.
The following link may provide some useful information and inspiration.
When you say "it would be better if the bell cranks were the other way round with slightly longer radius arms", I assume this is to achieve equal length of anti-tramp bar and the leaf spring from front eye to axle centre.
Re,. The MG Doc, - he has provided a lot of my inspiration and help with shoe horning the V8 where it was never intended to go..
|C J Bond|
Yes, and to make the pivot point the right angled corner of the bell cranks which is acceptably the right way to do it.
Have fun and keep us posted with your progress.
|The half spring used as a traction bar, does several good things, the two most important ones are:|
It helps launch the car forward car with out suspension shock thus preventing failures of "U" joints, differential etc.
Second, it does not increase the spring rate at all, it works with the motion of the spring, but it prevents the spring from becoming a "Horizontal S"
The early Muscle cars moved the axle forward in the spring thus making the front portion of the spring shorter. This was cheap fixing, but one that cause wheel hope during hard braking. I experience this with my 340 ci 6 pack Duster.
The added spring is not the same as a "Slaper Bar" this bars were made of square tubing and they do affect the spring by not allowing it to flex during cornering and normal driving.
With the half spring during acceleration you get a bit squat enough to transfer weight to the rear axle.
It does work well and it is simple and cheap.
You can see how it works on the page below.
This are the links that shows how the traction bars work. Using half of spring at fornt of the leaf spring pack.
Please don't think that I totlly shunned your suggestion, I was going to cut the leaves from the old springs but found that with the bottom plates for the Telescopic dampers being very thick, that there was not enough length on the new U bolts even for the small plates on the bottom of the new springs which we had to remove, don't know whether this effects the spring rate but it feels very good on the road and handles and grips beyond my expectations.
|Hi Kevin, The image you posted above is of the anti-tramp bars I made for my MGC GT (Ford 5.0 V8) and they seem to work quite well. I copied them from another car I saw! I agree that it would be preferable to reverse the triangular brackets so the bar was the same overall length as the forward half of the spring as there would not then be a "dimensional struggle" between the two items as the spring deflects. However I think the reality is that the front portion of the spring remains constant enough in length - it is pretty flat - and most of the length change occurs at the rear portion of the spring through the hanging shackle. The nice thing is that by threading the bars with left/right threads, they can be adjusted by turning them to alter the rate at which they start to counter the rearward twist of the axle as the car moves forward. On fast forward there is no trace of axle hop and it spins both wheels smoothly through 50MPH or so. It has a Quaife ATB - very progressive in action through tight corners and unnoticeable the rest of the time. They are pricey though at over 500 pounds. Best of luck, Bob Elwin |
|Bill, I cannot get your links to work. I'd like to see the traction bars.|
|David, the link in the his first post will take you to a section of his website that has video with sound of various V6 combinations. Check the ones for the 74B with the 3.4. He does a little tire burn for the camera and you can get an idea of how it hooks up and there's no sound of axle tramp. You can't see the springs or how they are reacting, but from the tire marks and sound there isn't any tramp or spring windup.|
Yes I remember our earlier discussion and your very nice CV8.
Your way of doing it is probably just as effective as the traditional method with a bellcrank that pivots on the hole in the right angled corner.
You say it works very well, and it will remove the conflict between spring and bar whilst doing the job.
|Hi Kevin, Yes the set-up still wortks OK but I would suggest reversing the bellcranks for any fresh sets so the forward lower bar attachment is directly underneath the spring pivot bolt. At least then the geometry would be as good as possible between the front of the spring and the bar underneath. Probably someone had reversed the set that I used as my model! Cheers, Bob.|
This thread was discussed between 12/11/2007 and 17/11/2007
This thread is from the archive. The Live MG MGB GT V8 Factory Originals Technical BBS is active now.