Rally X1/9 - Prototipo style

Marti80 said:
From what I understand the ideal parts would be Regata 100s gears with the X19 final drive.
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the term "internet wisdom" is the biggest misnomer in the English language...

100s has a crazy short first gear (4.09)

a short summary of gear ratios;

Regata 100s
1: 4.09
2: 2.235
3: 1.550
4: 1.163
5: 0.960 (47/49)

Ritmo 105TC
1: 3.583 (43/12)
2: 2.235 (38/17)
3: 1.550 (31/20)
4: 1.163 (50/43)
5: 0.959 (47/49)

Ritmo 125/130
1: 3.583 (43/12)
2: 2.235 (38/17)
3: 1.542 (37/24)
4: 1.154 (30/26)
5: 0.967 (29/30)

X19 five speed 79-80
1: 3.583
2: 2.235
3: 1.454
4: 1.042
5: 0.863

X19 five speed 81-82
1: 3.583
2: 2.235
3: 1.461
4: 1.033
5: 0.863

X19 five speed 83-87
1: 4.09 (45/11)
2: 2.235 (38/17)
3: 1.468 47/32)
4: 1.042 (49/47)
5: 0.863 (44/51)

the 105 / 125 / 130 homologated alternate close ratio set as used in Group A rally (not fitted to production cars)

1: 2.353 (40/17)
2: 1.842 (35/19)
3: 1.391 (32/23)
4: 1.160 (29/25)
5: 0.963 (27/29) 105TC 1.038 (27/26) 125/130

Tricks are things a magician does, engine building isn't a trick, it's simply physics.

SteveC
 
fiatfactory said:
the term "internet wisdom" is the biggest misnomer in the English language...

100s has a crazy short first gear (4.09)

a short summary of gear ratios;

Regata 100s
1: 4.09
2: 2.235
3: 1.550
4: 1.163
5: 0.960 (47/49)

Ritmo 105TC
1: 3.583 (43/12)
2: 2.235 (38/17)
3: 1.550 (31/20)
4: 1.163 (50/43)
5: 0.959 (47/49)

Ritmo 125/130
1: 3.583 (43/12)
2: 2.235 (38/17)
3: 1.542 (37/24)
4: 1.154 (30/26)
5: 0.967 (29/30)

X19 five speed 79-80
1: 3.583
2: 2.235
3: 1.454
4: 1.042
5: 0.863

X19 five speed 81-82
1: 3.583
2: 2.235
3: 1.461
4: 1.033
5: 0.863

X19 five speed 83-87
1: 4.09 (45/11)
2: 2.235 (38/17)
3: 1.468 47/32)
4: 1.042 (49/47)
5: 0.863 (44/51)

the 105 / 125 / 130 homologated alternate close ratio set as used in Group A rally (not fitted to production cars)

1: 2.353 (40/17)
2: 1.842 (35/19)
3: 1.391 (32/23)
4: 1.160 (29/25)
5: 0.963 (27/29) 105TC 1.038 (27/26) 125/130

Tricks are things a magician does, engine building isn't a trick, it's simply physics.

SteveC
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Thanks Steve, the 105 gearbox looks equally as attractive assuming it is compatible with the x19 final drive
 
To me the the taller gearing from Uno Turbo Mk1 (same as Ritmo/Regata 85) is a disappointment on track. A lot of shifting is necessary compared to stock X1/9 gearing. And this is with a 240hp/300Nm engine. However, the car is much nicer to drive on the street now. The Ritmo/Regata 105 gearing is even taller so that also wouldn't improve the performance on track. The UT MK2 (C510) would probably work the best on track with its slightly shorter gearing on 3rd and 4th gears compared to UT Mk1, and it would also handle the engine load much better. If going for 100% low cost racing I would definitely stay with stock X1/9 gearing.
 
Don't the X1/9 and 128 use the same steering rack? Classic motorsport sell a quick ratio rack... I have one in the 128.. 2.4 turns, lock to lock...
 
Lowtechprime said:
Don't the X1/9 and 128 use the same steering rack? Classic motorsport sell a quick ratio rack... I have one in the 128.. 2.4 turns, lock to lock...
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Depends on the year of the 128, and I think X19 too, if you have something pre 1974/75

Earlier models use an inner tie rod end that is adjustable, and this version of the rack is different where the inner TRE attaches (and many parts don't interchange) later cars use the exact same rack as the X19 with the sealed for life type of inner TRE.

SteveC
 
Marti80 said:
Thanks Steve, the 105 gearbox looks equally as attractive assuming it is compatible with the x19 final drive
Click to expand...
Thats why I mentioned the 105TC ratio set. It addresses the large gap between 3 and 4 in the stock X19 ratios

All bottom change five speeds with flange type inner CV joints (non tripode) all use the same PCD on the crown wheel to diff centre mounting, so they interchange.

IMO the 4.07 final drive will be too tall, so instead of spending thousands on a fancy gearset, save most of it but track down a 53/11 (4.818) final drive ratio.

SteveC
 
Bjorn Nilson said:
To me the the taller gearing from Uno Turbo Mk1 (same as Ritmo/Regata 85) is a disappointment on track. A lot of shifting is necessary compared to stock X1/9 gearing. And this is with a 240hp/300Nm engine. However, the car is much nicer to drive on the street now. The Ritmo/Regata 105 gearing is even taller so that also wouldn't improve the performance on track. The UT MK2 (C510) would probably work the best on track with its slightly shorter gearing on 3rd and 4th gears compared to UT Mk1, and it would also handle the engine load much better. If going for 100% low cost racing I would definitely stay with stock X1/9 gearing.
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Bjorn, you're talking final drive? (differential ratios)

Turbo car requirements are very different to a natmo car requirements

SteveC
 
fiatfactory said:
Depends on the year of the 128, and I think X19 too, if you have something pre 1974/75

Earlier models use an inner tie rod end that is adjustable, and this version of the rack is different where the inner TRE attaches (and many parts don't interchange) later cars use the exact same rack as the X19 with the sealed for life type of inner TRE.

SteveC
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Steve knows too much !
 
fiatfactory said:
Thats why I mentioned the 105TC ratio set. It addresses the large gap between 3 and 4 in the stock X19 ratios

All bottom change five speeds with flange type inner CV joints (non tripode) all use the same PCD on the crown wheel to diff centre mounting, so they interchange.

IMO the 4.07 final drive will be too tall, so instead of spending thousands on a fancy gearset, save most of it but track down a 53/11 (4.818) final drive ratio.

SteveC
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I should note here that the later versions of the 5 speed use different 5th gear configurations of the gear sleeves/bearings and pinion shaft diameters. It may not be as simple as a ring and pinion swap. Be sure you have the required parts.

And that 4.82 ring and pinion is a hard to find. At least in the US. I have had a couple.

You're note about turbo motors and gear ratios is also correct. For small displacement normally aspirated motors you need a close ratio set as the engine makes power at higher rpm in a narrower range. A turbo motor primarily makes torque accross a broader rpm range. So a taller ratio set lets the motor build boost and apply the torque without the need for a gear change.
 
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Another big factor to consider (only really applicable to UK/european) is if you chose a ritmo105TC gearset, make sure you use a post 1980 type transmission.

1978/1979 and into 1980 5 speed transmissions used a different method of securing the fifth gear onto the input and pinion shafts... early transmissions used a large single keyway. I have seen several with the keyways broken out (I'm sure Steve H has as well) so you want to stay away from this type

Everything post mid 1980 uses a spline to mount the fifth gears, this is what you want.

I've used several 53/11 final drives over the years, definitely my "go to" motorsport ratio, I've always managed to find one when I need it. I've found that the longer you have to find odd items like that, the better price you may get it for... if you want it yesterday, as with most thing, it will carry a premium.

I picked up the 53/11 (to suit tripode style 5 speed) brand new for $300aud for my lemons car from facebook. I've seen them advertised by some of our Croatian/Greek tuner members.

If you do end up getting a 105TC or Regata 100s transmission to cannibalise, you could sell the final drive to one of the members of this forum quite easily, as they didn't get many models with these transmissions with anything but a 4.077/1 ratio in the US.

SteveC
 
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fiatfactory said:
Bjorn, you're talking final drive? (differential ratios)

Turbo car requirements are very different to a natmo car requirements

SteveC
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Not really. I am talking about my total experience gears+ diff. But of course, the diff ratio has a big impact. Below are figures from my gearboxes. Obviously, they may differ between different markets, but I don't think Sweden differs from the rest of EU in this matter.
Yes, the requirements are different on a turbo car but I am surprised that my car doesn't perform better with UT Mk1/Ritmo gearing with 300Nm of torque in the mid/high range. I expect a NA car would suffer even more.

Skärmbild 2023-05-04 181503.jpg
 
Steve Hoelscher said:
You're note about turbo motors and gear ratios is also correct. For small displacement normally aspirated motors you need a close ratio set as the engine makes power at higher rpm in a narrower range. A turbo motor primarily makes torque accross a broader rpm range. So a taller ratio set lets the motor build boost and apply the torque without the need for a gear change.
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That is what I expected, but in general I need to shift more frequently with the taller UT gearing than with stock X1/9 gearing. But to be honest this was on a track I never raced the X before. I will return to the "Kinnekulle" track at least once during the summer and I have a lot of experience with the X with stock gearing from there. Maybe I'll change my perception after that.
 
fiatfactory said:
Thats why I mentioned the 105TC ratio set. It addresses the large gap between 3 and 4 in the stock X19 ratios

All bottom change five speeds with flange type inner CV joints (non tripode) all use the same PCD on the crown wheel to diff centre mounting, so they interchange.

IMO the 4.07 final drive will be too tall, so instead of spending thousands on a fancy gearset, save most of it but track down a 53/11 (4.818) final drive ratio.

SteveC
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What would items would I need from a 105 box to use the 105 gears, is it just as easy as swapping the gears onto the x19 main shaft but keeping the x19 final drive?

Edit - I think I need the input shaft (gears machined onto that shaft) and corresponding gears. I final drive will be kept along with the main shaft from the x19
 
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Marti80 said:
What would items would I need from a 105 box to use the 105 gears, is it just as easy as swapping the gears onto the x19 main shaft but keeping the x19 final drive?

Edit - I think I need the input shaft (gears machined onto that shaft) and corresponding gears. I final drive will be kept along with the main shaft from the x19
Click to expand...
yep you need the input shaft plus the fifth gear on it's end and all the gears from the cluster shaft, the gears are matched pairs, so no mixing and matching is possible (except for a pair of fifth gears that you know run together)

Yes you could reuse the CW and pinion of the X19 5 speed trans, but as I've already said that will be a poor choice for stage rallying, a shorter final drive while it may limit top speed, increases the torque applied to the wheels as gears are "torque multipliers", you want to be 3/4/5 as much as possible, but still have a useable 1/2 for very tight turns and switchbacks which is what makes the 105TC trans preferable to the 100s - you'll have a useable first.

The next thing to note is any transmission that was mated to a dohc engine like a 100s regata or a 105 ritmo will require the input shaft splines to be shortened, as the twin cam input shaft is longer.

And you definitely want to save up for a limited slip differential centre. The standard five speed cast iron diff carrier is the "weak link" in the five speed transmission. The cast iron isn't that strong and has some big holes cast into it, these are the weak spot. The diff carrier will crack and then takes out the trans casing with a big bang. An aftermarket LS differential centre will be machined from a far superior grade of metal and won't have this problem

The gears themselves are not the weak point, anyone that says so really doesn't know what they are talking about. The standard gears use a high tooth count, this is to make them as quiet as possible during operation (and possibly for less frictional losses) A coarser tooth (lower numbers per gear) is stronger than a fine gear tooth (like in a stock X19 trans) so the gear set from a 125/130 ritmo would be stronger than the 105 gear set due to this (but AFAIK and from pictures the 125/130 looks like it still uses the same diff carrier)

Finally for competition use a transmission oil cooler would be a wise investment, my lemons build thread details how I went about designing a suitable transmission oil cooler setup.

SteveC
 
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