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Thread: Help with Rear traction

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    Help with Rear traction

    Hello, I'm currently trying to race on historic gravel rallies here in italy, I have a std non RS chassis with rear ARB, english axle.

    But I have a lot of problem putting the power down on gravel roads, unfortunately I'm limited with group2 regs, meaning no 4 link, non turreted shock absorbers. Due to having to retire from last rally because of a big rock destroying one leaf spring carrier, and than the propshaft, I had the occasion of having the rear end out from the car.

    I purchased tramp bars and i'm in the process of fitting it, and i found myself wondering what the rear ARB utility is... it doesn't push the axle down, it obviously doesn't work like in the front (would need and indipendent rear suspension i guess), so am I right to take it out and put anti tramp bars on? I guess if the RS came with that sistem instead....

    Having them togheter could be doable, but again, what the arb utility is?

    Another thing, I currently have single leaf 146lb and bilstein gp1 shocks, but it tend to bounce up and down on fast bumpy sections, making it feel very loose at the back, a stiffer multi leaf spring could be of any use?

    Thanks to anyone who want to help.
    Last edited by Enea; 08-03-2021 at 17:49.

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    Re: Help with Rear traction

    a rear anti roll bar will rob you of traction out the corners.

    i cant see how stiffer rear springs would help, you probably need more/better damping

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    Re: Help with Rear traction

    Fit the anti-tramp bars and remove the rear anti-roll bar.
    Replace the 146 lb/in springs which softer items (112/115) and definitely remove the GP1 Bilsteins.
    Get the 872 fast road Bilsteins instead.

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    Re: Help with Rear traction

    The first thing to do if that's the std Ford ARB that was fitted to cars like the Escort GL, remove it and chuck it in the nearest scrap bin. You are correct in fitting the anti tramp bars, unfortunately you'll have to use the angled ones if you are using the std schocker position. Make sure you use good quality HD bushes.

    You say you have 146lb rear springs and Group 1 Bilsteins, what are their age and condition? Aftermarket springs are a bit of a Lottery as to what poundage they are, some too soft and some too stiff but the spring manufacturers all say they are the same rate. You could try a 146lb multi leaf spring if you can find one with a front bush and spring eye. I would start with the schockers first after fitting the tramp bars and work from there.

    When Ford RS dealers sold parts there was a Rally Bilstein rated at 200/80 and a Race version that was 220/110, we always used the latter which most of the top Group 1 runners ran in period.
    Last edited by Forest_rallying; 08-03-2021 at 19:20.

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    Re: Help with Rear traction

    So you guys think going softer is the way?

    I thought that a stiffer leaf may reduce the bumping effect in first place, also the feeling is to have a loose rear, definitely not too hard.
    Ideally it would be longer damper with harder rebound, an overall softer damper mean continuing to bounce.

    checking the rates, Gp1 is 207/100, b6 is either 160/75 or 180/90, maybe last is worth trying... expensive passion it is

    Next rally at the end of the month I'll have this setup with only anti tramp instead of arb, let's see if it gets better in the fast sections, If not, maybe worth trying a slightly softer damper and a softer spring.... damn if I hate those rules

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    Re: Help with Rear traction

    Quote Originally Posted by Forest_rallying View Post
    The first thing to do if that's the std Ford ARB that was fitted to cars like the Escort GL, remove it and chuck it in the nearest scrap bin. You are correct in fitting the anti tramp bars, unfortunately you'll have to use the angled ones if you are using the std schocker position. Make sure you use good quality HD bushes.

    You say you have 146lb rear springs and Group 1 Bilsteins, what are their age and condition? Aftermarket springs are a bit of a Lottery as to what poundage they are, some too soft and some too stiff but the spring manufacturers all say they are the same rate. You could try a 146lb multi leaf spring if you can find one with a front bush and spring eye. I would start with the schockers first after fitting the tramp bars and work from there.

    When Ford RS dealers sold parts there was a Rally Bilstein rated at 200/80 and a Race version that was 220/110, we always used the latter which most of the top Group 1 runners ran in period.
    springs and dampers have 4 years, looks like good conditions for both, not much use and abuse, like in my other post, I'll try only with anti tramp next rally, then work from there.

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    Re: Help with Rear traction

    Quote Originally Posted by Miniliteman View Post
    Fit the anti-tramp bars and remove the rear anti-roll bar.
    Replace the 146 lb/in springs which softer items (112/115) and definitely remove the GP1 Bilsteins.
    Get the 872 fast road Bilsteins instead.
    I don't think 116lb single leaf spring's are available anymore this side of the River, maybe the multi leaf CD8 could be.

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    Re: Help with Rear traction

    if the springs is too stiff for the dampers it will bounce around, you dont need stiff springs on the loose, look at rally cross cars, they clearly have soft springs, but they sure do get out the corners because they have very good damping control

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    Re: Help with Rear traction

    I'm starting to think that what I consider to be already soft is actually too hard for the escort, not having any real weight on the back.


    At this point might be worth trying check original springs and maybe work with those.

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    Re: Help with Rear traction

    Quote Originally Posted by Graham View Post
    if the springs is too stiff for the dampers it will bounce around, you dont need stiff springs on the loose, look at rally cross cars, they clearly have soft springs, but they sure do get out the corners because they have very good damping control
    They probably have minimum of 3 way dampers + progressive springs at a cost of possibly five grand a corner.

    It's difficult to convince a driver that a softer spring does give better traction as does a softer tyre with less pressure. However with an Escort fitted with leaf springs the poundage of them's rather limited on choice.

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    Re: Help with Rear traction

    Quote Originally Posted by Forest_rallying View Post

    It's difficult to convince a driver that a softer spring does give better traction as does a softer tyre with less pressure. However with an Escort fitted with leaf springs the poundage of them's rather limited on choice.
    i agree, take my beemer, in a drag race a bog standard road car would eat mine alive off the line, and out of a tight hairpin again it would probably get the better of me, but through a chicane or high speed corner the stiff settings i run would win by a mile, its horses for courses

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    Re: Help with Rear traction

    The GP1 Bilstein is the 871, the fast road (and softer) Bilstein is the 872.
    Think I have a set of these 872 in the garage, let me know if you are interested.
    The dampers are used but in good condition. (no longer needed)

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    Help with Rear traction

    Quote Originally Posted by Miniliteman View Post
    The GP1 Bilstein is the 871, the fast road (and softer) Bilstein is the 872.
    Think I have a set of these 872 in the garage, let me know if you are interested.
    The dampers are used but in good condition. (no longer needed)
    Interesting reading. I'm in a similar situation to the OP with a similar setup and struggling to put power down on loose too. I'm using rs single leafs, tramp bars and grp1 Billies ( the 'upside down ones)
    Why do you say to not run the grp1 bilstein? Too much bump? Thanks!

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    Re: Help with Rear traction

    The GP1 Bilsteins are too stiff. Not only on bump and rebound but also the low-speed leakage valve is too small.
    The settings given above are (damping force) for a damper-rod moving at 1 m/s.
    That is quite some movement; the low-speed leakage valve sets the way the damper-rod moves at slower damper-rod speeds, it determines how the car "feels" at lower speeds.
    I've tried most dampers on my RS2 road car (road rally) and the 872 worked best with 112 lb/in springs (but these are nla according to Forest Rallying).

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    Help with Rear traction

    Great info thanks! I always felt like the rear 'skips' over rough rocks rather than complying with the terrain.
    IL keep an eye out for a set of 872's
    Sorry for thread hijack but hopefully it's all helpful

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    Re: Help with Rear traction

    Anti tramp bars definatly
    Try use good condition gen ford leaf springs NOT cheap remade kangaroo ones hah. They terrible for competition,
    Bilstein 180/90 bump / rebound prob suit you best
    716 in part no. If i remember right without checking. Or next ones up max.
    If you were allowed turret and run turret dampers woykd be big improvement but i guess not allowed in class

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    Re: Help with Rear traction

    What tyre make,size are you running ? Also a massive factor is tyre pressures (not mentioned.)

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    Re: Help with Rear traction

    I found some b6 dampers rated 180/90, from some motosport company there in UK, maybe worth seeking also their advice.
    Tyre size is 185/70, Yokohama a035. Pressure is 2.1/2.2 bar at the rear, a little bit more at the front (hot tyres), soon I'll be upgrading to Pirelli as they seem to be some sort of magic tyres as almost everyone is running them. Changing tyres might improve traction out of hairpins and slow corners, but it won't change the bumpy rear in the fast

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    Re: Help with Rear traction

    rear tyre pressures sound high to me

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    Re: Help with Rear traction

    Lowering it means to go around 1.5bar with cold tyres (road sections)... Quite dangerous.

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    Re: Help with Rear traction

    Quote Originally Posted by Enea View Post
    Lowering it means to go around 1.5bar with cold tyres (road sections)... Quite dangerous.
    really? why? my background is racing not rallying, but 1.5 bar doesnt sound that low to me

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    Re: Help with Rear traction

    You risk the Tyre to fall off the rim bed, also you have to consider that you still have those cold temperatures at the start of every stage, because it's impossible to warm them enough before the start (where you have to wait at least 4/5 minutes before actually starting).

    Other guys with gp4 escorts stay around 2.3/2.4 bar, never heard anyone on Gravel rallies going under 2 bar at the end of a stage.

    Maybe tarmac tyres have stiffer wall and the can go under 2 bar.
    Last edited by Enea; 09-03-2021 at 09:05.

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    Re: Help with Rear traction

    I would say 18 to 20 psi on rear is not a problem. I've never seen a bead roll off the rim anything over 10psi.
    Maybe an idea to chech the diff nose angle (at ride height) Diff nose too high will without doubt loose you traction off slower corners.

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    Re: Help with Rear traction

    i run around 26psi cold on A021r's 185/70/13. plenty of traction on dry tarmac, but gets skippy and nervous on the loose. reading this thread i think i might try softer dampers! Im running OEM ford RS2000 single leafs.
    @piekey , do you know what the nose angle should be for optimum traction?

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    Re: Help with Rear traction

    i must be the only one that ditched the binding bars and fitted the roll bar
    still it copes with the 460 torques,but i will agree on dampers,trying to get one that is not too stiff but works for road use is pretty difficult,
    custom made looks like the only option

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    Re: Help with Rear traction

    Diff nose angle should be 3.5 degrees for what you want.
    could you not use the latest Gaz rear dampers with adj bump/rebound in group 2 spec ? soften them off for mega wet, rough work & stiffen them up for dry/gravel use.
    but defffo look at dropping pressures, if they start low ,they will work harder and warm up quicker.

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    Re: Help with Rear traction

    Quote Originally Posted by Enea View Post
    I found some b6 dampers rated 180/90, from some motosport company there in UK, maybe worth seeking also their advice.
    Rating of dampers can vary amongst advertisers; just make sure the Bilsteins are the 872 fast road items.

    Quote Originally Posted by piekey View Post
    Diff nose angle should be 3.5 degrees for what you want.
    Why is that?

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    Re: Help with Rear traction

    Quote Originally Posted by piekey View Post
    Diff nose angle should be 3.5 degrees for what you want.
    could you not use the latest Gaz rear dampers with adj bump/rebound in group 2 spec ? soften them off for mega wet, rough work & stiffen them up for dry/gravel use.
    but defffo look at dropping pressures, if they start low ,they will work harder and warm up quicker.
    No you can't have adjustable dampers in group2, only coilovers on the front.

    Dropping pressure will be something I'll try next rally, starting at 1.3-1.4 should end up at 1.9-2.0 bar at the end of the stages, hoping to not loose any tyre on road sections , or having punctures.
    I'll also check diff nose angle, but it should be already ok

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    Re: Help with Rear traction

    Quote Originally Posted by piekey View Post
    Diff nose angle should be 3.5 degrees for what you want.
    tilted up from the vertical?

    +1 on miniliteman's question, btw, why?

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    Re: Help with Rear traction

    If I were you I would try tyre pressures between 25 and 28 psi, going too low on the pressures will increase the chance of punctures, very low pressures are ideal for Production Car Trials and in snow and ice but not ideal for very rough Gravel events.

    Your lack of traction could be caused by excessive axle tramp so fitting the tramp bars will help eliminate that problem. Your next step then is to fit a new set of dampers to your desired choice (your old ones could be knackered) before even thinking about swapping the rear springs. Take one step at a time with changes.

    If the English axle spring saddles are as the car left the factory then the diff nose will be fine, we used them like that for many years and never had any problems.

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    Re: Help with Rear traction

    Diff angle, traction is all imaginary
    Its more correct to have diff angle match back of gearbox for important part, driveshaft angles correct

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    Re: Help with Rear traction

    Quick update: done the gravel rally on sunday, with anti tramp bars instead of arb and with softer dampers (thanks @Miniliteman ), the car felt much better out of slow corners and way more stable on fast sections, from there it was only about adjusting tyre pressure, I was around 1.8 bar with hot tyres.

    Now we only need 30hp more to compete with proper group2 cars (a bmw320, MK1 group2 with 5speed box, kadett), also with group A opel corsa and group N delta.
    If someone like @Graham is interested in building it


    here you can see how underpowered our gp1 escort is
    We still managed to stay ahead of that group2 kadett and not that far away from the red delta, but no chance to compete with the others.


    https://www.youtube.com/watch?v=pAX9KPM13YU
    Last edited by Enea; 30-03-2021 at 06:27.

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    Help with Rear traction

    Quote Originally Posted by Enea View Post
    Quick update: done the gravel rally on sunday, with anti tramp bars instead of arb and with softer dampers (thanks @Miniliteman ), the car felt much better out of slow corners and way more stable on fast sections, from there it was only about adjusting tyre pressure, I was around 1.8 bar with hot tyres.

    Now we only need 30hp more to compete with proper group2 cars (a bmw320, MK1 group2 with 5speed box, kadett), also with group A opel corsa and group N delta.
    If someone like @Graham is interested in building it


    here you can see how underpowered our gp1 escort is
    We still managed to stay ahead of that group2 kadett and not that far away from the red delta, but no chance to compete with the others.


    https://www.youtube.com/watch?v=pAX9KPM13YU
    Bravo Italians keeping rally’s going 👌👌

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