How do I cure wheel hop?

[JTs Bikes]

So, what is the best and, most inexpensive way, to cure wheel hop? I've heard some people say Torque Arm and some say Four Link, or is there some other way? Let me know what you think.

[86fiveoh]

Best and inexpensive don't typically go together

[FM2NOTCH]

install stiffer lower control arm bushings. you can also "box" the lca's to to stiffen them up.

a fun way to get the old ones out is to build a campfire and thro the lca's in it, then get out of the way, they usually blow out with force. or use a air hammer/chisel

[Kevins89notch5.0]

I had stock springs, no quad shocks, high mileage shocks, stock LCAs, and bad wheel hop. I installed new springs, some bilsteins, MM LCas, and magically no more wheel hop.

[xctasy]

The factory ways are the cost effective ones. In the mid 80's, Group 3 (Group C) cars with 500 hp were replaced with International Group 2 (Group A) cars, which were highly production based without the option of good modifications to the tires section size to cover off the awfull four and five link rear ends found in factory Fords.

Race ace Dick Johnston in Australia said the Fox four bar was great under brakes, around corners and for hook up, untill you tried to power up hills. Here it is at Lakeside, a handling circuit. Always taily. See the pattern?

http://www.youtube.com/watch?v=BUyM-xqG8M8

It was worse in the 2 miles of uphill section at the James Hardie 1000 race at Bathurst Austraila always had the rear end wheel walking, and that's where a two extra shockies or one or two extra links really settle the axle down. Ford and GM proved this when there replacements in the D/E car segment was equiped with either torque arm, Panhard rod or Watts Link or an IRS.

In the racing situation, the better tied down Panhard Rod Commodore, Iand in the Wellington Steetfront race, the semi traling arm IRS Atlas 7.5 Merkur 2300 XR4Ti and 9" Sierra Coworth RS500 were much better tied down.


Economical steps from the low point 78 to 80 Fox rear end are:
1st is Limited slip diff with 50% slip.
2nd is slapper bars,
3 rd is the eight shocker rear end.
4th is the IRS

Since cost wise with respect to exhasts and fabrication, Panhard rods, Watts, torque arms and better four bars are great if you do them yourself, you can trade off those costs verses an easy fit and forget 7.5 or 8.8" SN IRS.

Exhast and welding, then tuning costs a lot of time, and the live axle will always be inferior to a properly set up IRS. An IRS corners flatter, with less steering input and less inflection under mid corner pot holes, chicane humps and the like. In a drag racing situation, IRS set ups need a set of adjustable Koni D shocks to optimise launch, which is complicated by the removal of the live axles ability to remove drive line shunt. When you run small crown wheel IRS axles, the launch patter from drive line shunt causes cyclic loading. Live axles and De Dion axles eliminate this. Old IRS Jags and AC Cobras with HU4 8.8 inch diffs suffer this, yet the same axle in a DBS Aston Martin didn't. You can take a DBS V8 Aston Martin, and lay 50 feet skids at the drags, it has basically the same Salisbury axle centre as the Jag and AC and SN Cobra 8.8 diff As you drop to the 7.5 and 7 inch diff IRS axles, it gets worse, and this is why IRS's need to be protected from wheel patter on launch. Incidently, the HU4 diff is not real strong in an IRS setting, and the traction Lock equiped diff can be broken with just 400 hp in a 4000 pound 14 second Aston Martin. For this reason, people shy away from any IRS or de Dion axle, because a live axle will be stronger.

If you don't already have slapper bars or an eight shocker rear end, then there is an intermediate step. First is to set it up on a combination of supermarket slalom and a closed road course, and have a suspension expert rework the springs and shocks. There are some old inventory dampers and shocks which, armed with the right sway bars, bushes, can bring the stock four bar up a few pegs in under acceleration stability. That only goes so far, and then its ...Watts Link, Torque Arm, Panhard rod, adjustable aftermarket equal length four link.

The Watts link is the best and easist to fit, but the worst for exhast and fuel tank fitting. The Watts link provides the full lateral location totally missing on the Fox rear end. It was used on the World Rallye Championship Works Escort RS 1800's, and then on the Rover SDI 3500 'Chuckwagon', the TK Mazda RX-7 and DBS Aston Martins and 71 Alfasud, 75 on Transaxle Alfa Romeos used it to great effect. And the last of the Panther Fords. Its the best option, becasue there is a standard AVESCO 9", Panther 8.8" and BTR Camaro/7.625-7.875" Borg Warner diff which was used in the XE Falcon below. The GM diff was a factory Ford Falcon diff from the first Aussie styled Jack Talenak XR Falcon in 1966 until the last twin cam Falcon wagon in 2010. The BW 78 bolts right in to a Fox, is as cheap as french fries, and found in any G78/G52 code GM F car torque arm diff. It allows the use of stock disk rear end with a few basic rewelds to fit the Fox. And the XE/XF/E and A series Falcon Watts link had bolts right on it.


See http://fordsix.com/forum/viewtopic.p...512838#p512838

As an aside...

X, E and A body Live axle Falcons, copied in some Panther and some version of the S 197 chassis. Major handling problems on the circuit with this set up could only be fixed with double jointing the lower arms or major changes of upper arm length. When Watts links were used on Escorts and Falcons, both bars were almost parallel. For sedan racing, the lower link was often reduced for length to get closer to the shorter top, and the Watts link was reversed on most of the the Group 3 racers. With a 500 hp 351c, these were a real handfull untill these mods were made.[/size]





By 1993, on Australian Vee Eight Super Car set ups, they made the upper control arms travel up into where the rear seat would have been, so the system was now superbly stable, but impractical unless you don't like your passengers. Shades of the 350 GT-R Shelby set up.

In a similar way, the Zakspeed Escorts made the Watts link work. Zakspeed was helped along by Mike Kranefuss, later of Ford Motorsport. The homologated parts were used in BDA IMSA Mustangs. The lower and upper links in these little Escorts were the same length. Ford Australia undid the some of the good work by making the top arm shorter, when it should have been angled in to create more upper control arm length. See the 600 hp capable ZF Atlas diff again...


http://img97.imageshack.us/img97/4777/img2122zw6.jpg

The Panhard is an easy fit up, the G78/G52 GM diff was fitted with a Panhard rod in the 1980 to 1998 Australian Touring Car Championship Holden Commodores, and its a downgraded version of the Galaxie style torque arm and Panhard rod set up. It has problems in that the axle can slew under droop from one side of the car to the others, just like the old Galaxie/Parklane FE engined cars that formed the basis of the NASCAR rear suspension still in use today. A watss link is straig up and down, no side to side slew, which helps steering responses. Panhard rods create roll steer, and make a car feel like its got a semi trailing arm IRS on entry and exit.

The others, well, the aftermarket has you covered, so you can't go wrong.

The 2003 Cobra IRS is the ultimate solution.

[FM2NOTCH]

start with stiffer bushings

[xctasy]

Its possible that the heavier 8.8 and 9"diffs, even though they have more unsprung weight than the 6.75 and 7.5's, are less prone to wheel hop. Its the rolling pin effect.

Under load, more unspung mass is seen as bad, but on the four link Fox, it maybee the right option.

I've found the softer bushes seam to help, with the stiffer than stock shockies I have. The 78 to 80 Fords are the worst, not even an LSD option, and then the 5.0 2-bbl GT was always taily even with slipper and slappers. The 83 was much better, but still no cake walk. The 8 shockers were quite good, but they stopped you putting 275's on the back.

I bow to what works in practice. But always measure to quatify if you've made an improvement.

I calibrate my Mustang rear suspension with a 188 magnet hall effect prox and a data logger at down to 60 feet intervals, and find that the axle movement under load up hill in the Fox four bar is just huge, up about 2 times compared to the readings without a hill. If the IRI reading is 2, up a hill as little as 2% grade, its 4 in the Fox under load. Under down hill grades and curves, everything is about the same, so the Fox rear end is compromised by the four bar links not being enough to do the job in a stock production car, let alone a hard out racing Stang

[mustangxtreme]

JT, I would start with a set of aftermarket lower control arms. I picked up a set of no-names off craigslist for my 83L. It definitely made a big difference in how the car hooks up.

[4eyewanabe]

I thoght wheel hop is a result of the pinion not being at the optimal angle. I used to have real bad wheel hop in my 05 Mustang until I changed pinion angle. I have no more hop, but now I cannot get traction half way down the track.

[ry4ns302]

JT, I would start with a set of aftermarket lower control arms. I picked up a set of no-names off craigslist for my 83L. It definitely made a big difference in how the car hooks up.

+1. Uppers too while your at it, and change the bushings on the rear end (Ford part# M-4050-B). This with some new shocks, even stock replacements, will take away the wheel hop.

[JTs Bikes]

Wow! this is alot of info. Thanx guys. Just to be perfectly clear, I have a 98 GT 8.8 Posi rearend w/disc. Does that change anything?

[xctasy]

I can only measure what I've noticed over the years. A worn Panhard rod with excessive 0.5" compliance over stock made our old road roughness Commodore five link go from an average IRI of 40% lower after replacement. Just two bushes, and the calibrated ride numbers differed by 40%. So the advice supplied sounds good to me. This was a F car M78/G52 axle, but without torque arm.

In response, we went right to hard springs and a set of FE 2 dampers. Result, the wheels showed reduced axle movement to the point that the bushes were taking up all the compliance issues, the ride was hard. and we couldn't relate axle movement to road surface, with total upward axle movement per mile reduced by 75%. It was a "stiffen the spring and she shall handle" suspension set up. Wheel hop in that situation was worse than in the stock worn set up. The 177 HP, 221 LB-FT GM 3800 and THM 700 with Limited slip 3.08 diff resulted in poor launches with the stock tires. Point I'm making, is you can do stuff, and it helps one part but hurts another aspect.

Good info is actually 'what worked for me' stuff. If consensus says "it worked for me", it will most likely work on a similar situation on a later Fox body derivative. I'd just say this, if Ford were able to get a long term improvement by better control arms and bushes, they'd have used them on their premimum variants. Compliance and vibration supression are very important, and tires, shockies and bush stiffness can cause big differences to ride. To make the harder bushes survive long term is going to be a challange, so you might just have to swap 'em out more often, and that might give you your result.

The pinion angle does improve things. Wheel hop can be first minimised by tuning. Go for the little 2 per centers and see how things go. Lower link changes and reduction in suspension compliance by stiffers and harder bushes, its your choice.

Its still going to be $$$ verses results.

[JTs Bikes]

A little confused about why this thread got moved? I am talking about my 79 Cobra here!!

[86fiveoh]

I was wondering that too^ I think your post about the 98 rear confused someone.

[Floyd]

Pinion Snubber!!!

[RichV]

You never specified when you're getting wheel hop. I'm assuming when you spin the rear tires, but is it at the track? All around?

And how old are your shocks? Stock CAs out back? Quads?

As mentioned, bushings and old shocks have a lot to do with it, but if your rear setup is stockish and your tranny/motor/driveshaft configuration are stock, there is no reason that your pinion angle has changed, and there is not really a way to adjust it.

Not knowing what's been done, I'd probably replace or verify your engine/trans mounts are in good working order. Get some aftermarket lower rear CAs with stiff bushings, new upper stock CAs, new OEM bushings in the rear for the UCAs, verify your rear shocks are working properly along with the quads.

The other thing that reduces wheel hop is adjusting tire pressures. You should have a functional t-lok as well. I've run the above setup on 2 road race Mustangs and have never run quadshocks. Don't have any signs of wheelhop with r-compund tires when we do standing starts, either with 255/16 or 275/17 tire.

[RichV]

The other thing I meant to add is, is your frame straight? That could affect some suspension geometry and make less than ideal conditions as well.

[qtrracer]

Ford designed the the quad shocks to reduce axle tramp. But due to the soft bushing material that solution had limited utility. What I did on the 86 was change all the dampers to the Monroe Formula GPs including the quads (old Saleen set-up), put on MM's LCAs and replaced the uppers with the old Ford M5500A kit. That was it; no more hop.