After reading an artical about the different types of steering arms that have been used on Midgets over the years. I thought I would check which arms I have.
Had a surprise as there were two different types fitted. One is what I expected to see (BTA649 L/H) the other was from an early Mg/Sprite approx pre 1962 (ATA4130 R/H).
I never checked these arms when rebuilding the front end as they both came from my running donor.
When you hold them together they look very similar but when put on a surface plate they have different lengths/geometry's.
Rule no.1 Never take anything for granted.
The hunt is now is on for a BTA648 R/H, my usual providers have come up empty.
Daggers
Odd Arms
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Westfield 129
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- Joined: Sat Jun 04, 2011 4:20 am
Re: Odd Arms
I have run into this on a couple of cars that had a bump steer problem. One had a 1275 Sprite arm on one side, and a late 1500 midget arm on the other side. What was interesting about this was that there were two different rod ends involved.
On another car, the arms didn't match the skinny, slow ratio 1500 rack and the wrong rod ends were installed, which were quite loose. The front end would not alogn, and the car would not steer. This car was to be the distributor's press demo car... "professionally built"... I ended up replacing the slow skinny rack with a fat one and both steering arms (and just about everything else in the car prior to sending it out for its test duties).
Then there was the Bugeye conversion to disc front brakes, where the kit arrived with different arms as well as problematic spindles... Ended up sourcing a set of arms from a local breaker, and new competition spindles with kingpins. The whole kit was useless and returned.
Trust no one, measure everything, check part numbers, and if possible, the history of your donor car.
I have found that you can use any matched pair of spridget steering arms, provided you have the correct rod ends that match. The minor change in geometry is not a problem if you have the same on both sides. There may be a bump steer problem, but it will be very minor, if it is any bother at all. It is likely that with two of the same steering arms, any darting behavior you were probably experiencing will disappear completely if the chassis is set up with the lower suspension arms level to the ground when the chassis has a driver in it.
So, all you need to do is find a matched pair of arms from a 1275 car (if you can't find one to match what you have). And if you have a skinny rack, get a fat RHD one from Moss UK. The steering will be much quicker and the feel/feedback improved.
On another car, the arms didn't match the skinny, slow ratio 1500 rack and the wrong rod ends were installed, which were quite loose. The front end would not alogn, and the car would not steer. This car was to be the distributor's press demo car... "professionally built"... I ended up replacing the slow skinny rack with a fat one and both steering arms (and just about everything else in the car prior to sending it out for its test duties).
Then there was the Bugeye conversion to disc front brakes, where the kit arrived with different arms as well as problematic spindles... Ended up sourcing a set of arms from a local breaker, and new competition spindles with kingpins. The whole kit was useless and returned.
Trust no one, measure everything, check part numbers, and if possible, the history of your donor car.
I have found that you can use any matched pair of spridget steering arms, provided you have the correct rod ends that match. The minor change in geometry is not a problem if you have the same on both sides. There may be a bump steer problem, but it will be very minor, if it is any bother at all. It is likely that with two of the same steering arms, any darting behavior you were probably experiencing will disappear completely if the chassis is set up with the lower suspension arms level to the ground when the chassis has a driver in it.
So, all you need to do is find a matched pair of arms from a 1275 car (if you can't find one to match what you have). And if you have a skinny rack, get a fat RHD one from Moss UK. The steering will be much quicker and the feel/feedback improved.
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Daggers-xi
- Posts: 57
- Joined: Sun Aug 17, 2014 5:15 pm
- Location: Sunny Hampshire UK
Re: Odd Arms
Jan,
I am using a "fat rack" mounted with cast alloy brackets and BTA 648/649 steering arms and GSJ 169 track rod ends.
Whilst on the subject one thing that has concerned me is the amount of taper engagement between the track rod end and the steering arm, which in my case has resulted in the nyloc nut not being fully engaged.
I have included a photo to illustrate the point. First I would say the track rod end was purchased from a very reputable supplier.
Photo details.
A = as supplied nut with track rod end (seems a bit deep)
B = from my normal nyloc nut stock
Taper contact = bright area (about a third of the taper) shows engagement with steering arm
The drawing shows the track rod end dimensions in mm.
I don't have a old stock track rod end to measure as it is possible that these new manufactured tapers are slightly different.
The angle of taper seems to be correct when using engineers blue against the arm.
Daggers
I am using a "fat rack" mounted with cast alloy brackets and BTA 648/649 steering arms and GSJ 169 track rod ends.
Whilst on the subject one thing that has concerned me is the amount of taper engagement between the track rod end and the steering arm, which in my case has resulted in the nyloc nut not being fully engaged.
I have included a photo to illustrate the point. First I would say the track rod end was purchased from a very reputable supplier.
Photo details.
A = as supplied nut with track rod end (seems a bit deep)
B = from my normal nyloc nut stock
Taper contact = bright area (about a third of the taper) shows engagement with steering arm
The drawing shows the track rod end dimensions in mm.
I don't have a old stock track rod end to measure as it is possible that these new manufactured tapers are slightly different.
The angle of taper seems to be correct when using engineers blue against the arm.
Daggers
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Westfield 129
- Posts: 882
- Joined: Sat Jun 04, 2011 4:20 am
Re: Odd Arms
What you have is the rod end that works with the later 1500 Midget steering arm (bigger hole), when attached to the "fat rack" steering rod (larger diameter steering rod). This is sort of a special part used to mix and match.
The usual problem is that the later steering arm with the larger hole and taper is often fitted to the fat rack, with the smaller diameter rod end. This results in a mis match, and really poor steering... This is what I found in one of the cars that I was tasked with "reconstructing".
The rod ends you need are likely listed for the earlier car, perhaps from '62 through '68 (at least here in the US, but should be the same application aa UK domestic market cars). Try those. They should fit and you should get full engagement.
There are two different rod ends available for the skinny racks (late and early steering arms), and two different applications for the fat racks (also early and late). It appears that you have the rod ends with the larger diameter taper that fits the later 1500 steering arms. I am sure that this is a production variation in the UK cars that you are running into. I would not blame the supplier. I bet that this could be confusing... In any case, you can compare the parts when you get replacements for the correct fit.
Sometimes, the part numbers and applications are hard to figure (sometimes, they are by VIN, which is confusing since you are using a donor car with an unknown history). I am sure that if you go back for an earlier application part number, you should find the correct fit.
The usual problem is that the later steering arm with the larger hole and taper is often fitted to the fat rack, with the smaller diameter rod end. This results in a mis match, and really poor steering... This is what I found in one of the cars that I was tasked with "reconstructing".
The rod ends you need are likely listed for the earlier car, perhaps from '62 through '68 (at least here in the US, but should be the same application aa UK domestic market cars). Try those. They should fit and you should get full engagement.
There are two different rod ends available for the skinny racks (late and early steering arms), and two different applications for the fat racks (also early and late). It appears that you have the rod ends with the larger diameter taper that fits the later 1500 steering arms. I am sure that this is a production variation in the UK cars that you are running into. I would not blame the supplier. I bet that this could be confusing... In any case, you can compare the parts when you get replacements for the correct fit.
Sometimes, the part numbers and applications are hard to figure (sometimes, they are by VIN, which is confusing since you are using a donor car with an unknown history). I am sure that if you go back for an earlier application part number, you should find the correct fit.
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Westfield 129
- Posts: 882
- Joined: Sat Jun 04, 2011 4:20 am
Re: Odd Arms
You can also try a lower profile nylock nut. This would be the easiest thing to do if the tapers match.
I use a lower profile nylock on the steering rod ends. In many cases, the nylocks are supplied with the rod ends.
You can also use a thin jam nut or castle nut with a split pin. Depends on what parts you have.
I use a lower profile nylock on the steering rod ends. In many cases, the nylocks are supplied with the rod ends.
You can also use a thin jam nut or castle nut with a split pin. Depends on what parts you have.
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Daggers-xi
- Posts: 57
- Joined: Sun Aug 17, 2014 5:15 pm
- Location: Sunny Hampshire UK
Re: Odd Arms
Jan,
I am now really confused.
The steering arm and track rod end as shown in the original photo above is a matched pair I.e BTA648/9 arm and GSJ169 track rod end which is correct according to the Midget parts book.
The later 1500 arm AHA9958/9 and track rod end GSJ158 as far as I can see use smaller taper not larger.
Therefore the 1500 track rod end could not fit the into the earlier steering arm.
To illustrate the point the attached photo shows both the above combinations "A" show the fat rack pair and "B" shows the later, including 1500 type pair.
I just assumed that the newly manufactured GSJ169 track rod end had not been machined to the original spec and therefore did not penetrate the arm sufficiently to give full engagement to the supplied nut, I would think about .040"/.050".
Daggers
I am now really confused.
The steering arm and track rod end as shown in the original photo above is a matched pair I.e BTA648/9 arm and GSJ169 track rod end which is correct according to the Midget parts book.
The later 1500 arm AHA9958/9 and track rod end GSJ158 as far as I can see use smaller taper not larger.
Therefore the 1500 track rod end could not fit the into the earlier steering arm.
To illustrate the point the attached photo shows both the above combinations "A" show the fat rack pair and "B" shows the later, including 1500 type pair.
I just assumed that the newly manufactured GSJ169 track rod end had not been machined to the original spec and therefore did not penetrate the arm sufficiently to give full engagement to the supplied nut, I would think about .040"/.050".
Daggers
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Westfield 129
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Re: Odd Arms
Sorry, my error. You are indeed correct that the later harm has the smaller hole.
In any case, it is not likely that the arms parts machined incorrectly. However, you can take a taper reamer to the hole for better engagement. I would just use a lower profile lock nut
In any case, it is not likely that the arms parts machined incorrectly. However, you can take a taper reamer to the hole for better engagement. I would just use a lower profile lock nut
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Daggers-xi
- Posts: 57
- Joined: Sun Aug 17, 2014 5:15 pm
- Location: Sunny Hampshire UK
Re: Odd Arms
Just to add to the above I had cause to order some parts for the XI a couple of days ago and noticed that the supplier had some genuine Quinton Hazell track rod ends in stock, so I ordered a couple.
When compared to the first set I purchased it showed how different two sets of parts described as "To OEM specification" can be.
Photo shows the following:-
A - Quinton Hazell
B - My original purchase from a very reputable supplier.
The Same, slim nut used for both photos, the original full nut supplied with "B" gave no engagement to the nylon insert, the slim nut only gave a partial engagement.
In such a critical component I would never be have been satisfied with less than a full thread showing above the edge of the nylon insert, feel confident now that all is well.
Daggers
When compared to the first set I purchased it showed how different two sets of parts described as "To OEM specification" can be.
Photo shows the following:-
A - Quinton Hazell
B - My original purchase from a very reputable supplier.
The Same, slim nut used for both photos, the original full nut supplied with "B" gave no engagement to the nylon insert, the slim nut only gave a partial engagement.
In such a critical component I would never be have been satisfied with less than a full thread showing above the edge of the nylon insert, feel confident now that all is well.
Daggers
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StephenH
- Posts: 25
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Re: Odd Arms
To my eye, B looks like the earlier type, MkIII Midgets and earlier, whereas A looks like the MkIV type. Maybe you have Mk IV steering arms?
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Daggers-xi
- Posts: 57
- Joined: Sun Aug 17, 2014 5:15 pm
- Location: Sunny Hampshire UK
Re: Odd Arms
Both track rod ends in photo are "GSJ 169" pattern pre 1971 so called "fat rack" just different manufactures and are shown using the correct matching arms.
Both the rod end tapers have the same angle but "A" has a longer threaded portion and the taper minor diameter is slightly smaller on "A" thus giving a little more penetration to the threaded portion. The combind result is as you see in the photo.
Daggers
Both the rod end tapers have the same angle but "A" has a longer threaded portion and the taper minor diameter is slightly smaller on "A" thus giving a little more penetration to the threaded portion. The combind result is as you see in the photo.
Daggers